Dark Matter 2021: From the Smallest to the Largest Scales

Sep 13, 2021, 4:00 PM → Sep 16, 2021, 8:50 PM Europe/Madrid

Virtual

Alberto Ruiz Jimeno, Alicia Calderon Tazon (IFCA), Bradley Kavanagh, Enrique Martinez Gonzalez (IFCA), Jose Maria Diego Rodriguez (IFCA), Rocio Vilar Cortabitarte (IFCA), Sven Heinemeyer

The Dark Matter 2021 Conference has now concluded.

It was scheduled to take place in Summer 2020, but had to be postponed due to the pandemic. In the end, it took place virtually from September 13th to 16th, 2021. Given the circumstances, the conference had a lighter schedule than originally planned, running Monday - Thursday (4 days), from roughly 4pm - 7.30pm (CEST) each day.

Watch on Youtube - The conference was live-streamed on youtube and you can watch the full recordings on the IFCA Youtube Channel here: https://youtube.com/playlist?list=PLtLog61EkhOGW8TjKK0P_cJTmky40m6mJ.

Individual recordings for each talk have also been uploaded. Access them via the Timetable page, where you can click each individual talk to see the slides and recordings. 

Updates

• 16/09/2021: The conference has now concluded. Thanks to everyone for taking part!
• 07/09/2021: The schedule is now online here. Connection details will be sent out to participants by email shortly before the start of the conference.
• 27/08/2021: Notifications for accepted abstracts have now been sent out. Please let us know if you are no longer able to give a talk, so that we can re-assign your slot. More information about the schedule will be released next week.
• 23/08/2021: Abstract submission has now closed. We are reviewing the abstracts and we hope to notify the participants by the end of this week (26th or 27th August). Apologies for the delay!
• 31/07/2021: The abstract submission deadline has been extended until 7th August.
• 31/05/2021: Registration and abstract submission are now open!

Dark Matter 2021 is a meeting devoted to discussing the latest developments in the field of dark matter from the perspective of both theory and experiment. Presentations will include results from experiments in earth (accelerators, direct detection, gamma rays) and space (cosmic/gamma rays, X-rays), and indirect detection from astrophysical observations. In addition to the experimental discussion the theoretical status will be presented by world experts. Dark Matter 2021 is 'hosted' by the Instituto de Física de Cantabria (IFCA) in Santander, Spain. However, due to the situation with the COVID-19 pandemic, the meeting will take place with a predominantly virtual format.

Confirmed speakers include: Rebecca Leane (SLAC), Gordan Krnjaic (Fermilab), Teresa Marrodan-Undagoitia (MPIK Heidelberg) & Katelin Schutz (MIT).

Monday, September 13

1 Opening Remarks

Speaker: Bradley Kavanagh

DM2021_BradleyKavanagh.mp4

OpeningRemarks.pdf

DM Direct Detection

Convener: Bradley Kavanagh

2 Overview of dark-matter direct searches

Cosmological and astronomical observations give a consistent evidence for the existence of dark matter. New particles, that could account for this non-luminous matter, appear in several theories beyond the standard model of particle physics. Although several hypothetical particle candidates have been proposed, so far dark matter has eluded detection. Direct detection is a promising method to identify the nature of dark matter particles. It enables to probe the existence of WIMPs (Weakly Interacting Massive Particles) via their elastic scattering off target nuclei down to cross sections as low as 1e-48 cm2. Several experimental strategies have been developed to measure the tiny nuclear recoils induced by the interactions of dark matter particles. The talk will review the main experimental techniques and R&D projects as well as the most recent results.

Speaker: Teresa Marrodán Undagoitia (Max-Planck-Institut für Kernphysik, Heidelberg)

DM2021_TeresaMarrodan.mp4

Marrodan_DM_2021_Santander.pdf

3 The SuperCDMS SNOLAB experiment: A Broadband Dark Matter Search

Cold dark matter is one of the major constituents of the leading cosmological model for our Universe, with many ongoing experimental efforts at directly detecting interactions of the hypothetical particle with terrestrial detectors.

SuperCDMS SNOLAB is a Generation-2 dark matter experiment under construction at SNOLAB in Sudbury, Canada. The experiment will employ two types of state of the art cryogenic Ge and Si detectors capable of detecting sub-keV energy depositions from potential dark matter interactions. This talk will present the ongoing efforts in building the SuperCDMS SNOLAB experiment as well as future operational plans to ultimately deploy an array of 24 detectors with the goal of improving sensitivity to light dark matter particles, ranging in mass from eV to GeV, by orders of magnitude compared to existing limits.

