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541. NGC1052 twin-jet VLBI images
ID:
ivo://CDS.VizieR/J/A+A/623/A27
Title:
NGC1052 twin-jet VLBI images
Short Name:
J/A+A/623/A27
Date:
21 Oct 2021
Publisher:
CDS
Description:
Few active galactic nuclei (AGN) reveal double-sided jet systems. However, these systems are crucial to understand basic physical properties of extragalactic jets. We address the questions whether jets in AGN are symmetric in nature, how well they are collimated on small scales, and how they evolve with time. We monitored the sub-parsec scale morphology of NGC 1052 with the Very Long Baseline Array at 43GHz from 2005 to 2009. A detailed study of 29 epochs show a remarkable asymmetry between both jets. A kinematic analysis of the outflows reveals higher apparent velocities for the eastern (approaching) jet as compared to the western (receding) jet, i.e., {beta}_ej_=0.529+/-0.038 and {beta}_wj_=0.343+/-0.037, respectively. Contradictory to previous studies, we find higher flux densities for the western jet as compared to the eastern. The distribution of brightness temperature and jet width features well-collimated jets up to 1 mas distance to the dynamic center and a nearly conical outflow further outward. By combining flux density ratios and velocities of the jet flows, we were unable to find a combination of intrinsic velocities and inclination angles of the jets that is consistent for all four years of observation; this contradicts findings for symmetrically evolving jets. Spectral index maps between quasi-simultaneous 22GHz and 43GHz observations support the existence of an optically thick absorber covering the innermost ~=1.6mas around the 43GHz central feature and an optically thin jet emission with a spectral index of <=-1. Our results fit into a picture in which we expect larger internal energy and/or magnetic flux in the western jet and higher kinetic energy in the eastern jet. Previous observations at lower frequencies have found slower velocities of the moving jet features as compared to this work. Considering the different velocities in different areas, we suggest a spine-sheath structure with a faster inner layer and slower outer layer.
542. NGC 7469 X-ray spectra
ID:
ivo://CDS.VizieR/J/A+A/615/A72
Title:
NGC 7469 X-ray spectra
Short Name:
J/A+A/615/A72
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the physical structure of the active galactic nucleus (AGN) wind in the Seyfert-1 galaxy NGC 7469 through high-resolution X-ray spectroscopy with Chandra HETGS and photoionisation modelling. Contemporaneous data from Chandra, HST, and Swift are used to model the optical-UV-X-ray continuum and determine the spectral energy distribution (SED) at two epochs, 13yr apart. For our investigation we use new observations taken in December 2015-January 2016, and historical ones taken in December 2002. We study the impact of a change in the SED shape, seen between the two epochs, on the photoionisation of the wind. The HETGS spectroscopy shows that the AGN wind in NGC 7469 consists of four ionisation components, with their outflow velocities ranging from -400 to -1800km/s. From our modelling we find that the change in the ionising continuum shape between the two epochs results in some variation in the ionisation state of the wind components. However, for the main ions detected in X-rays, the sum of their column densities over all components remains in practice unchanged. For two of the four components, which are found to be thermally unstable in both epochs, we obtain 2<r<31pc and 12<r<29pc using the cooling and recombination timescales. For the other two thermally stable components, we obtain r<31pc and r<80pc from the recombination timescale. The results of our photoionisation modelling and thermal stability analysis suggest that the absorber components in NGC 7469 are consistent with being a thermally driven wind from the AGN torus. Finally, from analysis of the zeroth-order ACIS/HETG data, we discover that the X-ray emission in the range 0.2-1keV is spatially extended over 1.5-12". This diffuse soft X-ray emission is explained by coronal emission from the nuclear starburst ring in NGC 7469. The star formation rate inferred from this diffuse soft X-ray emission is consistent with those found by far-infrared studies of NGC 7469.
