Dark Matter 2023: From the Smallest to the Largest Scales

Santander (Spain)

Santander (Spain)

Hotel Chiqui Avenida Manuel Garcia Lago 9 39005 Santander

04/06/2023: Dark Matter 2023 has now concluded. Many thanks to all the organisers and participants. All slides can be found here.

Dark Matter 2023: From the Smallest to the Largest Scales is a conference devoted to discussing the latest developments in the field of dark matter, from experiments to theory and phenomenology. DM2023 will be held at Hotel Chiqui, just a few steps from the beautiful Sardinero Beach in the city of Santander, a well known Summer resort on the northern coast of Spain.

One of our participants, Stanley Shen, produced this beautiful video of Santander during the conference: https://www.youtube.com/watch?v=-pf_5-bRBic.

The meeting starts on the afternoon of May 29th and will end after the morning session on Jun 2nd. (approx. at 1:30 PM). On Tuesday 30th May, we will enjoy a welcome cocktail reception (included in the conference fee) at the beautiful Palacio de la Magdalena

A list of confirmed speakers can be found here

The contributions from the previous meetings can be found here: Dark Matter 2016, Dark Matter 2018, Dark Matter 2021 (virtual)

    • 1
      Arrival and Registration
    • Announcements: Welcome and Introduction
      • 2
        Welcome and Introduction from the LOC

        This will include logistical information about the conference.

      • 3
        Address from Carlos Beltrán (University of Cantabria)

        A short address from Carlos Beltrán, Vice-Rector for Research and Scientific Policy at the University of Cantabria

    • Direct searches
      • 4
        ANAIS-112: first direct test of the DAMA/LIBRA signal beyond 3 sigma

        To the date, the only positive signal of presence of dark matter (DM) in the Milky Way halo by direct observation of its interaction with a detector comes from the DAMA/LIBRA experiment in the Gran Sasso National Laboratory (LNGS). For more than 20 years it has observed an annual modulation in the low energy counting rate compatible with that expected due to the rotation of the Earth around the Sun. For most WIMP candidates this result is incompatible with the negative results of other experiments, remaining as one of the most intriguing puzzles in the field.
        The goal of ANAIS-112 is to provide a direct and independent check of the DAMA/LIBRA DM positive result using the same type of detector: NaI(Tl) scintillators. The experiment was installed in August 2017 in the Canfranc Underground Laboratory (LSC) and is taking data since then with excellent performance. The results published so far, corresponding to 1.5 and 3 years of data collection, show no modulation and are incompatible with DAMA/LIBRA for a sensitivity of 2.5-2.7σ C.L. In this talk I will present a reanalysis of the 3 years data using new filtering protocols based on machine learning techniques, which notably increases the experimental sensitivity. New sensitivity prospects and preliminary modulation results will also be presented.

        Speaker: Dr Maria Martinez (CAPA - UZ)
      • 5
        COSINUS - Progressing towards shedding light on the DAMA/LIBRA claim

        For a fully model-independent investigation of the nature of the DAMA/LIBRA signal, experiments which use the same material as DAMA/LIBRA are mandatory.
        COSINUS will use crystals of NaI, however not operating them as mere scintillation detectors, but as so-called cryogenic scintillating calorimeters cooled to milli-Kelvin temperatures. COSINUS detectors provide a simultaneous and independent measurement of both the temperature signal and the scintillation light signal caused by a particle interaction. Since the amount of produced light depends on the particle type (light quenching), this detection technique yields identification of the type of interacting particle on an event-by-event basis.
        In this talk we will show new results from the latest generation of COSINUS prototype detectors utilizing the so-called „remoTES“ readout concept. Furthermore we will present on the current status of the experimental setup installation presently ongoing at the Gran Sasso underground lab in Italy.

        Speaker: Moritz Kellermann
      • 6
        The SABRE South Experiment at the Stawell Underground Physics Laboratory

        The SABRE (Sodium iodide with Active Background REjection) experiment aims to detect an annual rate modulation from dark matter interactions in ultra-high purity NaI(Tl) crystals in order to provide a model independent test of the signal observed by DAMA/LIBRA. It is made up of two separate detectors; SABRE South located at the Stawell Underground Physics Laboratory (SUPL), in regional Victoria, Australia, and SABRE North at the Laboratori Nazionali del Gran Sasso (LNGS).
        SABRE South is designed to disentangle seasonal or site-related effects from the dark matter-like modulated signal by using an active veto and muon detection system. Ultra-high purity NaI(Tl) crystals are immersed in a linear alkyl benzene (LAB) based liquid scintillator veto, further surrounded by passive steel and polyethylene shielding and a plastic scintillator muon veto. Significant work has been undertaken to understand and mitigate the background processes that take into account radiation from detector materials, from both intrinsic and cosmogenic activated processes, and to understand the performance of both the crystal and veto systems.
        SUPL is a newly built facility located 1024 m underground (~2900m water equivalent) within the Stawell Gold Mine and its construction was completed in mid-2022. It will house rare event physics searches, including the SABRE dark matter experiment, as well as measurement facilities to support low background physics experiments and applications such as radiobiology and quantum computing. The SABRE South commissioning is expected to occur this year.
        This talk will report on the design of SUPL and the construction and commissioning of SABRE South.

        Speaker: Mr Owen Stanley (The University of Melbourne, SUBATECH)
      • 7
        Recent Results from the XENONnT Experiment

        The XENONnT detector is the latest in the series of XENON experiments, utilizing the concept of dual-phase time projection chambers (TPCs) for the direct detection of weakly interacting massive particles (WIMPs). Located at the INFN Gran Sasso National Laboratory in Italy, the detector was commissioned in 2021 and has already completed its first science run. With an increased liquid xenon target of 5.9 tonnes and novel subsystems, it has reached an unprecedented purity in both electro-negative and radioactive radon contaminations, resulting in the lowest ever achieved low-energy background in a dark matter detector.
        In this talk I will give an overview of the XENONnT experiment, and present the latest science results.

        Speaker: Luisa Hötzsch (Max-Planck-Institut für Kernphysik)
    • 4:30 PM
      Coffee break
    • Direct searches
      • 8
        Electron Trap as a Dark-Photon Detector

        Dark photon dark matter in the milli-eV mass range is notoriously difficult to detect, being too high in frequency for high-$Q$ cavity resonators yet below the energy threshold of single-photon detectors. I will present a new method that overcomes this difficulty, based on recent work (arXiv:2208.06519) with Peter Graham and Gerald Gabrielse et al. We propose to use trapped electrons as high-$Q$ resonators to detect dark photon dark matter. Initially cooled to its cyclotron ground state, the trapped electron's first excited state can be resonantly driven if the cyclotron frequency matches the dark photon mass. A proof-of-principle measurement demonstrates that the method is background free over a 7.4-day search, setting a limit on dark photon dark matter at 148 GHz (0.6 meV) which is around 75 times better than previous constraints. Dark photon dark matter in the 0.1-1 meV mass range (20-200 GHz) could likely be detected at a similar sensitivity in an apparatus designed for dark photon detection.

        Speaker: Mr Samuel S. Y. Wong (Stanford University)
    • Models and Theory
      • 9
        Glueball dark matter

        I explore the possibility of dark matter being composed of stable scalar glueballs from a confining dark SU(N) gauge theory. The relic abundance of these glueballs is studied for the first time in a thermal effective theory, using an effective potential fitted by lattice simulations. The predicted relic abundance is smaller than previously believed. Moreover, this framework can be easily extended to different gauge groups and modified cosmological histories to explore strongly coupled dark sectors and their cosmological implications.