Speaker: Tarek Saab (University of Florida)

DM2021_TarekSaab.mp4

Saab_DM2021_SuperCDMS.pdf

5:20 PM Coffee Break

Coffee is not provided :(

DM Direct Detection

Convener: Bradley Kavanagh

4 Direct Dark Matter searches with DEAP-3600

DEAP-3600 is performing direct dark matter searches since 2016. DEAP has a competitive sensitivity to WIMPs due to the
design of the detector, low levels of radioactivity, the large target mass possible with liquid argon (3.3 tons), and background level achieved at SNOLAB (2 km deep).
In addition to the WIMP searches, the latest scientific contributions of DEAP extend to the constraints on dark matter-nucleon effective couplings in the presence of kinematically distinct halo substructures, the characterization of the light production in liquid argon and the associated pulse shape discrimination and detector R&D, which are being implemented and will be fundamental for the design and construction of the next generation of low background experiments.
In this talk I plan to address our last publications, prospects and the latest developments performed at CIEMAT, consisting of the training and analysis of machine learning algorithms based to classify background events more efficiently.

Speaker: Vicente Pesudo (CIEMAT)

deap_dm2021_pesudo2.pdf

DM2021_VicentePesudo.mp4

5 DarkSide-20k and the Future Liquid Argon Dark Matter Program

DarkSide run since 2015 a 50-kg-active-mass dual-phase Liquid Argon Time Projection Chamber (LAr TPC), filled with low radioactivity Ar from an underground source and produced world-class results for both the low mass and high mass direct detection search for dark matter.
The next stage of the DarkSide program will be the DarkSide-20k detector, a 20-tonne fiducial mass dual-phase LAr TPC with SiPM cryogenic photosensors, expected to be free of any instrumental background for exposure of 100 tonne x year. DarkSide-20k will be housed at the LNGS underground laboratory, and it is expected to attain a WIMP-nucleon cross-section exclusion sensitivity of 7.4x10^-48 cm^2 for a WIMP mass of 1 TeV/c^2 in a 200 t yr run. The talk will give the latest updates of the ongoing R&D and prototype tests validating the initial design.
Towards the end of the next decade, the ultimate detector ARGO, with a 300 t fiducial mass, will push the sensitivity to the neutrino floor region for high mass WIMPs.

Speaker: Luca Pagani (UC Davis)

DM2021_LucaPagani.mp4

LP_DS20k_DM2021.pdf

6 Latest Results on Dark Matter Search from DAMIC at SNOLAB

The DAMIC experiment at SNOLAB uses thick, fully-depleted, scientific grade charge-coupled devices(CCDs) to search for the interactions between proposed dark matter particles in the galactic halo with silicon atoms in the detector. DAMIC CCDs operate with an extremely low instrumental noise and dark current,making them particularly sensitive to ionization signals expected from low-mass dark matter particles. DAMIC collected dark-matter search data with seven CCDs installed in a low radiation environment in the SNOLAB underground laboratory. We will focus on the search for hidden-sector DM particles with masses of a few MeV/c2 from their scattering with electrons and the search for nuclear recoils from the scattering of WIMPs with GeV/c2-scale masses in a 11 kg day exposure. Also present the status of DAMIC-M, a detector to be installed at the Laboratoire Souterrain de Modane, France, to acquire kg-year DM search exposures with unprecedentedly low backgrounds and energy threshold.

Speakers: Michelangelo Traina (LPNHE, Sorbonne Université), Damic

DM2021_MichelangeloTraina.mp4

Michelangelo_Traina_DM_2021.pdf

7 Searching for a daily modulation of Dark Matter signal in the DMSQUARE experiment

The Dark Matter Daily Modulation experiment (DMSQUARE) seeks for dark matter interactions with a Skipper CCD. The low threshold achieved by Skipper CCDs allows to search for electron recoil events with an ionization energy down to 1.2 eV. In order to extract a potential dark matter signal, we propose to search for a diurnal modulation of events at the single electron level. This modulation would result from the potential interaction of the dark matter wind through the Earth. Depending on the model, mass and cross-section of the hypothetic DM particle, the modulation can be maximum at 40deg of latitude in the Southern Hemisphere, where DMSQUARE is operated. It is currently running at surface level in Bariloche, Argentina, and will be moved to a shallow underground site at Sierra Grande in September 2021. In this talk we will present the experiment, report preliminary results with Skipper CCDs taking data at surface level and comment on future prospects.

