- ID:
- ivo://CDS.VizieR/J/A+A/563/A57
- Title:
- Long-term variability of AGN at hard X-rays
- Short Name:
- J/A+A/563/A57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Variability at all observed wavelengths is a distinctive property of active galactic nuclei (AGN). Hard X-rays provide us with a view of the innermost regions of AGN, mostly unbiased by absorption along the line of sight. Characterizing the intrinsic hard X-ray variability of a large AGN sample and comparing it to the results obtained at lower X-ray energies can significantly contribute to our understanding of the mechanisms underlying the high-energy radiation. Swift/BAT provides us with the unique opportunity to follow, on time scales of days to years and with regular sampling, the 14-195keV emission of the largest AGN sample available up to date for this kind of investigation. As a continuation of an early work using the first 9 months of BAT data, we study the amplitude of the variations and their dependence on subclass and on energy, for a sample of 110 radio quiet and radio loud AGN selected from the BAT 58-month survey.
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- ID:
- ivo://CDS.VizieR/J/A+A/561/A140
- Title:
- Low-luminosity type-1 QSO sample
- Short Name:
- J/A+A/561/A140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recognizing the properties of the host galaxies of quasi-stellar objects (QSOs) is essential to understand the suspected coevolution of central supermassive black holes (BHs) and their host galaxies. We selected a subsample of the Hamburg/ESO survey for bright UV-excess QSOs, containing only the 99 nearest QSOs with redshift z<=0.06, that are close enough to allow detailed structural analysis. From this "low-luminosity type-1 QSO sample", we observed 20 galaxies and performed aperture photometry and bulge-disk-bar-AGN-decomposition with BUDDA on near-infrared J, H, K band images. From the photometric decomposition of these 20 objects and visual inspection of images of another 26, we find that ~50% of the hosts are disk galaxies and most of them (86%) are barred. Stellar masses, calculated from parametric models based on inactive galaxy colors, range from 2x10^9^M_{sun}_ to 2x10^11^M_{sun}_. Black hole masses measured from single epoch spectroscopy range from 1x10^6^M_{sun}_ to 5x10^8^M_{sun}_. In comparison to higher luminosity QSO samples, LLQSOs tend to have lower stellar and BH masses. Also, in the effective radius vs. mean surface-brightness projection of the fundamental plane, they lie in the transition area between luminous QSOs and "normal" galaxies. This can be seen as further evidence that they can be pictured as a "bridge" between the local Seyfert population and luminous QSOs at higher redshift. Eleven low-luminosity QSOs for which we have reliable morphological decompositions and BH mass estimations lie below the published BH mass vs. bulge luminosity relations for inactive galaxies. This could be partially explained by bulges of active galaxies containing much younger stellar populations than bulges of inactive galaxies. Also, one could suspect that their BHs are undermassive. This might hint at the growth of the host spheroid to precede that of the BH.
- ID:
- ivo://CDS.VizieR/J/A+A/587/A138
- Title:
- Low-luminosity type-1 QSO sample. V.
- Short Name:
- J/A+A/587/A138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near-infrared (NIR) H+K-band long-slit spectra of eleven galaxies that were obtained with SOFI at the NTT (ESO). The galaxies are chosen from the low-luminosity type-1 quasi-stellar object (LLQSO) sample, which comprises the 99 closest (z<=0.06) QSOs from the Hamburg/ESO survey for bright UV-excess QSOs. These objects are ideal targets to study the gap between local Seyfert galaxies and high-redshift quasars because they show much stronger AGN activity than local objects, but are still close enough for a detailed structural analysis. We fit hydrogen recombination, molecular hydrogen, and [FeII] lines after carefully subtracting the continuum emission. From the broad Pa{alpha} components, we estimated black hole masses and enlarged the sample of LLQSOs that deviate from the MBH-Lbulge relations of inactive galaxies from 12 to 16 objects. All objects show emission from hot dust (T~1200K) as well as stellar contribution. However, the respective fractions vary strongly among the objects. More than half of the objects show H_2_ emission lines, which indicate a large reservoir of molecular gas that is needed to feed the AGN and star formation. In the NIR diagnostic diagram all objects lie in the location of AGN-dominated objects. However, most of the objects show indications of star formation activity, suggesting that their offset location with respect to MBH-Lbulge relations of inactive galaxies may be a consequence of overluminous bulges.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A146
- Title:
- MAGNUM survey galaxies images
- Short Name:
