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The Rise of an Ionized Wind in the Narrow-line Seyfert 1 Galaxy Mrk 335 Observed by XMM-Newton and HST
We present the discovery of an outflowing ionized wind in the Seyfert 1galaxy Mrk 335. Despite having been extensively observed by most of thelargest X-ray observatories in the last decade, this bright source wasnot known to host warm absorber gas until recent XMM-Newton observationsin combination with a long-term Swift monitoring program have shownextreme flux and spectral variability. High-resolution spectra obtainedby the XMM-Newton Reflection Grating Spectrometer (RGS) detector revealthat the wind consists of three distinct ionization components, alloutflowing at a velocity of ~5000 km s-1. This wind isclearly revealed when the source is observed at an intermediate fluxstate (2-5 × 10-12 erg cm-2s-1). The analysis of multi-epoch RGS spectra allowedus to compare the absorber properties at three very different fluxstates of the source. No correlation between the warm absorbervariability and the X-ray flux has been determined. The two higherionization components of the gas (log ξ ~ 2.3 and 3.3) may beconsistent with photoionization equilibrium, but we can exclude this forthe only ionization component that is consistently present in all fluxstates (log ξ ~ 1.8). We have included archival, non-simultaneous UVdata from Hubble Space Telescope (FOS, STIS, COS) with the aim ofsearching for any signature of absorption in this source that so far wasknown for being absorption-free in the UV band. In the Cosmic OriginsSpectrograph (COS) spectra obtained a few months after the X-rayobservations, we found broad absorption in C IV lines intrinsic to theactive galactic nucleus and blueshifted by a velocity roughly comparableto the X-ray outflow. The global behavior of the gas in both bands canbe explained by variation of the covering factor and/or column density,possibly due to transverse motion of absorbing clouds moving out of theline of sight at broad line region scale.
| On the Fate of the Matter Reinserted within Young Nuclear Stellar Clusters
This paper presents a hydrodynamical model describing the evolution ofthe gas reinserted by stars within a rotating young nuclear star cluster(NSC). We explicitly consider the impact of the stellar component on theflow by means of a uniform insertion of mass and energy within thestellar cluster. The model includes the gravity force of the stellarcomponent and a central supermassive black hole (SMBH), and accounts forthe heating from the central source of radiation and the radiativecooling of the thermalized gas. By using a set of parameters typical forNSCs and SMBHs in Seyfert galaxies, our simulations show that afilamentary/clumpy structure is formed in the inner part of the cluster.This "torus" is Compton-thick and covers a large fraction of the sky (asseen from the SMBH). In the outer parts of the cluster a powerful windis produced that inhibits the infall of matter from larger scales andthus the NSC-SMBH interplay occurs in isolation.
| Fluctuations of the intergalactic ionization field at redshift z ~ 2
Aims: To probe the spectral energy distribution (SED) of theionizing background radiation at z ≲ 2 and to specify the sourcescontributing to the intergalactic radiation field. Methods: Thespectrum of a bright quasar HS 1103+6416(zem = 2.19) contains five successive metal-line absorptionsystems at zabs = 1.1923, 1.7193, 1.8873, 1.8916, and 1.9410.The systems are optically thin and reveal multiple lines of differentmetal ions with the ionization potentials lying in the extremeultraviolet (EUV) range (~1 Ryd to ~0.2 keV). For each system, the EUVSED of the underlying ionization field is reconstructed by means of aspecial technique developed for solving the inverse problem inspectroscopy. For the zabs = 1.8916 system, the analysis alsoinvolves the He I resonance lines of the Lyman series and the Heiλ504 Å continuum, which are seen for the first time in anycosmic object except the Sun. Results: From one system toanother, the SED of the ionizing continuum changes significantly,indicating that the intergalactic ionization field at z ≲ 2fluctuates at the scale of at least Δz ~ 0.004. This isconsistent with Δz ≲ 0.01 estimated from He II andH I Lyman-α forest measurements between the redshifts 2 and 3. Aradiation intensity break by approximately an order of magnitude at E =4 Ryd in SEDs restored for the zabs = 1.1923, 1.8873, 1.8916,and 1.9410 systems points to quasars as the main sources of the ionizingradiation. The SED variability is mostly caused by a small number ofobjects contributing at any given redshift to the ionizing background;at scales Δz ≳ 0.05, the influence of localradiation sources becomes significant. A remarkable SED restored for thezabs = 1.7193 system, with a sharp break shifted to E ~ 3.5Ryd and a subsequent intensity decrease by ~1.5 dex, indicates a sourcewith comparable inputs of both hard (active galactic nuclei, AGN) andsoft (stellar) radiation components. Such a continuum can be emitted by(ultra) luminous infrared galaxies, many of which reveal both a strongAGN activity and intense star formation in the circumnuclear regions.
| The Structure of the Broad-line Region in Active Galactic Nuclei. I. Reconstructed Velocity-delay Maps
We present velocity-resolved reverberation results for five activegalactic nuclei. We recovered velocity-delay maps using the maximumentropy method for four objects: Mrk 335, Mrk 1501, 3C 120, and PG2130+099. For the fifth, Mrk 6, we were only able to measure mean timedelays in different velocity bins of the Hβ emission line. The fourvelocity-delay maps show unique dynamical signatures for each object.For 3C 120, the Balmer lines show kinematic signatures consistent withboth an inclined disk and infalling gas, but the He II λ4686emission line is suggestive only of inflow. The Balmer lines in Mrk 335,Mrk 1501, and PG 2130+099 show signs of infalling gas, but the He IIemission in Mrk 335 is consistent with an inclined disk. We also seetentative evidence of combined virial motion and infalling gas from thevelocity-binned analysis of Mrk 6. The maps for 3C 120 and Mrk 335 aretwo of the most clearly defined velocity-delay maps to date. These mapsconstitute a large increase in the number of objects for which we haveresolved velocity-delay maps and provide evidence supporting thereliability of reverberation-based black hole mass measurements.
