- 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.
Number of results to display per page
Search Results
- 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/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/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/AJ/143/83
- Title:
- Properties of a sample of Seyfert 1 galaxies
- Short Name:
- J/AJ/143/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a statistical study of a large, homogeneously analyzed sample of narrow-line Seyfert 1 (NLS1) galaxies, accompanied by a comparison sample of broad-line Seyfert 1 (BLS1) galaxies. Optical emission-line and continuum properties are subjected to correlation analyses, in order to identify the main drivers of the correlation space of active galactic nuclei (AGNs), and of NLS1 galaxies in particular. For the first time, we have established the density of the narrow-line region as a key parameter in Eigenvector 1 space, as important as the Eddington ratio L/L_Edd_. This is important because it links the properties of the central engine with the properties of the host galaxy, i.e., the interstellar medium (ISM). We also confirm previously found correlations involving the line width of H{beta} and the strength of the Fe II and [O III]{lambda}5007 emission lines, and we confirm the important role played by L/L_Edd_ in driving the properties of NLS1 galaxies. A spatial correlation analysis shows that large-scale environments of the BLS1 and NLS1 galaxies of our sample are similar. If mergers are rare in our sample, accretion-driven winds, on the one hand, or bar-driven inflows, on the other hand, may account for the strong dependence of Eigenvector 1 on ISM density.
- ID:
- ivo://CDS.VizieR/J/A+A/392/851
- Title:
- QSOs in the M3 field
- Short Name:
- J/A+A/392/851
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a variability and proper motion (VPM) search for QSOs in the field around M3. The VPM search is demonstrated to be powerful technique for efficiently finding QSOs without major selection effects with regard to the spectral energy distribution. Remarkably, the properties of the VPM QSOs do not significantly differ from those of samples from more conventional optical search techniques. The lightcurves of the QSOs from the resulting sample provide an interesting data set for the statistical investigation of QSO long-term variability.
- ID:
- ivo://CDS.VizieR/J/AJ/123/578
- Title:
- Quasars in the Coma cluster
- Short Name:
- J/AJ/123/578
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second paper of the series about our Multiwavelength Quasar Survey. We present the observational results for the X-ray candidates in the field of the Coma Cluster. Nine new X-ray active galactic nuclei are discovered.
- ID:
- ivo://CDS.VizieR/J/A+A/416/35
- Title:
- Radio Emission from VLA FIRST Survey AGN
- Short Name:
- J/A+A/416/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the most recent (April 2003) version of the VLA FIRST survey radio catalog (Cat. <VIII/71>), we have searched for radio emission from >2800 AGN taken from the most recent (2001) version of the Veron-Cetty and Veron AGN catalog (Cat. <VII/224>, superseded by 2003, Cat. <VII/235>). These AGN lie in the ~9033 square degrees of sky already covered by the VLA FIRST survey. Our work has resulted in positive detection of radio emission from 775 AGN of which 214 are new detections at radio wavelengths.
- ID:
- ivo://CDS.VizieR/J/MNRAS/333/100
- Title:
- Radio galaxies in the 2dFGRS
- Short Name:
- J/MNRAS/333/100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use redshift determinations and spectral analysis of galaxies in the 2dF Galaxy Redshift Survey (<VII/226>) to study the properties of local radio sources with S>=1mJy. 557 objects (hereafter called the spectroscopic sample) drawn from the FIRST survey(<VIII/71>) , corresponding to 2.3 per cent of the total radio sample, are found in the 2dFGRS catalogue within the area 9h 48min<=RA<=14h 32min and -2.77{deg}<=DE<=2.25{deg} (2000), down to a magnitude limit b_J_=19.45. The excellent quality of 2dF spectra allows us to divide these sources into classes, according to their optical spectra.
- ID:
- ivo://CDS.VizieR/J/A+A/435/521
- Title:
- Radio Sources in Low-Luminosity AGNs. IV
- Short Name:
- J/A+A/435/521
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the completed results of a high resolution radio imaging survey of all (~200) low-luminosity active galactic nuclei (LLAGNs) and AGNs in the Palomar Spectroscopic Sample of all (~488) bright northern galaxies. The high incidences of pc-scale radio nuclei, with implied brightness temperatures >~10^7K, and sub-parsec jets argue for accreting black holes in >=50% of all LINERs and low-luminosity Seyferts; there is no evidence against all LLAGNs being mini-AGNs. The detected parsec-scale radio nuclei are preferentially found in massive ellipticals and in type 1 nuclei (i.e. nuclei with broad Halpha emission). The radio luminosity function (RLF) of Palomar Sample LLAGNs and AGNs extends three orders of magnitude below, and is continuous with, that of 'classical' AGNs. We find marginal evidence for a low-luminosity turnover in the RLF; nevertheless LLAGNs are responsible for a significant fraction of present day mass accretion.