Speaker: Nicolás Avalos (CONICET)

DM2021_NicolasAvalos.mp4

DM2_DM2021_talk_compressed.pdf

Tuesday, September 14

DM Direct Detection

Convener: Jose Maria Diego Rodriguez (IFCA)

8 The SABRE South Experiment at the Stawell Underground Physics Laboratory

The SABRE experiments aim to detect an annual rate modulation from dark matter interactions in ultra-high purity NaI(Tl) crystals. The SABRE South experiment is located at the Stawell Underground Physics Laboratory (SUPL), Australia, the first deep underground laboratory in the Southern Hemisphere, due to be completed in late 2021. SABRE South is designed to disentangle seasonal or site-related effects from the dark matter-like modulated signal first observed by DAMA/LIBRA. It is a partner to the SABRE North effort at LNGS.

SABRE South is instrumented with ultra high purity NaI(Tl) crystals immersed in a liquid scintillator veto,. The experiment is under construction and will be commissioned from late 2021 to early 2022. We will present the status of SABRE South, its expected background, and its sensitivity to a DAMA/LIBRA like modulation. We will also present recent NaI(Tl) crystal quenching factor measurements performed with the ANU HIAF, and a report on the status of SUPL.

Speaker: Francesco Nuti (The University of Melbourne)

DM2021-day2_FrancescoNuti.mp4

nuti_DM2021_14_09_21.pdf

9 Dark matter annual modulation with ANAIS-112: three years results

ANAIS-112 is a dark matter direct detection experiment that operates 112 kg of NaI(Tl) scintillators at the Canfranc Underground Laboratory. Its main goal is to do a model independent test of the DAMA/LIBRA observation of an annual modulation in the detection rate compatible with that expected for dark matter. This signal is in strong tension with the negative results of other experiments. However, a direct comparison using the same target material was lacking. ANAIS-112 is taking data since August 2017 with excellent performance.
Results from the first three years are compatible with the absence of modulation and incompatible with the DAMA/LIBRA measured modulation at more than 2.5 sigma C.L. This result supports the projected goal of reaching a 3 sigma sensitivity for the five-year operation scheduled. In this talk we will describe the ANAIS-112 setup, performance and data analysis.
Then we will present the three-year results and discuss the physical implications and prospects.

Speaker: Maria Martinez (CAPA - UZ)

DM2021-day2_MariaMartinez.mp4

DM21_Martinez.pdf

10 The CYGNO experiment for Dark Matter direct detection

Innovative experimental techniques are needed to further search for dark matter. TPCs with optical readout are very promising candidates thanks to the 3D event reconstruction capability and the high sensitivity and granularity of sCMOS light sensors. The Cygno experiment is developing a TPC operated with He:CF4 at atmospheric pressure equipped with a GEM amplification stage that produces visible light collected by scientific CMOS camera and fast photodetectors. We present the performances of prototypes assessed exposing them to radioactive sources. We show that good energy and spatial resolution as well as discriminating power between nuclear and electron recoils is achieved in the keV energy range. Finally, we discuss the plan to build a 1m3 demonstrator expected to be installed and operated at LNGS in 2021/22. This experimental campaign aims at proving the scalability of such a detector concept to a bigger apparatus able to significantly extend our knowledge about DM and neutrinos.

Speaker: Andrea Messina (Sapienza Università di Roma & INFN Roma)

Cygno-messina-DM2021.pdf

DM2021-day2_AndreaMessina.mp4

5:00 PM Coffee Break

Coffee is not provided :(

DM Indirect Detection

Convener: Jose Maria Diego Rodriguez (IFCA)

11 Overview: Indirect searches for DM

I will discuss the latest developments for indirect dark matter searches. This will include the current limits on and status of anomalies in dark matter annihilation and decay searches using gamma rays, antiprotons, and neutrinos. I will also briefly overview other indirect probes of dark matter annihilation using celestial objects.

