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Aims. We study the X-ray power spectrum of active galactic nuclei (AGN) in order to investigate whether Seyfert I and II power spectra are similar or not and whether AGN variability depends on the mass and accretion rate of black holes as well as to compare the power spectra of AGN with the power spectra of Galactic X-ray black hole binaries. Method. We used 14–195 keV band light curves from the 157-month Swift/BAT hard X-ray survey, and we computed the mean power spectrum and excess variance of AGN in narrow black hole mass and AGN luminosity bins. We fitted a power-law model to the AGN power spectra, and we investigated whether the power spectrum parameters and the excess variance depend on the black hole mass, luminosity, and accretion rate of AGN. Results. We found the Seyfert I and Seyfert II power spectra to be identical, in agreement with AGN unification models. The mean AGN X-ray power spectrum has the same power-law like shape, with a slope of −1 in all AGN irrespective of their luminosity and black hole mass. We did not detect any flattening to a slope of zero at frequencies as low as 10−9 Hz. We detected an anti-correlation between the power spectral density function (PSD) amplitude and the accretion rate, similar to what has been seen in the past in the 2–10 keV band. This implies that the variability amplitude in AGN decreases with an increasing accretion rate. The universal AGN power spectrum is consistent with the mean 2–9 keV band Cyg X-1 power spectrum in its soft state. We detected a small difference in amplitude, but this is probably due to the difference in energy. Conclusions. The mean low-frequency AGN X-ray power spectrum is consistent with the extension of the mean 0.01–25 Hz Cyg X-1 power spectrum in its soft state to lower frequencies. We cannot prove that the mean AGN PSD is analogous to the mean Cyg X-1 PSD in its soft state, as we do not know the location of the high-frequency break in the hard X-ray AGN PSDs. However, if this is the case, then the accretion disc in AGN probably extends to the radius of the innermost circular stable orbit (as is probably the case with the black hole binaries in their soft state). The X-ray corona will then be located on top, illuminating the disc and producing the X-ray reflection and disc reverberation phenomena commonly observed in these objects. Furthermore, the agreement between the PSD amplitude in AGN and the Cyg X-1 (either in the soft or the hard state) over many decades in frequency indicates that the X-ray variability process is probably the same in all accreting objects, irrespective of the mass of the compact object. We plan to investigate this issue further in the near future. [ABSTRACT FROM AUTHOR]

We present a study of outburst activity in the BL Lacertae source OJ 287, which has been observed extensively with the X-ray telescope (XRT) on board the Neil Gehrels Swift Observatory. We demonstrate that the results of our analysis of X-ray flaring activity using the Swift/XRT data allow for the key characteristics of the OJ 287 secondary to be refined (its nature and mass). We discover that the energy spectra in all spectral states can be fitted using the XSPEC bulk motion Comptonization (BMC) model. As a result we find that the X-ray photon index of the BMC model, Γ, correlates with the mass accretion rate, Ṁ. We establish that Γ increases monotonically with Ṁ from the low-hard state, Γ ∼ 1.5, to the high-soft state, Γ ∼ 2.8, and finally saturates. The index behavior is similar to that in a number of black hole (BH) candidates in which we show that its saturation is observational evidence of the presence of a BH. Based on this correlation, we applied a scaling method and determine that a secondary BH mass in OJ 287 is about ∼1.25 × 108 solar masses, using the well-studied X-ray BH binaries XTE 1550–564, H 1743–322, 4U 1630–47, and GRS 1915+105 as well as extragalactic BHs ESO 243–49 and M101 ULX–1, as reference sources. Also, using the power spectrum analysis, we infer the size of the Compton cloud LCC ∼ 1013 cm where X-ray spectra were formed. Using this value of LCC, we confirm that a BH mass of the secondary in OJ 287 was on the order of 108 solar masses as we derived using the index, Γ–correlation (the scaling method) with respect of the mass accretion rate. [ABSTRACT FROM AUTHOR]

Here, we investigate the kinematics of the part of the broad-line region (BLR) in active galactic nuclei (AGNs) emitting H β and H α emission lines. We explore the widths and asymmetries of the broad H β and H α emission lines in a sample of high-quality (i.e. high signal-to-noise ratio) spectra of type-1 AGN taken from the Data Release 16 of the Sloan Digital Sky Survey in order to explore possible deviation from the gravitationally bound motion. To find only the broad component of H β and H α, we use the fantasy (Fully Automated pythoN Tool for AGN Spectra analYsis) code for the multicomponent modelling of the AGN spectra and for careful extraction of the broad emission-line parameters. We show that based on the broad-line profiles widths and asymmetries, the BLR gas emitting H β and H α lines follows similar kinematics, and seems to be virialized in our sample of type-1 AGN. [ABSTRACT FROM AUTHOR]

We analyse medium resolution optical spectra of 14 narrow-line Seyfert 1 galaxies with average to strong iron emission. The targets were observed several times over a 2-yr period to probe the nature of spectral variations. Parameters determined from fitting the line profiles include relative strength, width, and asymmetry. We explore the applicability of various profile combinations to H β. We achieve satisfactory fits using three components: the narrow and broad components characteristic of all Seyfert 1 galaxies and that are reasonably represented by Gaussian profiles, and an intermediate component with width similar to that of the Fe  ii lines. This intermediate component accounted for the largest fraction of the H β flux in most of our sample, especially when fitted with a Lorentzian instead of a Gaussian profile. This Lorentzian component improves the overall H β fits in most cases. In contrast to many other types of active galactic nucleus, no dramatic spectral changes were detected in our sample over the 2-yr period spanning this study, even though some of our targets are known for large and rapid X-ray variability. In particular, we find the variability of the Fe  ii lines relative to the H β intermediate component to be minimal. For the [O  iii ] lines, we identified asymmetries in almost all our targets well represented by two Gaussians: a primary central and a second blueshifted component. These may signify different gas dynamics connected with nuclear outflow. As in several previous studies, we identify a clear correlation between [O  iii ] asymmetry and its core component width. [ABSTRACT FROM AUTHOR]

We present Bayesian active galactic nucleus (AGN) Decomposition Analysis for Sloan Digital Sky Survey (SDSS) Spectra, an open source spectral analysis code designed for automatic detailed deconvolution of AGN and host galaxy spectra, implemented in python , and designed for the next generation of large-scale surveys. The code simultaneously fits all spectral components, including power-law continuum, stellar line-of-sight velocity distribution, Fe  ii emission, as well as forbidden (narrow), permitted (broad), and outflow emission line features, all performed using Markov chain Monte Carlo to obtain robust uncertainties and autocorrelation analysis to assess parameter convergence. Our code also utilizes multiprocessing for batch fitting large samples of spectra while efficiently managing memory and computation resources and is currently being used in a cluster environment to fit thousands of SDSS spectra. We use our code to perform a correlation analysis of 63 SDSS type 1 AGNs with evidence of strong non-gravitational outflow kinematics in the [O  iii ] λ5007 emission feature. We confirm findings from previous studies that show the core of the [O  iii ] profile is a suitable surrogate for stellar velocity dispersion σ*, however there is evidence that the core experiences broadening that scales with outflow velocity. We find sufficient evidence that σ*, [O  iii ] core dispersion, and the non-gravitational outflow dispersion of the [O  iii ] profile form a plane whose fit results in a scatter of ∼0.1 dex. Finally, we discuss the implications, caveats, and recommendations when using the [O  iii ] dispersion as a surrogate for σ* for the M BH−σ* relation. [ABSTRACT FROM AUTHOR]

NGC 5548 was recently monitored intensively from NIR to X-rays as part of the STORM campaign. Its disc emission was found to lag behind the observed X-rays, while the measured time lag was increasing with wavelength. These results are consistent with the assumption that short-term variability in AGN emission is driven by the X-ray illumination of the accretion disc. In this work, we studied the power spectrum of UV/optical and X-ray emission of NGC 5548, using the data of the STORM campaign as well as previous Swift data, in order to investigate the relation between the UV/optical and X-ray variability and to examine its consistency with the above picture. We demonstrate that even the power spectrum results are compatible with a standard disc being illuminated by X-rays, with low accretion rates, but the details are not entirely consistent with the results from the modelling of the 'τ versus λ' relation. The differences indicate that the inner disc might be covered by a 'warm corona' which does not allow the detection of UV/optical emission from the inner disc. Finally, we found strong evidence that the UV emission of NGC 5548 is not stationary. [ABSTRACT FROM AUTHOR]

