Outflows from AGNs: a brief overview of observations and models

Everett, J. E.

doi:10.1007/s10509-007-9536-2

Cited by 27 publications

(25 citation statements)

References 49 publications

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“…Mechanisms for producing such an outflow include radiation pressure acting on gas and dust (Everett 2007) or a hot wind that entrains the NLR clouds (Everett & Murray 2007). A potential problem with this scenario is the difficulty of the winds extending to typical NLR scales in order to affect the whole NLR.…”

Section: Accretion Disk Outflowsmentioning

confidence: 99%

“…Models for this alignment include reflection of the AGN emission (Tadhunter et al 1988), jet-induced star formation (De Young 1981), inverse Compton scattering of cosmic microwave background photons off the relativistic electrons in the radio jet (Daly 1992), material out-flowing from an accretion disk or entrained in a radio jet (Holt et al 2003(Holt et al , 2008Komossa et al 2008a), as well as a combination of shocks and photoionization by the central engine (Maxfield et al 2002). There is an extensive literature on the spatially extended, kinematically complex NLRs of powerful radio galaxies (van Ojik et al 1996;Villar-Martín et al 2000, 2007, 2010Zirm et al 2005;Nesvadba et al 2006). Though radio galaxy NLRs often appear vaguely reminiscent of dual AGN candidates, multiple AGNs are rarely suggested as possible interpretations of the complex radio galaxy NLRs.…”

Section: Introductionmentioning

confidence: 99%

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A CANDIDATE DUAL ACTIVE GALACTIC NUCLEUS ATz= 1.175

Barrows

Stern

Madsen

et al. 2011

ApJ

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The X-ray source CXOXBJ142607.6+353351 (CXOJ1426+35), which was identified in a 172 ks Chandra image in the Boötes field, shows double-peaked rest-frame optical/UV emission lines, separated by 0. 69 (5.5 kpc) in the spatial dimension and by 690 km s −1 in the velocity dimension. The high excitation lines and emission line ratios indicate both systems are ionized by an active galactic nucleus (AGN) continuum, and the double-peaked profile resembles that of candidate dual AGNs. At a redshift of z = 1.175, this source is the highest redshift candidate dual AGN yet identified. However, many sources have similar emission line profiles for which other interpretations are favored. We have analyzed the substantial archival data available in this field as well as acquired near-infrared (NIR) adaptive optics (AO) imaging and NIR slit spectroscopy. The X-ray spectrum is hard, implying a column density of several 10 23 cm −2 . Though heavily obscured, the source is also one of the brightest in the field, with an absorption-corrected 2-10 keV luminosity of ∼10 45 erg s −1 . Outflows driven by an accretion disk may produce the double-peaked lines if the central engine accretes near the Eddington limit. However, we may be seeing the narrow line regions of two AGNs following a galactic merger. While the AO image reveals only a single source, a second AGN would easily be obscured by the significant extinction inferred from the X-ray data. Understanding the physical processes producing the complex emission line profiles seen in CXOJ1426+35 and related sources is important for interpreting the growing population of dual AGN candidates.

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Section: Accretion Disk Outflowsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A CANDIDATE DUAL ACTIVE GALACTIC NUCLEUS ATz= 1.175

Barrows

Stern

Madsen

et al. 2011

ApJ

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“…A strong manifestation of AGN feedback are AGN outflows observed in a wide variety of forms (reviews by Crenshaw, Kraemer & George 2003;Everett 2007). Some examples are: blue-shifted broad absorption lines in the ultraviolet and optical (Reichard et al 2003;Rupke & Veilleux 2011), warm absorbers (Chartas, Brandt & Gallagher 2003;Krongold et al 2007) and ultra-fast outflows in X-rays (Tombesi et al 2013(Tombesi et al , 2015, molecular outflows and atomic outflows detected in the IR, sub-millimetre and millimetre wavelengths (Sturm et al 2011;Cicone et al 2014;Dasyra et al 2015;Feruglio et al 2015;Morganti et al 2016), ionized gas in rest-frame optical (Kakkad et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Quasar outflows at z ≥ 6: the impact on the host galaxies