| Characterizing the Circumgalactic Medium of Nearby Galaxies with HST/COS and HST/STIS Absorption-line Spectroscopy
The circumgalactic medium (CGM) of late-type galaxies is characterizedusing UV spectroscopy of 11 targeted QSO/galaxy pairs at z <= 0.02with the Hubble Space Telescope Cosmic Origins Spectrograph (COS) and~60 serendipitous absorber/galaxy pairs at z <= 0.2 with the SpaceTelescope Imaging Spectrograph. CGM warm cloud properties are derived,including volume filling factors of 3%-5%, cloud sizes of 0.1-30 kpc,masses of 10-108 M &sun;, and metallicities of~0.1-1 Z &sun;. Almost all warm CGM clouds within 0.5 Rvir are metal-bearing and many have velocities consistentwith being bound, "galactic fountain" clouds. For galaxies with L >~0.1 L*, the total mass in these warm CGM clouds approaches1010 M &sun;, ~10%-15% of the total baryons inmassive spirals and comparable to the baryons in their parent galaxydisks. This leaves >~ 50% of massive spiral-galaxy baryons "missing."Dwarfs (<0.1 L*) have smaller area covering factors and warm CGMmasses (<=5% baryon fraction), suggesting that many of their warmclouds escape. Constant warm cloud internal pressures as a function ofimpact parameter (P/k ~ 10 cm–3 K) support theinference that previous COS detections of broad, shallow O VI andLyα absorptions are of an extensive (~400-600 kpc), hot (T ≈106 K), intra-cloud gas which is very massive(>=1011 M &sun;). While the warm CGM cloudscannot account for all the "missing baryons" in spirals, the hotintra-group gas can, and could account for ~20% of the cosmic baryoncensus at z ~ 0 if this hot gas is ubiquitous among spiral groups.Based on observations with the NASA/ESA Hubble Space Telescope, obtainedat the Space Telescope Science Institute, which is operated by AURA,Inc., under NASA contract NAS 5-26555.
| Variability and the X-ray/UV ratio of active galactic nuclei. II. Analysis of a low-redshift Swift sample
Context. Variability, both in X-ray and optical/UV, affects thewell-known anti-correlation between the αox spectralindex and the UV luminosity of active galactic nuclei, contributing partof the dispersion around the average correlation (intra-sourcedispersion) in addition to the differences among the time-averageαox values from source to source (inter-sourcedispersion). Aims: We aim to evaluate the intrinsicαox variations in individual objects and their effecton the dispersion of the αox - LUVanti-correlation. Methods: We used simultaneous UV/X-ray datafrom Swift observations of a low-redshift sample to derive theepoch-dependent αox(t) indices. We corrected for thehost galaxy contribution by a spectral fit of the optical/UV data. Wecomputed ensemble structure functions to analyse the variability ofmulti-epoch data. Results: We find a strong intrinsicαox variability, which significantly contributes (~40%of the total variance) to the dispersion of the αox -LUV anti-correlation (intra-source dispersion). The strongX-ray variability and weaker UV variability of this sample arecomparable to other samples of low-z active galactic nuclei, and areneither caused by the high fraction of strongly variable narrow lineSeyfert 1 galaxies, nor by dilution of the optical variability by thehost galaxies. Dilution instead affects the slope of theanti-correlation, which steepens, once corrected, and becomes similar tohigher luminosity sources. The structure function ofαox increases with the time lag up to about one month.This indicates the important contribution of the intermediate-to-longtimescale variations, which are possibly generated in the outer parts ofthe accretion disk.Table 1 is available in electronic form at http://www.aanda.org
| A blurred reflection interpretation for the intermediate flux state in Mrk 335
As part of a long-term monitoring campaign of Mrk 335, deep XMM-Newtonobservations catch the narrow-line Seyfert 1 galaxy (NLS1) in a complex,intermediate flux interval as the active galaxy is transiting from lowto high flux. Other works on these same data examined the generalbehaviour of the NLS1 and the conditions of its warm absorber. Theanalysis presented here demonstrates the X-ray continuum and timingproperties can be described in a self-consistent manner adopting ablurred reflection model without any need to invoke partial covering.The rapid spectral variability appears to be driven by changes in theshape of the primary emitter that is illuminating the inner accretiondisc around a rapidly spinning black hole (a > 0.7). While lightbending is certainly prominent, the rather constant emissivity profileand break radius obtained in our spectral fitting suggest that theblurring parameters do not change as would be expected if the primarysource varies its distance from the disc. Instead changes could beintrinsic to the power-law component. One possibility is that materialin an unresolved jet above the disc falls to combine with material atthe base of the jet producing the changes in the primary emitter(spectral slope and flux) without changing its distance from the disc.
| The Chemical Properties of Low-redshift QSOs
We investigate the chemical properties of low-z QSOs, using archival UVspectra obtained with the Hubble Space Telescope and InternationalUltraviolet Explorer for a sample of 70 Palomar-Green QSOs at z <0.5. By utilizing the flux ratios of UV emission lines (i.e., N V/C IV,(Si IV+O IV])/C IV, and N V/He II) as metallicity indicators, we comparebroad-line region (BLR) gas metallicity with active galactic nucleus(AGN) properties, i.e., black hole (BH) mass, luminosity, and Eddingtonratio. We find that BLR metallicity correlates with Eddington ratiowhile the dependency on BH mass is much weaker. Although these trends oflow-z AGNs appear to be different from those of high-z QSOs, thedifference between low-z and high-z samples is partly caused by thelimited dynamical range of the samples. We find that metal enrichment atthe center of galaxies is closely connected to the accretion activity ofBHs and that the scatter of metallicity correlations with BH massincreases over cosmic time.