        Speaker: Pierluca Carenza (Stockholm University, Oskar Klein Centre)
      • 10
        Mirror Dark Matter and a High Quality Axion

        Hidden sectors provide a simple explanation for the origin of dark matter. What is the symmetry of such a hidden sector? One possibility is that the hidden sector is related to the Standard Model gauge group via a discrete or "mirror" symmetry. Such a Mirror Standard Model has three main advantages: 1) It provides a natural dark matter candidate in the lightest stable mirror particle, namely the mirror electron (& positron). 2) The mirror symmetry relates the couplings of the hidden sector to the Standard Model so the theory is highly predictive. 3) The axion, which acts as a portal between the Standard and Mirror sectors, acquires a large mass from mirror strong dynamics, making it more robust to higher dimensional PQ breaking operators which may perturb the axion from its minimum and generate a much larger neutron EDM than observed.
        From these features, I will discuss how the dark matter abundance is achieved for freeze-out of mirror electrons of mass near 200 GeV, fixing the mirror electroweak scale near 10^8 GeV and giving rise to a variety of highly predictive signals: (1) primordial gravitational waves from the first-order mirror QCD phase transition occurring at a temperature near 30 GeV, (2) effects on large-scale structure from dark matter self-interactions from mirror QED, (3) dark radiation affecting the cosmic microwave background, and (4) rare kaon decays to axions

        Speaker: David Dunsky (New York University)
      • 11
        Global fits of simplified dark matter models

        Many models of Dark Matter (DM) have been proposed to accommodate the overwhelming evidence from cosmological and astrophysical sources. One popular category of such models are simplified models, which extend the Standard Model (SM) with a singlet DM particle and a mediator as a portal to the SM. In this talk I will present the results of various global fits of simplified models of DM, in which the DM particle is either a scalar, a fermion or a vector, and it couples to SM quarks via an s-channel vector mediator. We include constraints from direct and indirect detection of DM, as well as relic density constraints and searches for DM at colliders. We also include a state-of-the-art computation for the unitarity bound on vector DM coupled to a vector mediator. We find that the scalar and vector DM models can only survive the constraints for DM masses > 1 TeV, preferably when resonant annihilation via s-channel mediator is allowed. More interestingly, fermionic DM models can survive at lower DM masses, where they can fit a small excess on the included CMS monojet search.

        Speaker: Tomas Gonzalo
    • Cosmology and Lensing
      • 12
        Axion dark matter search with the observations of cosmic birefringence

        Axions are hypothetical elementary particles with their small masses and tiny couplings to matter sectors, and they are known as the promising candidates for the dark matter in our Universe. Axions generically couple to the photon via the chiral anomaly effect and differentiate the phase velocities between two circularly-polarized photons, which leads to a rotation of photon's polarization plane called the birefringence effect. Interestingly, if the axion behaves as dark matter, the induced birefringence angle slightly oscillates in time with a frequency of axion mass, which is quite advantageous to extract the signal from the foreground in the real-time measurements of cosmological/astrophysical sources. In this talk, I will present a recent development of axion dark matter search with the observations of such a cosmic birefringence effect.

        Speaker: Ippei Obata (Kavli IPMU)
      • 13
        Search for ultra-light axions with the cosmic microwave background polarization

        When coupled to electromagnetism via a Chern-Simons interaction, axion-like particles (ALP) produce a rotation of the plane of linear polarization of photons known as cosmic birefringence. Recent measurements of cosmic birefringence obtained from the polarization of the cosmic microwave background (CMB) hint at the existence of an isotropic birefringence angle of $\beta\approx0.3^\circ$. Although it is still under scrutiny for its dependence on the modeling of Galactic dust emission, these results currently exclude $\beta=0$ with a statistical significance of $3.6\sigma$.

        Such measurements were focused on small-scale polarization data, but further insight can be gained from the study of large-scale information. As the birefringence rotation is proportional to the evolution of the ALP field during the flight of photons, the CMB photons emitted during reionization might experience a different rotation than those emitted during recombination. Therefore, a combined study of large- and small-scale CMB data provides a tomographic view into the ALP field.

        In this talk, I will discuss the extension of the methodology to large-scale polarization data, reviewing the impact that instrumental systematics and Galactic dust have in the measurement of isotropic cosmic birefringence. I will also show preliminary results on the measurement of birefringence from the epoch of reionization using Planck data.

        Speaker: Patricia Diego-Palazuelos (Instituto de Física de Cantabria (CSIC-UC))
      • 14
        Probing exotic energy injection with CMB spectral distortions and early star formation

        Dark matter interactions with Standard Model particles can inject energy at early times, altering the standard evolution of the early universe. In particular, this energy injection can perturb the spectrum of the cosmic microwave background (CMB) away from that of a perfect blackbody and affect processes by which the first stars form. For this study, I will discuss recent work to update the DarkHistory code package to more carefully track interactions among low energy electrons, hydrogen atoms, and radiation, in order to accurately compute the evolution of the CMB spectral distortion in the presence of Dark Matter energy injection. I will show results for the contribution to the spectral distortions from redshifts z < 3000 for arbitrary energy injection scenarios, as well as the effect of exotic energy injection on early star formation.

        Speaker: Wenzer Qin (MIT)
    • Lightning talks
      • 15
        Modelling JWST observation to probe the nature of dark matter

        We compare the latest JWST deep observations with semi-analytic galaxy formation models. We observe a clear break in the slope of the number counts. This break is more pronounced at longer wavelengths. Since our model is able to reproduce this wavelength-dependent feature very well, we investigate how this could be related to the merging history of galaxies which in turn is sensitive to the nature of dark matter. At the highest redshifts (z>9), we rely on multiply-lensed galaxies, with geometric redshift confirmation, to compare the redshift distribution predicted by our model for particle-like (pCDM) and wave-like CDM ($\psi$CDM).

        Speaker: Giorgio Manzoni (Hong Kong University of Science and Technology (HKUST) - Institute of Advance Studies (IAS))
      • 16
        More accurate dark matter density profiles using dynamical information

        The distribution of matter within dark matter halos contains key information about the nature and the properties of dark matter. Knowledge of the exact local dark matter density is not only important for cosmology, but also essential for precise calculations in both direct and indirect detection experiments. Getting the most out of the simulations from which the density profiles are inferred is therefore fundamental for the study of dark matter on all scales.
        We introduce a new dynamics-based method to calculate dark matter density profiles from halo simulations. Each particle in a snapshot is ‘smeared’ over its orbit to obtain a profile which is averaged over a dynamical time.
        The profiles calculated using this technique are in excellent agreement with the traditional ‘binned’ estimates and show significant reduction in Poisson noise. The profiles are generated subject to two main assumptions: phase mixing and spherical symmetry, both of which are widely used in dynamical analyses for their simplicity. Our work confirms the validity of these assumptions to recover the correct density structure in simulated halos for the majority of their radial extent.
        Including information about the spherically-averaged dynamics of the particles also allows for calculation of the gravitational potential at radii below the softening length of the simulation. This makes it possible to extrapolate the behaviour of the dynamical density profile below the softening scale, which shows promising results when compared to a higher resolution version of the same snapshot.

        Speaker: Claudia Muni
      • 17
        Cosmology of a strongly-interacting dark sector

        In a confining extension to the Standard Model, a stable composite particle could be a viable dark matter candidate. Often referred to as a strongly-interacting dark sector, such a theory along with a portal to the Standard Model can give rise to interesting semi-visible jet signatures at particle colliders. However, we still have a lot of work to do in improving our understanding of the cosmology of such dark sectors in order to identify consistent models worth of further exploration. In my talk, I will discuss lattice predictions for the mass spectrum of dark mesons and how to calculate the relic abundance of the lightest dark mesons from the freeze-out of conversion processes.

