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We present spatially resolved long-slit spectroscopy from the Southern African Large Telescope to examine the spatial extent of the narrow-line regions (NLRs) of a sample of eight luminous obscured quasars at 0.10 < z < 0.43. Our results are consistent with an observed shallow slope in the relationship between NLR size and L[O iii], which has been interpreted to indicate that NLR size is limited by the density and ionization state of the NLR gas rather than the availability of ionizing photons. We also explore how the NLR size scales with a more direct measure of instantaneous active galactic nucleus power using mid-IR photometry from the Wide Field Infrared Explorer, which probes warm to hot dust near the central black hole and so, unlike [Oiii], does not depend on the properties of the NLR. Using our results as well as samples from the literature, we obtain a power-law relationship between NLR size and L8μm that is significantly steeper than that observed for NLR size and L[O iii].We find that the size of the NLR goes approximately as L 1/2 8μm, as expected from the simple scenario of constant-density clouds illuminated by a central ionizing source.We further see tentative evidence for a flattening of the relationship between NLR size and L8μm at the high-luminosity end, and propose that we are seeing a limiting NLR size of 10-20 kpc, beyond which the availability of gas to ionize becomes too low. We find that L[O iii] ~ L1.4 8μm, consistent with a picture in which the L[O iii] is dependent on the volume of the NLR. These results indicate that high-luminosity quasars have a strong effect in ionizing the available gas in a galaxy. [ABSTRACT FROM AUTHOR]

Spectral fits to M87 core data from radio to hard X-ray are generated via a specially selected software suite, comprised of the High-Accuracy Relativistic Magnetohydrodynamics GRMHD accretion disk model and a two-dimensional Monte Carlo radiation transport code. By determining appropriate parameter changes necessary to fit X-ray-quiescent and flaring behavior of M87's core, we assess the reasonableness of various flaring mechanisms. This shows that an accretion disk model of M87's core out to 28 GM/c² can describe the inner emissions. High spin rates show GRMHD-driven polar outflow generation, without citing an external jet model. Our results favor accretion rate changes as the dominant mechanism of X-ray flux and index changes, with variations in density of approximately 20% necessary to scale between the average X-ray spectrum and flaring or quiescent spectra. The best-fit parameters are black hole spin a/M > 0.8 and maximum accretion flow density n ≤ 3 x 107 cm-3, equivalent to horizon accretion rates between ṁ = Ṁ/ ṀEdd ≈ 2 x 10-6 and 1 x 10-5 (with ṀEdd defined assuming a radiative efficiency η = 0.1). These results demonstrate that the immediate surroundings of M87's core are appropriate to explain observed X-ray variability. [ABSTRACT FROM AUTHOR]

SDSS J1356 + 1026 is a pair of interacting galaxies at redshift z = 0.123 that hosts a luminous obscured quasar in its northern nucleus. Here we present two long-slit Magellan LDSS-3 spectra that reveal a pair of symmetric ~ 10 kpc size outflows emerging from this nucleus, with observed expansion velocities of ~250 km s-1 in projection. We present a kinematic model of these outflows and argue that the deprojected physical velocities of expansion are likely ~ 1000 km s-1 and that the kinetic energy of the expanding shells is likely 1044-45 erg s-1, with an absolute minimum of > 1042 erg s-1. Although a radio counterpart is detected at 1.4 GHz, it is faint enough that the quasar is considered to be radio quiet by all standard criteria, and there is no evidence of extended emission due to radio lobes, whether aged or continuously powered by an ongoing jet. We argue that the likely level of star formation is insufficient to power the observed energetic outflow and that SDSS J1356 + 1026 is a good case for radio-quiet quasar feedback. In further support of this hypothesis, polarimetric observations show that the direction of quasar illumination is coincident with the direction of the outflow. [ABSTRACT FROM AUTHOR]

