- ID:
- ivo://CDS.VizieR/J/A+A/591/A88
- Title:
- [OIII] of radio-emitting narrow-line Seyfert 1
- Short Name:
- J/A+A/591/A88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The [OIII] {lambda}{lambda} 4959, 5007 lines are a useful proxy to test the kinematic of the narrow-line region (NLR) in active galactic nuclei (AGN). In AGN, and particularly in narrow-line Seyfert 1 galaxies (NLS1s) these lines often show few peculiar features, such as blue wings, often interpreted as outflowing component, and a shift - typically toward lower wavelengths - of the whole spectroscopic feature in some exceptional sources, the so-called blue outliers, which are often associated to strong winds. We investigated the incidence of these peculiarities in two samples of radio-emitting NLS1s, one radio-loud and one radio-quiet. We also studied a few correlations between the observational properties of the [OIII] lines and those of the AGN. Our aim was to understand the difference between radio-quiet and radio-loud NLS1s, which may in turn provide useful information on the jet formation mechanism. We find that the NLR gas is much more perturbed in radio-loud than in radio-quiet NLS1s. In particular the NLR dynamics in {gamma}-ray emitting NLS1s appears to be highly disturbed, and this might be a consequence of interaction with the relativistic jet. The less frequently perturbed NLR in radio-quiet NLS1s suggests instead that these sources likely do not harbor a fully developed relativistic jet. Nonetheless blue-outliers in radio-quiet NLS1s are observed, and we interpret them as a product of strong winds.
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- ID:
- ivo://CDS.VizieR/J/ApJS/98/477
- Title:
- Optical spectral atlas of Seyfert nuclei
- Short Name:
- J/ApJS/98/477
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an optical spectral atlas of the nuclear region (generally 2"x4", or r=<200pc) of a magnitude-limited survey of 486 nearby galaxies having B_T_=<12.5mag and {delta}>0deg. The double spectrograph on the Hale 5m telescope yielded simultaneous spectral coverage of ~4230-5110A and ~6210-6860A, with a spectral resolution of ~4A in the blue half and ~2.5A in the red half. This large, statistically significant survey contains uniformly observed and calibrated moderate-dispersion spectra of exceptionally high quality. The data presented in this paper will be used for various systematic studies of the physical properties of the nuclei of nearby galaxies, with special emphasis on searching for low-luminosity active galactic nuclei, or "dwarf" Seyferts. Our survey led to the discovery of four relatively obvious but previously uncataloged Seyfert galaxies (NGC 3735, 4395, 4639, and 6951), and many more galactic nuclei showing subtle evidence for Seyfert activity. We have also identified numerous low-ionization nuclear emission-line regions (LINERs), some of which may be powered by nonstellar processes. Of the many "starburst" nuclei in our sample, several exhibit the spectral features of Wolf-Rayet stars.
- ID:
- ivo://CDS.VizieR/J/PAZh/35/403
- Title:
- Optical Variabilities in 3C 120
- Short Name:
- J/PAZh/35/403
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on our UBVRI observations and X-ray data from the RXTE satellite we have investigated the variabilities of the Seyfert Galaxy 3C 120 over the period 1996-2008.
- ID:
- ivo://CDS.VizieR/J/PAZh/21/652
- Title:
- Optical variability in NGC 7469
- Short Name:
- J/PAZh/21/652
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of three-color UBV observations of rapid variability in the nucleus of the Seyfert galaxy NGC 7469 carried out in 1990-1994 are presented. The observations have been carried out during 15 different nights using the 60- and 125-cm telescopes with time resolution of 6-8min (50 hours monitoring) with the aperture of 27.5". The mean errors of one measurement are 1.8, 1.2 and 1.4% for U, B and V. The data set length during one night is from 2 up to 5h. The different nights show the variations at different level: from weak, when the standard deviation during the night exceeds the error of one measurement only by 10-20%, up to strong ones, when the standard deviation exceeds the error of the measurement by factor two.
- ID:
- ivo://CDS.VizieR/J/PAZh/25/403
- Title:
- Optical variability of NGC 4151
- Short Name:
- J/PAZh/25/403
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The UBV observations of performed between 1972 and 1998 are presented. The aperture is 27.5".
