Do extremely reddened quasars extinguish star formation? November 15, 2016 by Sean Nealon Please Register or Log in to view the hidden image! An artist's impression shows a very distant quasar powered by a black hole with a mass two billion times that of the Sun. Credit: ESO/M. Kornmesser Galaxies formed and grew billions of years ago by accumulating gas from their surroundings, or colliding and merging with other young galaxies. These early stages of galaxy assembly are believed to be accompanied by episodes of rapid star formation, known as starbursts, and rapid growth of a single super-massive black hole in the galactic centers. A popular paradigm for this evolution has the black holes growing mostly in obscurity, buried deep within the dusty gas. These are rich star-forming galaxies until a blowout of gas and dust (outflow) extinguishes the star formation and halts further growth in the black holes. The outflow then reveals a luminous, rapidly growing black hole in the galactic nucleus. These are known as quasars. Quasars can eject material at high speeds, possibly helping to drive the blowout and regulate star formation in their host galaxies. However, many aspects of this evolutionary scheme are not understood. Quasars that are partially obscured by dust, which reddens their light in a way that is similar to the sun viewed during sunsets on earth, might provide windows into galactic evolution during the brief transition stage when the starburst is winding down and the visibly luminous quasar is first being revealed in the galactic center. Read more at: http://phys.org/news/2016-11-extremely-reddened-quasars-extinguish-star.html#jCp
http://mnras.oxfordjournals.org/content/464/3/3431 Extremely red quasars in BOSS: Abstract Red quasars are candidate young objects in an early transition stage of massive galaxy evolution. Our team recently discovered a population of extremely red quasars (ERQs) in the Baryon Oscillation Spectroscopic Survey (BOSS) that has a suite of peculiar emission-line properties including large rest equivalent widths (REWs), unusual ‘wingless’ line profiles, large N V/Lyα, N V/C IV, Si IV/C IV and other flux ratios, and very broad and blueshifted [O III] λ5007. Here we present a new catalogue of C IV and N V emission-line data for 216 188 BOSS quasars to characterize the ERQ line properties further. We show that they depend sharply on UV-to-mid-IR colour, secondarily on REW(C IV), and not at all on luminosity or the Baldwin Effect. We identify a ‘core’ sample of 97 ERQs with nearly uniform peculiar properties selected via i–W3 ≥ 4.6 (AB) and REW(C IV) ≥ 100 Å at redshifts 2.0–3.4. A broader search finds 235 more red quasars with similar unusual characteristics. The core ERQs have median luminosity 〈log L(ergs s−1)〉 ∼ 47.1, sky density 0.010 deg−2, surprisingly flat/blue UV spectra given their red UV-to-mid-IR colours, and common outflow signatures including BALs or BAL-like features and large C IV emission-line blueshifts. Their SEDs and line properties are inconsistent with normal quasars behind a dust reddening screen. We argue that the core ERQs are a unique obscured quasar population with extreme physical conditions related to powerful outflows across the line-forming regions. Patchy obscuration by small dusty clouds could produce the observed UV extinctions without substantial UV reddening.