We present an analysis of the co-added and individual 0.7-40keV spectra from seven Suzaku observations of the Sy 1.5 galaxy NGC 5548 taken over a period of eight weeks. We conclude that the source has a moderately ionized, three-zone warm absorber, a power-law continuum, and exhibits contributions from cold, distant reflection. Relativistic reflection signatures are not significantly detected in the co-added data, and we place an upper limit on the equivalent width of a relativistically broad Fe Kα line at EW ≤ 26 eV at 90% confidence. Thus NGC 5548 can be labeled as a "weak" type 1 active galactic nucleus (AGN) in terms of its observed inner disk reflection signatures, in contrast to sources with very broad, strong iron lines such as MCG-6-30-15, which are likely much fewer in number. We compare physical properties of NGC 5548 and MCG-6-30-15 that might explain this difference in their reflection properties. Though there is some evidence that NGC 5548 may harbor a truncated inner accretion disk, this evidence is inconclusive, so we also consider light bending of the hard X-ray continuum emission in order to explain the lack of relativistic reflection in our observation. If the absence of a broad Fe Kα line is interpreted in the light-bending context, we conclude that the source of the hard X-ray continuum lies at radii rs ≳ 100rg. We note, however, that light-bending models must be expanded to include a broader range of physical parameter space in order to adequately explain the spectral and timing properties of average AGNs, rather than just those with strong, broad iron lines. [ABSTRACT FROM AUTHOR]

Close encounters between galaxies are expected to be a viable mechanism, as predicted by numerical simulations, by which accretion onto supermassive black holes can be initiated. To test this scenario, we construct a sample of 562 galaxies (M* > 2.5 x 1010 M⊙) in kinematic pairs over the redshift range 0.25 < z < 1.05 that are more likely to be interacting than a well-matched control sample of 2726 galaxies not identified as being in a pair, both from the zCOSMOS 20k spectroscopic catalog. Galaxies that harbor an active galactic nucleus (AGN) are identified on the basis of their X-ray emission (L0.5-10keV > 2 x 1042 erg s-1) detected by Chandra. We find a higher fraction of an AGN in galaxies in pairs relative to isolated galaxies of similar stellar mass. Our result is primarily due to an enhancement of AGN activity, by a factor of 1.9 (observed) and 2.6 (intrinsic), for galaxies in pairs of projected separation less than 75 kpc and line-of-sight velocity offset less than 500 km s-1. This study demonstrates that close kinematic pairs are conducive environments for black hole growth, either indicating a causal physical connection or an inherent relation, such as, to enhanced star formation. In the Appendix, we describe a method for estimating the intrinsic fractions of galaxies (either in pairs or the field) hosting an AGN with confidence intervals, and an excess fraction in pairs. We estimate that Due to images restrictions, multiple line equation(s) cannot be graphically displayed of all moderate-luminosity AGN activity takes place within galaxies undergoing early stages of interaction that leaves open the question as to what physical processes are responsible for fueling the remaining ~80% that may include late-stage mergers. [ABSTRACT FROM AUTHOR]

In this paper, we release accurate photometric redshifts for 1692 counterparts to Chandra sources in the central square degree of the Cosmic Evolution Survey (COSMOS) field. The availability of a large training set of spectroscopic redshifts that extends to faint magnitudes enabled photometric redshifts comparable to the highest quality results presently available for normal galaxies. We demonstrate that morphologically extended, faint X-ray sources without optical variability are more accurately described by a library of normal galaxies (corrected for emission lines) than by active galactic nucleus (AGN) dominated templates, even if these sources have AGN-like X-ray luminosities. Preselecting the library on the bases of the source properties allowed us to reach an accuracy σΔz/(1+spec) ~ 0.015 with a fraction of outliers of 5.8% for the entire Chandra-COSMOS sample. In addition, we release revised photometric redshifts for the 1735 optical counterparts of the XMM-detected sources over the entire 2 deg² of COSMOS. For 248 sources, our updated photometric redshift differs from the previous release by Δz > 0.2. These changes are predominantly due to the inclusion of newly available deep H-band photometry (HAB = 24 magi. We illustrate once again the importance of a spectroscopic training sample and how an assumption about the nature of a source together, with the number and the depth of the available bands, influences the accuracy of the photometric redshifts determined for AGN. These considerations should be kept in mind when defining the observational strategies of upcoming large surveys targeting AGNs, such as eROSITA at X-ray energies and the Australian Square Kilometre Array Pathfinder Evolutionary Map of the Universe in the radio band. [ABSTRACT FROM AUTHOR]

