- ID:
- ivo://CDS.VizieR/J/ApJ/825/126
- Title:
- SEAMBHs. V. The third year
- Short Name:
- J/ApJ/825/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper reports results of the third-year campaign of monitoring super-Eddington accreting massive black holes (SEAMBHs) in active galactic nuclei (AGNs) between 2014 and 2015. Ten new targets were selected from the quasar sample of the Sloan Digital Sky Survey (SDSS), which have generally been more luminous than the SEAMBH candidates in the last two years. H{beta} lags ({tau}_H{beta}_) in five of the 10 quasars have been successfully measured in this monitoring season. We find that the lags are generally shorter, by large factors, than those of objects with same optical luminosity, in light of the well-known R_H{beta}_-L_5100_ relation. The five quasars have dimensionless accretion rates of dM/dt=10-10^3^. Combining these with measurements of the previous SEAMBHs, we find that the reduction of H{beta} lags depends tightly on accretion rates, {tau}_H{beta}_/{tau}_R-L_{propto}(dM/dt)^-0.42^, where {tau}_R-L_ is the H{beta} lag from the normal R_H{beta}_-L_5100_ relation. Fitting 63 mapped AGNs, we present a new scaling relation for the broad-line region: R_H{beta}_={alpha}_1_l_44_^{beta}1^min [1,(dM/dt)/(dM/dt)_c_)^-{gamma}1^], where l_44_=L_5100_/10^44^erg/s is the 5100{AA} continuum luminosity, and the coefficients are {alpha}_1_=29.6_-2.8_^+2.7^ lt-day, {beta}1=0.56_-0.03_^+0.03^, {gamma}1=0.52_-0.16_^+0.33^, and (dM/dt)_c_=11.19_-6.22_^+2.29^. This relation is applicable to AGNs over a wide range of accretion rates, from 10^-3^ to 10^3^. Implications of this new relation are briefly discussed.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/253/20
- Title:
- SEAMBHs XII. Reberberation mapping for 15 PG QSOs
- Short Name:
- J/ApJS/253/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work, we present the first results of the long-term high-cadence spectroscopic monitoring of 15 PG quasars with relatively strong FeII emission, as a part of a broader reverberation mapping campaign performed using the Calar Alto Observatory's 2.2m telescope. The V-band, 5100{AA} continuum, and H{beta} broad emission line light curves are measured for a set of quasars for periods ranging from dozens to more than a hundred epochs between 2017 May and 2020 July. Accurate time lags between the variations of the H{beta} broad-line fluxes and the optical continuum strength are obtained for all 15 quasars, ranging from 17.0_-3.2_^+2.5^ to 95.9_-23.9_^+7.1^ days in the rest frame. The virial masses of the central supermassive black holes are derived for all 15 quasars, ranging between 0.50_-0.19_^+0.18^ and 19.17_-2.73_^+2.98^ in units of 10^7^M_{sun}_. For 11 of the objects in our sample, this is the first reverberation analysis to be published. Of the rest, two objects have been the subject of previous reverberation studies, but we determine time lags for these that are only half as long as those found in the earlier investigations, which had only been able to sample much more sparsely. The remaining two objects have previously been monitored with high sampling rates. Our results here are consistent with the earlier findings, in the sense that the time lag and the line width vary inversely, consistent with virialization.
- ID:
- ivo://CDS.VizieR/J/ApJ/896/1
- Title:
- SEAMBHs. XI. Mrk 142 X-ray to optical light curves
- Short Name:
- J/ApJ/896/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We performed an intensive accretion disk reverberation mapping campaign on the high accretion rate active galactic nucleus Mrk142 in early 2019. Mrk 142 was monitored with the Neil Gehrels Swift Observatory for four months in X-rays and six different UV/optical filters. Ground-based photometric monitoring was obtained from the Las Cumbres Observatory, the Liverpool Telescope, and the Dan Zowada Memorial Observatory in ugriz filters, as well as from the Yunnan Astronomical Observatory in V. Mrk 142 was highly variable throughout, displaying correlated variability across all wavelengths. We measure significant time lags between the different wavelength lightcurves. In the UV and optical, we find that the wavelength-dependent lags, {tau}({lambda}), generally follow the relation {tau}({lambda}){propto}{lambda}^4/3^, as expected for the T{propto}R^-3/4^ profile of a steady-state, optically thick, geometrically thin accretion disk, though they can also be fit by {tau}({lambda}){propto}{lambda}^2^, as expected for a slim disk. The exceptions are the u and U bands, where an excess lag is observed, as has been observed in other active galactic nuclei and attributed to continuum emission arising in the broad-line region. Furthermore, we perform a flux-flux analysis to separate the constant and variable components of the spectral energy distribution, finding that the flux dependence of the variable component is consistent with the f{nu}{propto}{nu}^1/3^ spectrum expected for a geometrically thin accretion disk. Moreover, the X-ray to UV lag is significantly offset from an extrapolation of the UV/optical trend, with the X-rays showing a poorer correlation with the UV than the UV does with the optical. The magnitude of the UV/optical lags is consistent with a highly super-Eddington accretion rate.
