Search

Aims. We present a multifrequency, dense radio monitoring program of the blazar OJ 287 using the 100-m E elsberg radio telescope. The program aims to test different binary supermassive black hole (SMBH) scenarios and studying the physical conditions in the central region of this bright blazar. Here, we analyze the evolution in total flux density, linear and circular polarization as a means to study the OJ 287 jet structure and its magnetic field geometry. Methods.We used a recently developed, high-precision data analysis methodology to recover all four Stokes parameters.We measured the total flux density of OJ 287 at nine bands from 2.64 GHz to 43 GHz, the linear polarization parameters at four bands between 2.64 GHz and 10.45 GHz, and the circular polarization at two bands, 4.85 GHz and 8.35 GHz. The mean cadence of our measurements is ten days. Results. Between December 2015 and January 2017 (MJD 57370-57785), OJ 287 showed flaring activity and complex linear and circular polarization behavior. The radio electric vector position angle (EVPA) showed a large clockwise (CW) rotation by 340 with a mean rate of-1.04°/day. Based on concurrent very long baseline interferometric (VLBI) polarization data at 15 GHz and 43 GHz, the rotation seems to originate within the jet core at 43 GHz (projected angular size 0.15 mas or 0.67 pc at the redshift of the source). Moreover, optical polarization data show a similar monotonic CW rotation with a rate of about-1.1°/day which is superposed with shorter and faster rotations that exhibit rates of about 7.8°/day, mainly in the CW sense. Conclusions. The flux density and polarization variability of the single dish, VLBI and optical data is consistent with a polarized emission component propagating on a helical trajectory within a bent jet. We constrained the helix arc length to 0.26 pc and radius to 0.04 pc as well as the jet bending arc length projected on the plane of the sky to ≤1.9-7.6 pc. A similar bending has been observed also in high angular resolution VLBI images of the OJ 287 jet at its innermost regions. The helical trajectory covers only a part of the jet width, possibly its spine. In addition, our results indicate the presence of a stable polarized emission component. Its EVPA (-10°) is oriented perpendicular to the large scale jet, suggesting dominance of the poloidal magnetic field component. Finally, the EVPA rotation begins simultaneously with an optical flare and hence the two might be physically connected. That optical flare has been suggested to be linked to the interaction of a secondary SMBH with the inner accretion disk or originating in the jet of the primary.© 2018 ESO., This program is supported by Fermi Guest Investigator grants NNX08AW56G, NNX09AU10G, NNX12AO93G, and NNX15AU81G.

We present the single-epoch black hole mass (M$_{\rm BH}$) calibrations based on the rest-frame UV and optical measurements of Mg II 2798\AA\ and H$\beta$ 4861\AA\ lines and AGN continuum, using a sample of 52 moderate-luminosity AGNs at z$\sim$0.4 and z$\sim$0.6 with high-quality Keck spectra. We combine this sample with a large number of luminous AGNs from the Sloan Digital Sky Survey to increase the dynamic range for a better comparison of UV and optical velocity and luminosity measurements. With respect to the reference M$_{\rm BH}$ based on the line dispersion of H$\beta$ and continuum luminosity at 5100\AA, we calibrate the UV and optical mass estimators, by determining the best-fit values of the coefficients in the mass equation. By investigating whether the UV estimators show systematic trend with Eddington ratio, FWHM of H$\beta$, the Fe II strength, and the UV/optical slope, we find no significant bias except for the slope. By fitting the systematic difference of Mg II-based and H$\beta$-based masses with the L$_{3000}$/L$_{5100}$ ratio, we provide a correction term as a function of the spectral index as $\Delta$C = 0.24 (1+$\alpha_{\lambda}$) + 0.17, which can be added to the Mg II-based mass estimators if the spectral slope can be well determined. The derived UV mass estimators typically show $>$$\sim$0.2 dex intrinsic scatter with respect to H$\beta$-based M$_{\rm BH}$, suggesting that the UV-based mass has an additional uncertainty of $\sim$0.2 dex, even if high quality rest-frame UV spectra are available.

We report the first results of a survey on 74 narrow-line Seyfert 1 galaxies (NLS1s) carried out in 2015 with the Karl G. Jansky Very Large Array (JVLA) at 5 GHz in A-configuration. So far, this is the largest survey aimed to image the radio continuum of NLS1s. We produced radio maps in order to compare the general properties of three different samples of objects: radio-quiet NLS1s (RQNLS1s), steep-spectrum radio-loud NLS1s (S-NLS1s), and flat-spectrum radio-loud NLS1s (F-NLS1s). We find that the three classes correspond to different radio morphologies, with F-NLS1s being more compact, and RQNLS1s often showing diffuse emission on kpc scales. We also find that F-NLS1s might be low-luminosity and possibly young blazars, and that S-NLS1s are part of the parent population of F-NLS1s. Dedicated studies to RQNLS1s are needed in order to fully understand their role in the unification pictures., 36 pages, 45 figures, 10 tables, accepted for publication by Astronomy & Astrophysics

We search for an isotropic stochastic gravitational-wave background (GWB) in the newly released $11$-year dataset from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav). While we find no significant evidence for a GWB, we place constraints on a GWB from a population of supermassive black-hole binaries, cosmic strings, and a primordial GWB. For the first time, we find that the GWB upper limits and detection statistics are sensitive to the Solar System ephemeris (SSE) model used, and that SSE errors can mimic a GWB signal. We developed an approach that bridges systematic SSE differences, producing the first PTA constraints that are robust against SSE uncertainties. We thus place a $95\%$ upper limit on the GW strain amplitude of $A_\mathrm{GWB}, 21 pages, 12 figures, 9 tables. Published in The Astrophysical Journal. Please send any comments/questions to S. R. Taylor (srtaylor@caltech.edu)