We present the results of a reverberation mapping (RM) campaign on the black hole (BH) associated with the active galactic nucleus (AGN) in SDSSJ114008.71+030711.4 (hereafter GH08). This object is selected from a sample of 19 candidate intermediate-mass BHs (MBH < 106 M⊙)found by Greene & Ho in the Sloan Digital Sky Survey. We used the Hobby-Eberly Telescope to obtain 30 spectra over a period of 178 days in an attempt to resolve the reverberation time lag (τ) between the continuum source and the broad-line region (BLR) in order to determine the radius of the BLR (RBLR) in GH08. We measure τ to be two days with an upper limit of six days. We estimate the AGN luminosity at 5100 Å to be λL5100 ≈ 1.1 x 1043 erg s-1 after deconvolution from the host galaxy. The most well-calibrated RBLR--L relation predicts a time lag that is four times larger than what we measure. Using the measured Hβ full width at half-maximum of 703 ± 110 km s-1 and an upper limit for RBLR = 6 light days, we find MBH ≲ 5.8 X 105 M⊙ as an upper limit to the BH virial mass in GH08, which implies super-Eddington accretion. Based on our measured MBH we propose that GH08 may be another candidate to add to the very short list of AGNs with MBH < 106 M⊙ determined using RM. [ABSTRACT FROM AUTHOR]

Most of the extragalactic sources detected at TeV energies are BL Lac objects. They belong to the subclass of high-frequency-peaked BL Lac objects (HBLs) exhibiting spectral energy distributions with a lower energy peak in the X-ray band; this is widely interpreted as synchrotron emission from relativistic electrons. The X-ray spectra are generally curved and well described in terms of a log-parabolic shape. In a previous investigation of TeV HBLs (TBLs) we found two correlations between their spectral parameters. (1) The synchrotron peak luminosity Lp increases with its peak energy Ep and (2) the curvature parameter b decreases as Ep increases. The first is consistent with the synchrotron scenario, while the second is expected from statistical/stochastic acceleration mechanisms for the emitting electrons. Here, we present an extensive X-ray analysis of a sample of HBLs observed with XMM-Newton and Swift but undetected at TeV energies (UBLs), to compare their spectral behavior with that of TBLs. Investigating the distributions of their spectral parameters and comparing the TBL X-ray spectra with that of UBLs, we develop a criterion to select the best HBL candidates for future TeV observations. [ABSTRACT FROM AUTHOR]

As part of an extensive study of the physical properties of active galactic nuclei (AGNs) we report high spatial resolution near-IR integral-field spectroscopy of the narrow-line region (NLR) and coronal-line region (CLR) of seven Seyfert galaxies. These measurements elucidate for the first time the two-dimensional spatial distribution and kinematics of the recombination line Bry and high-ionization lines [Si VI], [Al IX], and [Ca VIII] on scales <300 pc from the AGN. The observations reveal kinematic signatures of rotation and outflow in the NLR and CLR. The spatially resolved kinematics can be modeled as a combination of an outflow bicone and a rotating disk coincident with the molecular gas. High-excitation emission is seen in both components, suggesting it is leaking out of a clumpy torus. While NGC 1068 (Seyfert 2) is viewed nearly edge-on, intermediate-type Seyferts are viewed at intermediate angles, consistent with unified schemes. A correlation between the outflow velocity and the molecular gas mass in r < 30 pc indicates that the accumulation of gas around the AGN increases the collimation and velocity of the outflow. The outflow rate is 2-3 orders of magnitude greater than the accretion rate, implying that the outflow is mass loaded by the surrounding interstellar medium (ISM). In half of the observed AGNs, the kinetic power of the outflow is of the order of the power required by two-stage feedback models to be thermally coupled to the ISM and to match the MBH-σ* relation. In these objects, the radio jet is clearly interacting with the ISM, indicative of a link between jet power and outflow power. [ABSTRACT FROM AUTHOR]

