The Weak Absorbing Outflow in AGN Mrk 279: Evidence of Supersolar Metal Abundances

Fields, Dale L.; Mathur, S.; Krongold, Y.; Williams, R.; Nicastro, F.

doi:10.1086/520322

Cited by 32 publications

(34 citation statements)

References 35 publications

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“…values in quasars, Groves et al (2006) found that the narrow line regions had Z/Z ! ~2 -4, and Fields et al (2007) find evidence for Z/Z ! > 2 in a WA.…”

Section: Theoreticalmentioning

confidence: 98%

Quasar Rain: The Broad Emission Line Region as Condensations in the Warm Accretion Disk Wind

Elvis

2017

ApJ

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The origin of the broad emission line region (BELR) in quasars and active galactic nuclei is still unclear. I propose that condensations form in the warm, radiation pressure driven, accretion disk wind of quasars creating the BEL clouds and uniting them with the other two manifestations of cool (~10 4 K) gas in quasars, the low ionization phase of the warm absorbers (WAs) and the clouds causing X-ray eclipses. The cool clouds will condense quickly (days -years), before the WA outflows reach escape velocity (which takes months -centuries). Cool clouds form in equilibrium with the warm phase of the wind because the rapidly varying X-ray quasar continuum changes the force multiplier, causing pressure waves to move gas into stable locations in pressure-temperature space. The narrow range of 2-phase equilibrium densities may explain the (luminosity) 1/2 scaling of the BELR size, while the scaling of cloud formation timescales could produce the Baldwin effect. These dense clouds have force multipliers of order unity and so cannot be accelerated to escape velocity. They fall back on a dynamical timescale (monthscenturies), producing an inflow that rains down toward the central black hole. As they soon move at Mach ~10 -100 with respect to the WA outflow, these "raindrops" will be rapidly destroyed within months. This rain of clouds may produce the elliptical BELR orbits implied by velocity resolved reverberation mapping in some objects, and can explain the opening angle and destruction timescale of the narrow "cometary" tails of the clouds seen in X-ray eclipse observations. Some consequences and challenges of this "quasar rain" model are presented along with several avenues for theoretical investigation.

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“…values in quasars, Groves et al (2006) found that the narrow line regions had Z/Z ! ~2 -4, and Fields et al (2007) find evidence for Z/Z ! > 2 in a WA.…”

Section: Theoreticalmentioning

confidence: 98%

Quasar Rain: The Broad Emission Line Region as Condensations in the Warm Accretion Disk Wind

Elvis

2017

ApJ

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“…However, Fields et al (2007) found evidence for the presence of different layers of highly ionized absorbing material from the spectral analysis of the soft X-ray Chandra LETG data. The associated column densities are low, of the order of N H ∼ 10 20 cm −2 , and the outflow velocities are of few ∼1000 km s −1 .…”

