Gemini GNIRS Near-infrared Spectroscopy of 50 Quasars at z ≳ 5.7

Abstract

We report initial results from a large Gemini program to observe z 5.7 quasars with GNIRS near-IR spectroscopy. Our sample includes 50 quasars with simultaneous ∼ 0.85 − 2.5 µm spectra covering the rest-frame ultraviolet and major broad emission lines from Ly α to Mg II. We present spectral measurements for these quasars and compare to their lower-redshift counterparts at z = 1.5 − 2.3. We find that when quasar luminosity is matched, there are no significant differences between the rest-UV spectra of z 5.7 quasars and the low-z comparison sample. High-z quasars have similar continuum and emission line properties and occupy the same region in the black hole mass and luminosity space as the comparison sample, accreting at an average Eddington ratio of ∼ 0.3. There is no evidence for super-Eddington accretion or hypermassive (> 10 10 M ) black holes within our sample. We find a mild excess of quasars with weak C IV lines relative to the control sample. Our results, corroborating earlier studies but with better statistics, demonstrate that these high-z quasars are already mature systems of accreting supermassive black holes operating with the same physical mechanisms as those at lower redshifts.

The ALMA view of the high-redshift relation between supermassive black holes and their host galaxies

“…No BLR emission lines have been detected in all quasars but J2310+1855, for which we derived a CIV-based M BH estimate of 6 × 10 9 M (see Appendix D for full details of the observations). Our estimation is consistent, within the error, with that reported by Feruglio et al (2018) and Shen et al (2019). We note that Shen et al (2019), who published NIR spectra of a large sample of z ∼ 5.7 QSOs, also provide a M BH measurement for J2310+1855 through virial relation based on MgII as well.…”

“…Our estimation is consistent, within the error, with that reported by Feruglio et al (2018) and Shen et al (2019). We note that Shen et al (2019), who published NIR spectra of a large sample of z ∼ 5.7 QSOs, also provide a M BH measurement for J2310+1855 through virial relation based on MgII as well. In the following we will refer to the MgII estimate from Shen et al (2019), because of the aforementioned issues related to CIV-based measurements.…”

“…The latter values are consistent with the MgII-based M BH reported in Shen et al (2019), which has been used in this paper to study the M BH − M dyn relation. In Fig.…”

“…From the best-fit of the CIV line, we derived a FWHM ∼ 12500 km s −1 , and from the extrapolated continuum at 1350 Å, a flux of F 1350 ∼ 1.1 × 10 −17 erg s −1 cm −2 Å −1 , and a luminosity of ∼ 10 45.8 erg s −1 . Using the relation, we obtain log M BH ∼ 9.8, consistently with Shen et al (2019). The CIV line is blueshifted with respect to the [CII] 158µm systemic of ∆v ∼ −7200 km s −1 , strongly suggesting the presence of outflows in this source.…”

Catalogues of active galactic nuclei from Gaia and unWISE data

“…The variability from AGNs has been used to constrain the properties of supermassive black holes and the fuelling mechanisms (e.g., Blandford & McKee 1982;Vanden Berk et al E-mail: yiping.shu@ast.cam.ac.uk,nwe@ast.cam.ac.uk † Royal Society -K. C. Wong International Fellow 2004; Liu et al 2008;Li & Cao 2008;MacLeod et al 2010;Shen et al 2015;LaMassa et al 2015;Yang et al 2018). Among the most luminous sources in the sky, AGNs have been detected back to within the first billion years of the Universe and help to understand the growth of supermassive black holes (e.g., Fan et al 2006;Wu et al 2015;Wang et al 2018b;Pons et al 2019;Shen et al 2019). In addition, AGNs have been suggested to play an important role in regulating the formation and evolution of host galaxies (e.g., Silk & Rees 1998;Kang et al 2006;Fabian 2012;Dubois et al 2013).…”