The advent of new time domain surveys and the imminent increase in astronomical data expose the shortcomings of traditional time series analysis (such as power spectra analysis) in characterizing the abundantly varied, complex, and stochastic light curves of Active Galactic Nuclei (AGNs). Recent applications of novel methods from non-linear dynamics have shown promise in characterizing higher modes of variability and time-scales in AGN. Recurrence analysis in particular can provide complementary information about characteristic time-scales revealed by other methods, as well as probe the nature of the underlying physics in these objects. Recurrence analysis was developed to study dynamical trajectories in phase space, which can be constructed from 1D time series such as light curves. We apply the methods of recurrence analysis to two optical light curves of Kepler -monitored AGN. We confirm the detection and period of an optical quasi-periodic oscillation in one AGN, and confirm multiple other time-scales recovered from other methods ranging from 5 to 60 d in both objects. We detect regions in the light curves that deviate from regularity, provide evidence of determinism and non-linearity in the mechanisms underlying one light curve (KIC 9650712), and determine realizations of a linear stochastic process describe the dominant variability in the other light curve (Zwicky 229–015). We discuss possible underlying processes driving the dynamics of the light curves and their diverse classes of variability. [ABSTRACT FROM AUTHOR]

The gigahertz peaked spectrum (GPS) sources, compact steep spectrum (CSS) radio sources, and high-frequency peaker (HFP) radio sources are thought to be young radio active galactic nuclei (AGNs) at the early stage of AGN evolution. We investigated the optical properties of the largest sample of 126 young radio AGNs based on the spectra in SDSS DR12. We find that the black hole masses M BH range from 107.32 to 109.84 |$\rm M_{\odot }$| and the Eddington ratios R edd vary from 10−4.93 to 100.37, suggesting that young radio AGNs have various accretion activities and not all are accreting at high accretion rate. Our young radio sources generally follow the evolutionary trend towards large-scale radio galaxies with increasing linear size and decreasing accretion rate in the radio power–linear size diagram. The radio properties of low-luminosity young radio AGNs with low R edd are discussed. The line width of [O  iii ] λ5007 core (σ[O  iii ]) is found to be a good surrogate of stellar velocity dispersion σ*. The radio luminosity |$L_{\rm 5\, GHz}$| correlates strongly with [O  iii ] core luminosity L [O  iii ], suggesting that radio activity and accretion are closely related in young radio sources. We find one object that can be defined as a narrow-line Seyfert 1 galaxy, representing a population of young AGNs with both young jet and early accretion activity. The optical variabilities of 15 quasars with multi-epoch spectroscopy were investigated. Our results show that the optical variability in young AGN quasars presents low variations (⁠|$\leqslant \! 60{{\ \rm per\ cent}}$|⁠) similar to the normal radio-quiet quasars. [ABSTRACT FROM AUTHOR]

The object 4C 71.07 is a high-redshift blazar whose spectral energy distribution shows a prominent big blue bump and a strong Compton dominance. We present the results of a 2-yr multiwavelength campaign led by the Whole Earth Blazar Telescope (WEBT) to study both the quasar core and the beamed jet of this source. The WEBT data are complemented by ultraviolet and X-ray data from Swift , and by γ-ray data by Fermi. The big blue bump is modelled by using optical and near-infrared mean spectra obtained during the campaign, together with optical and ultraviolet quasar templates. We give prescriptions to correct the source photometry in the various bands for the thermal contribution, in order to derive the non-thermal jet flux. The role of the intergalactic medium absorption is analysed in both the ultraviolet and X-ray bands. We provide opacity values to deabsorb ultraviolet data, and derive a best-guess value for the hydrogen column density of |$N_{\rm H}^{\rm best}=6.3 \times 10^{20} \rm \, cm^{-2}$| through the analysis of X-ray spectra. We estimate the disc and jet bolometric luminosities, accretion rate, and black hole mass. Light curves do not show persistent correlations among flux changes at different frequencies. We study the polarimetric behaviour and find no correlation between polarization degree and flux, even when correcting for the dilution effect of the big blue bump. Similarly, wide rotations of the electric vector polarization angle do not seem to be connected with the source activity. [ABSTRACT FROM AUTHOR]

Considerable uncertainties remain about the nature of warm, AGN-driven outflows and their impact on the evolution of galaxies. This is because the outflows are often unresolved in ground-based observations. As part of a project to study the AGN outflows in some of the most rapidly evolving galaxies in the local Universe, here we present Hubble Space Telescope (HST)/ Space Telescope Imaging Spectrograph (STIS) observations of F14394+5332E that resolve the sub-kpc warm outflow for the first time in an ultra-luminous infrared galaxy. The observations reveal a compact, high-ionization outflow region (r max ∼ 0.9 kpc) set in a more extensive (r max ∼ 1.4 kpc) halo that is kinematically quiescent and has a lower ionization state. A large line width (600 < FWHM < 1500 km s−1) is measured throughout the outflow region, and the outflowing gas shows a steep velocity gradient with radius, with the magnitude of the blueshifted velocities increasing from ∼500 to 1800 km s−1 from the inner to the outer part of the outflow. We interpret the observations in terms of the local acceleration, and hydrodynamic destruction, of dense clouds as they are swept up in a hot, low-density wind driven by the AGN. We discuss the implications for measuring the mass outflow rates and kinetic powers for the AGN-driven outflows in such objects. [ABSTRACT FROM AUTHOR]

Aims. We characterise the properties of stars, dust, and gas and their spatial distribution in the central region of the Seyfert 2 galaxy NGC 1068. Method. Our study is based on near-infrared (YJH, 0.95−1.650 μm, R = 350) long-slit spectroscopy observations of the central region of NGC 1068 with a 0.4″ spatial resolution. We decomposed the observed continuum emission into three components: hot dust, stars, and scattered light from the central engine. We measured their contributions at various distances from the nucleus. We also measured fluxes and Doppler shifts for the emission lines in our spectrum to probe the physical conditions of the narrow line region. Results. Dust and stars are the main sources of continuum emission, but scattered light from the central engine has also been detected in the very central region. Together, these three components reproduce the observed continuum well. The dust emission is compatible with a 830 K blackbody. It has only been detected in the very central region and is not spatially resolved. The stellar content is ubiquitous. It harbours a 250 pc cusp centred around the nucleus, over-imposed on a young stellar background. The spectrum of the cusp is consistent with a 120 Myr old single stellar population. Finally, the emission lines exhibit a significant Doppler shift that is consistent with a radial outflow from the nucleus in a biconical structure. The [Fe II] behaviour strongly differs from other lines, indicating that it arises from a different structure. [ABSTRACT FROM AUTHOR]

We report the discovery of rapid variations of a high-velocity Mg ii broad absorption line (BAL) trough in the quasar SDSS J133356.02 + 001229.1 (⁠|$z$| em∼ 0.9197). Vivek et al. revealed the emergence and subsequent near disappearance of a BAL component in this source having an ejection velocity of ∼28 000  km s−1. Our further follow-up studies with South African Large Telescope (SALT) reveal the dramatic nature of the absorption line variability in this source. The absorption line emerged again at the same velocity and nearly disappeared within the SALT observations. Our observations allow us to probe variability over time-scales of the order of few days to 4.2 yr in the QSO rest frame. The observed velocity stability of BAL absorption does not point to any line-of-sight acceleration/deceleration of BAL clouds. The ionization parameter of the absorbing cloud is constrained from the column density ratio of Mg ii to Fe ii ground state absorption. In the absence of strong optical continuum variability, we suggest that photoionization-driven BAL variability due to changes in the shielding, multiple streaming clouds across our line of sight in a corotating wind, or a combination of both as possible explanations for the observed strong equivalent width variations. [ABSTRACT FROM AUTHOR]