Barai

Gallerani

Pallottini

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We investigate quasar outflows at z 6 by performing zoom-in cosmological hydrodynamical simulations. By employing the SPH code GADGET-3, we zoom in the 2R 200 region around a 2×1012 M ⊙ halo at z = 6, inside a (500 Mpc) 3 comoving volume. We compare the results of our AGN runs with a control simulation in which only stellar/SN feedback is considered. Seeding 10 5 M ⊙ BHs at the centers of 10 9 M ⊙ halos, we find the following results. BHs accrete gas at the Eddington rate over z = 9 − 6. At z = 6, our most-massive BH has grown to M BH = 4 × 10 9 M ⊙ . Fast (v r > 1000 km/s), powerful (Ṁ out ∼ 2000M ⊙ /yr) outflows of shock-heated low-density gas form at z ∼ 7, and propagate up to hundreds kpc. Star-formation is quenched over z = 8 − 6, and the total SFR (SFR surface density near the galaxy center) is reduced by a factor of 5 (1000). We analyse the relative contribution of multiple physical process: (i) disrupting cosmic filamentary cold gas inflows, (ii) reducing central gas density, (iii) ejecting gas outside the galaxy; and find that AGN feedback has the following effects at z = 6. The inflowing gas mass fraction is reduced by ∼ 12%, the high-density gas fraction is lowered by ∼ 13%, and ∼ 20% of the gas outflows at a speed larger than the escape velocity (500 km/s). We conclude that quasar-host galaxies at z 6 are accreting non-negligible amount of cosmic gas, nevertheless AGN feedback quenches their star formation dominantly by powerful outflows ejecting gas out of the host galaxy halo.

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“…High ionization lines (HILs, most notably Civλ1549) have been found to show systematic blueshifts that can reach several thousands km s −1 with respect to the low-ionization lines (LILs) and to the best estimates of the rest frame of the host galaxy. Evidence of outflows is now considered overwhelming on small (1pc) and large (kpc) spatial scales [33,60,23]. On small scales compelling evidence is provided by blueshifted emission lines [39,64], blueshifted broad absorptions lines (BAL) observed in ≈ 10 % of QSOs [see 88, for a fully developed line of reasoning], as well as by blueshifted features belonging to the soft X warm absorber or to "ultra-fast outflows" [e.g., 11,123].…”

Section: Introductionmentioning

confidence: 99%

Low- and High-zHighly Accreting Quasars in the 4D Eigenvector 1 Context

Marziani¹,

Sulentic²,

Negrete³

et al. 2014

Astronomical Review

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Highly accreting quasars are characterized by distinguishing properties in the 4D eigenvector 1 parameter space that make them easily recognizable over a broad range range of redshift and luminosity. The 4D eigenvector 1 approach allows us to define selection criteria that go beyond the restriction to Narrow Line Seyfert 1s identified at low redshift. These criteria are probably able to isolate sources with a defined physical structure i.e., a geometrically thick, optically thick advectiondominated accretion disk (a "slim" disk). We stress that the importance of highly accreting quasars goes beyond the understanding of the details of their physics: their Eddington ratio is expected to saturate toward values of order unity, making them possible cosmological probes.

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Outflows from AGNs: a brief overview of observations and models

Abstract: Recent observations show that outflows from Active Galactic Nuclei are much more common than previously thought, with such outflows seen in various wavebands. I review the recent advances in observations of wind signatures and the progress in modelling various wind launching mechanisms.

Cited by 27 publications

References 49 publications

A CANDIDATE DUAL ACTIVE GALACTIC NUCLEUS ATz= 1.175

A CANDIDATE DUAL ACTIVE GALACTIC NUCLEUS ATz= 1.175

Quasar outflows at z ≥ 6: the impact on the host galaxies

Low- and High-zHighly Accreting Quasars in the 4D Eigenvector 1 Context

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