        Speaker: Nicoline Hemme (Karlsruher Institut für Technologie)
      • 18
        Binary neutron star mergers in a dark environment with an effective Lagrangian approach.

        Using a simplified mechanical-Lagrangian model we describe the gravitational waveform during the last seconds of the BNS merger phases in a dark matter environment. By considering
        characteristic magnitudes for Neutron Stars from existing numerical simulations and magnitudes measurable during the BNS inspiral phase, i.e, chirp mass, mass ratio and distance we explore the effective parameter space of the Lagrangian so that the solutions of the gravitational wave polarizations, $h_+, h_x$, match with the available sensitivity ranges of the Ligo-Virgo-Kagra detectors. We discuss the relationship between this parameter space and that of the numerical simulations, which reproduce this same frequency range based on the experimental data.

        Speaker: Duvier Suárez Fontanella (Department of Fundamental Physics, University de Salamanca, Spain)
    • 11:30 AM
      Coffee break
    • Cosmology and Lensing
      • 19
        Lighting up the Crinkly Spacetime of Dark Matter

        Unveiling the true nature of Dark Matter (DM), which manifests itself only through gravity, is one of the principal quests in physics. Leading candidates for DM are weakly interacting massive particles (WIMPs) or ultralight bosons (axions), at opposite extremes in mass scales,that have been postulated by competing theories to solve deficiencies in the Standard Model of particle physics. Whereas DM WIMPs behave like discrete particles (ρDM), quantum interference between DM axions is manifested as waves (ψDM). In my talk, I present our research (Amruth et al. Nature Astronomy (2023)) which shows that gravitational lensing leaves signatures in multiply-lensed images of background galaxies that reveal whether the foreground lensing galaxy inhabits a ρDM or ψDM halo. Whereas ρDM lens models leave well documented anomalies between the predicted and observed brightnesses and positions of multiply-lensed images, ψDM lens models correctly predict the level of anomalies left over by ρDM lens models. More challengingly, when subjected to a battery of tests for reproducing the quadruply-lensed triplet images in the system HS 0810+2554, ψDM is able to reproduce all aspects of this system whereas ρDM often fails. The ability of ψDM to resolve lensing anomalies even in demanding cases like HS 0810+2554, together with its success in reproducing other astrophysical observations, tilt the balance toward new physics invoking axions. The ongoing JWST mission, and upcoming telescopes such as Euclid and the Square Kilometer Array will provide an abundance of lensing observations that will light the way to understanding the mystery of dark matter.

        Speaker: Alfred Amruth (University of Hong Kong)
      • 20
        Simulations of cosmic structure formation with fuzzy dark matter

        In the fuzzy dark matter model, dark matter consists of “axion-like” ultra-light scalar particles with a mass of around $10^{-22}$ eV. This candidate behaves similarly to cold dark matter on large scales, but exhibits different properties on smaller (galactic) scales due to macroscopic wave effects arising from the extremely light particles’ large de Broglie wavelengths. It has both particle physics motivations and a rich astrophysical phenomenology, giving rise to notable differences in the structures on highly non-linear scales due to the manifestation of wave effects, which can impact a number of contentious small-scale tensions in the standard cosmological model, $\Lambda$CDM. Some of the unique features include transient wave interference patterns and granules, the presence of flat-density cores (solitons) at the centers of dark matter halos, and the formation of quantized vortices. I will present large numerical simulations of cosmic structure formation with this dark matter model – including the full non-linear wave dynamics –, discussing observables such as the evolution of the matter power spectrum, the fuzzy dark matter halo mass function, dark matter halo density profiles, and the question of a fuzzy dark matter core–halo mass relation, using results obtained from these simulations, and contrast them with corresponding results for the cold dark matter model. Particularly striking is the difference in the structure of cosmic filaments, which, with fuzzy dark matter, rather than halos, could be the sites of first star formation.

        Speaker: Dr Simon May (Perimeter Institute for Theoretical Physics)
      • 21
        Flyby and COSWEB Galaxies: the effect of the environment on the DM and baryonic content of field galaxies

        It is known from theory and observations that galaxy evolution can be influenced by environmental effects. Processes like ram pressure stripping in groups, clusters or the cosmic web as well as tidal stripping can affect the final properties of galaxies. While the baryonic content can be influenced by both ram pressure and tidal forces, the DM content can only be influenced by tidal stripping when assuming a universe with cold dark matter. Based on a high-resolution cosmological simulation run in the $\Lambda$CDM framework I will show how a non negligible (25 %) galaxy population is affected by environmental processes and how this is affecting the baryon and DM content of these galaxies. I will further show that the galaxy sample that interacts with the environment can be divided into two sub-groups which both trace different parts of the large scale structure of the universe. First, galaxies that are only affected by ram pressure forces – which I will term COSWEBs – lose baryons and are tracing the filaments of the cosmic web. And second, galaxies that are affected by both, ram pressure and tidal forces, lose both baryons and DM. These galaxies – which I will term flyby galaxies – interact with the most massive systems in the simulation and trace the nodes of the cosmic web. At the end of the talk I will comment on the possibility to produce DM deficient field galaxies via this flyby process.

        Speaker: Georg Herzog
      • 22
        Endothermic Self-Interacting Dark Matter in Galaxy Formation Simulations

        In simulations of galaxy formation, dark matter is typically modeled as a cold, collisionless particle that interacts solely through the force of gravity. This is an excellent approximation in many aspects of structure formation, but discrepancies remain between predictions and observations especially in the density profile shape of various sizes of dark matter halos. Such discrepancies may be resolved by allowing additional interactions to occur between dark matter particles, so-called self-interacting dark matter (SIDM). SIDM is a broad class of dark matter models that encompasses a variety of reaction types and scattering cross sections. In my talk, I will focus on a subset of models that combine elastic, exothermic, and endothermic interactions in a two-state dark matter particle. In particular, I focus on models where each of these interactions occurs with significant probability. This combination of scattering provides a mechanism for endothermic scattering to excite particles from the ground state and leads to elastic and exothermic scattering in the late universe. I will present a suite of galaxy zoom-in simulations using a few representative dark matter models that show significant density cores with effects that vary across halo mass ranges and merger histories. Thus, these models are promising avenues for resolving dark matter problems like the core-cusp and diversity of shapes.

        Speaker: Stephanie O'Neil (Massachusetts Institution of Technology)
    • 1:30 PM
    • Accelerator searches
      • 23
        Recent results and future prospects for Dark matter searches at the LHC - a view from the LHC DM Working Group

        The talk will cover the latest searches for DM at LHC, with particular emphasis on the benchmark models used in the ongoing searches,
        including Higgs portal models, simplified models with s and t-channel mediators and models with extended Higgs and gauge sectors.
        Prospects for DM searches in Run-3 will also be discussed.

        Speaker: Dr Spyros Argyropoulos
      • 24
        Probing new physics at the LUXE experiment

        The proposed LUXE experiment (LASER Und XFEL Experiment) at DESY, Hamburg, using the electron beam from the European XFEL, aims to probe QED in the non-perturbative regime created in collisions between high-intensity laser pulses and high-energy electron or photon beams. This setup also provides a unique opportunity to probe physics beyond the standard model. In this talk we show that by leveraging the large photon flux generated at LUXE, one can probe axion-like-particles (ALPs) up to a mass of 350 MeV and with photon coupling of $3\times10^{-6}$ GeV$^{-1}$. This reach is comparable to the background-free projection from NA62. In addition, we will discuss other probes of new physics such as ALPs-electron coupling.