- ID:
- ivo://CDS.VizieR/J/ApJ/877/23
- Title:
- SEAMBHs. X. Reverberation mapping campaign compilation
- Short Name:
- J/ApJ/877/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compiled a sample of 73 active galactic nuclei (AGNs) with reverberation mapping (RM) observations from RM campaigns, including our ongoing campaign of monitoring super-Eddington accreting massive black holes (BHs). This sample covers a large range of BH mass (M_{bullet}_=10^6^-9^M_{sun}_), dimensionless accretion rates (dM/dt=10^-2.7^-10^2.7^), and 5100{AA} luminosity (L_5100_=10^42-46^erg/s), allowing us to systematically study the AGN variability and their relations with BH mass, accretion rates, and optical luminosity. We employed the damped random walk (DRW) model to delineate the optical variability of continuum at 5100{AA} and obtained damped variability timescale ({tau}_d_) and amplitude ({sigma}_d_) using a Markov Chain Monte Carlo method. We also estimated the traditional variability amplitudes (F_var_), which provide a model-independent measure and therefore are used to test the DRW results. We found that AGN variability characteristics are generally correlated with (M_{bullet}_, dM/dt, L_5100_). These correlations are smooth from sub-Eddington to super-Eddington accretion AGNs, probably implying that the AGN variability may be caused by the same physical mechanism.
- ID:
- ivo://CDS.VizieR/J/ApJ/695/276
- Title:
- Search for megamasers in type-2 AGNs
- Short Name:
- J/ApJ/695/276
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report a search for H_2_O megamasers in 274 SDSS type-2 active galactic nuclei (AGNs; 0.3<z<0.83), half of which can be classified as type-2 quasi-stellar objects (QSOs) from their [OIII]5007 luminosity, using the Robert C. Byrd Green Bank Telescope (GBT) and the Effelsberg 100m radio telescope. Apart from the detection of the extremely luminous water vapor megamaser SDSS J080430.99+360718.1, already reported by Barvainis & Antonucci (2005ApJ...628...89B), we do not find any additional line emission. This high rate of nondetections is compared to the water maser luminosity function created from the 78 water maser galaxies known to date and its extrapolation toward the higher luminosities of "gigamasers" that we would have been able to detect given the sensitivity of our survey. The properties of the known water masers are summarized and discussed with respect to the nature of high-z type-2 AGNs and megamasers in general. In the Appendix (tables 4 and 5), we list 173 additional objects (mainly radio galaxies, but also QSOs and galaxies) that were observed with the GBT, the Effelsberg 100m radio telescope, or Arecibo Observatory without leading to the detection of water maser emission.
- ID:
- ivo://CDS.VizieR/J/A+A/627/A13
- Title:
- Second AGILE catalogue of gamma-ray sources
- Short Name:
- J/A+A/627/A13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the second AGILE-GRID catalogue (2AGL) of gamma-ray sources in the energy range 100MeV-10GeV. With respect to previous AGILE-GRID catalogues, the current 2AGL catalogue is based on the first 2.3 years of science data from the AGILE mission (the so-called pointing mode) and incorporates more data and several analysis improvements, including better calibrations at the event reconstruction level, an updated model for the Galactic diffuse gamma-ray emission, a refined procedure for point-like source detection, and the inclusion of a search for extended gamma-ray sources. The 2AGL catalogue includes 175 high-confidence sources (above 4{sigma} significance) with their location regions and spectral properties and a variability analysis with four-day light curves for the most significant. Relying on the error region of each source position, including systematic uncertainties, 122 sources are considered as positionally associated with known counterparts at different wavelengths or detected by other gamma-ray instruments. Among the identified or associated sources, 62 are active galactic nuclei (AGNs) of the blazar class. Pulsars represent the largest Galactic source class, with 41 associated pulsars, 7 of which have detected pulsation; 8 supernova remnants and 4 high-mass X-ray binaries have also been identified. A substantial number of 2AGL sources are unidentified: for 53 sources no known counterpart is found at different wavelengths. Among these sources, we discuss a subclass of 29 AGILE-GRID-only gamma-ray sources that are not present in 1FGL, 2FGL, or 3FGL catalogues; the remaining sources are unidentified in both 2AGL and 3FGL catalogues. We also present an extension of the analysis of 2AGL sources detected in the energy range 50-100MeV.