- J/A+A/622/A146
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the interstellar medium (ISM) properties of the disk and outflowing gas in the central regions of nine nearby Seyfert galaxies, all characterised by prominent single- or bi-conical outflows. These objects are part of the MAGNUM (Measuring Active Galactic Nuclei Under MUSE Microscope) survey, that aims at probing their physical conditions and ionisation mechanism, by exploiting the unprecedented sensitivity of the Multi Unit Spectroscopic Explorer (MUSE), combined with its spatial and spectral coverage. Specifically, we study the different properties of the gas in the disk and in the outflow with spatially and kinematically resolved maps, by dividing the strongest emission lines in velocity bins. We associate the core of the lines to the disk, consistent with the stellar velocity, and the redshifted and the blueshifted wings to the outflow. We measure the reddening, density, ionisation parameter and dominant ionisation source of the emitting gas for both components in each galaxy. We find that the outflowing gas is characterised by higher values of density and ionisation parameter than the disk, which presents a higher dust extinction. Moreover, we distinguish high- and low-ionisation regions across the portion of spatially resolved narrow line region (NLR) traced by the outflowing gas. The high ionisation regions characterised by the lowest [NII]/H{alpha} and [SII]/H{alpha} line ratios, generally trace the innermost parts along the axis of the emitting cones, where the [SIII]/[SII] line ratio is enhanced, while the low ionisation ones follow the cone edges and/or the regions perpendicular to the axis of the outflows, characterised also by a higher [OIII] velocity dispersion. A possible scenario to explain these features relies on the presence of two distinct population of line emitting clouds: one is optically thin to the radiation and characterised by the highest excitation, while the other, optically thick, is impinged by a filtered - and thus harder - radiation field, which generates strong low-excitation lines. The highest values of [NII]/H{alpha} and [SII]/H{alpha} line ratios may be due to shocks and/or a hard filtered radiation field from the AGN.
- ID:
- ivo://CDS.VizieR/J/AJ/137/42
- Title:
- Matched SDSS and FIRST Sample
- Short Name:
- J/AJ/137/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The question as to whether the distribution of radio loudness in active galactic nuclei (AGNs) is actually bimodal has been discussed extensively in the literature. Furthermore, there have been claims that radio loudness depends on black hole mass (M_BH_) and Eddington ratio (L_bol_/L_Edd_).We investigate these claims using the low- redshift broad line AGN sample of Greene & Ho (2007ApJ...667..131G), which consists of 8434 objects at z<0.35 from the Sloan Digital Sky Survey Fourth Data Release (SDSS DR4). We obtained radio fluxes from the Very Large Array Faint Images of the Radio Sky at Twenty-centimeters (FIRST) survey for the SDSS AGN. Out of the 8434 SDSS AGNs, 821 have corresponding observed radio fluxes in the FIRST survey.
- ID:
- ivo://CDS.VizieR/J/A+A/530/A147
- Title:
- Megamaser detection in Seyfert galaxies
- Short Name:
- J/A+A/530/A147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We revisit the relation between H_2_O maser detection rate and nuclear obscuration for a sample of 114 Seyfert galaxies, drawn from the CfA, 12um and IRAS F25/F60 catalogs. These sources have mid-infrared spectra from the Spitzer Space Telescope and they are searched for X-ray and [OIII] (5007{AA}) fluxes from the literature. We use the strength of the [OIV] (25.9um) emission line as tracer for the intrinsic AGN strength. After normalization by [OIV] the observed X-ray flux provides information about X-ray absorption. The distribution of X-ray/[OIV] flux ratios is significantly different for masers and non-masers: The maser detected Seyfert-2s (Sy 1.8-2.0) populate a distinct X-ray/[OIV] range which is, on average, about a factor four lower than the range of Seyfert-2 non-masers and about a factor of ten lower than the range of Seyfert-1s (Sy 1.0-1.5). Non-masers are almost equally distributed over the entire X-ray/[OIV] range. This provides evidence that high nuclear obscuration plays a crucial role for the probability of maser detection. Furthermore, after normalization with [OIV], we find a similar but weaker trend for the distribution of the maser detection rate with the absorption of the 7um dust continuum. This suggests that the obscuration of the 7um continuum occurs on larger spatial scales than that of the X-rays. Hence, in the AGN unified model, at moderate deviation from edge-on, the 7um dust absorption may occur without proportionate X-ray absorption. The absorption of [OIII] appears unrelated to maser detections. The failure to detect masers in obscured AGN is most likely due to insufficient observational sensitivity.
