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Start Over Subject active galactic nuclei
761. SED of the Fermi blazars
ID:
ivo://CDS.VizieR/J/ApJ/709/1407
Title:
SED of the Fermi blazars
Short Name:
J/ApJ/709/1407
Date:
21 Oct 2021
Publisher:
CDS
Description:
We complied the optical, X-ray, and {gamma}-ray data for 54 Fermi blazars and studied the relationship between the broadband spectral index {alpha}_ox_ and {alpha}_x{gamma}_, as well as the relationship between the intrinsic composite spectral indices {alpha}_xox_ and {alpha}_{gamma}x{gamma}_ for this sample. The relationship between {alpha}_xox_ and {alpha}_{gamma}x{gamma}_ reveals that flat spectrum radio quasars and low-energy peaked BL Lacertae follow a continuous trend, which is consistent with previous results, whereas high-energy peaked BL Lacertae follow a separate distinct trend. Even so, a unified scheme is also revealed from {alpha}_xox_-{alpha}_{gamma}x{gamma}_ diagram when all three subclasses of blazars are considered.
762. SED-selected AGN in the VIPERS field
ID:
ivo://CDS.VizieR/J/MNRAS/495/1853
Title:
SED-selected AGN in the VIPERS field
Short Name:
J/MNRAS/495/1853
Date:
21 Oct 2021
Publisher:
CDS
Description:
The detection of X-ray emission constitutes a reliable and efficient tool for the selection of active galactic nuclei (AGNs), although it may be biased against the most heavily absorbed AGNs. Simple mid-infrared (IR) broad-band selection criteria identify a large number of luminous and absorbed AGNs, yet again host contamination could lead to non-uniform and incomplete samples. Spectral energy distribution (SED) decomposition is able to decouple the emission from the AGN versus that from star-forming regions, revealing weaker AGN components. We aim to identify the obscured AGN population in the VIMOS Public Extragalactic Redshift Survey in the Canada-France-Hawaii Telescope Legacy Survey W1 field through SED modelling. We construct SEDs for 6860 sources and identify 160 AGNs at a high confidence level using a Bayesian approach. Using optical spectroscopy, we confirm the nature of ~85 per cent of the AGNs. Our AGN sample is highly complete (~92 per cent) compared to mid-IR colour-selected AGNs, including a significant number of galaxy-dominated systems with lower luminosities. In addition to the lack of X-ray emission (80 per cent), the SED fitting results suggest that the majority of the sources are obscured. We use a number of diagnostic criteria in the optical, IR, and X-ray regimes to verify these results. Interestingly, only 35 per cent of the most luminous mid-IR-selected AGNs have X-ray counterparts suggesting strong absorption. Our work emphasizes the importance of using SED decomposition techniques to select a population of type II AGNs, which may remain undetected by either X-ray or IR colour surveys.
763. SEDs of ELAIS-S1 mid-IR sources
ID:
ivo://CDS.VizieR/J/ApJ/684/136
Title:
SEDs of ELAIS-S1 mid-IR sources
Short Name:
J/ApJ/684/136
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the broadband SEDs of the largest available highly complete (72%) spectroscopic sample of MIR-selected galaxies and AGNs at intermediate redshift. The sample contains 203 extragalactic sources from the 15um ELAIS-SWIRE survey, all with measured spectroscopic redshift. Most of these sources have full multiwavelength coverage from the FUV (GALEX) to the FIR (Spitzer) and lie in the redshift range 0.1<z<1.3. This large sample allows us for the first time to characterize the spectral properties of sources responsible for the strong evolution observed in the MIR. Based on SED-fitting, we have classified the MIR sources, identifying AGN signatures in about 50% of them. This fraction is significantly higher than that derived from optical spectroscopy (~29%) and is due in particular to the identification of AGN activity in objects spectroscopically classified as galaxies (the spectroscopic classification may be somewhat unreliable because of host galaxy dilution in the optical). It is likely that in most of our objects, the AGN is either obscured or low luminosity, and thus dominates the energetic output only in the MIR, showing up just in the range where the host galaxy SED has a minimum. The fraction of AGNs strongly depends on flux density, with that derived through the SED-fitting about 20% at S_15um_~0.5-1mJy and gradually increasing to 100% at S_15um_>10mJy, while that obtained from optical spectroscopy is never >30%, even at higher flux densities.