We present the 1–100 GeV spectral energy distribution (SED) for a population of 148 high-synchrotron-peaked (HSP) blazars recently detected with Fermi -LAT as part of the First Brazil-ICRANet Gamma-ray Blazar (1BIGB) catalogue. Most of the 1BIGB sources have their γ-ray spectral properties presented here for the first time, representing a significant new extension of the γ-ray blazar population. Since our sample was originally selected from an excess signal in the 0.3–500 GeV band, the sources stand out as promising TeV blazar candidates, potentially in reach of the forthcoming very high energy (VHE) γ-ray observatory, Cherenkov Telescope Array (CTA). The flux estimates presented here are derived considering PASS8 data, integrating over more than 9 yr of Fermi -LAT observations. We also review the full broad-band fit between 0.3 and 500 GeV presented in the original 1BIGB paper for all sources, updating the power-law parameters with currently available Fermi -LAT data set. The importance of these sources in the context of VHE population studies with both current instruments and the future CTA is evaluated. To do so, we select a subsample of 1BIGB sources and extrapolate their γ-ray SEDs to the highest energies, properly accounting for absorption due to the extragalactic background light. We compare those extrapolations to the published CTA sensitivity curves and estimate their detectability by CTA. Two notable sources from our sample, namely 1BIGB J224910.6 − 130002 and 1BIGB J194356.2+211821, are discussed in greater detail. All γ-ray SEDs are made publicly available via the Brazilian Science Data Center (BSDC) service, maintained at CBPF, in Rio de Janeiro. [ABSTRACT FROM AUTHOR]

Blazar PKS 2155–304 is one of the sources that has been well monitored under the SMARTS (Small Moderate Aperture Research Telescope System) project. SMARTS light curves in the BVRJK bands and spectral indices connecting the B with the J band of PKS 2155–304 from 2008 to 2015 are presented at near-nightly cadence, and divided into a number of segments without long observational gaps for comparison investigations on shorter time-scales. The optical and near-infrared (NIR) variations are simultaneous, with time lags of no longer than a couple of days, which suggests a temporal coherence of the corresponding jet-emitting regions. Long- and short-term optical–NIR variability shows that optical bands are fainter and vary less than the IR bands, while fractional variability amplitudes show no clear trend on long-term time-scales and in segments of light curves, probably owing to effects from stochastic processes. The prominent flares presented in the optical–NIR light curves tend to show an asymmetric feature with different rise and decay time-scales. The spectral indices varied on diverse time-scales, and the source showed no clear trend on long-term time-scales, an occasional appearance of tendencies of flatter-when-brighter on short-term time-scales, and an independent clockwise evolving loop pattern, suggesting a complex spectral evolution with the flux. [ABSTRACT FROM AUTHOR]

We performed quasi-simultaneous optical multi-band monitoring of the BL Lac object S5 0716+714 on seven nights from 2013 to 2016. Intra-day variability was found on all seven nights. The source was faintest on JD 245 6322 with 14.15 mag and brightest on JD 245 7437 with 12.51 mag in the R band. The maximum intra-day variation that we observed was 0.15 mag in the B band on JD 245 6322. Both bluer-when-brighter and achromatic spectral behaviours were observed on the intra-day timescale. On the longer-term scale, the object exhibited mild bluer-when-brighter behaviour between the B and R bands. We estimate the inter-band lags using two independent methods. The variation in the B band was observed to lag behind that in the I band by about 15 min on JD 245 7315. We compare this lag with one reported previously and discuss the origin of these lags. [ABSTRACT FROM AUTHOR]

We present a multi-epoch X-ray spectroscopy analysis of the nearby narrow-line Seyfert I galaxy NGC 5506. For the first time, spectra taken by Chandra, XMM–Newton, Suzaku, and NuSTAR– covering the 2000–2014 time span – are analysed simultaneously, using state-of-the-art models to describe reprocessing of the primary continuum by optical thick matter in the active galactic nucleus environment. The main goal of our study is determining the spin of the supermassive black hole (SMBH). The nuclear X-ray spectrum is photoelectrically absorbed by matter with column density ≃ 3 × 1022 cm−2. A soft excess is present at energies lower than the photoelectric cut-off. Both photoionized and collisionally ionized components are required to fit it. This component is constant over the time-scales probed by our data. The spectrum at energies higher than 2 keV is variable. We propose that its evolution could be driven by flux-dependent changes in the geometry of the innermost regions of the accretion disc. The black hole spin in NGC 5506 is constrained to be 0.93 $\pm _{ 0.04 }^{0.04}$ at 90 per cent confidence level for one interesting parameter. [ABSTRACT FROM AUTHOR]

We present a catalogue of ALMA flux density measurements of 754 calibrators observed between 2012 August and 2017 September, for a total of 16263 observations in different bands and epochs. The flux densities were measured by reprocessing the ALMA images generated in the framework of the ALMACAL project, with a new code developed by the Italian node of the European ALMA Regional Centre. A search in the online data bases yielded redshift measurements for 589 sources (∼78 per cent of the total). Almost all sources are flat spectrum, based on their low-frequency spectral index, and have properties consistent with being blazars of different types. To illustrate the properties of the sample, we show the redshift and flux density distributions as well as the distributions of the number of observations of individual sources and of timespans in the source frame for sources observed in bands 3 (84−116 GHz) and 6 (211−275 GHz). As examples of the scientific investigations allowed by the catalogue, we briefly discuss the variability properties of our sources in ALMA bands 3 and 6 and the frequency spectra between the effective frequencies of these bands. We find that the median variability index steadily increases with the source-frame time lag increasing from 100 to 800  d, and that the frequency spectra of BL Lacs are significantly flatter than those of flat-spectrum radio quasars. We also show the global spectral energy distributions of our sources over 17 orders of magnitude in frequency. [ABSTRACT FROM AUTHOR]

Context. The physical characteristics of the material closest to supermassive black holes (SMBHs) are primarily studied through X-ray observations. However, the origins of the main X-ray components such as the soft X-ray excess, the Fe Kα line complex, and the hard X-ray excess are still hotly debated. This is particularly problematic for active galactic nuclei (AGN) showing a significant intrinsic absorption, either warm or neutral, which can severely distort the observed continuum. Therefore, AGN with no (or very weak) intrinsic absorption along the line of sight, so-called "bare AGN", are the best targets to directly probe matter very close to the SMBH. Aims. We perform an X-ray spectral analysis of the brightest and cleanest bare AGN known so far, Ark 120, in order to determine the process(es) at work in the vicinity of the SMBH. Methods. We present spectral analyses of data from an extensive campaign observing Ark 120 in X-rays with XMM-Newton (4 × 120 ks, 2014 March 18-24), and NuSTAR (65.5 ks, 2014 March 22). Results. During this very deep X-ray campaign, the source was caught in a high-flux state similar to the earlier 2003 XMM-Newton observation, and about twice as bright as the lower-flux observation in 2013. The spectral analysis confirms the "softer when brighter" behavior of Ark 120. The four XMM-Newton/pn spectra are characterized by the presence of a prominent soft X-ray excess and a significant Fe Kα complex. The continuum is very similar above about 3 keV, while significant variability is present for the soft X-ray excess. We find that relativistic reflection from a constant-density, flat accretion disk cannot simultaneously produce the soft excess, broad Fe Kα complex, and hard X-ray excess. Instead, Comptonization reproduces the broadband (0.3-79 keV) continuum well, together with a contribution from a mildly relativistic disk reflection spectrum. Conclusions. During this 2014 observational campaign, the soft X-ray spectrum of Ark 120 below ~0.5 keV was found to be dominated by Comptonization of seed photons from the disk by a warm (kTe ~ 0.5 keV), optically-thick corona (τ ~ 9). Above this energy, the X-ray spectrum becomes dominated by Comptonization from electrons in a hot optically thin corona, while the broad Fe Kα line and the mild Compton hump result from reflection off the disk at several tens of gravitational radii. [ABSTRACT FROM AUTHOR]

