Simulating the cosmological 21-cm signal with various effects

by Dr. Debanjan Sarkar

at Astrophysics and Cosmology Seminar

Wed, 15 Dec 2021, 11:10
Sacta-Rashi Building for Physics (54), room 207


We model the cosmological 21-cm signal from cosmic dawn (CD) to epoch of reionization (EoR) using a semi-numerical simulation. We include various effects, like the relative velocity between dark matter and baryon, Lyman-Werner radiation feedback, CMB and Lyman-$\alpha$ heating, which shape the signal in different ways. We also consider possibilities beyond the `Cold Dark Matter' (CDM) scenario, and
study the effects of different dark matter models on the 21-cm signal. As a first application, we simulate the 21-cm signal for the `Fuzzy Dark Matter' (FDM) model. In the FDM model, dark matter is composed of ultra-light particles with a deBroglie wavelength of $\sim$ kpc, above which the particles behave like CDM. FDM suppresses the growth of structure on small scales which delays the onset of the CD and subsequent epochs like EoR. This leaves interesting signatures in the sky averaged 21-cm signal (global), as well as in the 21-cm fluctuations. Future 21-cm global and intensity mapping experiments have enough potential to find these signatures of FDM. We forecast the possibility of distinguishing the CDM and FDM models and estimate the constraints on the different model parameters. Intensity experiments, like HERA, are far more superior than the global signal experiments. HERA is expected to distinguish between CDM and FDM with a high statistical significance, and measure the FDM particle mass with great accuracy. However, the additional effects, like heating, lowers the significance and accuracy.

Created on 11-12-2021 by Zitrin, Adi (zitrin)
Updaded on 11-12-2021 by Zitrin, Adi (zitrin)