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81. AGN-host connection in partially obscured AGNs. I.
ID:
ivo://CDS.VizieR/J/ApJ/679/86
Title:
AGN-host connection in partially obscured AGNs. I.
Short Name:
J/ApJ/679/86
Date:
21 Oct 2021
Publisher:
CDS
Description:
The goal of our serial papers is to examine the evolutionary connection between an active galactic nucleus (AGN) and star formation in the AGN's host galaxy for partially obscured AGNs (i.e., Seyfert 1.8 and 1.9 galaxies). Taking advantage of these galaxies, the properties of both components can be studied together by direct measurements. In this paper, we focus on broad-line composite galaxies (composite AGNs), which are located between the theoretical and empirical separation lines in the [NII]/H{alpha} versus [OIII]/H{beta} diagram. These galaxies are selected from the composite galaxies provided by the SDSS DR4 MPA/JHU catalogs. After we reanalyze the spectra, we perform a fine classification for the 85 composite AGNs in terms of Baldwin-Phillips-Terlevich (BPT) diagrams. All objects located below the three theoretical separation lines are associated with a young stellar population (<1Gyr), while either a young or old stellar population is identified in the individual multiply classified objects. The multiply classified objects with very old stellar populations are located in the LINER region in the [OI]/H{alpha} versus [OIII]/H{beta} diagram. We then consider the connection between AGNs and star formation to derive the key results. The Eddington ratio inferred from the broad H{alpha} emission, the age of the stellar population of the AGN's host as assessed by D_n_(4000), and the line ratio [OI]/H{alpha} are found to be related to each other.
82. AGN in nearby galaxies
ID:
ivo://CDS.VizieR/J/MNRAS/398/1165
Title:
AGN in nearby galaxies
Short Name:
J/MNRAS/398/1165
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using Spitzer-infrared spectrograph (IRS) spectroscopy, we investigate the ubiquity of active galactic nuclei (AGN) in a complete (~94%), volume-limited sample of the most bolometrically luminous galaxies [L_IR,8-1000um_>=(0.3-20)x10^10^L_{sun}_] to D<15Mpc. Our analyses are based on the detection of the high-excitation emission line [NeV]({lambda}14.32{mu}m) (97.1eV) to unambiguously identify AGN activity. We find that 17 of the 64 infrared (IR) bright galaxies in our sample host AGN activity (~27^+8^_6_%), >=50t of which are not identified as AGN using optical spectroscopy.
83. 4 AGN optical spectra
ID:
ivo://CDS.VizieR/J/A+A/596/A64
Title:
4 AGN optical spectra
Short Name:
J/A+A/596/A64
Date:
21 Oct 2021
Publisher:
CDS
Description:
Intermediate-Mass Black Holes (IMBHs) are thought to be the seeds of early Supermassive Black Holes (SMBHs). While >~100 IMBH and small SMBH candidates have been identified in recent years, few have been robustly confirmed to date, leaving their number density in considerable doubt. Placing firmer constraints both on the methods used to identify and confirm IMBHs/SMBHs, as well as characterizing the range of host environments that IMBHs/SMBHs likely inhabit is therefore of considerable interest and importance. Additionally, finding significant numbers of IMBHs in metal-poor systems would be particularly intriguing, since such systems may represent local analogs of primordial galaxies, and therefore could provide clues of early accretion processes. Here we study in detail several candidate Active Galactic Nuclei (AGN) found in metal-poor hosts. We utilize new X-ray and optical observations to characterize these metal-poor AGN candidates and compare them against known AGN luminosity relations and well-characterized IMBH/SMBH samples.
84. AGN pairs from SDSS-DR7. I.
ID:
ivo://CDS.VizieR/J/ApJ/737/101
Title:
AGN pairs from SDSS-DR7. I.
Short Name:
J/ApJ/737/101
Date:
21 Oct 2021
Publisher:
CDS
Description:
Galaxy-galaxy mergers and close interactions have long been regarded as a viable mechanism for channeling gas toward the central supermassive black holes (SMBHs) of galaxies which are triggered as active galactic nuclei (AGNs). AGN pairs, in which the central SMBHs of a galaxy merger are both active, are expected to be common from such events. We conduct a systematic study of 1286 AGN pairs at \bar{z}~0.1 with line-of-sight velocity offsets {Delta}v<600km/s and projected separations r_p_<100h^-1^_70_kpc, selected from the Seventh Data Release of the Sloan Digital Sky Survey (SDSS, Cat. II/294). This AGN pair sample was drawn from 138070 AGNs optically identified based on diagnostic emission line ratios and/or line widths. The fraction of AGN pairs with 5h^-1^_70_kpc<~r_p_<100h^-1^_70_kpc among all spectroscopically selected AGNs at 0.02<z<0.16 is 3.6% after correcting for SDSS spectroscopic incompleteness; ~30% of these pairs show morphological tidal features in their SDSS images, and the fraction becomes >~80% for pairs with the brightest nuclei.