Speaker: Rebecca Leane

DM2021-day2_RebeccaLeane.mp4

RKLeane_DM21.pdf

12 Searching for dark matter subhalos with the Fermi-LAT

ΛCDM predicts light dark matter (DM) subhalos (SHs), not massive enough to retain baryons and become visible. If DM is composed of Weakly Interacting Massive Particles (WIMPs), we expect them to annihilate in SHs, producing gamma rays which can be detected with the Large Area Telescope (LAT) on the Fermi satellite, appearing as unidentified sources (unIDs) in the gamma-ray sky. We characterize the LAT sensitivity to DM and compare the sample of unIDs in LAT catalogs -filtered according to the expected DM signal- to predictions from N-body cosmological simulations, repopulated with light SHs below the mass resolution limit. This allows to place robust constraints on the annihilation cross section/WIMP mass parameter space. A spectral and spatial dedicated analysis is then performed for the best DM SH candidates with a decade of LAT data. Finally, we quantify if spatial extension is, as often claimed, a “smoking gun” for SH detection, by simulating the LAT response to extended SHs.

Speaker: Javier Coronado-Blázquez (IFT UAM-CSIC)

CoronadoBlazquez_DM2021.pdf

DM2021-day2_JavierCoronado-Blazquez.mp4

13 Thermal history of Neutron Stars admixed with self-annihilating Dark Matter

Neutron Stars (NSs) are born as hot, lepton rich objects that evolve according to the standard paradigm through subsequent time stages where they cool off the excess of energy by emitting, first, neutrinos and, later on, photons. Current descriptions based on Standard Model calculations can not fully explain all the existing cooling data series for the dozens of objects that have been reported. In this work we consider the intriguing possibility that NSs could actually be admixed with a fraction of Dark Matter (DM). We explore the case assuming that DM undergoes self-annihilating reactions inside a dark core thus allowing the NS having a local source of (temporary) energy injection. By performing simulations of the temperature evolution of the NS when DM is present in the core of the star we find that cooling patterns could be affected for some DM candidates studied. We discuss these results in light of their observability.

Speaker: M. Angeles Perez-Garcia

DM2021-day2_MariaAngelesPerez.mp4

dm2021_perez.pdf

14 Population III stars as Dark Matter laboratories

We show that the mere observation of the first stars (Pop~III stars) in the universe can be used to place tight constraints on the strength of the interaction between dark matter and regular, baryonic matter. We apply this technique to a candidate Pop~III stellar complex discovered with the Hubble Space Telescope at $z\sim7$ and find some of the deepest bounds to-date for both spin-dependent and spin-independent DM-nucleon interactions, over a large swath of DM particle masses. Additionally, we show that the most massive Pop~III stars could be used to bypass the main limitations of direct detection experiments: the neutrino background to which they will be soon sensitive.

Speaker: Cosmin Ilie (Colgate University)

DM2021-day2_CosminIlie.mp4

DMPOPIIIDM21.pdf

15 Dark Neutrons: Cosmology and New Astrophysical Signatures

New states that mix with the neutron, such as dark baryons and mirror neutrons, have been proposed to address dark matter, baryogenesis, the long-standing neutron lifetime anomaly, and the recent XENON1T excess. I show that such states are extensively probed by (1) Big Bang nucleosynthesis, (2) cosmic microwave background spectra, (3) stability of nuclides in low-metallicity stars, (4) a novel mechanism to heat neutron stars by tapping the energy stored in their Fermi seas. This latter effect already constrains a vast range of parameter space, and provides a powerful motivation for imminent optical, ultraviolet and infrared astronomical missions, namely, of directly probing the properties of the neutron. Talk based on 2012.09865 & 2105.09951.

Speaker: Nirmal Raj (TRIUMF)

DM2021-day2_NirmalRaj.mp4

Raj-darkneutrons-IFCA2021.pdf

Wednesday, September 15

DM at accelerators & Light DM

Convener: Alicia Calderon Tazon (IFCA)

16 Overview: DM at Accelerators

Over the next several years, fixed target and collider experiments will greatly improve our coverage of dark matter below the GeV scale. In this talk I will present a theoretical overview of these models and outline various search strategies at existing and future accelerator experiments.

Speaker: Gordan Krnjaic (Fermilab)

DM2021-day3_GordanKrnjaic.mp4

Santander-Plenary.pdf

17 Dark matter searches at LHCb

The LHCb detector at the LHC offers unique coverage of forward rapidities. The detector also has a flexible trigger that enables low-mass states to be recorded with high efficiency, and a precision vertex detector that enables excellent separation of primary interactions from secondary decays. This allows LHCb to make significant (and world-leading) contributions in these regions of phase space in the search for dark matter candidates, such as dark photons, hidden-sector particles, and dark matter candidates produced from heavy-flavour decays. A selection of results from these searches will be presented, alongside the potential for future measurements in these final states.