        Speaker: Raquel Quishpe (Karlsruhe Institute of Technology)
      • 25
        The Heavy Photon Search Experiment

        Evidence for Dark Matter particles arising from direct searches has proven to be extremely elusive. An alternative approach to probing the dark sector is to search for new force carriers which can interact with Standard Model particles. A theoretically well-motivated model has proposed the presence of a new U(1) gauge boson, the heavy photon A', which might be a mediator between light thermal Dark Matter and Standard Model particles. The Heavy Photon Search Experiment (HPS) at the Thomas Jefferson National Accelerator Facility, JLab, has been designed to search for such a heavy photon by exploiting its kinetic mixing with the Standard Model photon. Heavy photons could be created via electro-production reactions of electrons on a tungsten target with subsequent decays to electron-positron pairs. Experimental signatures for detection in HPS are either a resonance peak in the electron-positron invariant mass distribution or displaced decay vertices with a particular invariant mass, depending on the heavy photon mass and the strength of its coupling to electrons. HPS recently submitted the results of its analysis of data taken during an engineering run in 2016 for publication. Data taken during physics runs in 2019 and 2021 are currently being analyzed and offer the possibility of probing regions in the mass-coupling space which are favored by models of thermal dark matter production in the early universe. In this presentation, we will describe the design and performance of the HPS detector, the results of our 2016 data analysis, and the status of and prospects for the analysis of our two larger datasets.

        Speaker: Norman Graf (SLAC National Accelerator Laboratory)
      • 26
        Visible in the lab and invisible in cosmology: decaying sterile neutrinos

        HUNTER (Heavy Unseen Neutrinos from Total Energy-momentum Reconstruction) is a future experiment that will search for additional “sterile” neutrinos beyond the Standard Model (BSM) using an instrument for radioactive atom trapping and high-resolution decay product spectrometry. HUNTER will be a concise experimental test for the existence of a sterile neutrino with masses between a 10-100 keV range, at a level beyond current laboratory experimental constraints. Neutrinos in this parameter space would indicate new physics in the early universe. We explore possible mechanisms of suppressing production of keV scale sterile neutrinos, within the HUNTER parameter space. Some of these new physics paths include universes with a nontrivial cosmic lepton number, new neutrino interactions with light bosons, late-time neutrino mass generation, low reheating temperature universes, or phase transitions in the early universe. We analyze which of these scenarios could explain the first detected remnant from the untested pre-BBN era in the Universe.

        Speaker: Helena Garcia Escudero (University of California Irvine (UCI))
    • 4:30 PM
      Coffee break
    • Astrophysics
      • 27
        The properties of DM in star-forming galaxies with MUSE

        Using a novel 3D modeling approach, we determined the properties of the dark-matter halo of a dozen star-forming galaxies. We find that a significant fraction of the sample shows cored dark-matter profiles over the LCDM expectations (NFW). In addition, the cuspiness of the DM profiles is found to be a strong function of the recent star-formation activity. We will discuss on going work, new results from lensed galaxies, and prospective.

        Speaker: Nicolas Bouché (CRAL)
      • 28
        The massive relic galaxy NGC 1277 is dark matter deficient: from dynamical models of integral-field stellar kinematics out to five effective radii

        According to the LambdaCDM cosmology, present-day galaxies with stellar masses M>10^11 M_sun should contain a sizable fraction of dark matter within their stellar body. Models indicate that in massive early-type galaxies (ETGs) with M~1.5x10^11 Msun dark matter should account for ~15% of the dynamical mass within one effective radius (1 R_e) and for ~60% within 5 R_e. Most massive ETGs have been shaped through a two-phase process: the rapid growth of a compact core was followed by the accretion of an extended envelope through mergers. The exceedingly rare galaxies that have avoided the second phase, the so-called relic galaxies, are thought to be the frozen remains of the massive ETG population at z~2. The best relic galaxy candidate discovered to date is NGC 1277, in the Perseus cluster. We used deep integral field data to revisit NGC 1277 out to an unprecedented radius of 5 R_e. By using Jeans modelling we recovered the dark matter fraction of NGC 1277 within 5 R_e, and found it to be negligible (<7%; two-sigma confidence level), which is in strong tension with the LambdaCDM expectation. Since the lack of an extended envelope would reduce dynamical friction and prevent the accretion of an envelope, we propose that NGC 1277 lost its dark matter very early or that it was dark matter deficient ab initio. We discuss our discovery in the framework of recent proposals suggesting that some relic galaxies may result from dark matter stripping as they fell in and interacted within galaxy clusters. Alternatively, NGC 1277 might have been born in a high-velocity collision of gas-rich proto-galactic fragments, where dark matter left behind a disc of dissipative baryons. We speculate that the relative velocities of ~2000 km/s required for the latter process to happen were possible in the progenitors of the present-day rich galaxy clusters.

        Speaker: Sébastien Comerón (Universidad de La Laguna)
      • 29
        Gamma ray signals from cosmic ray scattering on axionlike particles

        Dark matter (DM) may be comprised of axionlike particles (ALPs) with couplings to photons and the standard model fermions. We study photon signals arising from cosmic ray (CR) electron scattering on background ALPs. For a range of masses we find that these bounds can place competitive new constraints on the ALP-electron coupling. In addition to current Fermi constraints, we also consider future e-Astrogram bounds which will have greater sensitivity to ALP-CR induced gamma-rays.

        Speaker: Natalia Tapia (University of Utah)
    • 7:15 PM
      Welcome reception Palacio de la Magdalena

      Palacio de la Magdalena

      Av. de la Magdalena, 1, 39005 Santander
    • Accelerator searches
      • 30
        The search for MeV-GeV Dark Matter and other feebly interacting particles at accelerators

        Particle physics today faces the challenge of explaining the mystery of dark matter, the
        origin of matter over anti-matter in the Universe, the origin of the neutrino masses, the apparent fine-tuning of the electro-weak scale, and many other aspects of fundamental physics. Perhaps the most striking frontier to emerge in the search for answers involves new physics at mass scales comparable to familiar matter, the MeV-GeV scale, and with very feebly interaction strength. A vibrant experimental program to discover such physics is under way, guided by a systematic theoretical approach firmly grounded on the underlying principles of the Standard Model. I will review the status of these searches at accelerator-based experiments, along with future projects currently under scrutiny.

        Speaker: Gaia Lanfranchi (INFN-LNF)
      • 31
        Search for Dark Matter with mono-X Signatures in CMS

        Searches in CMS for dark matter in final states with invisible particles recoiling against visible states are presented. Various topologies and kinematic variables are explored, including jet substructure as a means of tagging heavy bosons. In this talk, we focus on the recent results obtained using the full Run-II dataset collected at the LHC.

        Speaker: Praveen Chandra Tiwari (National Central University, Taiwan)
      • 32
        Hidden sector searches in CMS

        New physics may have gone unseen so far at the LHC due to it being hidden in a dark sector. This may result in a rich phenomenology which we can access through portal interactions. In this talk, we present recent results from dark-sector searches in CMS using the full Run-II data-set of the LHC. The analyses are based on proton-proton collision data corresponding to an integrated luminosity of 137 fb−1 taken at a center-of-mass energy of 13 TeV by the CMS experiment at the LHC.

        Speaker: Chiara Aimè (Univ. di Pavia e Sez. dell'INFN)
    • 11:30 AM
      Coffee break
    • Accelerator searches
      • 34
        Dark matter searches via Higgs SM or extended SM sectors with the ATLAS Detector

        The presence of a non-baryonic Dark Matter (DM) component in the Universe is inferred from the observation of its gravitational interaction. If Dark Matter interacts weakly with the Standard Model (SM) it could be produced at the LHC. The ATLAS Collaboration has developed a broad search program for DM candidates in final states with large missing transverse momentum produced in association with other SM particles (light and heavy quarks, photons, Z and H bosons, as well as additional heavy scalar particles) and searches where the Higgs boson provides a portal to Dark Matter, leading to invisible Higgs decays. The results of recent searches on 13 TeV pp data from the LHC, their interplay and interpretation will be presented.