543. NGC 5548 43 year-long monitoring in H{beta}
ID:
ivo://CDS.VizieR/J/ApJS/225/29
Title:
NGC 5548 43 year-long monitoring in H{beta}
Short Name:
J/ApJS/225/29
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an analysis of 43 years (1972 to 2015) of spectroscopic observations of the Seyfert 1 galaxy NGC 5548. This includes 12 years of new unpublished observations (2003 to 2015). We compiled about 1600 H{beta} spectra and analyzed the long-term spectral variations of the 5100 A continuum and the H{beta} line. Our analysis is based on standard procedures, including the Lomb-Scargle method, which is known to be rather limited to such heterogeneous data sets, and a new method developed specifically for this project that is more robust and reveals a ~5700 day periodicity in the continuum light curve, the H{beta} light curve, and the radial velocity curve of the red wing of the H{beta} line. The data are consistent with orbital motion inside the broad emission line region of the source. We discuss several possible mechanisms that can explain this periodicity, including orbiting dusty and dust-free clouds, a binary black hole system, tidal disruption events, and the effect of an orbiting star periodically passing through an accretion disk.
544. NGP+30{deg} zone galaxies I.
ID:
ivo://CDS.VizieR/J/ApJS/175/86
Title:
NGP+30{deg} zone galaxies I.
Short Name:
J/ApJS/175/86
Date:
21 Oct 2021
Publisher:
CDS
Description:
A database containing 618 active and star-forming (A/SF) galaxies and 564 normal galaxies in a 120{deg}x6{deg} wide strip crossing the North Galactic Pole was constructed in order to compare the global properties of "active" galaxies against a control sample of "normal" galaxies. This database combines a literature and catalog search with new optical measurements from the Fpg (red) and Jpg (blue) band images of the STScI Digitized Sky Survey (DSS). We provide alternative names, accurate coordinates, morphological type, activity classes, red and blue apparent magnitudes, 2MASS near-infrared J-H and H-K colors, apparent diameters, axial ratios, position angles, and number counts of neighboring objects in a circle of radius 50kpc. We also present an atlas of 103 interacting and merging systems among these galaxies. In this sample, all merging and interacting galaxies are A/SF objects. The near-infrared colors of the sample galaxies are independent parameters and do not correlate with activity level or any other parameter of the galaxies.
545. NICMOS observations of 3CR radio sources
ID:
ivo://CDS.VizieR/J/ApJS/164/307
Title:
NICMOS observations of 3CR radio sources
Short Name:
J/ApJS/164/307
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present newly acquired images of the near-infrared counterpart of 3CR radio sources. All the sources were selected to have a redshift of less than 0.3 to allow us to obtain the highest spatial resolution. The observations were carried out as a snapshot program using the Near-Infrared Camera and Multiobject Spectrograph (NICMOS) on-board the Hubble Space Telescope (HST). In this paper we describe 69 radio galaxies observed for the first time with NICMOS during HST cycle 13. All the objects presented here are elliptical galaxies. However, each of them has unique characteristics such as close companions, dust lanes, unresolved nuclei, arclike features, globular clusters, and jets clearly visible from the images or with basic galaxy subtraction.
546. NIR colors of hard X-ray-selected AGN
ID:
ivo://CDS.VizieR/J/ApJ/610/128
Title:
NIR colors of hard X-ray-selected AGN
Short Name:
J/ApJ/610/128
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results of near-infrared photometry (J, H, K_s_) for a hard X-ray-selected sample of active galactic nuclei (AGNs) obtained from optical identification of the sources detected in ASCA surveys (total ~75deg^2^) with a flux limit of (1-3)x10^-13^erg/s/cm^2^ (2-10keV). The sample covers the AGNs at 0.1<~z<~1 with L_2-10keV_=10^42^-10^46^erg/s with very high completeness. The near-infrared photometric data of the sample are obtained from the Two Micron All Sky Survey (2MASS, Cat. <II/246>) and observations with Kitt Peak National Observatory 2.1m telescope and the University of Hawaii 2.2m telescope.