The population of young stars near the Supermassive black hole (SMBH) in the Galactic Center (GC) has presented an unexpected challenge to theories of star formation. Kinematics measurements of these stars have revealed a stellar disk structure (with an apparent 20% disk membership) that has provided important clues to the origin of these mysterious young stars. However many of the apparent disk properties are difficult to explain, including the low disk membership fraction and the high eccentricities, given the youth of this population. Thus far, all efforts to derive the properties of this disk have made the simplifying assumption that stars at the GC are single stars. Nevertheless, stellar binaries are prevalent in our Galaxy, and recent investigations suggested that they may also be abundant in the Galactic Center. Here we show that binaries in the disk can largely alter the apparent orbital properties of the disk. The motion of binary members around each other adds a velocity component, which can be comparable to the magnitude of the velocity around the SMBH in the GC. Thus neglecting the contribution of binaries can significantly vary the inferred stars' orbital properties. While the disk orientation is unaffected the apparent disk's 2D width is increased to about 11.2deg, similar to the observed width. For a population of stars orbiting the SMBH with zero eccentricity, unaccounted for binaries will create a wide apparent eccentricity distribution with an average of 0.23.This is consistent with the observed average eccentricity of the stars' in the disk. We suggest that this high eccentricity value, which poses a theoretical challenge, may be an artifact of binary stars. Finally our results suggest that the actual disk membership might be significantly higher than the one inferred by observations that ignore the contribution of binaries, alleviating another theoretical challenge., Comment: Accepted to ApJ Lett, 5 figures, 8 pages

Hot, dust-obscured galaxies, or "Hot DOGs," are a rare, dusty, hyperluminous galaxy population discovered by the WISE mission. Predominantly at redshifts 2-3, they include the most luminous known galaxies in the universe. Their high luminosities likely come from accretion onto highly obscured supermassive black holes (SMBHs). We have conducted a pilot survey to measure the SMBH masses of five z ∼ 2 Hot DOGs via broad Hα emission lines, using Keck/MOSFIRE and Gemini/FLAMINGOS-2. We detect broad Hα emission in all five Hot DOGs. We find substantial corresponding SMBH masses for these Hot DOGs (∼ 109 M⊙), and their derived Eddington ratios are close to unity. These z ∼ 2 Hot DOGs are the most luminous active galactic nuclei for their BH masses, suggesting that they are accreting at the maximum rates for their BHs. A similar property is found for known z ∼ 6 quasars. Our results are consistent with scenarios in which Hot DOGs represent a transitional, high-accretion phase between obscured and unobscured quasars. Hot DOGs may mark a special evolutionary stage before the red quasar and optical quasar phases, and they may be present at other cosmic epochs.

We have used narrowband [O III] λλ4959, 5007 and Hα+[N II] λλ6548, 84 Hubble Space Telescope (HST) images of nine luminous (L[O III]>1042 erg s−1) type 2 QSOs with redshifts 0.1

Context. Quasars radiating at extreme Eddington ratios (hereafter xA quasars) are likely a prime mover of galactic evolution and have been hailed as potential distance indicators. Their properties are still scarcely known. Aims. We aim to test the effectiveness of the selection criteria defined on the >4D Eigenvector 1> (4DE1) for identifying xA sources. We provide a quantitative description of their rest-frame UV spectra (1300-2200 Å) in the redshift range 2 ≤ z ≤ 2.9, with a focus on major emission features. Methods. Nineteen extreme quasar candidates were identified using 4DE1 selection criteria applied to SDSS spectra: Alλ1860Siλ1892 ≥ 0.5 and Cλ1909/Siλ1892 ≤ 1. The emission line spectra was studied using multicomponent fits of deep spectroscopic observations (S/N ≥ 40-50; spectral resolution ≈ 250 km s) obtained with the OSIRIS at Gran Telescopio Canarias (GTC). Results. GTC spectra confirm that almost all of these quasars are xA sources with very similar properties. We provide spectrophotometric and line profile measurements for the Siλ1397+O, Cλ1549+Heλ1640, and the 1900 Å blend. This last feature is found to be predominantly composed of Alλ1860, Siλ1892 and Fe emission features, with weak Cλ1909. The spectra can be characterized as very low ionization (ionization parameter, logU ∼ -3), a condition that explains the significant Fe emission observed in the spectra. xA quasars show extreme properties in terms of Cλ1549 equivalent width and blueshift amplitudes. Cλ1549 shows low equivalent width, with a median value of 15 Å (≤ 30 Å for the most sources), and high or extreme blueshift amplitudes (-5000 ≤ c(1/2) ≤ -1000 km s). Weak-lined quasars appear as extreme xA quasars and not as an independent class. The Cλ1549 high amplitude blueshifts coexists in all cases save one with symmetric and narrower Alλ1860 and Siλ1892 profiles. Estimates of the Eddington ratio using the Alλ1860 FWHM as a virial broadening estimator are consistent with the ones of a previous xA sample. Conclusions. xA quasars show distinguishing properties that make them easily identifiable in large surveys and potential >standard candles> for cosmological applications. It is now feasible to assemble large samples of xA quasars from the latest data releases of the SDSS. We provide evidence that Alλ1860 could be associated with a low-ionization virialized subsystem, supporting previous suggestions that Al is a reliable virial broadening estimator.© ESO 2018., AdO, MLMA and JWS acknowledge financial support from the Spanish Ministry for Economy and Competitiveness through grants AYA2013-42227-P and AYA2016-76682-C3-1-P. MLMA, PM and MDO acknowledge funding from the INAF PRIN-SKA 2017 program 1.05.01.88.04. JP acknowledge financial support from the Spanish Ministry for Economy and Competitiveness through grants AYA2013-40609-P and AYA2016-76682-C3-3-P.