| The Global Implications of the Hard X-Ray Excess in Type 1 Active Galactic Nuclei
Recent evidence for a strong "hard excess" of flux at energies >~ 20keV in some Suzaku observations of type 1 active galactic nuclei (AGNs)has motivated an exploratory study of the phenomenon in the local type 1AGN population. We have selected all type 1 AGNs in the Swift BurstAlert Telescope 58 month catalog and cross-correlated them with theholdings of the Suzaku public archive. We find the hard excessphenomenon to be a ubiquitous property of type 1 AGNs. Taken together,the spectral hardness and equivalent width of Fe Kα emission areconsistent with reprocessing by an ensemble of Compton-thick clouds thatpartially cover the continuum source. In the context of such a model,~80% of the sample has a hardness ratio consistent with >50% coveringof the continuum by low-ionization, Compton-thick gas. A more detailedstudy of the three hardest X-ray spectra in our sample reveal a sharp FeK absorption edge at ~7 keV in each of them, indicating that blurredreflection is not responsible for the very hard spectral forms. Simpleconsiderations place the distribution of Compton-thick clouds at orwithin the optical broad-line region.
| Infrared Classification and Luminosities for Dusty Active Galactic Nuclei and the Most Luminous Quasars
Mid-infrared spectroscopic measurements from the Infrared Spectrometer(IRS) on Spitzer are given for 125 hard X-ray active galactic nuclei(AGNs; 14-195 keV) from the Swift Burst Alert Telescope (BAT) sample andfor 32 AGNs with black hole masses (BHMs) from reverberation mapping.The 9.7 μm silicate feature in emission or absorption defines aninfrared AGN classification describing whether AGNs are observed throughdust clouds, indicating that 55% of the BAT AGNs are observed throughdust. The mid-infrared dust continuum luminosity is shown to be anexcellent indicator of intrinsic AGN luminosity, scaling closely withthe hard X-ray luminosity, log νL ν(7.8 μm)/L(X) =-0.31 ± 0.35, and independent of classification determinedfrom silicate emission or absorption. Dust luminosity scales closelywith BHM, log νL ν(7.8 μm) = (37.2 ± 0.5) +0.87 log BHM for luminosity in erg s-1 and BHM in M&sun;. The 100 most luminous type 1 quasars as measured inνL ν(7.8 μm) are found by comparing Sloan DigitalSky Survey (SDSS) optically discovered quasars with photometry at 22μm from the Wide-Field Infrared Survey Explorer (WISE), scaled torest frame 7.8 μm using an empirical template determined from IRSspectra. The most luminous SDSS/WISE quasars have the same maximuminfrared luminosities for all 1.5 < z < 5, reaching total infraredluminosity L IR = 1014.4 L &sun;.Comparing with dust-obscured galaxies from Spitzer and WISE surveys, wefind no evidence of hyperluminous obscured quasars whose maximuminfrared luminosities exceed the maximum infrared luminosities ofoptically discovered quasars. Bolometric luminosities L bolestimated from rest-frame optical or ultraviolet luminosities arecompared to L IR. For the local AGN, the median log LIR/L bol = -0.35, consistent with a coveringfactor of 45% for the absorbing dust clouds. For the SDSS/WISE quasars,the median log L IR/L bol = 0.1, with extremesindicating that ultraviolet-derived L bol can be seriouslyunderestimated even for type 1 quasars.
| A Suzaku survey of Fe K lines in Seyfert 1 active galactic nuclei
We construct full broad-band models in an analysis of Suzakuobservations of nearby Seyfert 1 active galactic nuclei (AGN) (z ≤0.2) with exposures >50 ks and with greater than 30 000 counts inorder to study their iron line profiles. This results in a sample of 46objects and 84 observations. After a full modelling of the broad-bandSuzaku and Swift-Burst Alert Telescope data (0.6-100 keV), we findcomplex warm absorption is present in 59 per cent of the objects in thissample which has a significant bearing upon the derived Fe K regionparameters. Meanwhile 35 per cent of the 46 objects require some degreeof high column density partial coverer in order to fully model the hardX-ray spectrum. We also find that a large number of the objects in thesample (22 per cent) require high velocity, high ionization outflows inthe Fe K region resulting from Fe XXV and Fe XXVI. A further four AGNfeature highly ionized Fe K absorbers consistent with zero outflowvelocity, making a total of 14/46 (30 per cent) AGN in this sampleshowing evidence for statistically significant absorption in the Fe Kregion.Narrow Fe Kα emission from distant material at 6.4 keV is found tobe almost ubiquitous in these AGN. Examining the 6-7 keV Fe K region wenote that narrow emission lines originating from Fe XXV at 6.63-6.70 keVand from Fe XXVI at 6.97 keV are present in 52 and 39 per cent ofobjects, respectively.Our results suggest statistically significant relativistic Fe Kαemission is detected in 23 of 46 objects (50 per cent) at >99.5 percent confidence, measuring an average emissivity index of q = 2.4± 0.1 and equivalent width ( EW )=96±10 eV using theRELLINE model. When parametrized with a Gaussian we find an average lineenergy of 6.32 ± 0.04 keV, σwidth = 0.470± 0.05 keV and EW =97±19 eV. Where we can placeconstraints upon the black hole spin parameter a, we do not require amaximally spinning black hole in all cases.
| Constraints on Compton-thick Winds from Black Hole Accretion Disks: Can We See the Inner Disk?