We present ELDAR, a new method that exploits the potential of medium- and narrow-band filter surveys to securely identify active galactic nuclei (AGN) and determine their redshifts. Our methodology improves on traditional approaches by looking for AGN emission lines expected to be identified against the continuum, thanks to the width of the filters. To assess its performance, we apply ELDAR to the data of the ALHAMBRA (Advance Large Homogeneous Area Medium Band Redshift Astronomical) survey, which covered an effective area of 2.38 deg2 with 20 contiguous medium-band optical filters down to F814W ≃ 24.5. Using two different configurations of ELDAR in which we require the detection of at least two and three emission lines, respectively, we extract two catalogues of type-I AGN. The first is composed of 585 sources (79 per cent of them spectroscopically unknown) down to F814W = 22.5 at zphot > 1, which corresponds to a surface density of 209 deg-2. In the second, the 494 selected sources (83 per cent of them spectroscopically unknown) reach F814W= 23 at zphot > 1.5, for a corresponding number density of 176 deg-2. Then, using samples of spectroscopically known AGN in the ALHAMBRA fields, for the two catalogues we estimate a completeness of 73 per cent and 67 per cent, and a redshift precision of 1.01 per cent and 0.86 per cent (with outliers fractions of 8.1 per cent and 5.8 per cent). At z > 2, where our selection performs best, we reach 85 per cent and 77 per cent completeness and we find no contamination from galaxies. [ABSTRACT FROM AUTHOR]

We present theγ -ray observations of the flat-spectrum radio quasar PKS 1441+25 (z=0.939), using the Fermi large Area Telescope data accumulated during 2015 January-December. A γ-ray flare was observed in January 24, when the flux increased up to (2.22 ± 0.38) x 10-6 photon cm-2 s-1 with the flux-doubling time-scale being as short as ∼1.44 d. The spectral analysis shows that from 2015 April 13 to April 28, the MeV-to-GeV photon index has hardened and changes in the range of Γ = (1.73-1.79) for most of the time. The hardest photon index of Γ = 1.54 ± 0.16 has been observed on MJD 57 131.46 with 11.8σ which is not common for flat-spectrum radio quasars. For the same period theγ -ray spectrum shows a possible deviation from a simple power-law shape, indicating a spectral cutoff at Ecut = 17.7 ± 8.9 GeV. The spectral energy distributions during quiescent and flaring states are modelled using one-zone leptonic models that include the synchrotron, synchrotron self Compton and external inverse Compton processes; the model parameters are estimated using the Markov Chain Monte Carlo method. The emission in the flaring states can be modelled assuming that either the bulk Lorentz factor or the magnetic field has increased. The modelling shows that there is a hint of hardening of the low-energy index (∼1.98) of the underlying non-thermal distribution of electrons responsible for the emission in 2015 April. Such hardening agrees with theγ -ray data, which pointed out a significantγ -ray photon index hardening on 2015 April 13 to 28. [ABSTRACT FROM AUTHOR]

We present optical imaging and spectroscopic studies of the Fanaroff & Riley class I (FR I) radio galaxy CTD 086 based on Hubble Space Telescope ( HST) and Sloan Digital Sky Survey ( SDSS) observations. We use isophote shape analysis to show that there is no stellar disk component within CTD 086 and further that the morphological class of the galaxy is most likely E2. Optical spectroscopy of this galaxy reveals the presence of narrow emission lines only, and thus it qualifies to be termed as a narrow-line radio galaxy (type 2 AGN). We also extract stellar kinematics from the absorption-line spectra of CTD 086 using Penalized Pixel-Fitting method and derive the black hole mass $M_{BH}$ to be equal to $(8.8\pm2.4)\times10^{7}~{\mathrm{M}\odot}$ . [ABSTRACT FROM AUTHOR]

We present the results from a broad-band (1 to 3 GHz), spectro-polarimetry study of the integrated emission from 100 extragalactic radio sources with the Australia Telescope Compact Array, selected to be highly linearly polarized at 1.4 GHz. We use a general-purpose, polarization model-fitting procedure that describes the Faraday rotation measure (RM) and intrinsic polarization structure of up to three distinct polarized emission regions or 'RM components' of a source. Overall, 37 per cent/52 per cent/11 per cent of sources are best fitted by one/two/three RMcomponents. However, these fractions are dependent on the signal-to-noise ratio (S/N) in polarization (more RM components more likely at higher S/N). In general, our analysis shows that sources with high integrated degrees of polarization at 1.4 GHz have low Faraday depolarization, are typically dominated by a single RM component, have a steep spectral index and have a high intrinsic degree of polarization. After classifying our sample into radiative-mode and jet-mode AGN, we find no significant difference between the Faraday rotation or Faraday depolarization properties of jet-mode and radiative-mode AGN. However, there is a statistically significant difference in the intrinsic degree of polarization between the two types, with the jet-mode sources having more intrinsically ordered magnetic field structures than the radiative-mode sources. We also find a preferred perpendicular orientation of the intrinsic magnetic field structure of jet-mode AGN with respect to the jet direction, while no clear preference is found for the radiative-mode sources. [ABSTRACT FROM AUTHOR]

We present optical integral field spectroscopy - obtained with the Gemini Multi-Object Spectrograph - of the inner 4.0 × 5.8 kpc2 of the narrow line radio galaxy 3C 33 at a spatial resolution of 0.58 kpc. The gas emission shows three brightest structures: a strong knot of nuclear emission and two other knots at ≈1.4 kpc south-west and north-east of the nucleus along the ionization axis. We detect two kinematic components in the emission lines profiles, with a 'broader component' (with velocity dispersion σ ≥ 150 km s--1 )being dominant within an ~1 kpc wide strip ('the nuclear strip') running from the south-east to the north-west, perpendicular to the radio jet, and a narrower component (σ ≤ 100 km s--1 ) dominating elsewhere. Centroid velocity maps reveal a rotation pattern with velocity amplitudes reaching ~± 350 km s--1 in the region dominated by the narrow component, while residual blueshifts and redshifts relative to rotation are observed in the nuclear strip, where we also observe the highest values of the [NII]/Hα, [SII]/Hα and [OI]/Hα line ratios, and an increase of the gas temperature (~18 000 K), velocity dispersion and electron density (~500 cm--3 ). We interpret these residuals and increased line ratios as due to a lateral expansion of the ambient gas in the nuclear strip due to shocks produced by the passage of the radio jet. The effect of this expansion in the surrounding medium is very small, as its estimated kinetic power represents only 2.6 × 10--5 - 3.0 × 10--5 of the AGN bolometric luminosity. A possible signature of inflow is revealed by an increase in the [OI]/Hα ratio values and velocity dispersions in the shape of two spiral arms extending to 2.3 kpc north-east and south-west from the nucleus. [ABSTRACT FROM AUTHOR]

Broad absorption lines (BALs) found in a significant fraction of quasar spectra identify highvelocity outflows that might be present in all quasars and could be a major factor in feedback to galaxy evolution. Understanding the nature of these flows requires further constraints on their physical properties, including their column densities, for which well-studied BALs, such as CIV λλ1548,1551, typically provide only a lower limit because of saturation effects. Low abundance lines, such as P V λλ1118,1128, indicate large column densities, implying that outflows more powerful than measurements of C IV alone would indicate. We search through a sample of 2694 BAL quasars from the Sloan Digital Sky Survey III/Baryon Oscillation Spectroscopic Survey data release 9 quasar catalogue for such absorption, and we identify 81 ‘definite’ and 86 ‘probable’ detections of P V broad absorption, yielding a firm lower limit of 3.0–6.2 per cent for the incidence of such absorption among BAL quasars. The P V-detected quasars tend to have stronger C IV and Si IV absorption, as well as a higher incidence of LoBAL absorption, than the overall BAL quasar population. Many of the P V-detected quasars have C IV troughs that do not reach zero intensity (at velocities where P V is detected), confirming that the outflow gas only partially covers the UV continuum source. P V appears significantly in a composite spectrum of non-P V-detected BAL quasars, indicating that P V absorption (and large column densities) is much more common than indicated by our search results. Our sample of P V detections significantly increases the number of known P V detections, providing opportunities for follow-up studies to better understand BAL outflow energetics. [ABSTRACT FROM AUTHOR]

