astrobites | Daily Paper Summaries | 2019 Aug 07
Keir Birchall wrote:
It has long been understood that a connection exists between galaxies and the supermassive black holes (SMBHs) that exist at their centres. Gas from the host galaxy finds its way into the centre where it is consumed by the black hole. The sated black hole then bathes the host galaxy in huge amounts of radiation that can be detected across the electromagnetic spectrum, a phenomenon known as an active galactic nucleus (AGN). The difficult question is: how does the gas find its way into the centre and what effects might this have on the host galaxy? The well-cited Alexander & Hickox (2012) paper suggests that these AGN are fuelled mainly by mergers between galaxies and is outlined in figure 1. ...
Today’s authors studied a sample of obscured quasars in this so-called ‘adolescent’ phase (figure 1; stage 3) to investigate whether AGN and their host galaxies will always follow this evolutionary path. To accomplish this the authors identified and imaged a sample of 10 FeLoBAL quasars at the lowest possible redshifts (0.6 < z < 1.1) using the Hubble Space Telescope (HST). FeLoBAL quasars are active galaxies described by broad absorption lines in their spectrum, particularly iron, indicating powerful outflows of material. A sample of 20 blue, unobscured quasars from the author’s previous work were used as a control sample. The aim was to characterise and compare the shapes of both samples of galaxies. Assuming this merger-driven theory is correct, the authors would expect an enhancement of merger signatures in the FeLoBAL quasar sample when compared to their unobscured counterparts as FeLoBAL quasars more recently experienced the initial merger event. ...
The host galaxies of FeLoBAL quasars at z ∼ 0.9
are not dominated by recent major mergers ~ C. Villforth et al
- Monthly Notices of the RAS 483(2):2441 (Feb 2019) DOI: 10.1093/mnras/sty3271
- arXiv.org > astro-ph > arXiv:1811.11773 > 28 Nov 2019