Absorption-line Environments of High-redshift BOSS Quasars

Abstract

The early stage of massive galaxy evolution often involves outflows driven by a starburst or a central quasar plus cold mode accretion (infall), which adds to the mass build-up in the galaxies. To study the nature of these infall and outflows in the quasar environments, we have examined the correlation of narrow absorption lines (NALs) at positive and negative velocity shifts to other quasar properties, such as their broad absorption-line (BAL) outflows and radio-loudness, using spectral data from SDSS-BOSS DR12. Our results show that the incidence of associated absorption lines (AALs) and outflow AALs is strongly correlated with BALs, which indicates most AALs form in quasar-driven outflows. Multiple AALs are also strongly correlated with BALs, demonstrating quasar outflows tend to be highly structured and can create multiple gas components with different velocity shifts along our line of sight. Infall AALs appear less often in quasars with BALs than quasars without BALs. This suggests that BAL outflows act on large scale in host galaxies and inhibit the infall of gas from the IGM, supporting theoretical models in which quasar outflow plays an important role in the feedback to host galaxies. Despite having larger distances, infall AALs are more highly ionized than outflow AALs, which can be attributed to the lower densities in the infall absorbers.

Extreme High-velocity Outflows from High-redshift BOSS Quasars

“…In this paper, we continue our previous work (Chen et al 2020) to investigate the nature and origins of the diverse C iv narrow absorption lines (NALs) from high-redshift quasars measured in the Baryon Oscillation Spectroscopic Survey (BOSS, Dawson et al 2013;Pâris et al 2017) of the Sloan Digital Sky Survey III (SDSS-III, Eisenstein et al 2011), which is made possible by a new catalog of quasar absorption lines including C iv λ1548, 1551 NAL doublets at different velocity shifts developed by York et al (in prep. ) using spectra from BOSS data release 12 (DR12).…”

“…The BOSS spectra have a wavelength coverage from ∼ 3600 Å through ∼ 10, 000 Å at a resolutions of ∼ 1300 in the blue end to ∼ 2600 in the red end (Dawson et al 2013). We describe our quasar sample selection criteria and C iv NALs selection process in Chen et al (2020). We have a full sample of 100,376 quasars, in which 40,696 quasars exhibit a total of 54,154 wellmeasured C iv NALs in their spectra.…”

“…Quasar absorption lines give unique insight on the properties of the material associated with the quasar host galaxy or intervening galaxies along the line of sight, and are classified into broad absorption lines (BALs), narrow absorption lines (NALs) and minibroad absorption lines (mini-BALs). For example, lowspeed outflows or infall in the extended host galaxies should produce narrow associated absorption lines (AALs) with redshifts near the quasar emission-line redshifts and velocity widths less than a few hundred km s −1 (e.g., Weymann et al 1979;Foltz et al 1986;Hamann 1997;Hamann & Sabra 2004;Simon & Hamann 2010;Muzahid et al 2013;Chen et al 2020). Cosmologicallyintervening gas or galaxies unrelated to the quasars are detected via narrow absorption lines (NALs) at extreme velocity shifts (∼ 0.1c − 0.2c).…”

Probing the He II re-Ionization ERa via Absorbing C IV Historical Yield (HIERACHY) I: A Strong Outflow from a z~4.7 Quasar

“…Such P-Cygni profile is possibly produced when the cold gas clumps entrained in the foreground outflow shield the emission from outflow in the background. The narrow outflow absorbers (e.g, F W HM 700 km s −1 in the intermediate-resolution spectra) are found to be common for quasars in the statistic studies (Weymann et al 1979;Nestor et al 2008;Wild et al 2008;Perrotta et al 2018;Chen et al 2020). For example, by decomposing the observed ∼ 25000 narrow C iv absorbers within BOSS DR12 quasar spectra into several populations including outflows, Chen et al (2020) found that the majority of absorbers with blueshift velocities ∼ 1000 − 8000 km s −1 are from quasar outflows.…”

“…The narrow outflow absorbers (e.g, F W HM 700 km s −1 in the intermediate-resolution spectra) are found to be common for quasars in the statistic studies (Weymann et al 1979;Nestor et al 2008;Wild et al 2008;Perrotta et al 2018;Chen et al 2020). For example, by decomposing the observed ∼ 25000 narrow C iv absorbers within BOSS DR12 quasar spectra into several populations including outflows, Chen et al (2020) found that the majority of absorbers with blueshift velocities ∼ 1000 − 8000 km s −1 are from quasar outflows. The velocity of these narrow outflow absorbers could be up to ∼ −1.4×10 4 km s −1 (e.g., Wild et al 2008;Hamann et al 2011).…”