We present an ALMA high-resolution observation of the 840 um continuum and [CII] line emission in the WISE-SDSS selected hyper-luminous (WISSH) QSO J1015+0020 at z~4.4. Our analysis reveals an exceptional overdensity of [CII]-emitting companions with a very small (, Accepted

Open Access.--Attribution 4.0 International (CC BY 4.0), We present preliminary results of a spectroscopic analysis for a sample of type 1 highly accreting quasars (L/L-Edd similar to 1.0) at high redshift, z similar to 2-3. The quasars were observed with the OSIRIS spectrograph on the GTC 10.4 m telescope located at the Observatorio del Roque de los Muchachos in La Palma. The highly accreting quasars were identified using the 4D Eigenvector 1 formalism, which is able to organize type 1 quasars over a broad range of redshift and luminosity. The kinematic and physical properties of the broad line region have been derived by fitting the profiles of strong UV emission lines such as AlIII lambda 1860, SiIII]lambda 1892 and CIII]lambda 1909. The majority of our sources show strong blueshifts in the high-ionization lines and high Eddington ratios which are related with the productions of outflows. The importance of highly accreting quasars goes beyond a detailed understanding of their physics: their extreme Eddington ratio makes them candidates standard candles for cosmological studies.© Copyright © 2018 Martínez-Aldama, Del Olmo, Marziani, Sulentic, Negrete, Dultzin, Perea and D'Onofrio., MM-A acknowledge the postdoctoral grant from the CONACyT. MM-A and AD acknowledge financial support from Spanish Ministry for Economy and Competitiveness through grants AYA2013-42227-P and AYA2016-76682-C3-3-1-P.

For a sample of star forming galaxies in the redshift interval 0.15$, Comment: 31 pages, 23 figures

We introduce massive black holes (BHs) in the Feedback In Realistic Environments project and perform high-resolution cosmological hydrodynamic simulations of quasar-mass halos ($M_{\rm halo}(z=2) \approx 10^{12.5}\,\rm{M}_{\odot}$) down to $z=1$. These simulations model stellar feedback by supernovae, stellar winds, and radiation, and BH growth using a gravitational torque-based prescription tied to resolved properties of galactic nuclei. We do not include BH feedback. We show that early BH growth occurs through short ($\lesssim 1\,$Myr) accretion episodes that can reach or even exceed the Eddington rate. In this regime, BH growth is limited by bursty stellar feedback continuously evacuating gas from galactic nuclei, and BHs remain under-massive relative to the local $M_{\rm BH}$-$M_{\rm bulge}$ relation. BH growth is more efficient at later times, when the nuclear stellar potential retains a significant gas reservoir, star formation becomes less bursty, and galaxies settle into a more ordered state, with BHs rapidly converging onto the scaling relation when the host reaches $M_{\rm bulge} \sim 10^{10}\,\rm{M}_{\odot}$. Our results are not sensitive to the details of the accretion model so long as BH growth is tied to the gas content within $\sim 100\,$pc of the BH. Our simulations imply that bursty stellar feedback has strong implications for BH and AGN demographics, especially in the early Universe and for low-mass galaxies., 5 pages, 3 figures, submitted to MNRAS

The relativistic jets created by some active galactic nuclei are important agents of AGN feedback. In spite of this, our understanding of what produces these jets is still incomplete. X-ray observations, which can probe the processes operating in the central regions in immediate vicinity of the supermassive black hole, the presumed jet launching point, are potentially particularly valuable in illuminating the jet formation process. Here, we present the hard X-ray NuSTAR observations of the radio-loud quasar 4C 74.26 in a joint analysis with quasi-simultaneous, soft X-ray Swift observations. Our spectral analysis reveals a high-energy cut-off of 183$_{-35}^{+51}$ keV and confirms the presence of ionized reflection in the source. From the average spectrum we detect that the accretion disk is mildly recessed with an inner radius of $R_\mathrm{in}=4-180\,R_\mathrm{g}$. However, no significant evolution of the inner radius is seen during the three months covered by our NuSTAR campaign. This lack of variation could mean that the jet formation in this radio-loud quasar differs from what is observed in broad-line radio galaxies., Accepted for publication in ApJ

We report on the discovery in the LOFAR Multifrequency Snapshot Sky Survey (MSSS) of a giant radio galaxy (GRG) with a projected size of $2.56 \pm 0.07$ Mpc projected on the sky. It is associated with the galaxy triplet UGC 9555, within which one is identified as a broad-line galaxy in the Sloan Digital Sky Survey (SDSS) at a redshift of $0.05453 \pm 1 \times 10^{-5} $, and with a velocity dispersion of $215.86 \pm 6.34$ km/s. From archival radio observations we see that this galaxy hosts a compact flat-spectrum radio source, and we conclude that it is the active galactic nucleus (AGN) responsible for generating the radio lobes. The radio luminosity distribution of the jets, and the broad-line classification of the host AGN, indicate this GRG is orientated well out of the plane of the sky, making its physical size one of the largest known for any GRG. Analysis of the infrared data suggests that the host is a lenticular type galaxy with a large stellar mass ($\log~\mathrm{M}/\mathrm{M}_\odot = 11.56 \pm 0.12$), and a moderate star formation rate ($1.2 \pm 0.3~\mathrm{M}_\odot/\mathrm{year}$). Spatially smoothing the SDSS images shows the system around UGC 9555 to be significantly disturbed, with a prominent extension to the south-east. Overall, the evidence suggests this host galaxy has undergone one or more recent moderate merger events and is also experiencing tidal interactions with surrounding galaxies, which have caused the star formation and provided the supply of gas to trigger and fuel the Mpc-scale radio lobes., Compressed for arXiv, see journal for full resolution images