Speaker: Saul Lopez Solino

DM2021-day3_SaulSolino.mp4

DM_congress_v2.pdf

18 Dark-sector physics at Belle II

The Belle II experiment at the asymmetric $e^+e^-$ collider, SuperKEKB, is a substantial upgrade of the Belle/KEKB experiment. Belle II aims to record 50 ab$^{-1}$ of data over the course of the project. During the first physics runs in 2018-2020, around 100 fb$^{-1}$ of data were collected. These early data include specifically-designed low-multiplicity triggers which allow a variety of searches for light dark matter and dark-sector mediators in the GeV mass range.

This talk will present the very first world-leading physics results from Belle II: searches for the invisible decays of a new vector Z’, and visible decays of an axion-like particle; as well as the near-term prospects for other dark-sector searches. Many of these searches are competitive with the data already collected or the data expected in the next few years of operation.

Speaker: Giacomo De Pietro (INFN Roma Tre)

DarkMatter2021_DePietro.pdf

DM2021-day3_GiacomoDePietro.mp4

5:30 PM Coffee Break

Coffee is not provided :(

DM at accelerators & Light DM

Convener: Alicia Calderon Tazon (IFCA)

19 The Light Dark Matter eXperiment, LDMX

The constituents of dark matter are still unknown, and the viable possibilities span a very large mass range. Specific scenarios for the origin of dark matter sharpen the focus on a narrower range of masses: the natural scenario where dark matter originates from thermal contact with familiar matter in the early Universe requires the DM mass to lie within about an MeV to 100 TeV. Considerable experimental attention has been given to exploring Weakly Interacting Massive Particles in the upper end of this range (few GeV – ~TeV), while the region ~MeV to ~GeV is largely unexplored. Most of the stable constituents of known matter have masses in this lower range, tantalizing hints for physics beyond the Standard Model have been found here, and a thermal origin for dark matter works in a simple and predictive manner in this mass range as well. It is therefore a priority to explore. If there is an interaction between light DM and ordinary matter, as there must be in the case of a thermal origin, then there necessarily is a production mechanism in accelerator-based experiments. The most sensitive way, (if the interaction is not electron-phobic) to search for this production is to use a primary electron beam to produce DM in fixed-target collisions. The Light Dark Matter eXperiment (LDMX) is a planned electron-beam fixed-target missing-momentum experiment that has unique sensitivity to light DM in the sub-GeV range. Thiscontribution will give an overview of the theoretical motivation, the main experimental challenges and how they are addressed, as well as projected sensitivities in comparison to other experiments.

Speaker: Valentina Dutta

DM2021-day3_ValentinaDutta.mp4

ldmx_dm2021_vdutta.pdf

20 Dark matter searches with mono-photon signature at future e+e- colliders

Results on the sensitivity of ILC and CLIC to WIMP dark matter (DM) pair production are reviewed for processes with mono-photon signature, when DM production is accompanied by a hard photon emission from the initial state radiation. In the effective field theory (EFT) approach scales of up to 3 TeV can be tested at ILC for different operator types and DM masses almost up to half the collision energy. Beam polarisation allows to constrain SM background contributions and systematic uncertainties. For CLIC running at 3 TeV, limits on the DM and mediator masses are extracted from the ratio of the mono-photon energy distributions for left-handed and right-handed electron beams. Limits on the mediator coupling to electrons are also presented for ILC and CLIC, for scenarios with light mediator exchange. For masses up to the centre-of-mass energy of the collider, limits expected from the mono-photon analysis are more stringent than the limits from direct resonance search in SM decay channels.

Speaker: Aleksander Filip Zarnecki (Faculty of Physics, University of Warsaw)

DM2021-day3_AleksanderZarnecki.mp4

zarnecki_dm2021_v2.pdf

21 Status of the ALPS II experiment

Within the next couple of months the ALPS II experiment will be ready for a first data run. It will be able to explore a new region of the dark matter parameter space while probing hints for axion-like particles from stellar observations, all with a method that is independent of astrophysical models of the axion production and photon regeneration.
ALPS II is a second generation light-shining-through-a-wall experiment and located at DESY in Hamburg. It reaches an unprecedented sensitivity for experiments of its kind by employing 24 superconducting magnets and two low loss optical resonators. The resonators are split by an opaque wall and will be matched to each other by a sophisticated feedback control system. Two independent read out schemes with different systematics are subsequently installed: A heterodyne detection system and a transition edge sensor.
This talk will discuss the physics case for ALPS II. An overview of the optical system and the current status will be provided.

