- ID:
- ivo://CDS.VizieR/J/A+A/459/55
- Title:
- Narrow-band imaging of 5 Seyfert-1 galaxies
- Short Name:
- J/A+A/459/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spatially resolved emission-line spectroscopy is a powerful tool to determine the physical conditions in the narrow-line region (NLR) of active galactic nuclei (AGNs). We recently used optical long-slit spectroscopy to study the NLRs of a sample of six Seyfert-2 galaxies. We have shown that such an approach, in comparison to the commonly used [OIII] narrow-band imaging alone, allows us to probe the size of the NLR in terms of AGN photoionisation. Moreover, several physical parameters of the NLR can be directly accessed. We here apply the same methods to study the NLR of six Seyfert-1 galaxies and compare our results to those of Seyfert-2 galaxies. We employ diagnostically valuable emission-line ratios to determine the physical properties of the NLR, including the core values and radial dependencies of density, ionisation parameter, and reddening. Tracking the radial change of emission-line ratios in diagnostic diagrams allows us to measure the transition between AGN-like and HII-like line excitation, and thus we are able to measure the size of the NLR. In the diagnostic diagrams, we find a transition between line ratios falling in the AGN regime and those typical for HII regions in two Seyfert-1 galaxies, thus determining the size of the NLR. The central electron temperature and ionisation parameter are in general higher in type-1 Seyferts than in type 2s. In almost all cases, both electron density and ionisation parameter decrease with radius. In general, the decrease is faster in Seyfert-1 galaxies than in type 2s. In several objects, the gaseous velocity distribution is characteristic for rotational motion in an (inclined) emission-line disk in the centre. We give estimates of the black hole masses. We discuss our findings in detail for each object.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/124/3042
- Title:
- Narrow-line Seyfert 1 galaxies from SDSS EDR
- Short Name:
- J/AJ/124/3042
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of 150 narrow-line Seyfert 1 galaxies (NLS1's) found within the Sloan Digital Sky Survey (SDSS) Early Data Release (EDR) (Stoughton et al., 2002AJ....123..485S), only two of which were previously identified as such. This substantially increases the known number of NLS1's and provides a basic method by which to identify many more with subsequent releases of SDSS data. With its large size and homogeneous, well-defined selection criteria, this sample will help alleviate two major problems that have plagued NLS1 research in the past; namely, their relative rarity and significant differences in selection algorithms between the known samples. Forty-five of these SDSS-selected NLS1's are detected at energies of 0.1-2keV in the ROSAT All-Sky Survey (RASS) and are found to have ultrasoft X-ray spectra with photon indices of {Gamma}>~2, in agreement with previous results for NLS1's. However, about 10-20 of those NLS1's that were not detected by ROSAT have optical properties very similar to the detected objects and so should also have been detected by the RASS. This may be due to either significant intrinsic absorption in many NLS1's, or a significant subclass of NLS1's that have uncharacteristic, intrinsically flatter (hence harder) X-ray spectral energy distributions.
- ID:
- ivo://CDS.VizieR/J/AJ/131/1948
- Title:
- Narrow line Seyfert 1 galaxies in the FBQS
- Short Name:
- J/AJ/131/1948
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from the analysis of the optical spectra of 47 radio-selected narrow-line Seyfert 1 (NLS1) galaxies. These objects are a subset of the First Bright Quasar Survey (Cat. <J/AJ/112/407>) and were initially detected at 20cm (flux density limit 1Jy) in the VLA FIRST Survey.
- ID:
- ivo://CDS.VizieR/J/MNRAS/509/2377
- Title:
- Narrow-Line Seyfert 1 IR Survey
- Short Name:
- J/MNRAS/509/2377
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present a near-infrared spectroscopic survey of narrow-line Seyfert 1 galaxies in the southern hemisphere (using the SOFI instrument on the ESO-NTT telescope), sampled from optical surveys. We examine the kinematics of the broad-line region, probed by the emission line width of hydrogen (Paschen{alpha} and H{beta}). We observed 57 objects, of which we could firmly measure Paschen{alpha} in 49 cases. We find that a single Lorentzian fit (preferred on theoretical grounds) is preferred over multi-component Gaussian fits to the line profiles; a lack of narrow-line region emission, overwhelmed by the pole-on view of the broad line region (BLR) light, supports this. We recompute the catalog black hole (BH) mass estimates, using the values of FWHM and luminosity of H{beta}, both from catalog values and re-fitted Lorentzian values. We find a relationship slope greater than unity compared to the catalog values. We ascribe this to contamination by galactic light or difficulties with line flux measurements. However, the comparison of masses computed by the fitted Lorentzian and Gaussian measurements show a slope close to unity. Comparing the BH masses estimated from both Paschen{alpha} and H{beta}, the line widths and fluxes shows deviations from expected; in general, however, the computed BH masses are comparable. We posit a scenario where an intermixture of dusty and dust-free clouds (or alternately a structured atmosphere) differentially absorbs the line radiation of the BLR, due to dust absorption and hydrogen bound-free absorption.