We present quasar bolometric corrections using the [OIII]λ5007 narrow emission line luminosity based on the detailed spectral energy distributions of 53 bright quasars at low to moderate redshift (0.0345 < z < 1.0002). We adopted two functional forms to calculate Liso, the bolometric luminosity determined under the assumption of isotropy: Liso=AL[OIII] for comparison with the literature and log(Liso)=B+Clog(L[OIII]), which better characterizes the data. We also explored whether 'Eigenvector 1 (EV1)', which describes the range of quasar spectral properties and quantifies their diversity, introduces scatter into the L[OIII] -Liso relationship. We found that the [OIII] bolometric correction can be significantly improved by adding a term including the equivalent width ratio RFeII ≡EWFeII/EWHβ, which is an EV1 indicator. Inclusion of RFeII in predicting Liso is significant at nearly the 3σ level and reduces the scatter and systematic offset of the luminosity residuals. Typically, [OIII] bolometric corrections are adopted for Type 2 sources where the quasar continuum is not observed and in these cases, RFeII cannot be measured. We searched for an alternative measure of EV1 that could be measured in the optical spectra of Type 2 sources but were unable to identify one. Thus, the main contribution of this work is to present an improved [OIII] bolometric correction based on measured bolometric luminosities and highlight the EV1 dependence of the correction in Type 1 sources. [ABSTRACT FROM AUTHOR]

We present optical spectroscopy of candidate active galactic nuclei (AGN) pinpointed by a Swift follow-up campaign on unidentified transients in the XMM-Newton Slew Survey, increasing the completeness of the identifications of AGN in the Survey. Our Swift follow-up campaign identified 17 X-ray Telescope-detected candidate AGN, of which 9 were selected for optical follow-up and a further two were confirmed as AGN elsewhere. Using data obtained at the William Herschel Telescope, Very Large Telescope and New Technology Telescope, we find AGN features in seven of the candidates. We classify six as Seyfert types 1.0-1.5, with broad-line region velocities spanning 2000-12000 km s-1, and identify one as a possible type II AGN, consistent with the lack of a soft band X-ray detection in the Slew Survey. The virial black hole mass estimates for the sample lie between 1 × 108 and 3× 109 M☉, with one source likely emitting close to its Eddington rate, LBol/LEdd ~ 0.9. We find a wide redshift range 0.08 < z < 0.9 for the nine now confirmed AGN drawn from the unidentified Slew Survey sample. One source remaining unclassified shows outbursts rarely seen before in AGN. We conclude that AGN discovered in this way are consistent with the largely non-varying, Slew-selected, known AGN population. We also find parallels with XMM-Newton Bright Serendipitous Survey AGN selected from pointed observations, and postulate that shallow X-ray surveys select AGN drawn from the same populations that have been characterized in deeper X-ray-selected samples. [ABSTRACT FROM AUTHOR]

In an effort to understand the cause of the apparent depletion in the number density of radio-loud active galactic nuclei (AGNs) at z > 3, this work investigates the viability of the so-called cosmic microwave background (CMB) quenching mechanism of intrinsically jetted, high-z AGNs, whereby inverse Compton scattering of CMB photons off electrons within the extended lobes results in a substantial dimming of the lobe synchrotron emission at GHz frequencies, while simultaneously boosting their diffuse X-ray signal. We focus on five z > 3.5 radio galaxies that have sufficiently deep Chandra exposure (>50 ks) to warrant a meaningful investigation of any extended X-ray emission. For those objects with evidence for statistically significant extended X-ray lobes (4C 41.17 and 4C 03.24), we combine the Chandra measurements with literature data at lower frequencies to assemble the systems' spectral energy distributions (SEDs), and utilize state-of-the-art SED modelling - including emission from the disc, torus, jet, hotspots and lobes - to infer their physical parameters. For both radio galaxies, the magnetic energy density in the hotspots is found to exceed the energy density in CMB photons, whereas the opposite is true for the lobes. This implies that any extended synchrotron emission likely originates from the hotspots themselves, rather than the lobes. Conversely, inverse Compton scattering of CMB photons dominates the extended X-ray emission from the lobes, which are effectively 'radio-quenched'. As a result, CMB quenching is effective in these systems in spite of the fact that the observed X-ray to radio luminosity ratio does not bear the signature (1 + z)4 dependence of the CMB energy density. [ABSTRACT FROM AUTHOR]

We derive constraints on feedback by active galactic nuclei (AGN) by setting limits on their thermal Sunyaev-Zel'dovich (SZ) imprint on the cosmic microwave background. The amplitude of any SZ signature is small and degenerate with the poorly known sub-mm spectral energy distribution of theAGNhost galaxy and other unresolved dusty sources along the line of sight. Here we break this degeneracy by combining microwave and sub-mm data from Planck with all-sky far-infraredmaps from the AKARI satellite. We first test our measurement pipeline using the Sloan Digital Sky Survey (SDSS) redMaPPer catalogue of galaxy clusters, finding a highly significant detection (>20σ) of the SZ effect together with correlated dust emission. We then constrain the SZ signal associated with spectroscopically confirmed quasi-stellar objects (QSOs) from SDSS data release 7 (DR7) and the Baryon Oscillation Spectroscopic Survey (BOSS) DR12. We obtain a low-significance (1.6σ) hint of an SZ signal, pointing towards a mean thermal energy of≃5 × 1060 erg, lower than reported in some previous studies. A comparison of our results with high-resolution hydrodynamical simulations including AGN feedback suggests QSO host masses ofM200c ∼ 4 × 1012 h-1M☉, but with a large uncertainty. Our analysis provides no conclusive evidence for an SZ signal specifically associated with AGN feedback. [ABSTRACT FROM AUTHOR]

The narrow-line Seyfert 1 galaxy NGC 4051 is known to exhibit significant X-ray spectral/ flux variations and have a number of emission/absorption features. X-ray observations have revealed that these absorption features are blueshifted, which indicates that NGC 4051 has warm absorber outflow. In order to constrain physical parameters of the warm absorber outflow, we analyse the archival data with the longest exposure taken by XMM-Newton in 2009.We calculate the root-mean-square (rms) spectra with the grating spectral resolution for the first time. The rms spectra have a sharp peak and several dips, which can be explained by variable absorption features and non-variable emission lines; a lower ionized warm absorber (WA1: log ξ = 1.5, υ = -650 km s-1) shows large variability, whereas higher ionized warm absorbers (WA2: log ξ = 2.5, υ =-4100 km s-1, WA3: logξ = 3.4, υ =-6100 km s-1) show little variability. WA1 shows the maximum variability at a time-scale of ~104 s, suggesting that the absorber locates at ~103 times of the Schwarzschild radius. The depth of the absorption features due to WA1 and the observed soft X-ray flux are anticorrelated in several observational sequences, which can be explained by variation of partial covering fraction of the double-layer blobs that are composed of the Compton-thick core and the ionized layer (=WA1). WA2 and WA3 show little variability and presumably extend uniformly in the line of sight. The present result shows that NGC 4051 has two types of the warm absorber outflows; the static, high-ionized and extended line-driven disc winds and the variable, low-ionized and clumpy double-layer blobs. [ABSTRACT FROM AUTHOR]

We obtained optical spectroscopy of close (<80 kpc) companion objects of a sample of 12 lowredshift quasars (z < 0.3) selected from the SDSS Stripe82 area and that are in the subsample of 52 QSOs for which both multicolour host galaxies properties and galaxy environment were recently investigated in detail. We found that for 8 out of 12 sources the companion galaxy is associated with the QSO having a difference of radial velocity that is less than 400 km s-1. Many of these associated companions exhibit [OII] λ3727 Åemission lines suggestive of episodes of (recent) star formation possibly induced by past interactions. The star formation rate of the companion galaxies as derived from [O II] line luminosity is, however, modest, with a median value of 1.0 ± 0.8 M☉ yr-1, and the emission lines are barely consistent with expectation from gas ionization by the QSO. The role of the QSO for inducing star formation in close companion galaxies appears meager. For three objects we also detect the starlight spectrum of the QSO host galaxy, which is characterized by absorption lines of old stellar population and [O II] emission line. [ABSTRACT FROM AUTHOR]

The XXL survey currently covers two 25 deg2 patches with XMM observations of ~10 ks. We summarize the scientific results associated with the first release of the XXL dataset, which occurred in mid-2016.We review several arguments for increasing the survey depth to 40 ks during the next decade of XMM operations. X-ray (z<2) cluster, (z<4) active galactic nuclei (AGN), and cosmic background survey science will then benefit from an extraordinary data reservoir. This, combined with deep multi-observations, will lead to solid standalone cosmological constraints and provide a wealth of information on the formation and evolution of AGN, clusters, and the X-ray background. In particular, it will offer a unique opportunity to pinpoint the z>1 cluster density. It will eventually constitute a reference study and an ideal calibration field for the upcoming eROSITA and Euclid missions. [ABSTRACT FROM AUTHOR]