Speaker: Jan Põld

DM2021-day3_JanPold.mp4

dm2021_pold.pdf

22 Axion search with the BabyIAXO helioscope: status and prospects

The International Axion Observatory (IAXO) is a large-scale axion helioscope that will search for axions and axion-like particles produced in the Sun. It is conceived to reach a sensitivity on the axion-photon coupling in the range of 10^-12 GeV^-1. To facilitate the way to the gigantic IAXO helioscope, a smaller experiment BabyIAXO is in the construction phase. BabyIAXO will be important to test all IAXO subsystems (magnet, optics and detectors) and at the same time, as a fully-fledged helioscope, will reach a sensitivity on the axion-photon coupling of 1.5 ∙ 10^-11 GeV^-1 for masses up to 0.25 eV, covering a very interesting region of the parameter space. This presentation will report on the current status and progress of BabyIAXO, with a focus on the low background X-ray detectors, which are currently undergoing testing. Further we discuss the roadmap for BabyIAXO, which is scheduled to see first light in 2024.

Speaker: Konrad Altenmüller (Universidad de Zaragoza)

Axion_search_with_the_BabyIAXO_helioscope.pdf

DM2021-day3_KonradAltenmuller.mp4

23 Searching for dark matter with superconducting qubits

Detection mechanisms for low mass bosonic dark matter candidates, such the axion or hidden photon, leverage potential interactions with electromagnetic fields, whereby the dark matter (of unknown mass) on rare occasion converts into a single photon. We report the development of a novel microwave photon counting technique and a new exclusion limit on hidden photon dark matter. We operate a superconducting qubit to make repeated quantum non-demolition measurements of cavity photons and apply a hidden Markov model analysis to reduce the noise to 15.7 dB below the quantum limit. With the present device, we perform a hidden photon search and constrain the kinetic mixing angle to $\epsilon \leq 1.68 \times 10^{-15}$ in a band around 6.011 GHz (24.86 $\mu$eV) with an integration time of 8.33 s. This demonstrated noise reduction technique enables future dark matter searches to be sped up by a factor of 1300.
A. V. Dixit Phys. Rev. Lett. 126, 141302

Speaker: Akash Dixit (University of Chicago)

AVDixit_DM2021.pdf

DM2021-day3_AkashDixit.mp4

Thursday, September 16

DM and Cosmology

Convener: Sven Heinemeyer

24 Overview: Cosmological probes of DM

I will review some recent developments in cosmological probes of dark matter properties, including constraints on the dark matter thermal history, mass, and interaction with baryons. The cosmological probes covered in this talk will include Big Bang nucleosynthesis, the cosmic microwave background, 21 cm cosmology, the Lyman-alpha forest, and lensing as well as “near-field” probes like the local subhalo mass function.

Speaker: Katelin Schutz (McGill University)

DM2021-day4_KatelinSchutz.mp4

DM2021.pdf

25 How warm are non-thermal relics? Out-of-equilibrium dark matter production

By facing strong experimental constraints notably from direct detection, many dark matter scenarios based on the Weakly Interacting Massive Particles (WIMPs) paradigm are pushed towards corners of viable parameter space. Several alternative production mechanisms have received a lot of attention over the past few years. In this talk, I will present various possibilities of producing dark matter in a state out of thermal equilibrium. I will show that the non-thermal nature of the dark matter can leave an imprint on the matter power spectrum, which features a cutoff analogous to that for warm dark matter. I will present a mapping procedure that allows to translate the Lyman-alpha forest mass bound to such scenarios and discuss the phenomenological implications of these results.