- ID:
- ivo://CDS.VizieR/J/MNRAS/458/4512
- Title:
- Nearby Seyfert galaxies FIR emissions
- Short Name:
- J/MNRAS/458/4512
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present far-infrared (FIR) 70-500{mu}m imaging observations obtained with Herschel/Photodetector Array Camera (PACS) and Spectral and Photometric Imaging REceiver (SPIRE) of 33 nearby (median distance of 30Mpc) Seyfert galaxies from the Revised Shapley-Ames (RSA) catalogue. We obtain the FIR nuclear (r=1kpc and r=2kpc) and integrated spectral energy distributions (SEDs). We estimate the unresolved nuclear emission at 70{mu}m and we fit the nuclear and integrated FIR SEDs with a grey body model. We find that the integrated FIR emission of the RSA Seyferts in our sample is dominated by emission from the host galaxy, with dust properties similar to those of normal galaxies (non-AGN). We use four criteria to select galaxies whose nuclear 70{mu}m emission has a significant AGN contribution: (1) elevated 70/160{mu}m flux ratios, (2) spatially resolved, high dust temperature gradient, (3) 70{mu}m excess emission with respect to the fit of the FIR SEDs with a grey body, and (4) excess of nuclear SFR obtained from 70{mu}m over SFR from mid-infrared indicators. 16 galaxies (48 per cent of the initial sample) satisfy at least one of these conditions, whereas 10 satisfy half or more. After careful examination of these, we select six bona fide candidates (18 per cent of the initial sample) and estimate that ~40-70 per cent of their nuclear (r=1-2kpc) 70{mu}m emission is contributed by dust heated by the AGN.
- ID:
- ivo://CDS.VizieR/J/ApJ/510/637
- Title:
- Near IR properties of Galaxy disks
- Short Name:
- J/ApJ/510/637
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have derived the near-infrared structural components of a sample of Seyfert and starburst (SBN) host galaxies by fitting near-infrared images with a new two-dimensional decomposition algorithm. An analysis of the fitted parameters shows that Seyfert 1 and SBN bulges resemble normal early-type bulges in structure and color, with (J-K)^c^_b_ about 0.1 mag redder than disk (J-K)^c^_d_. Seyfert 2 bulges, on the other hand, are bluer than normal, with (J-K)^c^_b_{approx}(J-K)^c^_d_. Seyfert disks (especially type 1), but not those of SBNs, are abnormally bright (in surface brightness), significantly more so than even the brightest normal disks. Seyfert disks are also compact, but similar to those in normal early-type spirals. For a given mass, Seyfert and particularly SBN galaxies are abnormally rich in neutral hydrogen, and there is strong, albeit indirect, evidence for lower mass-to-light (M/L) ratios in Seyfert and SBN disks, but normal M/L ratios in their bulges. In Seyfert and SBN galaxies, H I mass fractions and M/L ratios are anticorrelated, and we attribute the high gas mass fractions and low M/L ratios in SBNs and several Seyfert galaxies to ongoing star formation. Such abundant gas in Seyfert galaxies would be expected to inhibit bar formation, which may explain why active galaxies are not always barred.
- ID:
- ivo://CDS.VizieR/J/ApJ/742/66
- Title:
- New Fermi/LAT extragalactic sources
- Short Name:
- J/ApJ/742/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the analysis of 2.1 years of Fermi Large Area Telescope (LAT) data on 491 Seyfert galaxies detected by the Swift Burst Alert Telescope (BAT) survey. Only the two nearest objects, NGC 1068 and NGC 4945, which were identified in the Fermi first year catalog (Abdo et al. 2010, Cat. J/ApJ/715/429), are detected. Using Swift/BAT and radio 20cm fluxes, we define a new radio-loudness parameter R_X,BAT_ where radio-loud objects have logR_X,BAT_> -4.7. Based on this parameter, only radio-loud sources are detected by Fermi/LAT. An upper limit to the flux of the undetected sources is derived to be ~2x10^-11^photons/cm^2^/s, approximately seven times lower than the observed flux of NGC 1068. Assuming a median redshift of 0.031, this implies an upper limit to the {gamma}-ray (1-100GeV) luminosity of <~3x10^41^erg/s. In addition, we identified 120 new Fermi/LAT sources near the Swift/BAT Seyfert galaxies with significant Fermi/LAT detections. A majority of these objects do not have Swift/BAT counterparts, but their possible optical counterparts include blazars, flat-spectrum radio quasars, and quasars.
