Name: V Aiswarya
Affiliation: Indian Institute of Space Science and Technology
Conference ID : ASI2022_260
Title : Finding Missing Baryons using Broad Lyman-α Absorbers
Authors : V Aiswarya, Vikram Khaire, Anand Narayanan
Abstract Type: Poster
Abstract Category : Extragalactic Astronomy
Abstract : Structure formation simulations show that 80-90% of baryons must exist in the intergalactic medium(IGM). In the low redshift universe, this gas is shock-heated to high temperatures due to gravitational shocks from structure formation and is called the warm-hot intergalactic medium(WHIM, T ∼ 105 − 107K). Earlier baryon surveys detected a 50% deficit in the low redshift universe. This missing baryon problem exists even today. WHIM is elusive to direct observations but is observable using absorption profiles in quasar spectra. A few studies have established the presence of WHIM through absorption spectra. We have sparse data on WHIM for any comprehensive baryon survey. We plan to survey quasar spectra from the high SNR observations of the HST COS instrument to find Broad Lyman-α(BLA) absorption lines and corresponding metal lines. We perform Voigt profile fitting of spectral lines. We then model the ionization conditions using the results of Voigt fitting. We have done the fitting for one system. Simple calculations show that this system is at a temperature of 10^5.2K. We also find that this system is not within the virial radius of any galaxy using the VIMOS galaxy information. We are further investigating to confirm that this system is a BLA and part of WHIM. We plan on modelling ionization conditions for other BLA candidates we find through Voigt profile fitting. The results of the ionization modelling will determine the results of the BLA survey.