We present the Large Area Radio Galaxy Evolution Spectroscopic Survey (LARGESS), a spectroscopic catalogue of radio sources designed to include the full range of radio AGN populations out to redshift z ~ 0.8. The catalogue covers ~800 deg² of sky, and provides optical identifications for 19 179 radio sources from the 1.4 GHz Faint Images of the Radio Sky at Twenty-cm (FIRST) survey down to an optical magnitude limit of imod < 20.5 in Sloan Digital Sky Survey (SDSS) images. Both galaxies and point-like objects are included, and no colour cuts are applied. In collaboration with the WiggleZ and Galaxy And Mass Assembly (GAMA) spectroscopic survey teams, we have obtained new spectra for over 5000 objects in the LARGESS sample. Combining these new spectra with data from earlier surveys provides spectroscopic data for 12 329 radio sources in the survey area, of which 10 856 have reliable redshifts. 85 per cent of the LARGESS spectroscopic sample are radio AGN (median redshift z = 0.44), and 15 per cent are nearby star-forming galaxies (median z = 0.08). Low-excitation radio galaxies (LERGs) comprise the majority (83 per cent) of LARGESS radio AGN at z < 0.8, with 12 per cent being high-excitation radio galaxies (HERGs) and 5 per cent radioloud QSOs. Unlike the more homogeneous LERG and QSO sub-populations, HERGs are a heterogeneous class of objects with relatively blue optical colours and a wide dispersion in mid-infrared colours. This is consistent with a picture in which most HERGs are hosted by galaxies with recent or ongoing star formation as well as a classical accretion disc. [ABSTRACT FROM AUTHOR]

We map the gas excitation and kinematics, and the stellar population properties of the Seyfert 1 galaxy NGC 5548 using Gemini Near Infrared Integral Field Spectrograph in the J and K bands at a spatial and velocity resolution of 105 pc and 45 km s-1, respectively. Emission-line flux distributions in ionized and molecular gas extend up to ≈400 pc from the nucleus, where they are found to peak. The mass of HII is 4.8±0.6 × 106 M⊙ and the mass of warm H2 is 1.1±0.2 × 10³ M⊙, while the mass of cold H2 is estimated as 5.8±1.2 × 108 M⊙. The Pa γ emission shows two kinematic components: one in blueshift, with velocity reaching ≈-300 km s-1 and another showing a velocity field characteristic of rotation in the galaxy plane. The blueshifted component is also observed in the coronal line [S IX]λ1.2523 μm, while the rotational component is also observed in the molecular gas. We interpret this velocity field as due to gas rotating in the galaxy plane plus an outflow, and estimate a mass outflow rate of 6.8±0.75 M⊙ yr-1. Spectral synthesis of the continuum shows nuclear emission dominated by a featureless AGN continuum combined with hot dust emission attributed to a dusty torus. The stellar population is dominated by an old (2 Gyr < t ≤ 15 Gyr) component between 160 and 300 pc, while closer to the nucleus, an intermediate age (50 Myr < t ≤ 2 Gyr) component contributes at levels ranging from ≈40 per cent to ≈100 per cent to the flux at 2.12 μm. [ABSTRACT FROM AUTHOR]

We present high-angular (0.17-0.35 arcsec) resolution imaging polarimetric observations of Mrk 231 in the 3.1 μm filter using MMT-Pol on the 6.5-m MMT, and in the 8.7, 10.3, and 11.6 μm filters using CanariCam on the 10.4-m Gran Telescopio CANARIAS. In combination with already published observations, we compile the 1-12 μm total and polarized nuclear spectral energy distribution (SED). The total flux SED in the central 400 pc is explained as the combination of (1) a hot (731 ± 4 K) dusty structure, directly irradiated by the central engine, which is at 1.6 ± 0.1 pc away and attributed to be in the pc-scale polar region, (2) an optically-thick, smooth and disc-like dusty structure ('torus') with an inclination of 48° ± 23° surrounding the central engine, and (3) an extinguished (AV = 36 ± 5 mag) starburst component. The polarized SED decreases from 0.77 ± 0.14 per cent at 1.2 μm to 0.31 ± 0.15 per cent at 11.6 μm and follows a power-law function, λ ~0.57. The polarization angle remains constant (~108°) in the 1-12 μm wavelength range. The dominant polarization mechanism is explained as scattering-off hot dust grains in the pc-scale polar regions. [ABSTRACT FROM AUTHOR]

The Lockman Hole is a well-studied extragalactic field with extensive multi-band ancillary data covering a wide range in frequency, essential for characterizing the physical and evolutionary properties of the various source populations detected in deep radio fields (mainly star-forming galaxies and AGNs). In this paper, we present new 150-MHz observations carried out with the LOw-Frequency ARray (LOFAR), allowing us to explore a new spectral window for the faint radio source population. This 150-MHz image covers an area of 34.7 square degrees with a resolution of 18.6×14.7 arcsec and reaches an rms of 160 μJy beam-1 at the centre of the field. As expected for a low-frequency selected sample, the vast majority of sources exhibit steep spectra, with a median spectral index of α1400 150 = -0.78 ± 0.015. The median spectral index becomes slightly flatter (increasing from α1400 150 = -0.84 to α1400 150 = -0.75) with decreasing flux density down to S150 ~10 mJy before flattening out and remaining constant below this flux level. For a bright subset of the 150-MHz selected sample, we can trace the spectral properties down to lower frequencies using 60-MHz LOFAR observations, finding tentative evidence for sources to become flatter in spectrum between 60 and 150 MHz. Using the deep, multi-frequency data available in the Lockman Hole, we identify a sample of 100 ultra-steepspectrum sources and 13 peaked-spectrum sources.We estimate that up to 21 per cent of these could have z > 4 and are candidate high-z radio galaxies, but further follow-up observations are required to confirm the physical nature of these objects. [ABSTRACT FROM AUTHOR]

High-redshift radio-loud quasars are used to, among other things, test the predictions of cosmological models, set constraints on black hole growth in the early Universe and understand galaxy evolution. Prior to this paper, 20 extragalactic radio sources at redshifts above 4.5 have been imaged with very long baseline interferometry (VLBI). Here, we report on observations of an additional ten z > 4.5 sources at 1.7 and 5 GHz with the European VLBI Network, thereby increasing the number of imaged sources by 50 per cent. Combining our newly observed sources with those from the literature, we create a substantial sample of 30 z > 4.5 VLBI sources, allowing us to study the nature of these objects. Using spectral indices, variability and brightness temperatures, we conclude that of the 27 sources with sufficient information to classify, the radio emission from one source is from star formation, 13 are flat-spectrum radio quasars and 13 are steep-spectrum sources. We also argue that the steep-spectrum sources are off-axis (unbeamed) radio sources with rest-frame self-absorption peaks at or below GHz frequencies and that these sources can be classified as gigahertz peaked-spectrum and megahertz peaked-spectrum sources. [ABSTRACT FROM AUTHOR]

1H 0707-495 is the most convincing example of a supermassive black hole with an X-ray spectrum being dominated by extremely smeared, relativistic reflection, with the additional requirement of strongly supersolar iron abundance. However, here we show that the iron features in its 2-10 keV spectrum are rather similar to the archetypal wind dominated source, PDS 456. We fit all the 2-10 keV spectra from 1H 0707-495 using the same wind model as used for PDS 456, but viewed at higher inclination so that the iron absorption line is broader but not so blueshifted. This gives a good overall fit to the data from 1H 0707-495, and an extrapolation of this model to higher energies also gives a good match to the NuSTAR data. Small remaining residuals indicate that the iron line emission is stronger than in PDS 456. This is consistent with the wider angle wind expected from a continuum-driven wind from the super-Eddington mass accretion rate in 1H 0707-495, and/or the presence of residual reflection from the underlying disc though the presence of the absorption line in the model removes the requirement for highly relativistic smearing, and highly supersolar iron abundance. We suggest that the spectrum of 1H 0707-495 is sculpted more by absorption in a wind than by extreme relativistic effects in strong gravity. [ABSTRACT FROM AUTHOR]