Speaker: Mathias Pierre (IFT-UAM Madrid)

DM2021-day4_MathiasPierre.mp4

MP_Dark_Matter_2021.pdf

26 Can we constrain dark matter at the limits of galaxy formation?

Current work to directly detect dark matter (DM) via experiment has so far yielded only upper limits to the interaction between DM and normal matter, leaving astrophysical tests as an intriguing test ground. I will present results from a flagship suite of cosmological hydrodynamic simulations of dwarf galaxies (including at the lowest masses, ultra-faint dwarfs) with results that concentrate on the interplay between galaxy formation (baryonic physics) and dark matter, pointing toward specific observables to disentangle the effects of galaxy formation physics from the effects of DM physics. My results will answer the following key question: What testable predictions can we make to constrain dark matter at the lowest dwarf masses? I will also briefly discuss observations we can make to distinguish alternative DM scenarios from Cold Dark Matter in the advent of JWST, the Vera Rubin Observatory and the Nancy Grace Roman Space Telescope.

Speaker: Prof. Ferah Munshi (University of Oklahoma)

DM2021-day4_FerahMunshi.mp4

DMSatander_Munshi.pdf

5:30 PM Coffee Break

Coffee is not provided :(

DM and Cosmology

Convener: Sven Heinemeyer

27 Dark-matter-deficient galaxies in the hydrodynamical simulation IllustrisTNG

Dark matter deficient galaxies (DMDGs) could have lost their dark matter halos due to interactions during their evolution; in particular, during their fusion history. The existence of these galaxies is a debated subject, both from the observational and theoretical points of view. In this work, we study the population of dark matter deficient galaxies at different redshifts using the hydrodynamical simulation IllustrisTNG, which follows the evolution of dark matter and baryonic matter. We analyse the dark matter fraction of these galaxies considering their total mass and also within their central regions. Moreover, we study the distribution of the DMDGs within their host halo at different redshifts. Finally, we analyse the evolution of their baryonic and dark matter, as the satellite orbits its host halo in order to determine if the loss of the dark matter is due to the tidal stipping that could be taking place.

Speaker: Elisa Tau (Universidad de La Serena)

DarkMatter2021-Presentation.pdf

DM2021-day4_ElisaTau.mp4

28 The Interplay Between Primordial Black Hole Evaporation and Dark Matter Production

Hawking evaporation of black holes is expected to copiously produce all kinds of particles, regardless of their charges. For primordial black holes of a certain mass, this effect has huge implications on dark matter phenomenology. I will discuss such implications in the context of models that contain one or more dark sector particles, as well as models which couple to the Standard Model. Specifically, we investigate when primordial black hole evaporation can have important effects on thermal freeze-in and out. We explore superradiant production of spin-2 particles, entropy dilution and the potential for re-thermalization after black hole evaporation. This talk will be based on the preprints arXiv:2107.00013 and arXiv:2107.00016 with additional updates from ongoing work.

Speaker: Andrew Cheek (CP3, UCL)

ACHEEK_DM2021.pdf

DM2021-day4_AndrewCheek.mp4

Link to interactive talk slides

29 Simulations of Axion Minihalos

Our work estimates the present-day abundance of axion substructures, as is necessary for predicting their effect on cosmological microlensing caustics and pulsar timing. Our calculations suggest that if pulsar timing and microlensing probes can reach recent sensitivity forecasts, they may be sensitive to the post-inflation axion dark matter scenario, even when accounting for uncertainties pertaining to axion strings. For pulsar timing, the most significant caveat is whether axion minihalos are disrupted by stars, which our estimates show is mildly important at the most relevant masses. Finally, as our gravitational simulations are scale invariant, the results can be extended to models where the dark matter is comprised of other axion-like particles and even clusters of primordial black holes.

Speaker: Huangyu Xiao (University of Washington)

DM2021-day4_HuangyuXiao.mp4

The axion abstract.pdf

30 Probing Baryonic Dark Matter Models with Gravitational Waves

Gravitational waves provide a unique method of testing theories with extended gauge symmetries. In particular, spontaneous symmetry breaking can lead to a detectable stochastic gravitational wave background generated by cosmic strings and first order phase transitions in the early universe. I will discuss the unique gravitational wave signature of a dark matter model with gauged baryon and lepton numbers, in which a high scale of lepton number breaking is motivated by the seesaw mechanism for the neutrinos, whereas a low scale of baryon number breaking is required by the observed dark matter relic density. This novel signature can be searched for in near-future gravitational wave experiments.

Speaker: Bartosz​ Fornal

Bartosz_Fornal_DM_2021.pdf

DM2021-day4_BartoszFornal.mp4

31 Round Table & Closing Remarks

Speakers: Joe Silk, Keith Olive, Simona Murgia, Tim Tait

DM2021-day4_RoundTableAndConcludingRemarks.mp4