764. SEDs of type I AGN in COSMOS. I. XMM-COSMOS
ID:
ivo://CDS.VizieR/J/ApJ/759/6
Title:
SEDs of type I AGN in COSMOS. I. XMM-COSMOS
Short Name:
J/ApJ/759/6
Date:
21 Oct 2021
Publisher:
CDS
Description:
The "Cosmic Evolution Survey" (COSMOS) enables the study of the spectral energy distributions (SEDs) of active galactic nuclei (AGNs) because of the deep coverage and rich sampling of frequencies from X-ray to radio. Here we present an SED catalog of 413 X-ray (XMM-Newton)-selected type 1 (emission line FWHM>2000km/s) AGNs with Magellan, SDSS, or VLT spectrum. The SEDs are corrected for Galactic extinction, broad emission line contributions, constrained variability, and host galaxy contribution. We present the mean SED and the dispersion SEDs after the above corrections in the rest-frame 1.4GHz to 40keV, and show examples of the variety of SEDs encountered. In the near-infrared to optical (rest frame ~8{mu}m-4000{AA}), the photometry is complete for the whole sample and the mean SED is derived from detections only. Reddening and host galaxy contamination could account for a large fraction of the observed SED variety.
765. SEDs of weak AGNs associated with LINERs
ID:
ivo://CDS.VizieR/J/ApJS/187/135
Title:
SEDs of weak AGNs associated with LINERs
Short Name:
J/ApJS/187/135
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a compilation of spectral energy distributions (SEDs) of 35 weak active galactic nuclei (AGNs) in low-ionization nuclear emission regions (LINERs) using recent data from the published literature. We make use of previously published compilations of data, after complementing and extending them with more recent data. The main improvement in the recent data is afforded by high-spatial-resolution observations with the Chandra X-Ray Observatory and high spatial resolution radio observations utilizing a number of facilities. In addition, a considerable number of objects have been observed with the Hubble Space Telescope in the near-IR through near-UV bands since the earlier compilations were published. The data include upper limits resulting from either non-detections or observations at low spatial resolution that do not isolate the AGN. For the sake of completeness, we also compute and present a number of quantities from the data, such as optical-to-X-ray spectral indices ({alpha}_ox_), bolometric corrections, bolometric luminosities, Eddington ratios, and the average SED. We anticipate that these data will be useful for a number of applications. In a companion paper, we use a subset of these data ourselves to assess the energy budgets of LINERs.
766. SEXSI Spitzer catalog
ID:
ivo://CDS.VizieR/J/ApJ/708/584
Title:
SEXSI Spitzer catalog
Short Name:
J/ApJ/708/584
Date:
21 Oct 2021
Publisher:
CDS
Description:
We compare the relative merits of active galactic nuclei (AGNs) selection at X-ray and mid-infrared wavelengths using data from moderately deep fields observed by both Chandra and Spitzer. The X-ray-selected AGN sample and associated photometric and spectroscopic optical follow-up are drawn from a subset of fields studied as part of the Serendipitous Extragalactic X-ray Source Identification (SEXSI) program. Mid-infrared data in these fields are derived from targeted and archival Spitzer imaging, and mid-infrared AGN selection is accomplished primarily through application of the Infrared Array Camera (IRAC) color-color AGN "wedge" selection technique. Nearly all X-ray sources in these fields which exhibit clear spectroscopic signatures of AGN activity have mid-infrared colors consistent with IRAC AGN selection. These are predominantly the most luminous X-ray sources. X-ray sources that lack high-ionization and/or broad lines in their optical spectra are far less likely to be selected as AGNs by mid-infrared color selection techniques. The fraction of X-ray sources identified as AGNs in the mid-infrared increases monotonically as the X-ray luminosity increases. Conversely, only 22% of mid-infrared-selected AGNs are detected at X-ray energies in the moderately deep (t_exp_~100ks) SEXSI Chandra data.
767. Seyfert galaxies in the mid-IR
ID:
ivo://CDS.VizieR/J/ApJ/705/14
Title:
Seyfert galaxies in the mid-IR
Short Name:
J/ApJ/705/14
Date:
21 Oct 2021
Publisher:
CDS
Description:
An analysis of archival mid-infrared (mid-IR) spectra of Seyfert galaxies from the Spitzer Space Telescope observations is presented. We characterize the nature of the mid-IR active nuclear continuum by subtracting a template starburst spectrum from the Seyfert spectra. The long wavelength part of the spectrum contains a strong contribution from the starburst-heated cool dust; this is used to effectively separate starburst-dominated Seyferts from those dominated by the active nuclear continuum. Within the latter category, the strength of the active nuclear continuum drops rapidly beyond ~20um. On average, type 2 Seyferts have weaker short-wavelength active nuclear continua as compared to type 1 Seyferts. Type 2 Seyferts can be divided into two types, those with strong polycyclic aromatic hydrocarbon (PAH) bands and those without.