- ID:
- ivo://CDS.VizieR/VII/171
- Title:
- Michigan Emission-Line Objects
- Short Name:
- VII/171
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The objects of this catalogue were detected by using the 61-cm aperture Curtis Schmidt telescope in combination with a thin objective prism (1.8{deg}) at the Cerro Tololo Inter-American Observatory. The low-dispersion spectra (174nm/mm at H{beta}) cover the wavelength range between 5350 and 3400 {AA}, where the emission lines such that those of [OII], [OIII] and Ly{alpha} are visible. The objects could be detected up to 18th magnitude. Note that the list archived here is not the same as the published lists (see the "References" section below): the positions in the "catalog.dat" file are generally more accurate than those in the original publication and the origin for these is not known. In the printed lists of papers , information presented for each object also includes image dimensions from the Palomar Observatory Sky Survey, an estimated continuum apparent magnitude, a redshift estimate when feasible, or (for galaxies) a spectral classification which involves compactness, color, and line-strength parameters.
- ID:
- ivo://CDS.VizieR/J/A+A/418/465
- Title:
- Mid-infrared and hard X-ray emission in AGN
- Short Name:
- J/A+A/418/465
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use mid-infrared spectral decomposition to separate the 6{mu}m mid-infrared AGN continuum from the host emission in the ISO low resolution spectra of 71 active galaxies and compare the results to observed and intrinsic 2-10keV hard X-ray fluxes from the literature.
- ID:
- ivo://CDS.VizieR/J/MNRAS/454/766
- Title:
- Mid-infrared-X-ray correlation for local AGNs
- Short Name:
- J/MNRAS/454/766
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an updated mid-infrared (MIR) versus X-ray correlation for the local active galactic nuclei (AGN) population based on the high angular resolution 12 and 18{mu}m continuum fluxes from the AGN subarcsecond MIR atlas and 2-10 keV and 14-195 keV data collected from the literature. We isolate a sample of 152 objects with reliable AGN nature and multi-epoch X-ray data and minimal MIR contribution from star formation. Although the sample is not homogeneous or complete, we show that our results are unlikely to be affected by significant biases. The MIR-X-ray correlation is nearly linear and within a factor of 2 independent of the AGN type and the wavebands used. The observed scatter is <0.4 dex. A possible flattening of the correlation slope at the highest luminosities probed (~10^45^ erg/s) towards low MIR luminosities for a given X-ray luminosity is indicated but not significant. Unobscured objects have, on average, an MIR-X-ray ratio that is only <=0.15 dex higher than that of obscured objects. Objects with intermediate X-ray column densities (22<logN_H_<23) actually show the highest MIR-X-ray ratio on average. Radio-loud objects show a higher mean MIR-X-ray ratio at low luminosities while the ratio is lower than average at high luminosities. This may be explained by synchrotron emission from the jet contributing to the MIR at low luminosities and additional X-ray emission at high luminosities. True Seyfert 2 candidates do not show any deviation from the general behaviour suggesting that they possess a dusty obscurer as in other AGN. Double AGN also do not deviate. Finally, we show that the MIR-X-ray correlation can be used to investigate the AGN nature of uncertain objects. Specifically, we give equations that allow us to determine the intrinsic 2-10 keV luminosities and column densities for objects with complex X-ray properties to within 0.34 dex. These techniques are applied to the uncertain objects of the remaining AGN MIR atlas, demonstrating the usefulness of the MIR-X-ray correlation as an empirical tool.
- ID:
- ivo://CDS.VizieR/J/ApJ/791/113
- Title:
- MIR-selected quasar parameters
- Short Name:
- J/ApJ/791/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We provide a catalog of 391 mid-infrared-selected (MIR; 24 {mu}m) broad-emission-line (BEL; type 1) quasars in the 22 deg^2^ SWIRE Lockman Hole field. This quasar sample is selected in the MIR from Spitzer MIPS with S_24_> 400 {mu}Jy, jointly with an optical magnitude limit of r(AB) < 22.5 for broad line identification. The catalog is based on MMT and Sloan Digital Sky Survey (SDSS) spectroscopy to select BEL quasars, extending the SDSS coverage to fainter magnitudes and lower redshifts, and recovers a more complete quasar population. The MIR-selected quasar sample peaks at z ~ 1.4 and recovers a significant and constant (20%) fraction of extended objects with SDSS photometry across magnitudes, which were not included in the SDSS quasar survey dominated by point sources. This sample also recovers a significant population of z < 3 quasars at i > 19.1. We then investigate the continuum luminosity and line profiles of these MIR quasars, and estimate their virial black hole masses and the Eddington ratios. The supermassive black hole mass shows evidence of downsizing, although the Eddington ratios remain constant at 1 < z < 4. Compared to point sources in the same redshift range, extended sources at z < 1 show systematically lower Eddington ratios. The catalog and spectra are publicly available online.
