ERQs are the BOSS of quasar samples: the highest velocity [O iii] quasar outflows

Abstract

We investigate Extremely Red Quasars (ERQs), a remarkable population of heavily-reddened quasars at redshift z ∼2 − 3 that might be caught during a short-lived "blow-out" phase of quasar/galaxy evolution. We perform a near-IR observational campaign using Keck/NIRSPEC, VLT/X-shooter and Gemini/GNIRS to measure restframe optical spectra of 28 ERQs with median infrared luminosity log L(erg/s) ∼46.2. They exhibit the broadest and most blue-shifted [OIII] λ4959,5007 emission lines ever reported, with widths (w 90 ) ranging between 2053 and 7227 km s −1 , and maximum outflow speeds (v 98 ) up to 6702 km s −1 . ERQs on average have [OIII] outflows velocities about 3 times larger than those of luminosity-matched blue quasar samples. We show that the faster [OIII] outflows in ERQs are strongly correlated with their extreme red colors and not with radio-loudness, larger quasar luminosities, nor higher Eddington ratios. We estimate for these objects that at least 3−5 per cent of their bolometric luminosity is being converted into the kinetic power of the observed wind. Our results reveal that ERQs have the potential to strongly affect the evolution of host galaxies.

Spectroscopy of Broad Absorption Line Quasars at 3 ≲ Z ≲ 5. I. Evidence for Quasar Winds Shaping Broad/Narrow Emission Line Regions

“…In particular, we applied two methods to decompose the plateau-like profile around the Hβ + [O iii] region in J0844+0503. One is followed by the above procedures; the other is based on the introduction of extremely blueshifted (>1700 km s −1 ) and broad [O iii] components (e.g., Coatman et al 2019;Perrotta et al 2019). The two methods yield a similar [O iii] EW including both narrow and broad Gaussians, but we favor the latter since this quasar has sub-relativistic BAL outflows that may affect its NEL region (e.g., Faucher-Giguère et al 2012).…”

The WISSH quasars project

“…Indeed, the fastest and most energetic winds have been reported in hyper-luminous quasars (i.e. with a bolometric luminosity of L bol 10 47 erg s −1 ; Wu et al 2011;Fiore et al 2017;Vietri et al 2018;Meyer et al 2019;Perrotta et al 2019). Luminous quasars are typically characterised by their low coronal X-ray luminosity (L X ) compared to the disc's ultraviolet (UV) and larger-scale dust-reprocessed mid-infrared (MIR) luminosities, which are represented as L UV and L UV , respectively.…”

Outflows & Feedback from Extremely Red Quasars

“…Perhaps the most remarkable property of ERQs is their strong tendency to have broader and more blueshifted [OIII] 4959,5007Å emission lines than blue quasar samples. This includes the broadest and most blueshifted [OIII] lines ever reported in quasars, with FWHMs and blueshifted wings reaching ∼6700 km s −1 (Zakamska et al 2016;Perrotta et al 2019). The right-hand panels in Figure 2 show examples of this extreme [OIII] behavior compared to the median spectrum of SDSS quasars.…”

“…Compared to this normal quasar spectrum, ERQs have very strong and blueshifted NV and CIV broad emission lines, peculiar line profiles, and spectacularly broad and blueshifted [OIII] lines at speeds reaching >6000 km s −1 . The [OIII] lines identify powerful outflows that could be driving important feedback effects in the host galaxies (Zakamska et al 2016;Hamann et al 2017;Perrotta et al 2019. Another common property of ERQs is large blueshifts in CIV 1549Å and other broad emission lines. These blueshifts identify outflows in quasar broad emission-line regions (BELRs, Richards et al 2011).…”