We conducted a high-sensitivity radio detection survey for 40 narrow-line Seyfert 1 (NLS1) galaxies using a very long baseline interferometry (VLBI) technique at 22GHz through phase-referencing long-time integration and using a newly developing recorder with a data rate of 8Gbps, which is a candidate of the next generation VLBI data recording systems of the Japanese VLBI Network. The baseline sensitivity was typically a few mJy. The observations resulted in a detection rate of 12/40 for our radio-selected NLS1 sample: 11 out of the 12 detected NLS1s showed inverted radio spectra between 1.4 and 22GHz on the basis of the Very Large Array flux densities and the VLBI detections. These high fractions suggest that a compact radio core with a high brightness temperature is frequently associated with NLS1 nuclei. On the other hand, at least half of the sample indicated apparently steep spectra even with the limited VLBI sensitivity. Both the inverted and the steep spectrum radio sources are included in the NLS1 population. [ABSTRACT FROM AUTHOR]

We observe the radio galaxy PKS 1934-63 (at z = 0.1825) using the Multi-Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT). The radio source is a gigahertz peaked spectrum source and is compact (0.13 kpc), implying an early stage of evolution (=104 yr). Our data show an interacting pair of galaxies, with projected separation 9.1 kpc and velocity difference Δ(v) = 216 km s-1. The larger galaxy is a M* ~ 1011M⊙ spheroidal with the emission-line spectrum of a high-excitation young radio active galactic nucleus (AGN; e.g. strong [O I]6300 and [O III]5007). Emission-line ratios indicate a large contribution to the line luminosity from high-velocity shocks (~ 550 km s-1). The companion is a non-AGN disc galaxy, with extended Ha emission from which its star formation rate is estimated as 0.61 M⊙ yr-1. Both galaxies show rotational velocity gradients in Ha and other lines, with the interaction being prograde-prograde. The SE-NW velocity gradient of the AGN host is misaligned from the E-W radio axis, but aligned with a previously discovered central ultraviolet source, and a factor of 2 greater in amplitude in Ha than in other (forbidden) lines (e.g. [O III]5007). This could be produced by a fast rotating (100-150 km s-1) disc with circumnuclear star formation. We also identify a broad component of [O III]5007 emission, blueshifted with a velocity gradient aligned with the radio jets, and associated with outflow. However, the broad component of [O I]6300 is redshifted. In spectral fits, both galaxies have old stellar populations plus ~0.1 per cent of very young stars, consistent with the galaxies undergoing first perigalacticon, triggering infall and star formation from ~40 Myr ago followed by the radio outburst. [ABSTRACT FROM AUTHOR]

Quasi-periodic oscillations (QPOs) are coherent peaks of variability power observed in the X-ray power spectra (PSDs) of stellar mass X-ray binaries (XRBs). A scale invariance of the accretion process implies they should be present in the active galactic nuclei. The first robust detection was a ∼ 1 h periodicity in the Seyfert galaxy RE J1034+396 from a ∼ 90 ks XMM- Newton observation; however, subsequent observations failed to detect the QPO in the 0.3-10.0 keV band. In this talk we present the recent detection of the ∼ 1 h periodicity in the 1.0-4.0 keV band of 4 further low-flux/spectrally-harder observations of RE J1034+396 (see Alston et al. 2014). We also present recent work on the discovery of a QPO in the Seyfert galaxy, MS 2254.9-3712, which again is only detected in energy bands associated with the primary power-law continuum emission (Alston et al. 2015). We conclude these features are most likely analogous to the high-frequency QPOs observed in XRBs. In both sources, we also see evidence for X-ray reverberation at the QPO frequency, where soft X-ray bands and Iron Kα emission lag the primary X-ray continuum. These time delays may provide another diagnostic for understanding the underlying QPO mechanism observed in accreting black holes. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We report on the multi-wavelength identification of the X-ray sources found in the Subaru-XMM-Newton Deep Survey (SXDS) using deep imaging data covering the wavelength range between the far-UV and mid-IR (MIR). We select a primary counterpart of each X-ray source by applying the likelihood ratio method to R-band, 3.6μm, near- UV, and 24μm source catalogs as well as matching catalogs of active galactic nucleus (AGN) candidates selected in 1.4 GHz radio and i'-band variability surveys. Once candidates for Galactic stars, ultra-luminous X-ray sources in a nearby galaxy, and clusters of galaxies are removed there are 896 AGN candidates in the sample. We conduct spectroscopic observations of the primary counterparts with multi-object spectrographs in the optical and NIR; 65% of the X-ray AGN candidates are spectroscopically identified. For the remaining X-ray AGN candidates, we evaluate their photometric redshift with photometric data in 15 bands. Utilizing the multi-wavelength photometric data of the large sample of X-ray-selected AGNs, we evaluate the stellar masses, M*, of the host galaxies of the narrow-line AGNs. The distribution of the stellarmass is remarkably constant from z=0.1 to 4.0. The relation between M* and 2-10 keV luminosity can be explained with strong cosmological evolution of the relationship between the black hole mass and M*. We also evaluate the scatter of the UV-MIR spectral energy distribution (SED) of the X-ray AGNs as a function of X-ray luminosity and absorption by the nucleus. The scatter is compared with galaxies which have redshift and stellarmass distributionmatched with the X-ray AGN. The UV-NIR (near-IR) SEDs of obscured X-ray AGNs are similar to those of the galaxies in the matched sample. In the NIR-MIR range, the median SEDs of X-ray AGNs are redder, but the scatter of the SEDs of the X-ray AGN broadly overlaps that of the galaxies in the matched sample. [ABSTRACT FROM AUTHOR]

The high-frequency-peaked BL Lac (HBL) 1ES 0806+524 (z = 0.138) was discovered in very high energy (VHE) γ-rays in 2008. Until now, the broad-band spectrum of 1ES 0806+524 has been only poorly characterized, in particular at high energies. We analysed multiwave-length observations from γ-rays to radio performed from 2011 January to March, which were triggered by the high activity detected at optical frequencies. These observations constitute the most precise determination of the broad-band emission of 1ES 0806+524 to date. The stereoscopic Major Atmospheric Gamma-Ray Imaging Cherenkov (MAGIC) observations yielded a γ-ray signal above 250 GeV of (3.7 ± 0.7) per cent of the Crab Nebula flux with a statistical significance of 9.9σ. The multiwavelength observations showed significant variability in essentially all energy bands, including a VHE γ-ray flare that lasted less than one night, which provided unprecedented evidence for short-term variability in 1ES 0806+524. The spectrum of this flare is well described by a power law with a photon index of 2.97 ± 0.29 between ~150 GeV and 1 TeV and an integral flux of (9.3 ± 1.9) per cent of the Crab nebula flux above 250 GeV. The spectrum during the non-flaring VHE activity is compatible with the only available VHE observation performed in 2008 with VERITAS when the source was in a low optical state. The broad-band spectral energy distribution can be described with a one-zone synchrotron self-Compton model with parameters typical for HBLs, indicating that 1ES 0806+524 is not substantially different from the HBLs previously detected. [ABSTRACT FROM AUTHOR]

A multi-epoch, multi-instrument analysis of the Seyfert 1 galaxy HE 0436-4717 is conducted using optical to X-ray data from XMM-Newton and Swift (including the Burst Alert Telescope). Fitting of the UV-to-X-ray spectral energy distribution shows little evidence of extinction and the X-ray spectral analysis does not confirm previous reports of deep absorption edges from O VIII. HE 0436-4717 is a 'bare' Seyfert with negligible line-of-sight absorption making it ideal to study the central X-ray emitting region. Three scenarios were considered to describe the X-ray data: partial covering absorption, blurred reflection, and soft Comptonization. All three interpretations describe the 0.5-10.0 keV spectra well. Extrapolating the models to 100 keV results in poorer fits for the partial covering model. When also considering the rapid variability during one of the XMM-Newton observations, the blurred reflection model appears to describe all the observations in the most self-consistent manner. If adopted, the blurred reflection model requires a very low iron abundance in HE 0436-4717. We consider the possibilities that this is an artefact of the fitting process, but it appears possible that it is intrinsic to the object. [ABSTRACT FROM AUTHOR]