Strong evidence is emerging that winds can be driven from the centralregions of accretion disks in both active galactic nuclei and Galacticblack hole binaries. Direct evidence for highly ionized, Compton-thininner-disk winds comes from observations of blueshifted (v ~ 0.05-0.1c)iron-K X-ray absorption lines. However, it has been suggested that theinner regions of black hole accretion disks can also drive Compton-thickwinds—such winds would enshroud the inner disk, preventing us fromseeing direct signatures of the accretion disk (i.e., the photosphericthermal emission, or the Doppler/gravitationally broadened iron Kαline). Here, we show that, provided the source is sub-Eddington, thewell-established wind-driving mechanisms fail to launch a Compton-thickwind from the inner disk. For the accelerated region of the wind to beCompton-thick, the momentum carried in the wind must exceed theavailable photon momentum by a factor of at least 2/λ, whereλ is the Eddington ratio of the source, ruling out radiativeacceleration unless the source is very close to the Eddington limit.Compton-thick winds also carry large mass fluxes, and a consideration ofthe connections between the wind and the disk shows this to beincompatible with magneto-centrifugal driving. Finally, thermal drivingof the wind is ruled out on the basis of the large Compton radii thattypify black hole systems. In the absence of some new accelerationmechanisms, we conclude that the inner regions of sub-Eddingtonaccretion disks around black holes are indeed naked.
| The Low-redshift Intergalactic Medium as Seen in Archival Legacy HST/STIS and FUSE Data
We present a comprehensive catalog of ultraviolet (HST/STIS and FUSE)absorbers in the low-redshift intergalactic medium (IGM) at z < 0.4.The catalog draws from much of the extensive literature on IGMabsorption and reconciles discrepancies among several previous catalogsthrough a critical evaluation of all reported absorption features inlight of new HST/COS data. We report on 746 H I absorbers down to arest-frame equivalent width of 12 mÅ over a maximum redshift pathlength Δz = 5.38. We also confirm 111 O VI absorbers, 29 C IVabsorbers, and numerous absorption lines due to other metal ions. Wecharacterize the bivariate distribution of absorbers in redshift andcolumn density as a power law, \left(\partial ^2 {N}/\partial z\partialN\right) \propto N^{-\beta }, where β = 2.08 ± 0.12 for O VIand β = 1.68 ± 0.03 for H I. Utilizing a more sophisticatedaccounting technique than past work, our catalog accounts for ~43% ofthe baryons: 24% ± 2% in the photoionized Lyα forest and19% ± 2% in the warm-hot IGM as traced by O VI. We discuss thelarge systematic effects of various assumed metallicities and ionizationstates on these calculations, and we implement recent simulation resultsin our estimates.Based on observations made with the NASA/ESA Hubble Space Telescope,obtained from the data archive at the Space Telescope Science Institute.STScI is operated by the Association of Universities for Research inAstronomy, Inc., under NASA contract NAS5-26555.
| NGC 2207/IC 2163: A Grazing Encounter with Large-scale Shocks
Radio continuum, Spitzer infrared, optical, and XMM-Newton X-ray andultraviolet observations (UVW1 and UVM2) are used to study large-scaleshock fronts, young star complexes, and the galactic nuclei in theinteracting galaxies NGC 2207/IC 2163. There are two types oflarge-scale shock fronts in this galaxy pair. The large-scale shockfront along the rim of the ocular oval in IC 2163 has produced vigorousstar formation in a dusty environment, bright in the Spitzer 8 μm and24 μm images. In the outer part of the companion side of NGC 2207, alarge-scale front attributed to halo scraping is particularly bright inthe λ6 cm and λ20 cm radio continuum but not in anytracers of recent star formation (Hα, 8 μm, 24 μm, orultraviolet emission) or in X-rays. This radio-continuum front may befrom compression of the halo magnetic field on the back side of NGC2207, between the two galaxies. The X-ray emission sets an upper limitto the gas density in the halo. Values of the flux density ratio Sν(8 μm)/S ν(6 cm) of prominent,kiloparsec-size, Spitzer/IRAC star-forming clumps in NGC 2207/IC 2163are compared with those of giant radio H II regions in M81. For thebright clumps in NGC 2207, the mean value of this ratio is the same asfor the M81 H II regions, whereas for the bright clumps on the rim ofthe IC 2163 ocular oval, the mean value is nearly a factor of twogreater. Possible explanations for this are discussed. The galaxy pairhas global values of the ratios of infrared-to-radio continuum fluxdensity in the Spitzer 8 μm, 24 μm, and 70 μm bands, and theIRAS FIR significantly below the medians/means for large samples ofgalaxies. Feature i, a mini-starburst on an outer arm of NGC 2207 on itsanti-companion side, is the most luminous 8 μm, 24 μm, 70 μm,radio continuum, and Hα source in the galaxy pair. We findevidence that a radio supernova was present in the core of feature i in2001. X-ray emission is detected from the nucleus of NGC 2207 and fromnine discrete sources whose X-ray luminosities make them possiblecandidates for Ultraluminous X-ray sources. One of these correspondswith the Type Ib SN 1999ec, which is also bright in the ultraviolet, andanother may be a radio supernova or a background quasar. The X-rayluminosity of the NGC 2207 nucleus is log L 0.3-10.0 keV =40.6 erg s-1, which, together with its X-ray spectrum,suggests that this is a highly absorbed, low-luminosity, active galacticnucleus.