        Speaker: Janna Katharina Behr (DESY)
    • Direct searches
      • 35
        Recent progress on BSM and dark matter searches in CUORE

        The Cryogenic Underground Observatory for Rare Events (CUORE) is the first bolometric 0νββ experiment to reach the one-tonne mass scale. The detector, located underground at the Laboratori Nazionali del Gran Sasso in Italy, consists of 988 TeO2 crystals arranged in a compact cylindrical structure of 19 towers, operating at a base temperature of about 10 mK. After beginning its first physics data run in 2017, CUORE has since collected the largest amount of data ever acquired with a solid state detector and provided the most sensitive measurement of 0νββ decay in 130Te ever conducted. The large exposure, sharp energy resolution, segmented structure and radio-pure environment make CUORE an ideal instrument for a wide array of searches for rare events and symmetry violations. New searches for low mass dark matter, solar axions, CPT and Lorenz violations, and refined measurements of the 2νββ spectrum in CUORE have the potential to provide new insight and constraints on extensions to the standard model complementary to other particle physics searches. In this talk, we discuss recent progress on BSM and dark matter searches in CUORE.

        Speaker: Samantha Pagan (Yale University)
      • 36
        DMRadio: Overview, Status Updates, and Plans

        The QCD axion is a promising dark matter candidate whose discovery would also solve the Strong CP problem of particle physics. The DMRadio suite of experiments, which consists of DMRadio-50L, DMRadio-m3, and DMRadio-GUT, are designed to be sensitive to QCD axions in the peV to ueV mass range. Axions in this mass range may be produced in the measured dark matter abundance in the early universe if Peccei-Quinn symmetry breaking occurred prior to inflation. However, state-of-the-art searches for axions using resonant cavities cannot probe axions in this mass range because the axion’s Compton wavelength is very large compared to the size of the detector. Therefore, the DMRadio suite of experiments uses lumped-element LC resonators to decouple the resonance frequency from the physical size of the detector. DMRadio-50L probes axions in the 100 kHz to 5 MHz range and is nearing construction completion. DMRadio-m3 is sensitive to the DFSZ axion model within 30 MHz-200 MHz, is sensitive to the KSVZ axion model within 10 MHz-30 MHz, and its design is nearing completion. Here we present an overview of the design and status updates of DMRadio-50L and DMRadio-m3, and briefly describe the next-generation experiment DMRadio-GUT.

        Speaker: Alex Droster (UC Berkeley)
    • Cosmology and Lensing
      • 37
        Studying Dark Matter Interactions in the Early Universe

        Cosmological and astrophysical observations provide a unique opportunity to probe the fundamental properties of dark matter. Dark matter interactions with the Standard Model of particle physics, for example, can alter predictions from the standard cosmological model, permitting robust tests of new dark matter physics. In this talk, I will describe the effects of dark matter elastic scattering in the early Universe and show constraints using CMB anisotropies and the abundance of Milky Way satellites. I will also discuss the impact on BBN and 21-cm observables.

        Speaker: Kim Boddy (University of Texas at Austin)
    • 1:30 PM
      Conference Photo
    • 1:40 PM
    • Astrophysics
      • 38
        Too early, too young, too obscure: a clash between JWST and the LCDM paradigm?
        Speaker: Pablo G. Pérez-González
      • 39
        Seeking dark matter with γ-ray attenuation

        The flux of high-energy astrophysical γ rays is attenuated by the production of electron-positron pairs from scattering off of extragalactic background light (EBL). We use the most up-to-date information on galaxy populations to compute their contributions to the pair-production optical depth. We find that the optical depth inferred from γ-ray measurements exceeds that expected from galaxies at the ∼2σ level. If the excess is modeled as a frequency-independent re-scaling of the standard contribution to the EBL from galaxies, then it is detected at the 2.7σ level (an overall 14−30% increase of the EBL). If the frequency dependence of the excess is instead modeled as a two-photon decay of a dark-matter axion, then the excess is favored over the null hypothesis of no excess at the 2.1σ confidence level. While we find no evidence for a dark-matter signal, the analysis sets the strongest current bounds on the photon-axion coupling over the 8−25 eV mass range.

        Speaker: José Luis Bernal (IFCA)
      • 40
        Probing dark matter with neutron stars and their mergers

        Compact stars due to their enormous gravitational field can accumulate a sizable amount of dark matter in their interior. Depending on its nature, accumulated dark matter may affect the properties of neutron stars in quite different ways. I will give an overview of the impact of dark matter on various observable properties of neutron stars, i.e. the mass-radius relation, tidal deformability, merger dynamics, gravitational waveform, etc. For two scenarios, asymmetric fermionic and bosonic dark matter, the conditions at which dark matter particles tend to condensate in the core of the star or create an extended halo will be presented. I will show how dark matter condensed in a core tends to decrease the total gravitational mass and tidal deformability compared to a pure baryonic star, which appears as an effective softening of the equation of state. On the other hand, the presence of a dark matter halo has an opposite effect, causing an increase of those observable quantities. Thus, observational data on compact stars could be affected by accumulated dark matter and, consequently, constraints we put on the strongly interacting matter at high densities.

        In addition, I will present the numerical-relativity simulations of compact stars admixed with a dark matter component. We perform single star tests as well as the first binary neutron star simulations of this kind. I will discuss how the ongoing and future x-ray, radio, and gravitational wave observations could shed light on dark matter admixed compact stars and put multi-messenger constraints on the corresponding effect.

        Speaker: Violetta Sagun (University of Coimbra)
    • Lightning talks
      • 41
        Precision ionization calibrations of silicon skipper CCDs for dark matter detection

        Direct dark matter detection experiments can reach the thresholds as low as O(10eV). In that regime, we report precision ionization measurements induced by Compton scattering of gamma rays and nuclear recoils from neutrons. A skipper charge-coupled device (CCD) with single electron resolution developed for DAMIC-M experiment was used to collect data. Compton scattering on sil- icon atomic shell electrons down to 23 eV was measured using a 241Am source and compared with Monte Carlo simulations and ab initio calculations. Nuclear recoil ionization efficiency of silicon nuclei was measured using a SbBe source and Monte Carlo simulations were used to model the nuclear recoil spectrum. Agreements with simulations for Compton scattering and the deviation of nu- clear recoil ionization efficiency from the extrapolated Lindhard model will be dicussed.

        Speakers: Agustín Lantero (IFCA (UC-CSIC)), Rachana Yajur (University of Chicago)
      • 42
        Underground commissioning of the LIME prototype for the CYGNO experiment

        The CYGNO collaboration aims to propose a large volume (O(30m^3)) gaseous Time Projection Chamber (TPC) with optical readout to search for rare events, such as interactions of DM in the GeV mass range and solar neutrinos. The TPC, operated with a He:CF4 gas mixture at atmospheric pressure, uses a triple Gas Electron Multiplier (GEM) stack to amplify primary ionization charges and produce light. A low-noise sCMOS camera and fast light sensors detect the light, allowing a full 3D-reconstruction of the tracks with good energy resolution and high sensitivity in the few keV energy range. This detailed reconstruction of the event topology provides a powerful tool to discriminate DM signal nuclear recoils from background electronic recoils. A 50 liter prototype, the Long Imaging ModulE (LIME), was built to conclude the R&D phase of the CYGNO project. It is currently being commissioned underground at Laboratori Nazionali del Gran Sasso. We present preliminary estimates of the environmental and internal background and assessments of detector performance, whose characterization is essential to pursue CYGNO's approach. We also present the results of the overground campaign at Laboratori Nazionali di Frascati (LNF) in terms of energy response, track reconstruction, and event identification, which were carried out by means of radioactive sources. These results are used to evaluate the sensitivity of the CYGNO proposal in searching for DM in the GeV mass range.

