Munich Dark Matter Meeting -- Silas Zelmer

Tuesday 28 Jan 2025, 12:30 → 13:30 Europe/Berlin

A.2.25/27 - Atlas (New)

Title: Ultra-light Axion Constraints from eRASS1 Galaxy Cluster Number Counts

 

Abstract: Ultra-light axion-like particles (ULAs) are viable dark matter candidates that naturally fit within the concordance Lambda-CDM cosmological model. Their bosonic nature enables them to form Bose-Einstein condensates with characteristic scales determined by their thermal de-Broglie wavelength. ULAs with masses below ~10^(-24) eV can form condensates on scales comparable to those of galaxy cluster dark matter halos, thereby suppressing halo formation on all smaller scales. 

For the first time, we use the observed abundance of galaxy clusters to constrain the parameter space ofULAs. The galaxy clusters used in this work have been observed by the first eROSITA All-Sky Survey (eRASS1), the largest intracluster-medium-selected sample to date. Our analysis covers the full ULA mass range from 10^(-32) eV to 10^(-24) eV, assuming a mixture of axion dark matter and cold dark matter. 

We obtain the most stringent upper bounds on the ULA abundance to date in the higher mass regime of the considered mass range, using only the eRASS1 galaxy cluster data. Combining our results with CMB probes further tightens the ULA relic density bounds.

 

Remote access via zoom: https://zoom.us/j/93858139672?pwd=NkNPZ1ltY2xnT2E1bS94M3VBZ1JUQT09 (Meeting ID: 938 5813 9672, Passcode: 522402)

 

https://wwwmpa.mpa-garching.mpg.de/darkmatter/