1. Disentangling the Cosmic Web toward FRB 190608
- Author
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Simha, Sunil, Burchett, Joseph N, Prochaska, J Xavier, Chittidi, Jay S, Elek, Oskar, Tejos, Nicolas, Jorgenson, Regina, Bannister, Keith W, Bhandari, Shivani, Day, Cherie K, Deller, Adam T, Forbes, Angus G, Macquart, Jean-Pierre, Ryder, Stuart D, and Shannon, Ryan M
- Subjects
Astronomical Sciences ,Physical Sciences ,astro-ph.GA ,Astronomical and Space Sciences ,Atomic ,Molecular ,Nuclear ,Particle and Plasma Physics ,Physical Chemistry (incl. Structural) ,Astronomy & Astrophysics ,Astronomical sciences ,Particle and high energy physics ,Space sciences - Abstract
FRB 190608 was detected by ASKAP and localized to a spiral galaxy at$z_{host}=0.11778$ in the SDSS footprint. The burst has a large dispersionmeasure ($DM_{FRB}=339.8$ $pc/cm^3$) compared to the expected cosmic average atits redshift. It also has a large rotation measure ($RM_{FRB}=353$ $rad/m^2$)and scattering timescale ($\tau=3.3$ $ms$ at $1.28$ $GHz$). Chittidi et al(2020) perform a detailed analysis of the ultraviolet and optical emission ofthe host galaxy and estimate the host DM contribution to be $110\pm 37$$pc/cm^3$. This work complements theirs and reports the analysis of the opticaldata of galaxies in the foreground of FRB 190608 to explore their contributionsto the FRB signal. Together, the two manuscripts delineate an observationallydriven, end-to-end study of matter distribution along an FRB sightline; thefirst study of its kind. Combining KCWI observations and public SDSS data, weestimate the expected cosmic dispersion measure $DM_{cosmic}$ along thesightline to FRB 190608. We first estimate the contribution of hot, ionized gasin intervening virialized halos ($DM_{halos} \approx 7-28$ $pc/cm^3$). Then,using the Monte Carlo Physarum Machine (MCPM) methodology, we produce a 3D mapof ionized gas in cosmic web filaments and compute the DM contribution frommatter outside halos ($DM_{IGM} \approx 91-126$ $pc/cm^3$). This implies agreater fraction of ionized gas along this sightline is extant outsidevirialized halos. We also investigate whether the intervening halos can accountfor the large FRB rotation measure and pulse width and conclude that it isimplausible. Both the pulse broadening and the large Faraday rotation likelyarise from the progenitor environment or the host galaxy.
- Published
- 2020