We present XMM-Newton observations of three active galactic nuclei (AGNs) taken as part of a hunt to find very heavily obscured Compton-thick AGNs. For obscuring columns greater than 1025 cm-2, AGNs are only visible at energies below 10 keV via reflected/scattered radiation, characterized by a flat power law. We therefore selected three objects (ESO 417-G006, IRAS 05218-1212, and MCG - 01-05-047) from the Swift Burst Alert Telescope (BAT) hard X-ray survey catalog with Swift X-ray Telescope (XRT) 0.5-10 keV spectra with flat power-law indices as candidate Compton-thick sources for follow-up observations with the more sensitive instruments on XMM-Newton. The XMM spectra, however, rule out reflection-dominated models based on the weakness of the observed Fe Kα lines. Instead, the spectra are well fit by a model of a power-law continuum obscured by a Compton-thin absorber plus a soft excess. This result is consistent with previous follow-up observations of two other flat-spectrum BAT-detected AGNs. Thus, out of the six AGNs in the 22 month BAT catalog with apparently flat Swift XRT spectra, all five that have had follow-up observations are not likely Compton thick. We also present new optical spectra of two of these objects, IRAS 05218-1212 and MCG -01-05-047. Interestingly, though both the AGNs have similar X-ray spectra, their optical spectra are completely different, adding evidence against the simplest form of the geometric unified model of AGNs. IRAS 05218-1212 appears in the optical as a Seyfert 1, despite the ~8.5 x 1022 cm-2 line-of-sight absorbing column indicated by its X-ray spectrum. MCG - 01-05-047's optical spectrum shows no sign of AGN activity; it appears as a normal galaxy. [ABSTRACT FROM AUTHOR]

We report the results from Chandra and XMM-Newton observations of a sample of 10 type 1 quasars selected to have unusual UV emission-line properties (weak and blueshifted high-ionization lines; strong UV Fe emission) similar to those of PHL 1811, a confirmed intrinsically X-ray weak quasar. These quasars were identified by the Sloan Digital Sky Survey at high redshift (z ≈ 2.2); eight are radio quiet while two are radio intermediate. All of the radio-quiet PHL 1811 analogs, without exception, are notably X-ray weak by a mean factor of ≈13. These sources lack broad absorption lines and have blue UV/optical continua, supporting the hypothesis that they are intrinsically X-ray weak like PHL 1811 itself. However, their average X-ray spectrum appears to be harder than those of typical quasars, which may indicate the presence of heavy intrinsic X-ray absorption. Our sample of radio-quiet PHL 1811 analogs supports a connection between an X-ray weak spectral energy distribution and PHL 1811-like UV emission lines; this connection provides an economical way to identify X-ray weak type 1 quasars. The fraction of radio-quiet PHL 1811 analogs in the radio-quiet quasar population is estimated to be ≲ 1.2%. We have investigated correlations between relative X-ray brightness and UV emission-line properties (e.g., C IV equivalent width and blueshift) for a sample combining our radio-quiet PHL 1811 analogs, PHL 1811 itself, and typical type 1 quasars. These correlation analyses suggest that PHL 1811 analogs may have extreme wind-dominated broad emission-line regions. Observationally, the radio-quiet PHL 1811 analogs appear to be a subset (≈30%) of radio-quiet weak-line quasars (WLQs). The existence of a subset of quasars in which high-ionization "shielding gas" covers most of the broad emission-line region (BELR), but little more than the BELR, could potentially unify the PHL 1811 analogs and WLQs. The two radio-intermediate PHL 1811 analogs are X-ray bright. X-ray spectral analyses and consideration of their multiwavelength properties suggest that one of them has jet-dominated X-ray emission, while the nature of the other remains unclear. [ABSTRACT FROM AUTHOR]