We study the acceleration, transport, and emission of particles in relativistic jets. Localized stochastic particle acceleration, spatial diffusion, and synchrotron as well as synchrotron self-Compton (SSC) emission are considered in a leptonic model. To account for inhomogeneity, we use a 2D axisymmetric cylindrical geometry for both relativistic electrons and magnetic field. In this first phase of our work, we focus on steady-state spectra that develop from a time-dependent model. We demonstrate that small isolated acceleration region in a much larger emission volume are sufficient to accelerate particles to high energy. Diffusive escape from these small regions provides a natural explanation for the spectral form of the jet emission. The location of the acceleration regions within the jet is found to affect the cooling break of the spectrum in this diffusive model. Diffusion-caused energy-dependent inhomogeneity in the jets predicts that the SSC spectrum is harder than the synchrotron spectrum. There can also be a spectral hardening towards the high-energy section of the synchrotron spectrum, if particle escape is relatively slow. These two spectral hardening effects indicate that the jet inhomogeneity might be a natural explanation for the unexpected hard γ-ray spectra observed in some blazars. [ABSTRACT FROM AUTHOR]

We analyse a sample of 26 active galactic nuclei (AGN) with deep XMM-Newton observations, using principal component analysis (PCA) to find model-independent spectra of the different variable components. In total, we identify at least 12 qualitatively different patterns of spectral variability, involving several different mechanisms, including five sources which show evidence of variable relativistic reflection (MCG-6-30-15, NGC 4051, 1H 0707-495, NGC 3516 and Mrk 766) and three which show evidence of varying partial covering neutral absorption (NGC 4395, NGC 1365 and NGC 4151). In over half of the sources studied, the variability is dominated by changes in a power-law continuum, both in terms of changes in flux and power-law index, which could be produced by propagating fluctuations within the corona. Simulations are used to find unique predictions for different physical models, and we then attempt to qualitatively match the results from the simulations to the behaviour observed in the real data. We are able to explain a large proportion of the variability in these sources using simple models of spectral variability, but more complex models may be needed for the remainder. We have begun the process of building up a library of different principal components, so that spectral variability in AGN can quickly be matched to physical processes. We show that PCA can be an extremely powerful tool for distinguishing different patterns of variability in AGN, and that it can be used effectively on the large amounts of high-quality archival data available from the current generation of X-ray telescopes. We will make our PCA code available upon request to the lead author. [ABSTRACT FROM AUTHOR]

The γ-ray spectrum of the low-frequency-peaked BL Lac (LBL) object AP Librae is studied, following the discovery of very-high-energy (VHE; E>100GeV) γ-ray emission up to the TeV range by the H.E.S.S. experiment. This makes AP Librae one of the few VHE emitters of the LBL type. The measured spectrum yields a flux of (8.8±1.5stat±1.8sys)Ã--10-12 cm-2s-1 above 130 GeV and a spectral index of γ=2.65±0.19stat±0.20sys. This study also makes use of \textit{Fermi}-LAT, observations in the high energy (HE, E>100 MeV) range, providing the longest continuous light curve (5 years) ever published on this source. The source underwent a flaring event between MJD 56306-56376 in the HE range, with a flux increase of a factor 3.5 in the 14-day bin light curve and no significant variation in spectral shape with respect to the low-flux state. While the H.E.S.S., and (low state) \textit{Fermi}-LAT fluxes are in good agreement where they overlap, a spectral curvature between the steep VHE spectrum and the \textit{Fermi}-LAT, spectrum is observed. The maximum of the γ-ray emission in the spectral energy distribution is located below the GeV energy range. [ABSTRACT FROM AUTHOR]

In the past five years, a flurry of X-ray reverberation lag measurements of accreting supermassive black holes have been made using the XMM–Newton telescope in the 0.3–10 keV energy range. In this work, we use the NuSTAR (Nuclear Spectroscopic Telescope Array) telescope to extend the lag analysis up to higher energies for two Seyfert galaxies, SWIFT J2127.4+5654 and NGC 1365. X-ray reverberation lags are due to the light travel time delays between the direct continuum emission and the reprocessed emission from the inner radii of an ionized accretion disc. XMM–Newton has been particularly adept at measuring the lag associated with the broad Fe K emission line, where the gravitationally redshifted wing of the line is observed to respond before the line centroid at 6.4 keV, produced at larger radii. Now, we use NuSTAR to probe the lag at higher energies, where the spectrum shows clear evidence for Compton reflection, known as the Compton ‘hump’. The XMM–Newton data show Fe K lags in both SWIFT J2127.4+5654 and NGC 1365. The NuSTAR data provide independent confirmation of these Fe K lags, and also show evidence for the corresponding Compton hump lags, especially in SWIFT J2127.4+5654. These broad-band lag measurements confirm that the Compton hump and Fe K lag are produced at small radii. At low frequencies in NGC 1365, where the spectrum shows evidence for eclipsing clouds in the line of sight, we find a clear negative (not positive) lag from 2 to 10 keV, which can be understood as the decrease in column density from a neutral eclipsing cloud moving out of our line of sight during the observation. [ABSTRACT FROM AUTHOR]

We report on the deepest X-ray observation of the narrow-line Seyfert 1 galaxy Mrk 335 in the low-flux state obtained with Suzaku. The data are compared to a 2006 high-flux Suzaku observation when the source was ∼10 times brighter. Describing the two flux levels self-consistently with partial covering models would require extreme circumstances, as the source would be subject to negligible absorption during the bright state and 95 per cent covering with near Compton-thick material when dim. Blurred reflection from an accretion disc around a nearly maximum spinning black hole (a > 0.91, with preference for a spin parameter as high as ∼0.995) appears more likely and is consistent with the long-term and rapid variability. Measurements of the emissivity profile and spectral modelling indicate the high-flux Suzaku observation of Mrk 335 is consistent with continuum-dominated, jet-like emission (i.e. beamed away from the disc). It can be argued that the ejecta must be confined to within ∼ 25rg if it does not escape the system. During the low-flux state, the corona becomes compact and only extends to about 5rg from the black hole, and the spectrum becomes reflection dominated. The low-frequency lags measured at both epochs are comparable indicating that the accretion mechanism is not changing between the two flux levels. Various techniques to study the spectral variability (e.g. principal component analysis, fractional variability, difference spectra, and hardness ratio analysis) indicate that the low-state variability is dominated by changes in the power-law flux and photon index, but that changes in the ionization state of the reflector are also required. Most notably, the ionization parameter becomes inversely correlated with the reflected flux after a long-duration flare-like event during the observation. [ABSTRACT FROM AUTHOR]

Active galactic nuclei (AGN) are the most luminous persistent objects in the universe. The X-ray domain is particularly important because the X-ray flux represents a significant fraction of the bolometric emission from such objects and probes the innermost regions of accretion disks, where most of this power is generated. An excess of X-ray emission below ~2 keV, called soft-excess, is very common in Type 1 AGN spectra. The origin of this feature remains debated. Originally modeled with a blackbody, there are now several possibilities to model the soft-excess, including warm Comptonization and blurred ionized reflection. In this paper, we test ionized-reflection models on Mrk 509, a bright Seyfert 1 galaxy for which we have a unique data set, in order to determine whether it can be responsible for the strong soft-excess. We use ten simultaneous XMM-Newton and INTEGRAL observations performed every four days. We present here the results of the spectral analysis, the evolution of the parameters, and the variability properties of the X-ray emission. The application of blurred ionized-reflection models leads to a very strong reflection and an extreme geometry, but fails to reproduce the broad-band spectrum of Mrk 509. Two different scenarios for blurred ionized reflection are discussed: stable geometry and lamp-post configuration. In both cases we find that the model parameters do not follow the expected relations, indicating that the model is fine-tuned to fit the data without physical justification. A large, slow variation in the soft-excess without a counterpart in the hard X-rays could be explained by a change in ionization of the reflector. However, such a change does not naturally follow from the assumed geometrical configuration. Warm Comptonization remains the most probable origin of the soft-excess in this object. Nevertheless, it is possible that both ionized reflection and warm Comptonization mechanisms can explain the soft-excess in all objects, one dominating the other one, depending on the physical conditions of the disk and the corona. [ABSTRACT FROM AUTHOR]