- ID:
- ivo://CDS.VizieR/J/A+A/621/A83
- Title:
- NGC 1566 ALMA and Gemini-GMOS/IFU datacubes
- Short Name:
- J/A+A/621/A83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Tracing nuclear inflows and outflows in AGNs, determining the mass of gas involved in them, and their impact on the host galaxy and nuclear black hole requires 3-D imaging studies of both the ionized and molecular gas. We map the distribution and kinematics of molecular and ionized gas in a sample of active galaxies to quantify the nuclear inflows and outflows. Here, we analyze the nuclear kinematics of NGC 1566 via ALMA observations of the CO J:2-1 emission at 24pc spatial and ~2.6km/s spectral resolution, and Gemini-GMOS/IFU observations of ionized gas emission lines and stellar absorption lines at similar spatial resolution, and 123km/s of intrinsic spectral resolution. The morphology and kinematics of stellar, molecular (CO), and ionized ([NII]) emission lines are compared to the expectations from rotation, outflows, and streaming inflows. While both ionized and molecular gas show rotation signatures, there are significant non-circular motions in the innermost 200pc and along spiral arms in the central kpc (CO). The nucleus shows a double-peaked CO profile (full width at zero intensity of 200km/s), and prominent (~80km/s) blue- and redshifted lobes are found along the minor axis in the inner arcseconds. Perturbations by the large-scale bar can qualitatively explain all features in the observed velocity field. We thus favor the presence of a molecular outflow in the disk with true velocities of ~180km/s in the nucleus and decelerating to 0 by ~72pc. The implied molecular outflow rate is 5.6M_{Sun}_/yr, with this gas accumulating in the nuclear 2" arms. The ionized gas kinematics support an interpretation of a similar but more spherical outflow in the inner 100pc, with no signs of deceleration. There is some evidence of streaming inflows of ~50km/s along specific spiral arms, and the estimated molecular mass inflow rate, ~0.1M_{Sun}_/yr, is significantly higher than the SMBH accretion rate (dM/dt=4.8x10^-5^M_{Sun}_/yr).
- ID:
- ivo://CDS.VizieR/J/A+A/656/A60
- Title:
- NGC1808 ALMA datacubes
- Short Name:
- J/A+A/656/A60
- Date:
- 21 Mar 2022 07:01:58
- Publisher:
- CDS
- Description:
- We report on Atacama Large Millimeter Array (ALMA) observations of CO(3-2) emission in the Seyfert2/starburst galaxy NGC 1808, at a spatial resolution of 4pc. Our aim is to investigate the morphology and dynamics of the gas inside the central 0.5kpc and to probe the nuclear feeding and feedback phenomena. We discovered a nuclear spiral of radius 1"=45pc. Within it, we found a decoupled circumnuclear disk or molecular torus of a radius of 0.13"=6pc. The HCN(4-3) and HCO^+^(4-3) and CS(7-6) dense gas line tracers were simultaneously mapped and detected in the nuclear spiral and they present the same misalignment in the molecular torus. At the nucleus, the HCN/HCO^+^ and HCN/CS ratios indicate the presence of an active galactic nucleus (AGN). The molecular gas shows regular rotation, within a radius of 400pc, except for the misaligned disk inside the nuclear spiral arms. The computations of the torques exerted on the gas by the barred stellar potential reveal that the gas within a radius of 100pc is feeding the nucleus on a timescale of five rotations or on an average timescale of ~60Myr. Some non-circular motions are observed towards the center, corresponding to the nuclear spiral arms. We cannot rule out that small extra kinematic perturbations could be interpreted as a weak outflow attributed to AGN feedback. The molecular outflow detected at >=250pc in the NE direction is likely due to supernovae feedback and it is connected to the kpc-scale superwind.
- ID:
- ivo://CDS.VizieR/J/A+A/629/A54
- Title:
- NGC4388 and NGC2110 spectral files
- Short Name:
- J/A+A/629/A54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to measure the physical properties of the hot X-ray corona of two active galactic nuclei, NGC 4388 and NGC 2110. We analysed the hard X-ray (20-300keV) INTEGRAL spectrum in conjunction with archival XMM-Newton and NuSTAR data. The X-ray spectrum of both sources is phenomenologically well described by an absorbed cut-off power law. In agreement with previous results, we find no evidence of a Compton reflection component in these sources. We obtain a high-energy cut-off of 200_-40_^+75^keV for NGC 4388 and 320_-60_^+100^keV for NGC 2110. A fit with a thermal Comptonisation model yields a coronal temperature of 80_-20_^+40^keV and 75_-15_^+20^keV, respectively, and an optical depth of approximately two, assuming a spherical geometry. The coronal temperature and luminosity of both sources are consistent with pair production that acts as a thermostat for the thermal plasma. These results emphasise the importance of good signal-to-noise X-ray data above 100keV to probe the high-energy emission of AGNs.