PHL 6625 is a luminous quasi-stellar object (QSO) at z = 0.3954 located behind the nearby galaxy NGC 247 (z = 0.0005). Hubble Space Telescope (HST) observations revealed an arc structure associated with it. We report on spectroscopic observations with the Very Large Telescope (VLT) and multiwavelength observations from the radio to the X-ray band for the system, suggesting that PHL 6625 and the arc are a close pair of merging galaxies, instead of a strong gravitational lens system. The QSO host galaxy is estimated to be (4-28) x 10^10 M_sun, and the mass of the companion galaxy of is estimated to be M_* = (6.8 +/- 2.4) x 10^9 M_sun, suggesting that this is a minor merger system. The QSO displays typical broad emission lines, from which a black hole mass of about (2-5) x 10^8 M_sun and an Eddington ratio of about 0.01-0.05 can be inferred. The system represents an interesting and rare case where a QSO is associated with an ongoing minor merger, analogous to Arp 142., Comment: ApJ to appear

We use the coadded spectra of 32 epochs of Sloan Digital Sky Survey (SDSS) Reverberation Mapping Project observations of 482 quasars with z>1.46 to highlight systematic biases in the SDSS- and BOSS-pipeline redshifts due to the natural diversity of quasar properties. We investigate the characteristics of this bias by comparing the BOSS-pipeline redshifts to an estimate from the centroid of HeII 1640. HeII has a low equivalent width but is often well-defined in high-S/N spectra, does not suffer from self-absorption, and has a narrow component that, when present (the case for about half of our sources), produces a redshift estimate that, on average, is consistent with that determined from [OII] to within 1-sigma of the quadrature sum of the HeII and [OII] centroid measurement uncertainties. The large redshift differences of ~1000 km/s, on average, between the BOSS-pipeline and HeII-centroid redshifts suggest there are significant biases in a portion of BOSS quasar redshift measurements. Adopting the HeII-based redshifts shows that CIV does not exhibit a ubiquitous blueshift for all quasars, given the precision probed by our measurements. Instead, we find a distribution of CIV centroid blueshifts across our sample, with a dynamic range that (i) is wider than that previously reported for this line, and (ii) spans CIV centroids from those consistent with the systemic redshift to those with significant blueshifts of thousands of kilometers per second. These results have significant implications for measurement and use of high-redshift quasar properties and redshifts and studies based thereon., Comment: 13 pages, 7 figures, submitted to ApJ

A. Boehle et. al., We present new, more precise measurements of the mass and distance of our Galaxy's central supermassive black hole, Sgr A∗. These results stem from a new analysis that more than doubles the time baseline for astrometry of faint stars orbiting Sgr A∗, combining 2 decades of speckle imaging and adaptive optics data. Specifically, we improve our analysis of the speckle images by using information about a star's orbit from the deep adaptive optics data (2005-2013) to inform the search for the star in the speckle years (1995-2005). When this new analysis technique is combined with the first complete re-reduction of Keck Galactic Center speckle images using speckle holography, we are able to track the short-period star S0-38 (K-band magnitude = 17, orbital period = 19 yr) through the speckle years. We use the kinematic measurements from speckle holography and adaptive optics to estimate the orbits of S0-38 and S0-2 and thereby improve our constraints of the mass (M ) and distance (R ) of Sgr A∗: M = (4.02 ±0.16 ±0.04) x10 M and 7.86 ±0.14 ±0.04 kpc. The uncertainties in M and R as determined by the combined orbital fit of S0-2 and S0-38 are improved by a factor of 2 and 2.5, respectively, compared to an orbital fit of S0-2 alone and a factor of ∼2.5 compared to previous results from stellar orbits. This analysis also limits the extended dark mass within 0.01 pc to less than 0.13 x10 M at 99.7% confidence, a factor of 3 lower compared to prior work.© 2016. The American Astronomical Society. All rights reserved., RS acknowledges funding from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement no. 614922.

We present an analysis of 43 years (1972 to 2015) of spectroscopic observations of the Seyfert 1 galaxy NGC 5548. This includes 12 years of new unpublished observations (2003 to 2015). We compiled about 1600 H$\beta$ spectra and analyzed the long-term spectral variations of the 5100 \AA\ continuum and the H$\beta$ line. Our analysis is based on standard procedures including the Lomb-Scargle method, which is known to be rather limited to such heterogeneous data sets, and new method developed specifically for this project that is more robust and reveals a $\sim$5700 day periodicity in the continuum light curve, the H$\beta$ light curve and the radial velocity curve of the red wing of the H$\beta$ line. The data are consistent with orbital motion inside the broad emission line region of the source. We discuss several possible mechanisms that can explain this periodicity, including orbiting dusty and dust-free clouds, a binary black hole system, tidal disruption events, and the effect of an orbiting star periodically passing through an accretion disc., Comment: Accepted in ApJS, 64 pages, 10 figures and 4 tables

We propose that one of the sources in the recently detected system CR7 by Sobral et al. (2015) through spectro-photometric measurements at $z = 6.6$ harbors a direct collapse blackhole (DCBH). We argue that the LW radiation field required for direct collapse in source A is provided by sources B and C. By tracing the LW production history and star formation rate over cosmic time for the halo hosting CR7 in a $\Lambda$CDM universe, we demonstrate that a DCBH could have formed at $z\sim 20$. The spectrum of source A is well fit by nebular emission from primordial gas around a BH with MBH $\sim 4.4 \times 10^6 \ \rm M_{\odot}$ accreting at a 40 % of the Eddington rate, which strongly supports our interpretation of the data. Combining these lines of evidence, we argue that CR7 might well be the first DCBH candidate., Comment: 8 pages, 4 figures. Accepted for publication in MNRAS

