Speaker
Description
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.