547. NIR obs. of X-ray AGNs in COSMOS, SXDS & E-CDF-S
ID:
ivo://CDS.VizieR/J/ApJS/239/22
Title:
NIR obs. of X-ray AGNs in COSMOS, SXDS & E-CDF-S
Short Name:
J/ApJS/239/22
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present near-IR spectroscopy in the J- and H-bands for a large sample of 243 X-ray-selected, moderate-luminosity Type 1 active galactic nuclei (AGNs) in the COSMOS, SXDS, and E-CDF-S survey fields using the multi-object spectrograph Subaru/FMOS. Our sample covers the redshift range 0.5<=z<=3.0 and X-ray luminosity range of 10^43^<=L_[2-10keV]_<=10^45^erg/s. We provide emission-line properties and derived virial black hole mass estimates, bolometric luminosities, and Eddington ratios, based on H{alpha} (211), H{beta} (63), and MgII (4). We compare line widths, luminosities, and black hole mass estimates from H{alpha} and H{beta}, and augment these with commensurate measurements of MgII and CIV detected in optical spectra. We demonstrate the robustness of using H{alpha}, H{beta}, and MgII as reliable black hole mass estimators for high-z moderate-luminosity AGNs, while the use of CIV is prone to large uncertainties (>=0.4dex). We extend a recently proposed correction based on the CIV blueshift to lower luminosities and black hole masses. While our sample shows an improvement in their CIV black hole mass estimates, the deficit of high blueshift sources reduces its overall importance for moderate-luminosity AGNs compared to the most luminous quasars. In addition, we revisit luminosity correlations between Lbol, L_[2-10keV]_, L[OIII], L5100, and LH{alpha} and find them to be consistent with a simple empirical model, based on a small number of well-established scaling relations. Finally, we highlight our highest redshift AGN, CID 781, at z=4.6, which has the lowest black hole mass (~10^8^M_{sun}_) among current near-IR samples at this redshift and is in a state of fast growth.
548. NIR photometry of hot dust-obscured galaxies
ID:
ivo://CDS.VizieR/J/ApJ/804/27
Title:
NIR photometry of hot dust-obscured galaxies
Short Name:
J/ApJ/804/27
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Wide-field Infrared Survey Explorer (WISE) mission has unveiled a rare population of high-redshift (z=1-4.6), dusty, hyper-luminous galaxies, with infrared luminosities L_IR_>10^13^L_{sun}_, and sometimes exceeding 10^14^L_{sun}_. Previous work has shown that their dust temperatures and overall far-infrared spectral energy distributions (SEDs) are significantly hotter than expected to be powered by star formation. We present here an analysis of the rest-frame optical through mid-infrared SEDs for a large sample of these so-called "hot, dust-obscured galaxies" (Hot DOGs).
549. Nitrogen abundance of Seyfert 2 AGN
ID:
ivo://CDS.VizieR/J/MNRAS/468/L113
Title:
Nitrogen abundance of Seyfert 2 AGN
Short Name:
J/MNRAS/468/L113
Date:
21 Oct 2021
Publisher:
CDS
Description:
We obtained new quantitative determinations of the nitrogen abundance and a consistent relation between the nitrogen and oxygen abundances for a sample of Seyfert 2 galaxies located at redshift z<0.1. We carried out this analysis using the CLOUDY code to build detailed photoionization models. We were able to reproduce observed optical narrow emission line intensities for 44 sources compiled from the literature. Our results show that Seyfert 2 nuclei have nitrogen abundances ranging from ~0.3 to ~7.5 times the solar value. We derived the relation log (N/H)=1.05(+/-0.09)x[log(O/H)]-0.35(+/-0.33). Results for N/O versus O/H abundance ratios derived for Seyfert 2 galaxies are in consonance with those recently derived for a sample of extragalactic disc HII regions with high metallicity.
550. NLS1 at 37GHz
ID:
ivo://CDS.VizieR/J/A+A/614/L1
Title:
NLS1 at 37GHz
Short Name:
J/A+A/614/L1
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have detected six narrow-line Seyfert 1 (NLS1) galaxies at 37GHz that were previously classified as radio silent and two that were classified as radio quiet. These detections reveal the presumption that NLS1 galaxies labelled radio quiet or radio silent and hosted by spiral galaxies are unable to launch jets to be incorrect. The detections are a plausible indicator of the presence of a powerful, most likely relativistic jet because this intensity of emission at 37GHz cannot be explained by, for example, radiation from supernova remnants. Additionally, one of the detected NLS1 galaxies is a newly discovered source of gamma rays and three others are candidates for future detections.