Talks by Yacine Ali-Haimoud

Insights into searches for the nanohertz gravitational-wave background with a Fisher analysis

Yacine Ali-Haimoud Johns Hopkins University

Within the next several years pulsar timing arrays (PTAs) are positioned to detect the stochastic gravitational-wave background (GWB) likely produced by the collection of inspiralling supermassive black holes binaries, and potentially constrain some exotic physics. Searches for a GWB in real PTA data rely on Markov-Chain Monte Carlo (MCMC) analyses, which are computationally demanding and not easily accessible to non-experts.

Dark matter phenomenology across cosmic times

Yacine Ali-Haimoud Johns Hopkins University
The nature of dark matter remains one of the most nagging problems in cosmology. In this talk I will discuss several existing or potential probes of dark matter. I will start with a well known hot dark matter, massive neutrinos, and discuss their effect on large-scale structure in the non-linear regime. I will then talk about the effect of dark matter interactions with standard model particles on the spectrum of the CMB and on 21cm fluctuations. I will conclude by discussing whether LIGO could have detected primordial-black-hole dark matter.

21cm fluctuations in the dark ages and cosmic heat flows

Yacine Ali-Haimoud Johns Hopkins University
The spin-flip transition in neutral hydrogen may be used to probe large-scale structure at high redshifts, before the first luminous objects formed. The huge number of modes potentially accessible make this a very promising avenue. I will discuss several key unknowns that could be measured with high-redshift 21cm surveys: primordial non-gaussianity, the primordial small-scale power spectrum, and dark-matter-baryon interactions.