- ID:
- ivo://CDS.VizieR/J/A+A/658/A12
- Title:
- Origins of radio emission in NLS1s
- Short Name:
- J/A+A/658/A12
- Date:
- 02 Feb 2022 14:01:48
- Publisher:
- CDS
- Description:
- Narrow-line Seyfert 1 galaxies (NLS1s) are believed to be active galactic nuclei (AGN) in the early stages of their evolution. Several dozen of them have been found to host relativistic jets, whilst the majority of NLS1s have not even been detected in radio, emphasising the heterogeneity of the class in this band. In this paper, our aim is to determine the predominant source of radio emission in a sample of 44 NLS1s, selected based on their extended kiloparsec-scale radio morphologies at 5.2GHz. We accomplish this by analysing their spatially resolved radio spectral index maps, centred at 5.2 GHz, as the spectral index carries information about the production mechanisms of the emission. In addition, we utilise several diagnostics based on mid-infrared emission to estimate the star formation activity of their host galaxies. These data are complemented by archival data to draw a more complete picture of each source. We find an extraordinary diversity among our sample. Approximately equal fractions (~10-12 sources) of our sources can be identified as AGN-dominated, composite, and host-dominated. Among the AGN-dominated sources are a few NLS1s with very extended jets, reaching distances of tens of kiloparsecs from the nucleus. One of these, J0814+5609, hosts the most extended jets found in an NLS1 so far. We also identify five NLS1s that could be classified as compact steep-spectrum sources. In addition, one source shows a possible kiloparsec-scale relic that reaches well outside the host galaxy as well as restarted nuclear activity, and one could belong to the sub-class of NLS1s that host relativistic jets that seem to be absorbed at lower radio frequencies (<10GHz). We further conclude that, due to the variety seen in NLS1s, simple proxies, such as the star formation diagnostics also employed in this paper and the radio loudness parameter, are not ideal tools for characterising NLS1s. We emphasise the necessity of examining NLS1s as individuals instead of making assumptions based on their classification. When these issues are properly taken into account, NLS1s offer an exceptional environment for studying the interplay between the host galaxy and several AGN-related phenomena, such as jets and outflows.
- ID:
- ivo://CDS.VizieR/J/A+A/551/A100
- Title:
- Panchromatic SED of Herschel sources
- Short Name:
- J/A+A/551/A100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Combining far-infrared Herschel photometry from the PACS Evolutionary Probe (PEP) and Herschel Multi-tiered Extragalactic Survey (HerMES) guaranteed time programs with ancillary datasets in the GOODS-N, GOODS-S and COSMOS fields, it is possible to sample the 8-500 micron spectral energy distributions of galaxies with at least 7-10 bands. Extending to the UV, optical, and near- infrared, the number of bands increases up to 43. We reproduce the distribution of galaxies in a carefully selected 10 restframe color space, based on this rich data-set, using a superposition of multi-variate Gaussian modes. We use this model to classify galaxies and build median spectral energy distributions (SEDs) of each class, which are then fitted with a modified version of the MAGPHYS code that combines stellar light, emission from dust heated by stars and a possible warm dust contribution heated by an Active Galactic Nucleus (AGN). The color distribution of galaxies in each of the considered fields can be well described with the combination of 6-9 classes, spanning a large range of far- to near-IR luminosity ratios, as well as different strength of the AGN contribution to bolometric luminosities. The defined Gaussian grouping is used to identify rare or odd sources. The zoology of outliers includes Herschel-detected ellipticals, very blue z~1 Ly{alpha}-break galaxies, quiescent spirals, and torus-dominated AGN with star formation. Out of these groups and outliers, a new template library is assembled, consisting of 32 SEDs describing the intrinsic scatter in the restframe UV-to-submm colors of infrared galaxies. This library is tested against L(IR) estimates with and without Herschel data included, and compared to eight other popular methods often adopted in the literature. When implementing Herschel photometry, these approaches produce L(IR) values consistent with each other within a median absolute deviation of 10-20%, the scatter being dominated more by fine tuning of the codes, rather than by the choice of SED templates. Finally, the library is used to classify 24 micron detected sources in PEP GOODS fields on the basis of AGN content, L(60)/L(100) color and L(160)/L(1.6) luminosity ratio. AGN appear to be distributed in M*-SFR along with all other galaxies, regardless of the amount of infrared luminosity they are powering, with the tendency to lie on the high SFR side of the "main sequence". The incidence of warmer star-forming sources grows for objects with higher specific star formation rates, and they tend to populate the "off-sequence" region of the M*-SFR-z space.
