Spectral Evolution in High Redshift Quasars From the Final Baryon Oscillation Spectroscopic Survey Sample

Abstract

We report on the diversity in quasar spectra from the Baryon Oscillation Spectroscopic Survey. After filtering the spectra to mitigate selection effects and Malmquist bias associated with a nearly flux-limited sample, we create high signal-to-noise ratio composite spectra from 58,656 quasars (   z 2.1 3.5), binned by luminosity, spectral index, and redshift. With these composite spectra, we confirm the traditional Baldwin effect (BE, i.e., the anticorrelation of C IV equivalent width (EW) and luminosity) that follows the relation µ , and −0.41±0.005 for z=2.25, 2.46, and 2.84, respectively. In addition to the redshift evolution in the slope of the BE, we find redshift evolution in average quasar spectral features at fixed luminosity. The spectroscopic signature of the redshift evolution is correlated at 98% with the signature of varying luminosity, indicating that they arise from the same physical mechanism. At a fixed luminosity, the average C IV FWHM decreases with increasing redshift and is anti-correlated with C IV EW. The spectroscopic signature associated with C IV FWHM suggests that the trends in luminosity and redshift are likely caused by a superposition of effects that are related to black hole mass and Eddington ratio. The redshift evolution is the consequence of a changing balance between these two quantities as quasars evolve toward a population with lower typical accretion rates at a given black hole mass.

The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the Extended Baryon Oscillation Spectroscopic Survey and from the Second Phase of the Apache Point Observatory Galactic Evolution Experiment

“…These spectra, based on the DR12 BOSS quasar catalog (Alam et al 2015), are binned by luminosity, spectral index, and redshift. As discussed in Jensen et al (2016), these composite spectra can be used to reveal spectral evolution while holding luminosity and spectral index constant. These composite spectra allow investigations into quasar diversity and can be used to improve the templates used in redshift classification.…”

“…These composite spectra allow investigations into quasar diversity and can be used to improve the templates used in redshift classification. See Jensen et al (2016) for more details.…”

“…We include in DR14 the first part of the ELG target catalog (see Table 2) described in Raichoor et al (2017). Other eBOSS value added catalogs (VACs) are also released, namely (1) the redshift measurement and spectral classification catalog using Redmonster (Hutchinson et al 2016), (2) the quasar catalog (Pâris et al 2017b), and (3) a set of composite spectra of quasars binned on spectroscopic parameters (Jensen et al 2016). 2.…”

High-redshift Galaxies and Black Holes Detectable with the JWST: A Population Synthesis Model from Infrared to X-Rays

“…See Jensen et al (2016) for a first attempt at using observations to constrain AGN redshift spectral evolution.…”

The SDSS-IV Extended Baryon Oscillation Spectroscopic Survey: Baryon Acoustic Oscillations at Redshift of 0.72 with the DR14 Luminous Red Galaxy Sample

“…19 The extraction algorithm has improved since BOSS; its description can be found in Appendix B of Bautista et al (2017). Recent improvements on coaddition and fluxcalibration are described in Hutchinson et al (2016) and Jensen et al (2016). The final eBOSS LRG spectra were classified and their redshifts measured primarily by redmonster 20 (Hutchinson et al 2016), complemented by redshifts obtained using spec1d (Bolton et al 2012).…”