S20A0016abst
S20A0016
We aim to find out the reason why there exists an anisotropic H1 absorption around quasars; i.e., the environments around quasars are highly biased toward producing strong H1 absorption in transverse direction while there exists a significant deficit of H1 absorption within a few Mpc of quasars along line-of-sight (i.e., proximity effect). The most plausible explanation for this opposite trend is that the transverse direction is shadowed from the quasar UV radiation due to dusty torus, a frequently invoked structure in AGN unification models. However, a critical weakness of this idea is that we have no information on inclination angle of our sightline relative to the torus. In this program, we examine environments of quasars with broad absorption troughs in their spectra (i.e., BAL quasars) because it is widely believed that BAL troughs are observed only if the central continuum is viewed from the side. With closely separated (ΞΈ < 60β²β²) 13 quasar pairs at different redshift, we examine H1 absorption at foreground BAL quasars in spectra of background quasars. We then confirm whether the anisotropic H1 absorption is also observed around BAL quasars. This is a continuation of our program in semesters S17B and S19A, but the latter was canceled due to an earthquake.
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