        Speaker: Francesco Borra
      • 43
        The Dark SHINE Experiment

        Dark photons have been well motivated as strong candidates for dark force carriers and light dark matter in the sub-GeV mass range. Fixed-target experiments as a promising complementary approach to the collider could have good sensitivity in the low mass range. We would present the proposed study of Dark SHINE experiment searching for dark photon produced via electron-nucleon interaction and decay invisibly based on the 10MHz 8GeV single electron beam at the future Shanghai SHINE facility. With 9E14 electron-on-target events (estimated about three years running), this experiment is expected to rule out most of the sensitive regions predicted by popular dark photon models.

        Speaker: Qibin LIU (TDLI., Shanghai JiaoTong University)
      • 44
        Fast and accurate AMS-02 antiproton likelihoods for global dark matter fits

        Global analyses of different dark matter searches are necessary to determine the status of dark matter models. Highly accurate antiproton measurements from AMS-02 would add valuable information to such global analyses. I will present an analysis pipeline for fast and accurate antiproton likelihoods in global scans. The pipeline consists of a neural network emulator for antiproton flux simulations, and a likelihood calculator for accurate treatment of correlations and marginalization of propagation uncertainties. I will conclude with the status of scalar singlet dark matter, considering new direct detection and LHC likelihoods in addition to the antiproton likelihood.

        Speaker: Sri Sankari alias Sowmiya Balan (Institute for Theoretical Particle Physics, Karlsruhe Institute of Technology)
    • 4:30 PM
      Coffee break
    • Astrophysics
      • 45
        Indirect detection of dark matter in the low-frequency radio band. A 2022 LOFAR study

        Radio observations can provide useful information about the nature of dark matter: axion line, etc. In this talk, I will briefly review the relevant dark matter phenomenology in these frequencies and present fresh results from the stacked analysis of six dwarf spheroidal galaxies by the LOw Frequency ARray (LOFAR). This is the first time such an analysis has been carried out using LOFAR data. I will also briefly introduce diffsph, a python library for the computation of diffuse radio emission profiles and spectra in dwarf galaxies from any source.

        Speaker: Martin Vollmann
      • 46
        The effect of stellar encounters on the dark matter annihilation signal from prompt cusps

        Prompt cusps are the densest quasi-equilibrium dark matter objects; one forms at the instant of collapse within every isolated peak of the initial cosmological density field. They have power-law density profiles, ρ∝r−1.5 with central phase-space density set by the primordial velocity dispersion of the dark matter. At late times they account for ∼1% of the dark matter mass but for >90% of its annihilation luminosity in all but the densest regions, where they are tidally disrupted. Here we demonstrate that individual stellar encounters, rather than the mean galactic tide, are the dominant disruptors of prompt cusps within galaxies. Their cumulative effect is fully (though stochastically) characterised by an impulsive shock strength B∗=2πG∫ρ∗(x(t))dt where ρ∗, the total mass density in stars, is integrated over a cusp's entire post-formation trajectory. Stellar encounters and mean tides have only a small effect on the halo annihilation luminosity seen by distant observers, but this is not true for the Galactic halo because of the Sun's position. For a 100 GeV WIMP, Earth-mass prompt cusps are predicted, and stellar encounters suppress their mean annihilation luminosity by a factor of two already at 20 kpc, so that their annihilation emission is predicted to appear almost uniform over the sky. The Galactic Center γ-ray Excess is thus unaffected by cusps. If it is indeed dark matter annihilation radiation, then prompt cusps in the outer Galactic halo and beyond must account for 20-80% of the observed isotropic γ-ray background in the 1 to 10 GeV range.

        Speaker: Jens Stucker (Donostia International Physics Centre)
      • 47
        Dark matter in galaxy clusters from X-ray & SZ effect

        Galaxy clusters are dark-matter-dominated systems enclosed in a volume that is a high-density microcosm of the rest of the universe. I will present the most recent results on the distribution of their gravitating and baryonic mass obtained from our XMM-Newton Multi-year Heritage and Large Programmes complemented with Planck maps (CHEX-MATE, X-COP), highlighting the role of X-ray and SZ data in resolving the astrophysics of the most massive collapsed halos in the universe and in studying the interplay between the hot plasma and dark matter. I will discuss the role of non-thermal pressure support as a major source of the difference between the hydrostatic and the total ``true'' halo mass. These studies will pave the way for using the next generation of X-ray observatories, like XRISM and Athena, in constructing a consistent picture of the formation and composition in mass and energy of galaxy clusters.

        Speaker: Stefano Ettori (INAF OAS Bologna (Italy))
    • Round Tables
      • 48
        Round Table: "Testing Lambda-CDM"
    • Models and Theory
      • 49
        Progress in the direct detection of light Dark Matter

        While the experimental program to directly detect light dark matter is proceeding full steam ahead, the theoretical one is at a crossroads. I will review the status of both, highlighting the obstacles theories of sub-GeV dark matter must overcome. I will detail two such benchmarks future direct detection experiments will explore.

        Speaker: Robert McGehee (University of Michigan)
    • Direct searches
      • 50
        DAMIC-M status and first results

        The DAMIC-M (DArk Matter In CCDs at Modane) experiment employs a novel technique to search for the elusive particles which make up most of the matter in the universe, called dark matter. The aim is direct detection of light dark matter (WIMPs, Hidden Sector Particles) via interaction with silicon in the bulk of the CCDs (Charged Coupled Devised). These CCDs use skipper amplifiers to non-destructively measure charge multiple times to provide single electron resolution, pushing our detection threshold to a few eVs.
        The LBC (Low Background Chamber), a prototype detector of DAMIC-M, containing 20g target silicon CCDs, was commissioned near the end of 2021 at the Laboratoire Souterrain de Modane. After two successful science runs, LBC was able to set unparalleled exclusionary limits on dark matter-electron scattering interactions. This talk would focus on the status of DAMIC-M and the first results with the prototype LBC.

        Speaker: Claudia De Dominicis (CNRS, LPNHE)
      • 52
        Effective Field Theory Dark Matter Search with the LZ Detector

        The LUX-ZEPLIN (LZ) dark matter search experiment, a dual-phase xenon time projection chamber operating at the Sanford Underground Research Facility in Lead, South Dakota, USA, has the world's leading sensitivity to searches for Weakly Interacting Massive Particles (WIMPs). It is comprised of a 10-tonne target mass (7-tonne active) and outfitted with photomultiplier tubes in both the central and the self-shielding regions of the liquid xenon, which is enclosed within an active gadolinium-loaded liquid scintillator veto and all submerged in an ultra-pure water tank veto system. LZ has completed its first science run, collecting data from an exposure of 60 live-days. This talk will provide an overview of LZ’s search and sensitivity goals to a model-agnostic Effective Field Theory (EFT) framework that describes several possible dark matter interactions with nucleons. In this talk, we highlight the key backgrounds, data analysis techniques, and signal models relevant to this study.

        Speaker: Billy Boxer (UC Davis)
    • 11:30 AM
      Coffee break
    • Models and Theory
      • 53
        QCD-like strongly interacting dark matter: connecting theories to experiments

        An overview of QCD-like strongly interacting dark matter.