| Optical Monitoring of the Broad-line Radio Galaxy 3C 390.3
We have undertaken a new ground-based monitoring campaign on thebroad-line radio galaxy 3C 390.3 to improve the measurement of the sizeof the broad emission-line region and to estimate the black hole mass.Optical spectra and g-band images were observed in late 2005 for threemonths using the 2.4 m telescope at MDM Observatory. Integratedemission-line flux variations were measured for the hydrogen Balmerlines Hα, Hβ, Hγ, and for the helium line HeIIλ4686, as well as g-band fluxes and the optical active galacticnucleus (AGN) continuum at λ = 5100 Å. The g-band fluxesand the optical AGN continuum vary simultaneously within theuncertainties, τcent = (0.2 ± 1.1) days. We findthat the emission-line variations are delayed with respect to thevariable g-band continuum by τ(Hα) = 56.3+2.4- 6.6 days, τ(Hβ) = 44.3+3.0 -3.3 days, τ(Hγ) = 58.1+4.3 - 6.1days, and τ(He II 4686) = 22.3+6.5 - 3.8 days.The blue and red peaks in the double-peaked line profiles, as well asthe blue and red outer profile wings, vary simultaneously within±3 days. This provides strong support for gravitationally boundorbital motion of the dominant part of the line-emitting gas. Combiningthe time delay of the strong Balmer emission lines of Hα andHβ and the separation of the blue and red peaks in the broaddouble-peaked profiles in their rms spectra, we determine Mvir bh = 1.77+0.29 - 0.31× 108 M &sun; and usingσline of the rms spectra M vir bh = 2.60+0.23 - 0.31 × 108 M&sun; for the central black hole of 3C 390.3, respectively.Using the inclination angle of the line-emitting region which ismeasured from superluminal motion detected in the radio range, accretiondisk models to fit the optical double-peaked emission-line profiles, andX-ray observations, the mass of the black hole amounts to Mbh = 0.86+0.19 - 0.18 ×109 M &sun; (peak separation) and M bh= 1.26+0.21 - 0.16 × 109 M&sun; (σline), respectively. This result isconsistent with the black hole masses indicated by simple accretion diskmodels to describe the observed double-peaked profiles, derived from thestellar dynamics of 3C 390.3, and with the AGN radius-luminosityrelation. Thus, 3C 390.3 as a radio-loud AGN with a low Eddington ratio,L edd/L bol = 0.02, follows the same AGNradius-luminosity relation as radio-quiet AGNs.Based on observations collected at the MDM Observatory.
| Photometric reverberation mapping of 3C 120
We present the results of a five month monitoring campaign of the localactive galactic nuclei (AGN) 3C 120. Observationswith a median sampling of two days were conducted with the robotic 15 cmtelescope VYSOS-6 located near Cerro Armazones in Chile. Broad band (B,V) and narrow band (NB) filters were used in order to measure fluxes ofthe AGN and the Hβ broad line region (BLR) emission line. The NBflux is constituted by about 50% continuum and 50% Hβ emissionline. To disentangle line and continuum flux, a synthetic Hβ lightcurve was created by subtracting a scaled V-band light curve from the NBlight curve. Here we show that the Hβ emission line responds tocontinuum variations with a rest frame lag of 23.6 ± 1.69 days.We estimate a virial mass of the central black hole MBH = 57± 27 × 106 M&sun;, by combining theobtained lag with the velocity dispersion of a single contemporaneousspectrum. Using the flux variation gradient method, we determined thehost galaxy subtracted rest frame 5100 Å luminosity at the time ofour monitoring campaign with an uncertainty of 10% (LAGN =(6.94 ± 0.71) × 1043 erg s-1).Compared with recent spectroscopic reverberation results, 3C120 shifts in the RBLR - LAGN diagramremarkably close to the theoretically expected relation of R ∝L0.5. Our results demonstrate the performance of photometricAGN reverberation mapping, in particular for efficiently determining theBLR size and the AGN luminosity.Table 5 is available in electronic form at http://www.aanda.org
| Reverberation Mapping Results for Five Seyfert 1 Galaxies
We present the results from a detailed analysis of photometric andspectrophotometric data on five Seyfert 1 galaxies observed as a part ofa recent reverberation mapping program. The data were collected atseveral observatories over a 140 day span beginning in 2010 August andending in 2011 January. We obtained high sampling-rate light curves forMrk 335, Mrk 1501, 3C 120, Mrk 6, and PG 2130+099, from which we havemeasured the time lag between variations in the 5100 Å continuumand the Hβ broad emission line. We then used these measurements tocalculate the mass of the supermassive black hole at the center of eachof these galaxies. Our new measurements substantially improve previousmeasurements of M BH and the size of the broad line-emittingregion for four sources and add a measurement for one new object. Ournew measurements are consistent with photoionization physics regulatingthe location of the broad line region in active galactic nuclei.
| X-ray variability of 104 active galactic nuclei. XMM-Newton power-spectrum density profiles
Context. Active galactic nuclei (AGN), powered by accretion ontosupermassive black holes (SMBHs), are thought to be scaled up versionsof Galactic black hole X-ray binaries (BH-XRBs). In the past few yearsevidence of such correspondence include similarities in the broadbandshape of the X-ray variability power spectra, with characteristic bendtimes-scales scaling with mass. Aims: The aim of this project isto characterize the X-ray temporal properties of a sample of AGN tostudy the connection among different classes of AGN and their connectionwith BH-XRBs. Methods: We have performed a uniform analysis ofthe power spectrum densities (PSDs) of 104 nearby (z < 0.4) AGN using209 XMM-Newton/pn observations. These PSDs span ? 3 decades intemporal frequencies, ranging from minutes to days. The PSDs have beenestimated in three energy bands: 0.2-10 (total), 0.2-2 (soft), and 2-10keV (hard). The sample comprises 61 Type-1 AGN, 21 Type-2 AGN, 15 NLSy1,and 7 BLLACS. We have fitted each PSD to two models: (1) a singlepower-law model and (2) a bending power-law model. Results: Amongthe entire sample, 72% show significant variability in at least one ofthe three bands tested. A high percentage of low-luminosity AGN do notshow any significant variability (86% of LINERs). The PSD of themajority of the variable AGN was well described by a simple power-lawwith a mean index of ? = 2.01 ± 0.01. In 15 sources wefound that the bending power law model was preferred with a mean slopeof ? = 3.08 ± 0.04 and a mean bend frequency of ??b ? ? 2 × 10-4 Hz. Only KUG1031+398 (RE J1034+396) shows evidence for quasi-periodic oscillations.The "fundamental plane" relating variability timescale, black hole mass,and luminosity is demonstrated using the new X-ray timing resultspresented here together with a compilation of the previously detectedtimescales from the literature. Conclusions: Both quantitative(i.e. scaling with BH mass) and qualitative (overall PSD shapes) foundin this sample of AGN are in agreement with the expectations for theSMBHs and BH-XRBs being the same phenomenon scaled-up with the size ofthe BH. The steep PSD slopes above the high frequency bend bear a closerresemblance to those of the "soft/thermal dominated" BH-XRB states thanother states.Tables 1-4 and Appendices A and B are available in electronic form at http://www.aanda.org
| Investigating the reflection contribution to the X-ray emission of Ton S180
There is now growing evidence that the soft X-ray excess is almostubiquitous among unobscured active galaxies. In spite of the variousinterpretations that have been considered in the past few years, thenature of this foremost spectral feature is not firmly established yet.In this context, we review from a reflection perspective the threehighest quality X-ray observations of the narrow-line type 1 Seyfertgalaxy Tonantzintla (Ton) S180, obtained by XMM-Newton and Suzaku. TheX-ray spectrum of Ton S180 shows only moderate variations over a timespan of several years, suggesting that the same physical processaccounts for the bulk of the broad-band X-ray emission at the differentepochs, and that the properties of the X-ray source are fairly stable.We have successfully applied in our spectral analysis a dual-reflectormodel, consisting of two separate components: one arises from thesurface of the accretion disc, is highly ionized and blurred byrelativistic effects; the other is cold, quite faint and can beassociated with a distant reprocessor. Due to the strength and thenearly power-law shape of its soft excess emission, Ton S180 is one ofthe most challenging sources to test the X-ray reflection scenario. Inthis work we provide a clear illustration of the great potential andspectral flexibility of blurred reflection models, while discussing someof their current limitations and possible shortcomings.