We present a long (116 ks) Suzaku observation of the broad-line radio galaxy (BLRG) 3C 382 acquired in 2007 April. A Swift BAT spectrum in 15-200 keV from the 58 month survey is also analyzed, together with an archival XMM-Newton EPIC exposure of 20 ks obtained one year after Suzaku. Our main result is the finding with Suzaku of a broad Fe K line with a relativistic profile consistent with emission from an accretion disk at tens of gravitational radii from the central black hole. The XIS data indicate emission from highly ionized iron and allow us to set tight, albeit model-dependent, constraints on the inner and outer radii of the disk reflecting region, rin≅ 10rg and rout ≅ 20rg, respectively, and on the disk inclination, i ≅ 30°. Two ionized reflection components are possibly observed, with similar contributions of ∼10% to the total continuum-a highly ionized one, with logϵ ≅ 3 erg s-1 cm, which successfully models the relativistic line, and a mildly ionized one, with logϵ 1.5 erg s-1 cm, which models the narrow Fe Kα and high energy hump. When both these components are included, there is no further requirement for an additional blackbody soft excess below 2 keV. The Suzaku data confirm the presence of a warm absorber previously known from grating studies. After accounting for all the spectral features, the intrinsic photon index of the X-ray continuum is Γx ≅ 1.8 with a cutoff energy at ∽200 keV, consistent with Comptonization models and excluding jet-related emission up to these energies. Comparison of the X-ray properties of 3C 382 and other BLRGs to Seyferts recently observed with Suzaku and BAT confirms the idea that the distinction between radio-loud and radio-quiet active galactic nucleus at X-rays is blurred. The two classes form a continuum distribution in terms of X-ray photon index, reflection strength, and Fe K line width (related to the disk emission radius), with BLRGs clustered at one end of the distribution. This points to a common structure of the central engine, with only a few fundamental parameter(s) responsible for the radio-loud/radio-quiet division. The black hole spin, and in particular its rotation compared to the disk's, may be a key one. [ABSTRACT FROM AUTHOR]

Direct measurements of the extragalactic background light (EBL) in the near-IR to mid-IR waveband are extremely difficult due to an overwhelming foreground from the zodiacal light that outshines the faint cosmological diffuse radiation field by more than an order of magnitude. Indirect constraints on the EBL are provided by γ-ray observations of active galactic nuclei. Using the combination of the Fermi Gamma-Ray Space Telescope together with the current generation of ground-based air Cherenkov telescopes (H.E.S.S., MAGIC, and VERITAS) provides unprecedented sensitivity and spectral coverage for constraining the EBL in the near- to mid-IR. In this paper, we present new limits on the EBL based on the analysis of the broadband spectra of a select set of γ-ray blazars covering 200 MeV to several TeV. The EBL intensity at 15 μm is constrained to be 1.36 ± 0.58 nW m-2 sr-1. We find that the fast evolution and baseline EBL models of Stecker et al., as well as the model of Kneiske et al., predict significantly higher EBL intensities in the mid-IR (15 μm) than is allowed by the constraints derived here. In addition, the model of Franceschini et al. and the fiducial model of Domínguez et al. predict near- to mid-IR ratios smaller than that derived from our analysis. Namely, their intensities in the near-IR are too low while their intensities in the mid-IR are marginally too high. All of the aforementioned models are inconsistent with our analysis at the >3σ level. [ABSTRACT FROM AUTHOR]