We investigate black hole-host galaxy scaling relations in cosmological simulations with a self-consistent black hole growth and feedback model. The sub-grid accretion model captures the key scalings governing angular momentum transport from galactic scales down to parsec scales, while our kinetic feedback implementation enables the injection of outflows with properties chosen to match observed nuclear outflows. We show that "quasar mode" feedback can have a large impact on the thermal properties of the intergalactic medium and the growth of galaxies and massive black holes for kinetic feedback efficiencies as low as 0.1% relative to the bolometric luminosity. Nonetheless, our simulations suggest that the black hole-host scaling relations are only weakly dependent on the effects of black hole feedback on galactic scales, owing to feedback suppressing the growth of galaxies and massive black holes by a similar amount. In contrast, the rate at which gravitational torques feed the central black hole relative to the host galaxy star formation rate governs the slope and normalization of the black hole-host correlations. Our results suggest that a common gas supply regulated by gravitational torques is the primary driver of the observed co-evolution of black holes and galaxies., 13 pages, 11 figures, submitted to MNRAS

Capitalizing on the all-sky coverage of {\it WISE}, and the 35\% and 50\% sky coverage from SDSS and Pan-STARRS, respectively, we explore the efficacy of $m_{R}$ (optical) - $m_{3.4 \mu m}$ (mid-infrared), hereafter $R-W1$, as a color diagnostic to identify obscured supermassive black hole accretion in wide-area X-ray surveys. We use the $\sim$16.5 deg$^2$ Stripe 82 X-ray survey data as a test-bed to compare $R-W1$ with $R-K$, an oft-used obscured AGN selection criterion, and examine where different classes of objects lie in this parameter space. Most stars follow a well-defined path in $R-K$ vs. $R-W1$ space. We demonstrate that optically normal galaxies hosting X-ray AGN at redshifts $0.54$ color-cut, while they typically are not selected as AGN based on their $W1-W2$ colors. Additionally, different observed X-ray luminosity bins favor different regions in $R-W1$ parameter space: moderate luminosity AGN ($10^{43}$ erg s$^{-1} < L_{\rm 0.5-10 keV} < 10^{44}$ erg s$^{-1}$) tend to have red colors while the highest luminosity AGN ($L_{\rm 0.5-10 keV} > 10^{45}$ erg s$^{-1}$) have bluer colors; higher spectroscopic completeness of the Stripe 82X sample is needed to determine whether this is a selection effect or an intrinsic property. Finally, we parameterize X-ray obscuration of Stripe 82X AGN by calculating their hardness ratios (HRs) and find no clear trends between HR and optical reddening. Our results will help inform best-effort practices in following-up obscured AGN candidates in current and future wide-area, shallow X-ray surveys, including the all-sky {\it eROSITA} mission., Comment: accepted for publication to ApJ; 17 pages (emulateapj style), 21 figures, 3 tables

Active Galactic Nuclei (AGN) vary in their brightness across all wavelengths. Moreover, longer wavelength ultraviolet - optical continuum light curves appear to be delayed with respect to shorter wavelength light curves. A simple way to model these delays is by assuming thermal reprocessing of a variable point source (a lamp post) by a blackbody accretion disc. We introduce a new method, CREAM (\textbf{C}ontinuum \textbf{RE}processed \textbf{A}GN \textbf{M}arkov Chain Monte Carlo), that models continuum variations using this lamp post model. The disc light curves lag the lamp post emission with a time delay distribution sensitive to the disc temperature-radius profile and inclination. We test CREAM's ability to recover both inclination and product of black hole mass and accretion rate $\mmdot$, and show that the code is also able to infer the shape of the driving light curve. CREAM is applied to synthetic light curves expected from 1000 second exposures of a 17th magnitude AGN with a 2m telescope in Sloan g and i bands with signal to noise of 500 - 900 depending on the filter and lunar phase. We also tests CREAM on poorer quality g and i light curves with SNR = 100. We find in the high SNR case that CREAM can recover the accretion disc inclination to within an uncertainty of 5 degrees and an $\mmdot$ to within 0.04 dex., Comment: Accepted to MNRAS November 18 2015

AGN driven outflows are invoked in numerical simulations to reproduce several observed properties of local galaxies. The z > 1 epoch is of particular interest as it was during this time that the volume averaged star formation and the accretion rate of black holes were maximum. Radiatively driven outflows are therefore believed to be common during this epoch. We aim to trace and characterize outflows in AGN hosts with high mass accretion rates at z > 1 using integral field spectroscopy. We obtain spatially-resolved kinematics of the [OIII]5007 line in two targets which reveal the morphology and spatial extension of the outflows. We present J and H+K band SINFONI observations of 5 AGNs at 1.2 < z < 2.2. To maximize the chance of observing radiatively driven outflows, our sample was pre-selected based on peculiar values of the Eddington ratio and the hydrogen column density of the surrounding interstellar medium. We observe high velocity (~600-1900 km/s) and kiloparsec scale extended ionized outflows in at least 3 of our targets, using [OIII]5007 line kinematics tracing the AGN narrow line region. We estimate the total mass of the outflow, the mass outflow rate, and the kinetic power of the outflows based on theoretical models and report on the uncertainties associated with them. We find mass outflow rates of ~1-10 M_sun/yr for the sample presented in this paper. Based on the high star formation rates of the host galaxies, the observed outflow kinetic power and the expected power due to the AGN, we infer that both star formation and AGN radiation could be the dominant source for the outflows. The outflow models suffer from large uncertainties, hence we call for further detailed observations for an accurate determination of the outflow properties to confirm the exact source of these outflows., M.B. and G.L. acknowledge support from the FP7 Career Integration Grant “eEASy: supermassive black holes through cosmic time from current surveys to eROSITA-Euclid Synergies” (CIG 321913)., This is the author accepted manuscript. The final version is available from EDP Sciences via http://dx.doi.org/10.1051/0004-6361/201527968