| Infrared and Hard X-Ray Diagnostics of Active Galactic Nucleus Identification from the Swift/BAT and AKARI All-sky Surveys
We combine data from two all-sky surveys in order to study theconnection between the infrared and hard X-ray (>10 keV) propertiesfor local active galactic nuclei (AGNs). The Swift Burst Alert Telescopeall-sky survey provides an unbiased, flux-limited selection of hardX-ray-detected AGNs. Cross-correlating the 22 month hard X-ray surveywith the AKARI all-sky survey, we studied 158 AGNs detected by the AKARIinstruments. We find a strong correlation for most AGNs between theinfrared (9, 18, and 90 ?m) and hard X-ray (14-195 keV) luminosities,and quantify the correlation for various subsamples of AGNs. Partialcorrelation analysis confirms the intrinsic correlation after removingthe redshift contribution. The correlation for radio galaxies has aslope and normalization identical to that for Seyfert 1 galaxies,implying similar hard X-ray/infrared emission processes in both. Incontrast, Compton-thick (CT) sources show a large deficit in the hardX-ray band, because high gas column densities diminish even their hardX-ray luminosities. We propose two photometric diagnostics for sourceclassification: one is an X-ray luminosity versus infrared colordiagram, in which type 1 radio-loud AGNs are well isolated from theothers in the sample. The other uses the X-ray versus infrared color asa useful redshift-independent indicator for identifying CT AGNs.Importantly, CT AGNs and starburst galaxies in composite systems canalso be differentiated in this plane based upon their hard X-ray fluxesand dust temperatures. This diagram may be useful as a new indicator toclassify objects in new and upcoming surveys such as WISE and NuSTAR.
| HST-COS Observations of AGNs. I. Ultraviolet Composite Spectra of the Ionizing Continuum and Emission Lines
The ionizing fluxes from quasars and other active galactic nuclei (AGNs)are critical for interpreting the emission-line spectra of AGNs and forphotoionization and heating of the intergalactic medium. Usingultraviolet spectra from the Cosmic Origins Spectrograph (COS) on theHubble Space Telescope (HST), we have directly measured the rest-frameionizing continua and emission lines for 22 AGNs. Over the redshiftrange 0.026 < z < 1.44, COS samples the Lyman continuum and manyfar-UV emission lines (Lyα λ1216, C IV λ1549, SiIV/O IV] λ1400, N V λ1240, O VI λ1035). Strong EUVemission lines with 14-22 eV excitation energies (Ne VIIIλλ770, 780, Ne V λ569, O II λ834, O IIIλ833, λ702, O IV λ788, 608, 554, O V λ630, NIII λ685) suggest the presence of hot gas in the broademission-line region. The rest-frame continuum, F_{\nu } \propto \nu^{\alpha _{\nu }}, shows a break at wavelengths λ < 1000Å, with spectral index αν = -0.68 ±0.14 in the FUV (1200-2000 Å) steepening to αν= -1.41 ± 0.21 in the EUV (500-1000 Å). The COS EUV indexis similar to that of radio-quiet AGNs in the 2002 HST/FOS survey(αν = -1.57 ± 0.17). We see no Lyman edge(τH I < 0.03) or He I λ584 emission in the AGNcomposite. Our 22 AGNs exhibit a substantial range of FUV/EUV spectralindices and a correlation with AGN luminosity and redshift, likely dueto observing below the 1000 Å spectral break.Based on observations made with the NASA/ESA Hubble Space Telescope,obtained from the data archive at the Space Telescope Science Institute.STScI is operated by the Association of Universities for Research inAstronomy, Inc. under NASA contract NAS5-26555.
| Modeling the Fe K Line Profiles in Type I Active Galactic Nuclei with a Compton-thick Disk Wind
We have modeled a small sample of Seyfert galaxies that were previouslyidentified as having simple X-ray spectra with little intrinsicabsorption. The sources in this sample all contain moderately broadcomponents of Fe K-shell emission and are ideal candidates for testingthe applicability of a Compton-thick accretion disk wind model to activegalactic nucleus (AGN) emission components. Viewing angles through thewind allow the observer to see the absorption signature of the gas,whereas face-on viewing angles allow the observer to see the scatteredlight from the wind. We find that the Fe K emission line profiles arewell described with a model of a Compton-thick accretion disk wind ofsolar abundances, arising tens to hundreds of gravitational radii fromthe central black hole. Further, the fits require a neutral component ofFe Kα emission that is too narrow to arise from the inner part ofthe wind, and likely comes from a more distant reprocessing region. Ourstudy demonstrates that a Compton-thick wind can have a profound effecton the observed X-ray spectrum of an AGN, even when the system is notviewed through the flow.