- ID:
- ivo://CDS.VizieR/J/AJ/157/99
- Title:
- Photometric redshifts of emission-line galaxies
- Short Name:
- J/AJ/157/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Broadband photometric redshifts are routinely obtained for galaxies to estimate their distances. While effective for many uses, the common resolution in z of 0.01-0.02 is too coarse for detailed large-scale structure mapping, particularly in low-density volumes where the galaxy distribution is least understood. To map galaxies in these low-density volumes, and noting that the percentage of galaxies having emission tends to rise as number density decreases, we have designed a filter system to photometrically measure the redshifts of galaxies with emission. The system consists of two "ramp" filters that cover a common wavelength range with transmission curves sloping from blue to red and from red to blue respectively. This causes the intensity of the image through either filter to be a function of the wavelength of the emission line. A third filter with a bandpass to the side is used to measure and remove the continuum. We have obtained a set of such filters that are tuned for isolating H{alpha} in the redshift range of 3000-9000 km/s. Simulated photometry, applied to spectra of 197 emission-line galaxies from the SDSS, shows the accuracy of the method to be between 250 and 620 km/s, depending on line strength. Actual photometry of a sample of 16 active galaxies measured their redshifts with an accuracy of 573 km/s. This is approximately an order of magnitude more accurate than broadband photometric redshifts. We discuss the errors inherent in this method and present ways to modify the filter set to further improve accuracy.
- ID:
- ivo://CDS.VizieR/J/MNRAS/433/1709
- Title:
- PKS 0558-504 UVOT and XRT monitoring
- Short Name:
- J/MNRAS/433/1709
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- PKS 0558-504 is a highly-variable, X-ray-bright, radio-loud, narrow-line Seyfert 1 galaxy with super-Eddington accretion rate and extended jets that do not dominate the emission beyond the radio band. Therefore, this source represents an ideal laboratory to shed some light on the central engine in highly accreting systems and specifically on the link between accretion disc and corona. Here we present the results from a 1.5-year monitoring with Swift-XRT and Swift-UVOT. The simultaneous coverage at several wavelengths confirms that PKS 0558-504 is highly variable in any band from the optical to ultraviolet (UV) and X-rays, with the latter showing the largest amplitude changes but with the UV emission dominating the radiative output. A cross-correlation analysis reveals a tight link between the emission in the optical and UV bands and provides suggestive evidence in favour of a scenario where the variability originates in the outer part of the accretion flow and propagates inwards before triggering the activity of the X-ray-emitting corona. Finally, a positive correlation between the soft-X-ray flux and the hard photon index suggests that in PKS 0558-504 the seed photons are provided to the corona by the soft-excess component.
- ID:
- ivo://CDS.VizieR/J/A+A/548/A106
- Title:
- PMN J0948+0022 radio-to-gamma-ray monitoring
- Short Name:
- J/A+A/548/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present more than three years of observations at different frequencies, from radio to high-energy gamma-rays, of the Narrow-Line Seyfert 1 (NLS1) Galaxy PMN J0948+0022 (z=0.585). This source is the first NLS1 detected at energies above 100 MeV and therefore can be considered the prototype of this emerging new class of gamma-ray emitting active galactic nuclei (AGN). The observations performed from 2008 August 1 to 2011 December 31 confirmed that PMN J0948+0022 generates a powerful relativistic jet, able to develop an isotropic luminosity at gamma-rays of the order of 10^48^erg/s, at the level of powerful quasars. The evolution of the radiation emission of this source in 2009 and 2010 followed the canonical expectations of relativistic jets, with correlated multiwavelength variability (gamma-rays followed by radio emission after a few months), but it was difficult to retrieve a similar pattern in the light curves of 2011. The comparison of gamma-ray spectra before and including 2011 data suggested that there was a softening of the high-energy spectral slope. We selected five specific epochs to be studied by modelling the broad-band spectrum, characterised by an outburst at gamma-rays or very low/high flux at other wavelengths. The observed variability can largely be explained either by changes in the injected power, the bulk Lorentz factor of the jet or the electron spectrum. The characteristic time scale of doubling/halving flux ranges from a few days to a few months, depending on the frequency and the sampling rate. The shortest doubling time scale at gamma-rays is 2.3+/-0.5days. These small values underline the need of highly-sampled multiwavelength campaigns to better understand the physics of these sources.
