Abstract
We present ultraviolet to near infrared spectroscopic observations of the quasar SDSS J001514+184212 and its proximate molecular absorber atz = 2.631. The [O III] emission line of the quasar is composed of a broad (FWHM∼ 1600 km s−1), spatially unresolved component, blueshifted by about 600 km s−1from a narrow, spatially-resolved component (FWHM∼ 650 km s−1). The wide, blueshifted, unresolved component is consistent with the presence of outflowing gas in the nuclear region. The narrow component can be further decomposed into a blue and a red blob with a velocity width of several hundred km s−1each, seen ∼5 pkpc on opposite spatial locations from the nuclear continuum emission, indicating outflows on galactic scales. The presence of ionised gas on kpc scales is also seen from a weak C IVemission component, detected in the trough of a saturated C IVabsorption that removes the strong nuclear emission from the quasar. Towards the nuclear emission, we observe absorption lines from atomic species in various ionisation and excitation stages and confirm the presence of strong H2lines originally detected in the SDSS spectrum. The overall absorption profile is very wide, spread over ∼600 km s−1, and it roughly matches the velocities of the narrow blue [O III] blob. From a detailed investigation of the chemical and physical conditions in the absorbing gas, we infer densities of aboutnH ∼ 104 − 105cm−3in the cold (T ∼ 100 K) H2-bearing gas, which we find to be located at ∼10 kpc distances from the central UV source. We conjecture that we are witnessing different manifestations of a same AGN-driven multi-phase outflow, where approaching gas is intercepted by the line of sight to the nucleus. We corroborate this picture by modelling the scattering of Ly-αphotons from the central source through the outflowing gas, reproducing the peculiar Ly-αabsorption-emission profile, with a damped Ly-αabsorption in which red-peaked, spatially offset, and extended Ly-αemission is seen. Our observations open up a new way to investigate quasar outflows at high redshift and shed light on the complex issue of AGN feedback.
Highlights
Feedback from active galactic nuclei (AGN) is an essential element in modern models of galaxy formation and evolution (e.g., Silk & Rees 1998)
The most supportive evidence for AGN feedback is the presence of kiloparsecscale outflows, which result from the propagation of energy and momentum from accretion disc winds to the host galaxy
Taking systematic uncertainties due to variations in the intrinsic quasar shape into account, we found a best-fit solution of A(V) = 0.4 ± 0.1 mag, Fe2 = 0.5 ± 0.2, Fe3 = −1.5 ± 0.5, c3 = 0.7 ± 0.1, where A(V) is the amount of extinction and Fe2 and Fe3 multiplicative factors parametrising the strengths of the Fe ii and Fe iii lines with respect to the template
Summary
Feedback from active galactic nuclei (AGN) is an essential element in modern models of galaxy formation and evolution (e.g., Silk & Rees 1998) It may quench star formation (e.g., Zubovas & King 2012; Pontzen et al 2017; Terrazas et al 2020), impact galaxy morphology (Dubois et al 2016), regulate the growth of the supermassive black holes (Volonteri et al 2016), and so on. Outflows have been observed in unobscured, luminous AGN (Type 1 quasars), but mostly at low redshift, such as the well-known Mrk 231 at z = 0.04 (Rupke & Veilleux 2011; Feruglio et al 2015). Observational constraints on hot and cold outflows in high-redshift Type 1 quasars are much harder to obtain, because of the dimming of the light, and because the coarser angular resolution impedes observations close to the bright nucleus
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