768. Seyfert population in SSRS2
ID:
ivo://CDS.VizieR/J/AJ/126/1750
Title:
Seyfert population in SSRS2
Short Name:
J/AJ/126/1750
Date:
21 Oct 2021
Publisher:
CDS
Description:
The magnitude-limited catalog of the Southern Sky Redshift Survey (SSRS2, Cat. <J/AJ/116/1>) is used to characterize the properties of galaxies hosting active galactic nuclei (AGNs). Using emission-line ratios, we identify a total of 162 (3%) Seyfert galaxies out of the parent sample with 5399 galaxies. The sample contains 121 Seyfert 2 galaxies and 41 Seyfert 1 galaxies. The SSRS2 Seyfert galaxies are predominantly in spirals of types Sb and earlier or in galaxies with perturbed appearance as the result of strong interactions or mergers. Seyfert galaxies in this sample are twice as common in barred hosts as the non-Seyfert galaxies. By assigning galaxies to groups using a percolation algorithm, we find that the Seyfert galaxies in the SSRS2 are more likely to be found in binary systems when compared with galaxies in the SSRS2 parent sample. However, there is no statistically significant difference between the Seyfert and SSRS2 parent sample when systems with more than two galaxies are considered. The analysis of the present sample suggests that there is a stronger correlation between the presence of the AGN phenomenon with internal properties of galaxies (morphology, presence of bar, luminosity) than with environmental effects (local galaxy density, group velocity dispersion, nearest neighbor distance).
769. 5 Seyferts reduced CO(2-1) cubes
ID:
ivo://CDS.VizieR/J/A+A/643/A127
Title:
5 Seyferts reduced CO(2-1) cubes
Short Name:
J/A+A/643/A127
Date:
21 Oct 2021
Publisher:
CDS
Description:
Active galactic nucleus (AGN) driven outflows are believed to play an important role in regulating the growth of galaxies, mostly via negative feedback. However, their effects on their hosts are far from clear, especially for low- and moderate-luminosity Seyferts. To investigate this issue, we obtained cold molecular gas observations, traced by the CO(2-1) transition, using the NOEMA interferometer of five nearby (distances between 19 and 58Mpc) Seyfert galaxies. The resolution of ~0.3-0.8 (~30-100pc) and field of view of NOEMA allowed us to study the CO(2-1) morphology and kinematics in the nuclear regions (~100pc) and up to radial distances of ~900pc. We detected CO(2-1) emission in all five galaxies with disky or circumnuclear ring-like morphologies. We derived cold molecular gas masses on nuclear (~100pc) and circumnuclear (~650pc) scales in the range from 10^6^ to 10^7^M_{sun}_ and from 10^7^ to 10^8^M_{sun}_, respectively. In all of our galaxies, the bulk of this gas is rotating in the plane of the galaxy. However, noncircular motions are also present. In NGC 4253, NGC 4388, and NGC 7465, we can ascribe the streaming motions to the presence of a large-scale bar. In Mrk 1066 and NGC 4388, the noncircular motions in the nuclear regions are explained as outflowing material due to the interaction of the AGN wind with molecular gas in the galaxy disk. We conclude that for an unambiguous and precise interpretation of the kinematics of the cold molecular gas, we need detailed knowledge of the host galaxy (i.e., presence of bars, interactions, etc.), and also of the ionized gas kinematics and ionization cone geometry.
770. SFR & AGN in most luminous local universe LINERs
ID:
ivo://CDS.VizieR/J/MNRAS/462/2878
Title:
SFR & AGN in most luminous local universe LINERs
Short Name:
J/MNRAS/462/2878
Date:
21 Oct 2021
Publisher:
CDS
Description:
This work presents the properties of 42 objects in the group of the most luminous, highest star formation rate (SFR) low-ionization nuclear emission-line regions (LINERs) at z=0.04-0.11. We obtained long-slit spectroscopy of the nuclear regions for all sources, and FIR data (Herschel and IRAS) for 13 of them. We measured emission-line intensities, extinction, stellar populations, stellar masses, ages, active galactic nuclei (AGN) luminosities, and SFRs. We find considerable differences from other low-redshift LINERs, in terms of extinction, and general similarity to star-forming galaxies. We confirm the existence of such luminous LINERs in the local universe, after being previously detected at z~0.3 by Tommasin et al. The median stellar mass of these LINERs corresponds to 6-7x10^10^M_{sun}_ which was found in previous work to correspond to the peak of relative growth rate of stellar populations and therefore for the highest SFRs. Other LINERs although showing similar AGN luminosities have lower SFR. We find that most of these sources have LAGN~LSF suggesting co-evolution of black hole and stellar mass. In general, the fraction of local LINERs on the main sequence of star-forming galaxies is related to their AGN luminosity.