        Speaker: Suchita Kulkarni (Graz U.)
    • Direct searches
      • 54
        General dark matter electron interactions in graphene

        We employ a non-relativistic effective theory to model dark matter (DM) induced electron ejections from graphene and carbon nanotubes (CNTs), materials currently in the R&D phase for direct detection experiments. The material properties of graphene are modelled using Density Functional Theory, and we obtain observable ejection rates for arbitrary forms of scalar and spin-1/2 DM. We show how the anisotropy of graphene and CNTs cause a strong daily modulation in the rate of electron ejections, a smoking gun signal for DM. We project 3 sigma discovery potential of such a daily modulation pattern, as well as expected exclusion bounds in the case of no observed daily modulation.

        Speaker: Einar Urdshals (Chalmers Technical University)
      • 55
        Quantum Information Science Techniques for direct dark matter detection

        The direct detection of sub-GeV dark matter particles is a major experimental challenge. In this low energy range, the energy transfer between sub-GeV particles and a solid target media is only in the range of a few millielectron-volts to a few electron-volts, which dares the current capabilities of sensors. However, the application of state-of-the-art developments in quantum information science show promise for detecting low-energy particles.

        In this presentation, we will discuss some work being done in the frame of the CSIC Quantum Technology Platform, which includes research groups belonging to ICMAB, IFCA, INMA, and IMB-CNM. Specifically, we focus on the development of superconducting micro-calorimeters that could detect athermal phonons created by the interaction of dark matter particles with selected single crystals. Complementary, the IMB-CNM is involved on several projects to fabricate qubit solid-state implementations. In collaboration with IFAE and LSC, for instance, the aim is to understand the interaction and effect of cosmic rays with superconducting devices and circuits. We will provide details of our progress on manufacturing the sensing and qubit devices, as well as of the detection concept of sub-Gev DM particles.

        Speaker: Gemma Rius (IMB-CNM-CSIC)
      • 56
        Towards quantum detection of axions in the QUAX experiment

        The QUAX experiment is committed in the search of light dark matter candidates, such as axions and axion-like particles, with a haloscope setup involving microwave resonant cavities. Many avenues to push further the haloscope sensitivity are being tested, facing some technological challenges. One of these is the development of superconducting cavities and dielectric cavities, showing unprecedented quality factors in magnetic fields. Then, haloscopes require ultra-low-noise amplification: for this purpose, we are developing i) a custom Josephson Parametric Amplifier (JPA) as a preamplification stage at cryogenic temperature giving noise at the Standard Quantum Limit (SQL); ii) a Travelling Wave JPA (TWJPA), giving a large bandwidth amplification ($\sim 5$ GHz) near the SQL; iii) a single microwave photon detector (SPD) exploiting Josephson junctions.

        Here I present the latest advances in the measurements of dielectric cavities made of sapphire shells, and superconducting cavities, such as YBCO and Nb$_3$Sn, the latter having very promising values of quality factor, of the order of $2.5\times 10^5$ at 9 T. I also present the status of the art on the design and characterization of the first prototypes of JPA, TWJPA and SPD.

        Moreover I present the first qubit characterization in the COLD laboratory at LNF, opening the route to the possibility of coupling the qubit to a haloscope to perform quantum non-demolition detection of single microwave photons for axion searches.

        Speaker: Alessio Rettaroli (INFN - LNF)
    • 1:30 PM
    • Cosmology and Lensing
      • 57
        Closing in on primordial black holes

        Observational constraints have closed off all but one mass-window for primordial black holes making up all of the dark matter, and there are some specific conditions required for their production in the first place. However, they remain a tantalising dark matter candidate because they require no new beyond the standard model particles and they would additionally provide a lot of information about the very early universe, particularly about inflation, if found. I will highlight some key recent results in the literature that describe how the viable parameter space for primordial black holes making up all of the dark matter is closing up, but also why it’s worth checking every last window for signatures of their existence.

        Speaker: Pippa Cole (University of Amsterdam)
      • 58
        Extreme magnification events: cosmic microscopes

        Caustic crossing events of stars in galaxies lensed by galaxy clusters can lead to extreme magnification factors, $\mu > 1000$. Several stars at cosmological redshifts, $z > 1$, have already been observed by the Hubble Space Telescope, and the number is rapidly increasing with the Jame Webb Space Telescope. The probability distribution of magnification depends on the galaxy cluster and the microlenses within the cluster. These microlenses could be a mix of baryonic stars and an astrophysical compact dark matter component such as primordial black holes. Monitoring these extreme magnification events helps reveal the underlying microlens population allowing us to constrain the dark matter abundance within the cluster. As there is no analytical method to estimate the magnification probability distribution, we have to rely on costly numerical simulations to obtain these probabilities. In this work, we have created a set of state-of-the-art simulations varying the physical parameters that control the magnification probabilities. We have obtained a semi-analytic approximation method to obtain the probability distributions bypassing the numerical simulations, saving thousands of CPU-hours and providing a physible method to constrain the dark matter abundances within these galaxy clusters.

        Speaker: Jose Maria Palencia
      • 59
        The first stars in the Unvierse as Dark Matter laboratories

        The first stars in the Universe, soon to be observed with the James Webb Space Telescope (JWST) can be extremely powerful Dark Matter (DM) probes. If DM does not play a significant role in the formation of some of the first stars, then, zero metallicity Hydrogen burners (Population III stars) form. Conversely, for scenarios where DM plays a significant role during the formation of a star from a primordial gas cloud, Dark Stars (DS) can form. The later are powered by DM annihilations and can grow to be supermassive (SMDSs), with masses as large as a million suns . As such, SDMSs are easily observable with JWST. The discovery of any Dark Star would constitute indirect evidence of annihilating Dark Matter. In this talk I will outline how both of those classes of objects (Pop~III stars and Dark Stars) can be used as powerful DM probes.

        The main focus will be on Dark Stars (DS), their observable properties and ways to differentiate them from Pop~III/II galaxies, as seen by either the JWST or the upcoming Roman Space Telescope. In less than six months from becoming fully operational the JWST has already shaken our understanding of the formation of the first galaxies. Simply put, it keeps finding too many, too massive, too early bright objects out there, that according to simulations, are highly unlikely to exist, assuming the standard picture of the first galaxies being dominated by Pop~III stars. This strong tension (between data and simulations) can at least partly alleviated if some of those high redshift objects are Supermassive Stars, such as for example SMDS. In fact, we expect SMDS to exist in abundance at the redshift range those “paradigm breaker” galaxy candidates are found. Moreover, in terms of photometry we show that in many instances SMDSs look just like Pop~III galaxies. We identify one excellent SDMS candidate in the JWST data: the JADES-GS-z13-0 object, at a spectroscopically confirmed redshift of $z_{spec}\simeq 13.2$. In terms of photometry, a $10^6 M_{\odot}$ SMDS can fit this unresolved objet really well. With spectroscopy one could disambiguate most SMDS from Pop~III galaxies, based on the HeII 1640A absorption line that is a tell-tell signature of SMDSs. Current spectroscopic data for JADES-GS-z-13 indicates a hint of the HeII 1640A absorption feature, thus furthering our confidence that this object could be the first Dark Star ever identified.

        We will also briefly describe the role of Pop~III stars as DM probes, and how they could, if sufficiently massive (i.e. $M >300 M_{\odot}$) be used to probe below the neutrino floor that will soon limit the usefulness of direct detection experiments.

        Speaker: cosmin ilie (Colgate University)
      • 60
        Fuzzy dark matter constraints from a single VLBI observation of a gravitationally lensed radio jet

        Strong gravitational lensing by galaxies provides us with a powerful laboratory for testing dark matter models. Various particle models for dark matter give rise to different small-scale distributions of mass in the lens galaxy, which can be differentiated if the observation is sensitive enough. The sensitivity of a gravitational lens observation to the presence (or absence) of low-mass dark structures in the lens galaxy is determined mainly by the angular resolution of the instrument and the spatial structure of the source.