Mrk 231 is a nearby quasar with an unusually red near-UV-to-optical continuum, generally explained as heavy reddening by dust (e.g., Leighly et al. 2014). Yan et al. 2015 proposed that Mrk~231 is a milli-parsec black-hole binary with little intrinsic reddening. We show that if the observed FUV continuum is intrinsic, as assumed by Yan et al. 2015, it fails by a factor of about 100 in powering the observed strength of the near-infrared emission lines, and the thermal near and mid-infrared continuum. In contrast, the line and continuum strengths are typical for a reddened AGN spectral energy distribution. We find that the HeI*/Pbeta ratio is sensitive to the spectral energy distribution for a one-zone model. If this sensitivity is maintained in general broad-line region models, then this ratio may prove a useful diagnostic for heavily reddened quasars. Analysis of archival HST STIS and FOC data revealed evidence that the far-UV continuum emission is resolved on size scales of ~40 parsecs. The lack of broad absorption lines in the far-UV continuum might be explained if it were not coincident with the central engine. One possibility is that it is the central engine continuum reflected from the receding wind on the far side of the quasar., Comment: Consistent with the accepted ApJ paper

We investigate the role of magnetic fields in the fragmentation of self-gravitating discs using 3D global ideal magnetohydrodynamic simulations performed with the "phantom" smoothed particle hydrodynamics code. For initially toroidal fields, we find two regimes. In the first, where the cooling time is greater than five times the dynamical time, magnetic fields reduce spiral density wave amplitudes, which in turn suppresses fragmentation. This is the case even if the magnetic pressure is only a tenth of the thermal pressure. The second regime occurs when the cooling time is sufficiently short that magnetic fields cannot halt fragmentation. We find that magnetised discs produce more massive fragments, due to both the additional pressure exerted by the magnetic field, and the additional angular momentum transport induced by Maxwell stresses. The fragments are confined to a narrower range of initial semimajor axes than those in unmagnetised discs. The orbital eccentricity and inclination distributions of unmagnetised and magnetised disc fragments are similar. Our results suggest the fragmentation boundary could be at cooling times a factor of two lower than predicted by purely hydrodynamical models., Comment: 12 pages, 22 figures, accepted for publication in MNRAS

We report simultaneous observations at different energy bands in radio, optical, UV, X-rays and $\gamma$ rays of the flat-spectrum radio-quasar 3C 345. We built the light curve of the source at different frequencies from 2008, the beginning of the \textit{Fermi} all-sky survey, to 2016, using new data and public archives. In particular we obtained several optical spectra, to study the behavior of emission lines and the continuum in different activity states and to derive the black hole mass. 3C 345 showed two flaring episodes in 2009, which occurred simultaneously in $\gamma$ ray, optical/UV and X-rays, and were later followed in radio. The source shows an inverse Compton dominated spectral energy distribution, which moved from higher to lower frequencies from the high to the low state. The reverberation of emission lines during one outburst event allowed us to constrain the location of production of $\gamma$ rays very close to the broad-line region, and possibly in the jet-base. We report the observation of an increased accretion after the outburst, possibly induced by the decrease of magnetic field intensity with respect to the low state., Comment: 14 pages, 14 figures, 4 tables, accepted for publication in Astronomy & Astrophysics

In a single optical spectrum, the quasar narrow-line region (NLR) reveals low density, photoionized gas in the host galaxy interstellar medium, while the immediate vicinity of the central engine generates the accretion disk continuum and broad emission lines. To isolate these two components, we construct a library of high S/N optical composite spectra created from the Sloan Digital Sky Survey (SDSS-DR7). We divide the sample into bins of continuum luminosity and Hbeta FWHM that are used to construct median composites at different redshift steps up to 0.75. We measure the luminosities of the narrow-emission lines [NeV]3427, [NeIII]3870, [OIII]5007, and [OII]3728 with ionization potentials (IPs) of 97, 40, 35, and 13.6 eV respectively. The high IP lines' luminosities show no evidence of increase with redshift consistent with no evolution in the AGN SED or the host galaxy ISM illuminated by the continuum. In contrast, we find that the [OII] line becomes stronger at higher redshifts, and we interpret this as a consequence of enhanced star formation contributing to the [OII] emission in host galaxies at higher redshifts. The SFRs estimated from the [OII] luminosities show a flatter increase with z than non-AGN galaxies given our assumed AGN contribution to the [OII] luminosity. Finally, we confirm an inverse correlation between the strength of the FeII4570 complex and both the [OIII] EW (though not the luminosity) and the width of the Hbeta line as known from the eigenvector 1 correlations., 17 pages, colour figures, accepted for publication in MNRAS

We have assembled a sample of five X-ray-absorbed and submm-luminous type 1 QSOs at z ∼ 2 which are simultaneously growing their central black holes through accretion and forming stars copiously. We present here the analysis of their rest-frame UV-to-submm spectral energy distributions (SEDs), including new Herschel data. Both AGN (direct and reprocessed) and star formation (SF) emission are needed to model their SEDs. From the SEDs and their UV–optical spectra we have estimated the masses of their black holes MBH ∼ 109–1010 M⊙, their intrinsic AGN bolometric luminosities LBOL ∼ (0.8–20) × 1013 L⊙, Eddington ratios LBOL/LEdd ∼ 0.1–1.1 and bolometric corrections LBOL/LX,2−10∼30−500LBOL/LX,2−10∼30−500. These values are common among optically and X-ray-selected type 1 QSOs (except for RX J1249), except for the bolometric corrections, which are higher. These objects show very high far-infrared luminosities LFIR ∼ (2–8) × 1012 M⊙ and star formation rates SFR ∼1000 M⊙ yr−1. From their LFIR and the shape of their FIR–submm emission we have estimated star-forming dust masses of MDUST ∼ 109 M⊙. We have found evidence of a tentative correlation between the gas column densities of the ionized absorbers detected in X-ray (NHionNHion) and SFR. Our computed black hole masses are amongst the most massive known., AKA, FJC and SM acknowledge financial support from the Spanish Ministerio de Economía y Competitividad, under project AYA2012-31447. SM acknowledges financial support from the ARCHES project (7th Framework of the European Union, No. 313146).

