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 catalog 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 color, 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-W 3 ≥ 4.6 (AB) and REW(C iv) ≥ 100Å 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) ∼ 47.1, sky density 0.010 deg −2 , surprisingly flat/blue UV spectra given their red UV-to-mid-IR colors, 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.

First Spectroscopic Confirmations of z ∼ 7.0 Lyα Emitting Galaxies in the LAGER Survey

“…We identify it as N vλ1239 line at the same redshift of Lyα (z = 6.925) 2 , with a 3σ upper limit of ∼ 130 km/s to the potential velocity shift between Lyα and N v. We fit the line with a Gaussian and derive a flux of 1.13±0.34×10 −17 erg s −1 cm −2 , corresponding to a N v/Lyα line ratio of 1.33±0.50. Note Hamann et al (2017) presents an extreme red quasar population which exhibits similarly large N v/Lyα ratios at z ∼ 2 − 3.4. Tilvi et al (2016) also shows a tentative N v line with N v/Lyα line ratio of 0.85±0.25 in a z = 7.512 LBG.…”

Luminous WISE-selected Obscured, Unobscured, and Red Quasars in Stripe 82∗

“…We note that while SDSS is highly effective at finding blue Type-1 AGNs, ∼35% of obscured sources (both Type-2 and red Type-1) are missed by SDSS and recovered in this work. This is crucial, as many red quasar studies have been conducted out of the SDSS spectroscopic sample, noting unusual and extreme properties of the red quasars found therein (e.g., Richards et al 2003;Ross et al 2015;Hamann et al 2017;Tsai & Hwang 2017). Those obscured sources are likely just the tip of a population that may be significantly larger.…”

Ionized Gas Outflows in Infrared-bright Dust-obscured Galaxies Selected with WISE and SDSS

“…The IR luminosities of the 36 IR-bright DOG sample are log L IR [L ⊙ ] = 10.5 -13.1, and 25/36 (∼ 69 %) objects are classified as ULIRGs/HyLIRGs (see Table 1). Recently some authors have discovered many (obscured) ULIRGs/HyLIRGs based on the SDSS and WISE data and reported powerful ionized outflows seen in their spectra (Ross et al 2015;Zakamska et al 2016;Bischetti et al 2017;Hamann et al 2017;Zhang et al 2017), although they basically focus on high-z (z > 2) objects.…”

“…Since SEABASs outputs stellar mass (M * ) and we measured [O iii] and Hβ line flux, we here investigate where IR-bright DOGs lie in the MEx diagram. Note the our estimate based on this method have an uncertainty because we did not take into account the influence from the scattered light by AGNs (see also Hamann et al 2017;Toba et al 2017b). We also note that we excluded DOGs classified as type 1 AGN (see Section 2) in this analysis because MEx diagram is optimized for galaxies/AGNs with narrow line emission.…”