        In this talk, I will present results from the analysis of a global VLBI observation of a gravitationally lensed radio jet. With an angular resolution better than 5 milli-arcseconds and a highly extended, spatially resolved arc, we are able to place competitive constraints on the particle mass in fuzzy dark matter models using this single observation. I will also present preliminary results from our analysis of warm dark matter models using this lens system. Our results illustrate the key role that VLBI observations will play in revealing the nature of dark matter, especially in light of the ~10^5 gravitational lens systems with radio-bright sources which will be discovered by the Square Kilometre Array.

        Speaker: Devon Powell (Max Planck Institute for Astrophysics)
    • 4:30 PM
      Coffee break
    • Astrophysics
      • 61
        Black holes in dark matter environments

        There are several well-motivated scenarios in which dark matter could be present around black holes at a sufficient level to impact on the gravitational waveform of a merger. However, developing templates for the impact of such environments is challenging - in particular one issue that requires more attention is how to select and impose appropriate initial conditions that represent the state of the binary and its environment at the late, dynamical, strong field phase of the merger. A correct specification will be crucial in obtaining sufficiently accurate waveforms and avoiding degeneracies with other effects.

        Speaker: Katy Clough (Queen Mary University of London)
      • 62
        Axion weak leaks: extreme mass-ratio inspirals in light scalar environments

        Ultralight dark matter is an exciting alternative to the standard cold dark matter paradigm, reproducing its large scale predictions, while solving most of its potential tension with small scale observations (like the "cusp-core" and "missing satellites" problems). If dark matter is made of some new light scalar particle, relatively dense and large structures are expected to form at the center of galaxies, like solitonic cores or superradiant clouds around spinning massive black holes. These non-trivial environments may affect the evolution of black hole or neutron star binaries, opening the possibility for using future space-borne gravitational-wave observatories to probe the nature of dark matter.
        In this talk I will discuss the flux of scalar particles and gravitational waves sourced by extreme mass-ratio inspirals in these environments. We use for the first time relativistic (linear) perturbation theory to compute the adiabatic evolution of the secondary orbit and study the consequent effect on their gravitational waveforms.

        Speaker: Rodrigo Vicente (IFAE - Barcelona)
      • 63
        Dark matter heating vs vortex creep heating in old neutron stars

        Old isolated neutron stars have been gathering attention as targets to probe Dark Matter (DM) through temperature observations. DM will anomalously heat neutron stars through its gravitational capture and annihilation process, which predicts $T_s \simeq (1-3) \times 10^3$ K for $t > 10^{6}$ years. We may put constraints on DM-nucleon scattering cross section by finding even colder neutron stars. This story, however, assumed that there is no relevant heating source for old neutron stars. In this talk, we discuss the creep motion of vortex lines in the neutron superfluid of the inner crust as the heating mechanism. This mechanism is inherent in the structure of neutron stars and is expected to be universal. Therefore, in order to constrain DM physics through temperature observations, this mechanism may cause serious background heating. We evaluate the vortex creep heating by inputting the vortex-nucleon interactions and conclude the significance of DM heating in neutron stars.

        Speaker: Motoko Fujiwara (Technische Universität München)
    • 8:00 PM
      Conference Dinner Restaurante Deluz

      Restaurante Deluz

      C. Ramón y Cajal, 18, 39005 Santander
    • Models and Theory
      • 64
        Asymmetries in Extended Dark Sectors

        The observed dark matter relic abundance may be explained by different mechanisms, such as thermal freeze-out/freeze-in, with one or more symmetric/asymmetric components. In this work we investigate the role played by asymmetries in determining the yield and nature of dark matter in scenarios with more than one dark matter particle. In particular, we show that the energy density of a particle may come from an asymmetry,
        even if the particle is asymptotically symmetric by nature. To illustrate the different effects of asymmetries we adopt a model with two dark matter components. We embed it in a cogenesis scenario that is also able to reproduce neutrino masses and the baryon asymmetry. The framework predicts a monochromatic neutrino line for some of the scenarios.

        Speaker: Drona Vatsyayan (IFIC, Universitat de Valencia)
      • 65
        Models of light thermal relic dark matter

        WIMP particles down to MeV-scale masses can be thermal relic dark matter candidates, provided they fulfill two requirements. These dictate what kind of models can realise them.
        First, to have a sufficiently large annihilation rate in the early Universe, a new light mediator particle coupled to the light SM degrees of freedom is necessary. Due to the chiral structure of the SM, the number of mediator candidates is limited. This talk will place some emphasis on the possibility of a light scalar from a second Higgs doublet.
        Second, the present day annihilation into visible particles is such a sensitive probe that it needs to be suppressed compared to the early Universe. In the case of kinematically forbidden annihilations into charged fermions, loop-level annihilation into gamma rays emerges as an informative probe. Coupling to neutrinos instead could still result in observable signals at neutrino experiments due to the large annihilation rate of sub-GeV thermal relic DM.

        Speaker: Johannes Herms (Max-Planck-Institut für Kernphysik)
      • 66
        Black Holes as Probes for Ultralight Dark Matter

        We consider the phenomenological nightmare scenario where dark matter is only coupled gravitationally, thinking of black holes as probes. We choose to focus on wave dark matter because an oscillating massive scalar endows a black hole with hair, whose profile we study.
        We examine some assumptions implicit in the existing literature, and we do so by taking a fully analytic approach. We describe the field profile for a wide range of parameters, including rotating dark matter.
        We then include the self-gravity of the scalar, focusing on the case
        where dark matter forms a soliton in the center of the galaxy. We discuss the consequences of imposing causal boundary conditions at the horizon, which are usually neglected.

        Speaker: Bruno Bucciotti (Scuola Normale Superiore di Pisa)
      • 67
        Catastrogenesis: Dark Matter ALPs, PBHs and gravitational waves from cosmic string-wall system annihilation

        A cosmic string-wall network is associated with the breaking of a U(1) global symmetry into a discrete Z(N) symmetry with N>1. Its annihilation due to a small bias between the N minima is accompanied by “catastrogenesis” (from the greek for annihilation), the production of pseudo-Goldstone bosons (pGBs) - e.g. axions, ALPs, or majorons - gravitational waves, and primordial black holes (PBH). The pGBs can be stable, and be the dark matter. But they may be unstable and not contribute to the dark matter population, in which case we show that PBHs can instead constitute 100% of the dark matter for pGBs that decay into products that thermalize in the early Universe. We show that the gravitational wave background produced by catastrogenesis could be observable by cosmological probes or future interferometers.

        Speaker: Graciela Gelmini (UCLA)
    • 11:30 AM
      Coffee break
    • Direct searches
      • 68
        LIDA: Laser-Interferometric Detector for Axions

        We present the design, status and first results of a detector to search for axions and axion-like particles in the galactic halo using laser interferometry enhanced via squeezed states of light. The detector is sensitive to the polarisation rotation of linearly polarised light induced by an axion field in the mass range from 10^−16 eV up to 10^−8 eV, and is likely to significantly surpass the CAST limit. Our experiment has the potential to be further scaled up to a multi-kilometre long detector, and to then set constraints of the axion-photon coupling coefficient of ∼10^−18 /GeV for axion masses of 10^−16 eV, or detect a signal.

        Speaker: Joscha Heinze (University)
    • Round Tables
      • 69
        Round Table: "The Future of DM Detection"
    • Announcements: Closing Remarks
    • 70