We have determined the relation between the AGN luminosities at rest-frame 6 μm associated with the dusty torus emission and at 2–10 keV energies using a complete, X-ray-flux-limited sample of 232 AGN drawn from the Bright Ultra-hard XMM-Newton Survey. The objects have intrinsic X-ray luminosities between 1042 and 1046 erg s−1 and redshifts from 0.05 to 2.8. The rest-frame 6 μm luminosities were computed using data from the Wide-field Infrared Survey Explorer and are based on a spectral energy distribution decomposition into AGN and galaxy emission. The best-fitting relationship for the full sample is consistent with being linear, L6 μm ∝ L0.99±0.032−10keVL2−10keV0.99±0.03, with intrinsic scatter, Δ log L6 μm ∼ 0.35 dex. The L6μm/L2−10keVL6μm/L2−10keV luminosity ratio is largely independent of the line-of-sight X-ray absorption. Assuming a constant X-ray bolometric correction, the fraction of AGN bolometric luminosity reprocessed in the mid-IR decreases weakly, if at all, with the AGN luminosity, a finding at odds with simple receding torus models. Type 2 AGN have redder mid-IR continua at rest-frame wavelengths, SM, FJC, XB, AH-C and AA-H acknowledge funding from the Spanish Ministry of Economy and Competitiveness under grant AYA2012-31447, which is partly funded by the FEDER programme. SM, FJC and AA-H acknowledge financial support from the ARCHES project (7th Framework of the European Union, no. 313146). AA-H acknowledges support from the Universidad de Cantabria through the Augusto G. Linares programme. AC, RDC and PS acknowledge financial support from the Italian Ministry of Education, Universities and Research (PRIN2010-2011, grant no. 2010NHBSBE) and from ASI (grant no. I/088/06/0).

© 2014. The American Astronomical Society. All rights reserved.. We explore the effects of long-term secular perturbations on the distribution of dark matter particles around supermassive black hole (BH) binaries. We show that in the hierarchical (in separation) three-body problem, one of the BHs and a dark matter particle form an inner binary. Gravitational perturbations from the BH companion, on a much wider orbit, can cause the dark matter particle to reach extremely high eccentricities and even get accreted onto the BH by what is known as the eccentric Kozai-Lidov (EKL) mechanism. We show that this may produce a torus-like configuration for the dark matter distribution around the less massive member of the BH binary. We first consider an intermediate BH (IMBH) in the vicinity of our galactic center, which may be a relic of a past minor merger. We show that if the IMBH is close enough (i.e.; near the stellar disk) the EKL mechanism is very efficient in exciting the eccentricity of dark matter particles in near-polar configurations to extremely high values where they are accreted by the IMBH. We show that this mechanism is even more effective if the central BH grows in mass, where we have assumed adiabatic growth. Because near-polar configurations are disrupted, a torus-like shape is formed. We also show that this behavior is also likely to be relevant for supermassive BH binaries. We suggest that if the BHs are spinning, the accreted dark matter particles may linger in the ergosphere, and thereby generate self-annihilations and produce an indirect signature of potential interest.

We present the results of a Palomar Transient Factory (PTF) archival search for blue transients which lie in the magnitude range between "normal" core-collapse and superluminous supernovae (i.e. with $-21\,{\leq}M_{R\,(peak)}\,{\leq}-19$). Of the six events found after excluding all interacting Type~IIn and Ia-CSM supernovae, three (PTF09ge, 09axc and 09djl) are coincident with the centers of their hosts, one (10iam) is offset from the center, and for two (10nuj and 11glr) a precise offset can not be determined. All the central events have similar rise times to the He-rich tidal disruption candidate PS1-10jh, and the event with the best-sampled light curve also has similar colors and power-law decay. Spectroscopically, PTF09ge is He-rich, while PTF09axc and 09djl display broad hydrogen features around peak magnitude. All three central events are in low star-formation hosts, two of which are E+A galaxies. Our spectrum of the host of PS1-10jh displays similar properties. PTF10iam, the one offset event, is different photometrically and spectroscopically from the central events and its host displays a higher star formation rate. Finding no obvious evidence for ongoing galactic nuclei activity or recent star formation, we conclude that the three central transients likely arise from the tidal disruption of a star by a super-massive black hole. We compare the spectra of these events to tidal disruption candidates from the literature and find that all of these objects can be unified on a continuous scale of spectral properties. The accumulated evidence of this expanded sample strongly supports a tidal disruption origin for this class of nuclear transients., Comment: Minor changes and clarifications, added radio non-detection limits for one of the events, accepted to ApJ

Improving the capabilities of detecting faint X-ray sources is fundamental to increase the statistics on faint high-z AGN and star-forming galaxies. We performed a simultaneous Maximum Likelihood PSF fit in the [0.5-2] keV and [2-7] keV energy bands of the 4 Ms{\em Chandra} Deep Field South (CDFS) data at the position of the 34930 CANDELS H-band selected galaxies. For each detected source we provide X-ray photometry and optical counterpart validation. We validated this technique by means of a raytracing simulation. We detected a total of 698 X-ray point-sources with a likelihood $\mathcal{L}$$>$4.98 (i.e. $>$2.7$��$). We show that the prior knowledge of a deep sample of Optical-NIR galaxies leads to a significant increase of the detection of faint (i.e. $\sim$10$^{-17}$ cgs in the [0.5-2] keV band) sources with respect to "blind" X-ray detections. By including previous X-ray catalogs, this work increases the total number of X-ray sources detected in the 4 Ms CDFS, CANDELS area to 793, which represents the largest sample of extremely faint X-ray sources assembled to date. Our results suggest that a large fraction of the optical counterparts of our X-ray sources determined by likelihood ratio actually coincides with the priors used for the source detection. Most of the new detected sources are likely star-forming galaxies or faint absorbed AGN. We identified a few sources sources with putative photometric redshift z$>$4. Despite the low number statistics and the uncertainties on the photo-z, this sample significantly increases the number of X--ray selected candidate high-z AGN., 15 Pages, 10 Figures, Accepted by ApJ, version before editing, Catalog available at: http://www.astrodeep.eu/chandra-counterparts/ , CDS and www.astrodeep.edu