Section: Appendix B: Notes On Single Sourcesmentioning

confidence: 99%

Evidence for ultra-fast outflows in radio-quiet AGNs

Tombesi

Cappi²,

Reeves

et al. 2010

A&A

645

750

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Context. Blue-shifted Fe K absorption lines have been detected in recent years between 7 and 10 keV in the X-ray spectra of several radio-quiet AGNs. The derived blue-shifted velocities of the lines can often reach mildly relativistic values, up to 0.2-0.4c. These findings are important because they suggest the presence of a previously unknown massive and highly ionized absorbing material outflowing from their nuclei, possibly connected with accretion disk winds/outflows. Aims. The scope of the present work is to statistically quantify the parameters and incidence of the blue-shifted Fe K absorption lines through a uniform analysis on a large sample of radio-quiet AGNs. This allows us to assess their global detection significance and to overcome any possible publication bias. Methods. We performed a blind search for narrow absorption features at energies greater than 6.4 keV in a sample of 42 radio-quiet AGNs observed with XMM-Newton. A simple uniform model composed by an absorbed power-law plus Gaussian emission and absorption lines provided a good fit for all the data sets. We derived the absorption lines parameters and calculated their detailed detection significance making use of the classical F-test and extensive Monte Carlo simulations. Results. We detect 36 narrow absorption lines on a total of 101 XMM-Newton EPIC pn observations. The number of absorption lines at rest-frame energies higher than 7 keV is 22. Their global probability to be generated by random fluctuations is very low, less than 3 × 10 −8 , and their detection have been independently confirmed by a spectral analysis of the MOS data, with associated random probability <10 −7 . We identify the lines as Fe XXV and Fe XXVI K-shell resonant absorption. They are systematically blue-shifted, with a velocity distribution ranging from zero up to ∼0.3c, with a peak and mean value at ∼0.1c. We detect variability of the lines on both EWs and blue-shifted velocities among different XMM-Newton observations even on time-scales as short as a few days, possibly suggesting somewhat compact absorbers. Moreover, we find no significant correlation between the cosmological red-shifts of the sources and the lines blue-shifted velocities, ruling out any systematic contamination by local absorption. If we define ultra-fast outflows (UFOs) those highly ionized absorbers with outflow velocities higher than 10 4 km s −1 , then the majority of the lines are consistent with being associated to UFOs and the fraction of objects with detected UFOs in the whole sample is at least ∼35%. This fraction is similar for type 1 and type 2 sources. The global covering fraction of the absorbers is consequently estimated to be in the range C ∼ 0.4−0.6, thereby implying large opening angles. Conclusions. From our systematic X-ray spectral analysis on a large sample of radio-quiet AGNs we have been able to clearly assess the global veracity of the blue-shifted Fe K absorption lines at E > 7 keV and to overcome their publication bias. These lines indicate that UFOs are a rather ...

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“…These lines also appear to be observed in the RGS (Smith et al 2008) and the HETGS (Matsumoto et al 2004) spectra of Ark 564. If the ionized gas has solar abundances, oxygen absorption features are expected and have been detected in several AGNs with warm absorbers (e.g., Kaastra et al 2000;Sako et al 2001;Lee et al 2001;Blustin et al 2003;Krongold et al 2003;Netzer et al 2003;Fields et al 2007;Costantini et al 2007;Krongold et al 2007). However, only a few of them have well-measured column densities.…”

Section: High-resolution Spectral Analysismentioning

confidence: 99%

ChandraLETGS observation of the variable NLS1 galaxy Ark 564

Ramírez

2013

A&A

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We present an analysis of the 100 ks X-ray spectrum of the narrow-line Seyfert 1 Galaxy Ark 564, taken with the Low Energy Transmission Grating Spectrometer (LETGS) on board Chandra. Using χ 2 statistics, several continuum models of the time-averaged spectrum of this object are compared, obtaining a semi-empirical solution for the description of the intrinsic emission continuum and a physical solution for the intrinsic absorption of the system. We find that the 0.1−10 keV spectrum can be well described by a power law plus two thermal components that account for the soft step. We are also able to detect and measure several narrow, unresolved absorption lines arising from highly ionized species of C, N, O, and Fe. The material seems to have a velocity consistent with the systemic velocity of the galaxy. This piece of evidence, in addition to the very low observed column density of N H ∼ 10 20 cm −2 , is in good agreement with the scenario of a transverse biconical outflow with a gas density of n 3 × 10 12 cm −3 at distances beyond the broad-line region r 10 lt-days, but a dust torus origin cannot be ruled out.

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The Weak Absorbing Outflow in AGN Mrk 279: Evidence of Supersolar Metal Abundances

Cited by 32 publications

References 35 publications

Quasar Rain: The Broad Emission Line Region as Condensations in the Warm Accretion Disk Wind

Quasar Rain: The Broad Emission Line Region as Condensations in the Warm Accretion Disk Wind

Evidence for ultra-fast outflows in radio-quiet AGNs

ChandraLETGS observation of the variable NLS1 galaxy Ark 564

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