| CAIXA: a catalogue of AGN in the XMM-Newton archive. III. Excess variance analysis
Context. We report on the results of the first XMM-Newton systematic"excess variance" study of all the radio quiet, X-ray un-obscured AGN.The entire sample consist of 161 sources observed by XMM-Newton for morethan 10 ks in pointed observations, which is the largest sample used sofar to study AGN X-ray variability on time scales less than a day. Aims: Recently it has been suggested that the same engine might be atwork in the core of every black hole (BH) accreting object. In thishypothesis, the same variability should be observed in all AGN, oncerescaled by the MBH (MBH) and accretion rate(ṁ). Methods: We systematically compute the excess variancefor all AGN, on different time-scales (10, 20, 40 and 80 ks) and indifferent energy bands (0.3-0.7, 0.7-2 and 2-10 keV). Results: Weobserve a highly significant and tight (~0.7 dex) correlation betweenσ2rms and MBH. The subsample ofreverberation mapped AGN shows an even smaller scatter (only a factor of2-3) comparable to the one induced by the MBH uncertainties.This implies that X-ray variability can be used as an accurate tool tomeasure MBH and this method is more accurate than the onesbased on single epoch optical spectra. This allows us to measureMBH for 65 AGN and estimate lower limits for the remaining 96AGN. On the other hand, the σ2rms vs.accretion rate dependence is weaker than expected based on the PSD breakfrequency scaling. This strongly suggests that both the PSD highfrequency break and the normalisation depend on accretion rate in such away that they almost completely counterbalance each other(PSDamp ∝ ṁ-0.8). A highly significantcorrelation between σ2rms and 2-10 keVspectral index is observed. The highly significant correlations betweenσ2rms and both the LBol and theFWHMHβ are consistent with being just by-products of theσ2rms vs. MBH relation. The softand medium σ2rms is very well correlatedwith the hard σ2rms, with no deviations froma linear one to one correlation. This suggests that the additional softcomponents (i.e. soft excess, warm absorber) add a minor contribution tothe total variability. Once the variability is rescaled forMBH and ṁ, no significant difference between narrow-lineand broad-line Seyfert 1 is observed. Conclusions: The resultsare in agreement with a picture where, to first approximation, all localAGN have the same variability properties once rescaled forMBH and ṁ.Appendix A is available in electronic form at http://www.aanda.orgFull Tables 1 and 2are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/542/A83
| The influence of soft spectral components on the structure and stability of warm absorbers in active galactic nuclei
The radiation from the central regions of active galactic nuclei,including that from the accretion disc surrounding the black hole, islikely to peak in the extreme-ultraviolet ˜13-100 eV. However, dueto Galactic absorption, we are limited to constrain the physicalproperties, i.e. the black hole mass and the accretion rate, from whatobservations we have below ˜10 eV or above ˜100 eV. In thispaper, we predict the thermal and ionization states of warm absorbers asa function of the shape of the unobservable continuum. In particular wemodel an accretion disc at kTin˜ 10 eV and a softexcess at kTse˜ 150 eV. The warm absorber, which is thehighly ionized gas along the line of sight to the continuum, showssignatures in the ˜0.3-2 keV energy range consisting of numerousabsorption lines and edges of various ions, some of the prominent onesbeing H- and He-like oxygen, neon, magnesium and silicon. We find thatthe properties of the warm absorber are significantly influenced by thechanges in the temperature of the accretion disc, as well as by thestrength of the soft excess, as they affect the optical depthparticularly for iron and oxygen. These trends may help develop a methodof characterizing the shape of the unobservable continuum and theoccurrence of warm absorbers.
| Suzaku Observation of the Black Hole Candidate Maxi J1836-194 in a Hard/Intermediate Spectral State
We report on a Suzaku observation of the newly discovered X-ray binaryMAXI J1836-194. The source is found to be in the hard/intermediatespectral state and displays a clear and strong relativisticallybroadened iron emission line. We fit the spectra with a variety ofphenomenological, as well as physically motivated disk reflectionmodels, and find that the breadth and strength of the iron line arealways characteristic of emission within a few gravitational radiiaround a black hole. This result is independent of the continuum usedand strongly points toward the central object in MAXI J1836-194 being astellar mass black hole rotating with a spin of a = 0.88 ± 0.03(90% confidence). We discuss this result in the context of spectralstate definitions, physical changes (or lack thereof) in the accretiondisk, and on the potential importance of the accretion disk corona instate transitions.
| A Near-infrared Template Derived from I Zw 1 for the Fe II Emission in Active Galaxies
In active galactic nucleus spectra, a series of Fe II multiplets form apseudo-continuum that extends from the ultraviolet to the near-infrared(NIR). This emission is believed to originate in the broad-line region,and it has been known for a long time that pure photoionization fails toreproduce it in the most extreme cases, as does the collisionalexcitation alone. The most recent models by Sigut & Pradhan includedetails of the Fe II ion microphysics and cover a wide range in theionization parameter log U ion = (- 3.0 ?-1.3) and density log n H = (9.6 ? 12.6). With theaid of such models and a spectral synthesis approach, we studied for thefirst time in detail the NIR emission of I Zw 1. The main goals were toconfirm the role played by Ly? fluorescence mechanisms in theproduction of the Fe II spectrum and to construct the firstsemi-empirical NIR Fe II template that best represents this emission,consequently allowing its clean subtraction in other sources. A goodoverall match between the observed Fe II+Mg II features with thosepredicted by the best-fitted model was obtained, corroborating theLy? fluorescence as a key process to understand the Fe IIspectrum. The best model was fine-tuned by applying a deconvolutionmethod to the observed Fe II+Mg II spectrum. This derived semi-empiricaltemplate was then fitted to the spectrum of Ark 564, showing that itnicely reproduced its observed Fe II+Mg II emission. Our work extendsthe current set of available Fe II templates into the NIR region.
