THE REDSHIFTED HYDROGEN BALMER AND METASTABLE He i ABSORPTION LINE SYSTEM IN MINI-FELOBAL QUASAR SDSS J112526.12+002901.3: A PARSEC-SCALE ACCRETION INFLOW?

Abstract

The accretion of interstellar medium onto the central super massive black holes is widely accepted as the source of the gigantic energy released by the active galactic nuclei. But few pieces of observational evidence have been confirmed directly demonstrating the existence of the inflows. The absorption line system in the spectra of quasar SDSS J112526.12+002901.3 presents an interesting example, in which the rarely detected hydrogen Balmer and metastable He I absorption lines are found redshifted to the quasar's rest frame along with the low-ionization metal absorption lines Mg II, Fe II, etc. The repeated SDSS spectroscopic observations suggest a transverse velocity smaller than the radial velocity. The motion of the absorbing medium is thus dominated by infall. The He I* lines present a powerful probe to the strength of ionizing flux, while the Balmer lines imply a dense environment. With the help of photoionization simulations, we find the absorbing medium is exposed to the radiation with ionization parameter U ≈ 10 −1.8 , and the density is n(H) ≈ 10 9 cm −3 . Thus the absorbing medium is located ∼ 4 pc away from the central engine. According to the similarity in the distance and physical conditions between the absorbing medium and the torus, we strongly propose the absorption line system as a candidate for the accretion inflow which originates from the inner surface of the torus.

On the emergence of thousands of absorption lines in the quasar PG 1411+442: a clumpy high-column density outflow from the broad emission-line region?

“…A similar situation occurs in the FeLoBAL quasar LBQS 0059−2735, where narrow absorption lines at low speeds 500 km s −1 identify high-density high-column density clumps that also appear gravitationally bound (Wampler et al 1995, Hamann et al, in prep.). Shi et al (2016b) report similar results for another FeLoBAL quasar. These gravitationally bound clumps might be the upper envelope of clumpy BLRs composed of material rising and falling above the accretion disk plane (Czerny & Hryniewicz 2011;Czerny et al 2016;Baskin & Laor 2018).…”

“…The only previous report of visible Fe ii* lines in an AGN spectrum was by Shi et al (2016b). The H i* Balmer and Na i D absorption lines are rare, but they have been measured in several AGN outflows including the Seyfert 1 galaxy NGC 4151 (Anderson & Kraft 1971;Hutchings et al 2002) and some FeLoBAL quasars (Boroson & Meyers 1992;Rupke et al 2002Rupke et al , 2005Hall et al 2002Hall et al , 2007Ji et al 2015;Zhang et al 2015a;Shi et al 2016b;Sun et al 2017). The Balmer lines were also measured in the transient absorber in PG 1411+442 by Shi et al (2017) Line identifications in the UV are much more difficult due to line blending.…”

Fast Inflow Directly Feeding Black Hole Accretion Disk in Quasars

“…3, we present seven additional objects manifesting redshifted BALs or mini-BALs for H I Balmer and He I* absorptions, besides J1035+1422. One of the mini-BAL systems, the H I Balmer and He I* absorption system in J1125+0029, has been scrutinized and confirmed to be a parsec-scale inflow [10], even though we could not confirm if the inflow can go further into the center to directly feed the accretion disk around the the central SMBH. This is because that the H I Balmer and He I* absorption only trace the intermediate-to low-ionization and neutral regions in the absorbing medium.…”

“…Nevertheless, it is not yet clear to connect them to disk-feeding inflows, given the large uncertainties in the quasar systemic redshifts (several times 10 2−3 km s −1 , as estimated from high-ionization broad emission lines) and a lacking of other evidence. In fact, metal BALs are of little diagnostic value in probing cold and dense gas with high column densities (subject to serious saturation and line blending effects; see Method for details), which are thought to be most probably the case of disk-feeding inflows [10], if existing. Motivated by the fundamental questions above, we have developed a novel approach to diagnosing dense BAL gas of high column densities and low/moderate ionization, based on extensive studies of our own [11][12][13][14][15] and other teams [16,17].…”

Correlation between the ionizing continuum and the variable C iv broad absorption line in multi-epoch observations of SDSS J141007.74+541203.3

“…The reason for the variations of BAL with time is generally considered to be the transverse motion of the gas (e.g. Hamann et al 2008;Shi et al 2016;Hemler et al 2019) or the ionization variation of the outflowing gas (e.g. Grier et al 2015;Lu et al 2017;Lu et al 2018;Hemler et al 2019).…”