We present integral field spectrograph (IFS) with laser guide star adaptive optics (LGS-AO) observations of z=2 quasi-stellar objects (QSOs) designed to resolve extended nebular line emission from the host galaxy. Our data was obtained with W. M. Keck and Gemini-North Observatories using OSIRIS and NIFS coupled with the LGS-AO systems. We have conducted a pilot survey of five QSOs, three observed with NIFS+AO and two observed with OSIRIS+AO at an average redshift of z=2.15. We demonstrate that the combination of AO and IFS provides the necessary spatial and spectral resolutions required to separate QSO emission from its host. We present our technique for generating a PSF from the broad-line region of the QSO and performing PSF subtraction of the QSO emission to detect the host galaxy. We detect H$\alpha$ and [NII] for two sources, SDSS J1029+6510 and SDSS J0925+06 that have both star formation and extended narrow-line emission. Assuming that the majority of narrow-line H$\alpha$ is from star formation, we infer a star formation rate for SDSS J1029+6510 of 78.4 M$_\odot$yr$^{-1}$ originating from a compact region that is kinematically offset by 290 - 350 km/s. For SDSS J0925+06 we infer a star formation rate of 29 M$_\odot$yr$^{-1}$ distributed over three clumps that are spatially offset by $\sim$ 7 kpc. The null detections on three of the QSOs are used to infer surface brightness limits and we find that at 1.4 kpc distance from the QSO that the un-reddened star formation limit is $, Comment: 17 pages, 7 figures, 7 tables, Accepted to ApJ

The progenitors of astronomical transients are linked to a specific stellar population and galactic environment, and observing their host galaxies hence constrains the physical nature of the transient itself. Here, we use imaging from the Hubble Space Telescope, and spatially resolved, medium-resolution spectroscopy from the Very Large Telescope obtained with X-shooter and MUSE to study the host of the very luminous transient ASASSN-15lh. The dominant stellar population at the transient site is old (around 1 to 2 Gyr) without signs of recent star formation. We also detect emission from ionized gas, originating from three different, time invariable, narrow components of collisionally excited metal and Balmer lines. The ratios of emission lines in the Baldwin-Phillips-Terlevich diagnostic diagram indicate that the ionization source is a weak active galactic nucleus with a black hole mass of M = 5 × 10 M, derived through the M-σ relation. The narrow line components show spatial and velocity offsets on scales of 1 kpc and 500 km s, respectively; these offsets are best explained by gas kinematics in the narrow-line region. The location of the central component, which we argue is also the position of the supermassive black hole, aligns with that of the transient within an uncertainty of 170 pc. Using this positional coincidence as well as other similarities with the hosts of tidal disruption events, we strengthen the argument that the transient emission observed as ASASSN-15lh is related to the disruption of a star around a supermassive black hole, most probably spinning with a Kerr parameter a â0.5.© ESO, 2018., T.K. acknowledges support through the Sofja Kovalevskaja Award to P. Schady from the Alexander von Humboldt Foundation of Germany. M.F. acknowledges the support of a Royal Society - Science Foundation Ireland University Research Fellowship. N.C.S. received financial support from NASA through Einstein Postdoctoral Fellowship Award Number PF5-160145, and thanks the Aspen Center for Physics for its hospitality during the completion of this work. D.A.K. acknowledges support from the from the Spanish research project AYA 2014-58381-P and the Juan de la Cierva Incorporacion fellowship IJCI-2015-26153. R.A. acknowledges support from the ERC Advanced Grant 695671 >QUENCH>.

We present new Adaptive Optics (AO) imaging and spectroscopic measurements of Galactic Center source G1 from W. M. Keck Observatory. Our goal is to understand its nature and relationship to G2, which is the first example of a spatially-resolved object interacting with the supermassive black hole (SMBH). Both objects have been monitored with AO for the past decade (2003 - 2014) and are comparatively close to the black hole ($a_{\rm{min}} \sim$200-300 AU) on very eccentric orbits ($e_{\rm{G1}}\sim$0.99; $e_{\rm{G2}}\sim$0.96). While G2 has been tracked before and during periapse passage ($T_{0} \sim$ 2014.2), G1 has been followed since soon after emerging from periapse ($T_{0} \sim$ 2001.3). Our observations of G1 double the previously reported observational time baseline, which improves its orbital parameter determinations. G1's orbital trajectory appears to be in the same plane as that of G2, but with a significantly different argument of periapse ($\Delta\omega$ = 21$\pm$4 degrees). This suggests that G1 is an independent object and not part of a gas stream containing G2 as has been proposed. Furthermore, we show for the first time that: (1) G1 is extended in the epochs closest to periapse along the direction of orbital motion and (2) G1 becomes significantly smaller over time, (450 AU in 2004 to less than 170 AU in 2009). Based on these observations, G1 appears to be the second example of an object tidally interacting with a SMBH. G1's existence 14 years after periapse, along with its compactness in epochs further from the time of periapse, suggest that this source is stellar in nature., Comment: submitted to ApJ