| A Remarkable Long-term Light Curve and Deep, Low-state Spectroscopy: Swift and XMM-Newton Monitoring of the NLS1 Galaxy Mkn 335
The narrow-line Seyfert 1 galaxy (NLS1) Mkn 335 is remarkable because ithas repeatedly shown deep, long X-ray low states that show pronouncedspectral structure. It has become one of the prototype active galacticnuclei (AGNs) in deep minimum X-ray states. Here we report on thecontinuation of our ongoing monitoring campaign with Swift and theexamination of the low-state X-ray spectra based on a 200 ks triggeredobservation with XMM-Newton in 2009 June. Swift has continuouslymonitored Mkn 335 since 2007 May typically on a monthly basis. This isone of the longest simultaneous UV/X-ray light curves so far obtainedfor an AGN. Mkn 335 has shown strong X-ray variability even ontimescales of hours. In the UV, it turns out to be one of the mostvariable among NLS1s. Long-term Swift monitoring allows us to examinecorrelations between the UV, X-rays, and X-ray hardness ratios. We findno significant correlation or lag between the UV and X-ray variability;however, we do find distinct trends in the behavior of the hardnessratio variability. The hardness ratio and count rate are correlated inthe low-flux state, but no correlation is seen in the high state. TheX-ray low-state spectra of the 2007 and 2009 XMM-Newton observationsdisplay significant spectral variability. We fit the X-ray spectra witha suite of phenomenological models in order to characterize the data.The broadband CCD spectrum can be fitted equally well with partialabsorption and blurred reflection models. These more complicated modelsare explored in further detail in upcoming work.
| Characterizing Transition Temperature Gas in the Galactic Corona
We present a study of the properties of the transition temperature (T ~105 K) gas in the Milky Way corona, based on the measurementsof O VI, N V, C IV, Si IV, and Fe III absorption lines seen in thefar-ultraviolet spectra of 58 sight lines to extragalactic targets,obtained with the Far-Ultraviolet Spectroscopic Explorer and the SpaceTelescope Imaging Spectrograph. In many sight lines the Galacticabsorption profiles show multiple components, which are analyzedseparately. We find that the highly ionized atoms are distributedirregularly in a layer with a scale height of about 3 kpc, which rotatesalong with the gas in the disk, without an obvious gradient in therotation velocity away from the Galactic plane. Within this layer thegas has randomly oriented velocities with a dispersion of 40-60 kms-1. On average the integrated column densities are logN(O VI) = 14.3, log N(N V) = 13.5, log N(C IV) = 14.2, log N(Si IV) =13.6, and log N(Fe III) = 14.2, with a dispersion of just 0.2 dex ineach case. In sight lines around the Galactic center and Galactic northpole, all column densities are enhanced by a factor ~2, while atintermediate latitudes in the southern sky there is a deficit in N(O VI)of about a factor of two, but no deficit for the other ions. We comparethe column densities and ionic ratios to a series of theoreticalpredictions: collisional ionization equilibrium, shock ionization,conductive interfaces, turbulent mixing, thick disk supernovae, staticnon-equilibrium ionization (NIE) radiative cooling, and an NIE radiativecooling model in which the gas flows through the cooling zone. None ofthese models can fully reproduce the data, but it is clear that NIEradiative cooling is important in generating the transition temperaturegas.
| The 60 Month All-sky Burst Alert Telescope Survey of Active Galactic Nucleus and the Anisotropy of nearby AGNs
Surveys above 10 keV represent one of the best resources to provide anunbiased census of the population of active galactic nuclei (AGNs). Wepresent the results of 60 months of observation of the hard X-ray skywith Swift/Burst Alert Telescope (BAT). In this time frame, BAT-detected(in the 15-55 keV band) 720 sources in an all-sky survey of which 428are associated with AGNs, most of which are nearby. Our sample hasnegligible incompleteness and statistics a factor of ~2 larger oversimilarly complete sets of AGNs. Our sample contains (at least) 15 bonafide Compton-thick AGNs and 3 likely candidates. Compton-thick AGNsrepresent ~5% of AGN samples detected above 15 keV. We use the BAT dataset to refine the determination of the log N-log S of AGNs which isextremely important, now that NuSTAR prepares for launch, towardassessing the AGN contribution to the cosmic X-ray background. We showthat the log N-log S of AGNs selected above 10 keV is now established to~10% precision. We derive the luminosity function of Compton-thick AGNsand measure a space density of 7.9+4.1 - 2.9× 10-5 Mpc-3 for objects with a de-absorbedluminosity larger than 2 × 1042 erg s-1. Asthe BAT AGNs are all mostly local, they allow us to investigate thespatial distribution of AGNs in the nearby universe regardless ofabsorption. We find concentrations of AGNs that coincide spatially withthe largest congregations of matter in the local (<=85 Mpc) universe.There is some evidence that the fraction of Seyfert 2 objects is largerthan average in the direction of these dense regions.
| A Compilation of Interstellar Column Densities
We have collated absorption line data toward 3008 stars in order tocreate a unified database of interstellar column densities. These datahave been taken from a number of different published sources and includemany different species and ionizations. The preliminary results from ouranalysis show a tight relation [N(H)/E(B - V) = 6.12 ×1021] between N(H) and E(B - V). Similar plots havebeen obtained with many different species, and their correlations alongwith the correlation coefficients are presented.
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