- ID:
- ivo://CDS.VizieR/J/ApJ/663/81
- Title:
- SED of hard X-ray selected AGN in XMDS
- Short Name:
- J/ApJ/663/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the SEDs of a hard X-ray selected sample containing 136 sources with F(2-10)keV>10^-14^erg/cm^2^/s; 132 are AGNs. The sources are detected in a 1deg^2^ area of the XMM-Newton Medium Deep Survey where optical data from the VVDS and CFHTLS and infrared data from the SWIRE survey are available. Based on a SED fitting technique we derive photometric redshifts with {sigma}(1+z)=0.11 and 6% of outliers and identify AGN signatures in 83% of the objects. This fraction is higher than derived when a spectroscopic classification is available. The remaining 17% of AGNs show star-forming galaxy SEDs (SF class).
- ID:
- ivo://CDS.VizieR/J/ApJ/709/1407
- Title:
- SED of the Fermi blazars
- Short Name:
- J/ApJ/709/1407
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We complied the optical, X-ray, and {gamma}-ray data for 54 Fermi blazars and studied the relationship between the broadband spectral index {alpha}_ox_ and {alpha}_x{gamma}_, as well as the relationship between the intrinsic composite spectral indices {alpha}_xox_ and {alpha}_{gamma}x{gamma}_ for this sample. The relationship between {alpha}_xox_ and {alpha}_{gamma}x{gamma}_ reveals that flat spectrum radio quasars and low-energy peaked BL Lacertae follow a continuous trend, which is consistent with previous results, whereas high-energy peaked BL Lacertae follow a separate distinct trend. Even so, a unified scheme is also revealed from {alpha}_xox_-{alpha}_{gamma}x{gamma}_ diagram when all three subclasses of blazars are considered.
- ID:
- ivo://CDS.VizieR/J/MNRAS/495/1853
- Title:
- SED-selected AGN in the VIPERS field
- Short Name:
- J/MNRAS/495/1853
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The detection of X-ray emission constitutes a reliable and efficient tool for the selection of active galactic nuclei (AGNs), although it may be biased against the most heavily absorbed AGNs. Simple mid-infrared (IR) broad-band selection criteria identify a large number of luminous and absorbed AGNs, yet again host contamination could lead to non-uniform and incomplete samples. Spectral energy distribution (SED) decomposition is able to decouple the emission from the AGN versus that from star-forming regions, revealing weaker AGN components. We aim to identify the obscured AGN population in the VIMOS Public Extragalactic Redshift Survey in the Canada-France-Hawaii Telescope Legacy Survey W1 field through SED modelling. We construct SEDs for 6860 sources and identify 160 AGNs at a high confidence level using a Bayesian approach. Using optical spectroscopy, we confirm the nature of ~85 per cent of the AGNs. Our AGN sample is highly complete (~92 per cent) compared to mid-IR colour-selected AGNs, including a significant number of galaxy-dominated systems with lower luminosities. In addition to the lack of X-ray emission (80 per cent), the SED fitting results suggest that the majority of the sources are obscured. We use a number of diagnostic criteria in the optical, IR, and X-ray regimes to verify these results. Interestingly, only 35 per cent of the most luminous mid-IR-selected AGNs have X-ray counterparts suggesting strong absorption. Our work emphasizes the importance of using SED decomposition techniques to select a population of type II AGNs, which may remain undetected by either X-ray or IR colour surveys.
- ID:
- ivo://CDS.VizieR/J/ApJ/684/136
- Title:
- SEDs of ELAIS-S1 mid-IR sources
- Short Name:
- J/ApJ/684/136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the broadband SEDs of the largest available highly complete (72%) spectroscopic sample of MIR-selected galaxies and AGNs at intermediate redshift. The sample contains 203 extragalactic sources from the 15um ELAIS-SWIRE survey, all with measured spectroscopic redshift. Most of these sources have full multiwavelength coverage from the FUV (GALEX) to the FIR (Spitzer) and lie in the redshift range 0.1<z<1.3. This large sample allows us for the first time to characterize the spectral properties of sources responsible for the strong evolution observed in the MIR. Based on SED-fitting, we have classified the MIR sources, identifying AGN signatures in about 50% of them. This fraction is significantly higher than that derived from optical spectroscopy (~29%) and is due in particular to the identification of AGN activity in objects spectroscopically classified as galaxies (the spectroscopic classification may be somewhat unreliable because of host galaxy dilution in the optical). It is likely that in most of our objects, the AGN is either obscured or low luminosity, and thus dominates the energetic output only in the MIR, showing up just in the range where the host galaxy SED has a minimum. The fraction of AGNs strongly depends on flux density, with that derived through the SED-fitting about 20% at S_15um_~0.5-1mJy and gradually increasing to 100% at S_15um_>10mJy, while that obtained from optical spectroscopy is never >30%, even at higher flux densities.
