Probing the Inner Circumgalactic Medium and Quasar Illumination around the Reddest `Extremely Red Quasar' (ERQ)

Abstract

Dusty quasars might be in a young stage of galaxy evolution with prominent quasar feedback. We study a population of luminous, extremely red quasars at redshifts 𝑧 ∼ 2-4 that has a suite of extreme spectral properties that may all be related to exceptionally powerful quasar-driven outflows. We present Keck/KCWI observations of the reddest known ERQ, at 𝑧 = 2.3184, with an extremely fast [O ] 𝜆5007 outflow at ∼6000 km s −1 . The Ly𝛼 halo spans ∼100 kpc. The halo is kinematically quiet, with velocity dispersion ∼300 km s −1 and no broadening above the dark matter circular velocity down to the spatial resolution ∼6 kpc from the quasar. We detect spatially-resolved He 𝜆1640 and C 𝜆1549 emissions with kinematics similar to the Ly𝛼 halo and a narrow component in the [O ] 𝜆5007. Quasar reddening acts as a coronagraph allowing views of the innermost halo. A narrow Ly𝛼 spike in the quasar spectrum is inner halo emission, confirming the broad C 𝜆1549 in the unresolved quasar is blueshifted by 2242 km s −1 relative to the halo frame. We propose the inner halo is dominated by past/moderate-speed outflow and the outer halo dominated by inflow. The high central concentration of the surface brightness and the circularly symmetric morphology of the inner halo are consistent with the ERQ being young. The He 𝜆1640/Ly𝛼 ratio of the inner halo and the asymmetry level of the overall halo are dissimilar to Type II quasars, implying central ionizing photons can escape along the line of sight. While quasar dominates the ionization, we find no evidence of mechanical quasar feedback on circumgalactic scales.

The Active Galactic Nuclei in the Hobby–Eberly Telescope Dark Energy Experiment Survey (HETDEX). II. Luminosity Function

“…Besides J1150+5048, we found that other high EW AGN in our catalog are all narrow-line AGN with FWHM ∼ 1000 km s −1 , corresponding to the velocity dispersion of ∼ 400 km s −1 . Lau et al (2022) also found that the Lyα halo of the ERQ they studied is kinematically quiet with the velocity dispersion of ∼ 300 km s −1 .…”

“…Unfortunately, the C III] λ1909 emission is out of the HETDEX wavelength range. Lau et al (2022) suggested that the the ionization parameter can be assumed to be lg U ∼ −1. The C IV λ1549/He II λ1640 ratio of ∼ 1 in at the Lyα density peak (shown by the cyan circle) would suggest a metallicity of ∼ Z .…”

“…Spatially extended ionized gas and powerful outflow winds have been observed in a few high-redshift obscured quasars (Cai et al 2017;Fluetsch et al 2021;Vayner et al 2021;Lau et al 2022). These sources were pre-identified in large surveys and followed-up with hours of observation time for spatially resolved spectra on the Large Binocular Telescope/Medium-Dispersion Grating Spectroscopy, Keck/Keck Cosmic Web Imager, Very Large Telescope/Multi Unit Spectroscopic Explorer, etc.…”

The Pathfinder Dragonfly Spectral Line Mapper: pushing the limits for ultra-low surface brightness spectroscopy

“…4 In the past decade, integral field units with spectroscopic capability have discovered an abundance of extragalactic gaseous structures, including gaseous bridges between galaxies and quasars, 5,6 enormous hundreds-of-kpc-sized gas clouds, 7,8 and extensive gaseous haloes detected in a variety of emission lines including Lyα, [Oii], and Mg ii. [9][10][11][12] These techniques work well for medium to high redshift observations, where bright UV lines such as the Lyα λ1216 and Mg ii λ2796, 2803 emission lines are redshifted into the visible wavelength regime and where the 1 arcmin 2 fields of view of these instruments can cover an appreciable area around the targeted galaxies. In the local universe, though, the bright UV emission lines are not accessible from the ground and while visible wavelength emission lines such as Hα and [Oiii] are accessible, they are an order of magnitude fainter, requiring sensitivity to surface brightnesses down to ∼ 10 −20 erg cm −2 s −1 arcsec −2 to detect.…”