85. AGNs emission-line from Post-COSTAR
ID:
ivo://CDS.VizieR/J/ApJS/150/165
Title:
AGNs emission-line from Post-COSTAR
Short Name:
J/ApJS/150/165
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present consistent emission-line measurements for active galactic nuclei (AGNs), useful for reliable statistical studies of emission line properties. This paper joins a series including similar measurements of 993 spectra from the Large Bright Quasar Survey and 174 spectra of AGNs obtained from the Faint Object Spectrograph (FOS) on the Hubble Space Telescope (HST) prior to the installation of COSTAR. This time we concentrate on 220 spectra obtained with the FOS after the installation of COSTAR, completing the emission line analysis of all FOS archival spectra. We use the same automated technique as in previous papers, which accounts for Galactic extinction, models blended optical and UV iron emission, includes Galactic and intrinsic absorption lines, and models emission lines using multiple Gaussians. We present UV and optical emission line parameters (equivalent widths, fluxes, FWHM, and line positions) for a large number (28) of emission lines including upper limits for undetected lines. Further scientific analyses will be presented in subsequent papers.
86. AGNs in LSB galaxies
ID:
ivo://CDS.VizieR/J/other/RAA/9.269
Title:
AGNs in LSB galaxies
Short Name:
J/other/RAA/9.26
Date:
21 Oct 2021
Publisher:
CDS
Description:
Active galactic nuclei (AGNs) in low surface brightness galaxies (LSBGs) have received little attention in previous studies. We present a detailed spectral analysis of 194 LSBGs from the Impey et al. (1996, Cat. J/ApJS/105/209) APM LSBG sample which has been observed spectroscopically by the Sloan Digital Sky Survey Data Release 5 (SDSS DR5). Our elaborate spectral analysis enables us to carry out, for the first time, reliable spectral classification of nuclear processes in LSBGs based on the standard emission line diagnostic diagrams in a rigorous way. Star-forming galaxies are common, as found in about 52% of LSBGs.We find that, contrary to some previous claims, the fraction of galaxies that contain AGNs is significantly lower than that found in nearby normal galaxies of high surface brightness. This is qualitatively in line with the finding of Impey et al. This result holds true even within each morphological type from Sa to Sc. LSBGs that have larger central stellar velocity dispersions or larger physical sizes tend to have a higher chance of harboring an AGN. For three AGNs with broad emission lines, the black hole masses estimated from the emission lines are broadly consistent with the well known M-{sigma}* relation established for normal galaxies and AGNs.
87. AGNs rest-frame UV and optical parameters
ID:
ivo://CDS.VizieR/J/ApJ/815/128
Title:
AGNs rest-frame UV and optical parameters
Short Name:
J/ApJ/815/128
Date:
21 Oct 2021
Publisher:
CDS
Description:
The ability to accurately derive black hole (BH) masses at progressively higher redshifts and over a wide range of continuum luminosities has become indispensable in the era of large-area extragalactic spectroscopic surveys. In this paper, we present an extension of existing comparisons between rest-frame UV and optical virial BH mass estimators to intermediate redshifts and luminosities comparable to the local H{beta} reverberation-mapped active galactic nuclei (AGNs). We focus on the Mg II, C IV, and C III] broad emission lines and compare them to both H{alpha} and H{beta}. We use newly acquired near-infrared spectra from the Fiber-fed Multi-object Spectrograph instrument on the Subaru telescope for 89 broad-lined AGNs at redshifts between 0.3 and 3.5, complemented by data from the AGES survey. We employ two different prescriptions for measuring the emission line widths and compare the results. We confirm that Mg II shows a tight correlation with H{alpha} and H{beta}, with a scatter of ~0.25 dex. The C IV and C III] estimators, while showing larger scatter, are viable virial mass estimators after accounting for a trend with the UV-to-optical luminosity ratio. We find an intrinsic scatter of ~0.37 dex between Balmer and carbon virial estimators by combining our data set with previous high redshift measurements. This updated comparison spans a total of three decades in BH mass. We calculate a virial factor for C IV/C III] logf_C IV/C III]_=0.87 with an estimated systematic uncertainty of ~0.4 dex and find excellent agreement between the local reverberation mapped AGN sample and our high-z sample.
88. AGNs with double-peaked [OIII] lines
ID:
ivo://CDS.VizieR/J/ApJ/705/L76
Title:
AGNs with double-peaked [OIII] lines
Short Name:
J/ApJ/705/L76
Date:
21 Oct 2021
Publisher:
CDS
Description:
Double-peaked [OIII] profiles in active galactic nuclei (AGNs) may provide evidence for the existence of dual AGNs, but a good diagnostic for selecting them is currently lacking. Starting from ~7000 active galaxies in Sloan Digital Sky Survey DR7, we assemble a sample of 87 type 2 AGNs with double-peaked [OIII] profiles. The nuclear obscuration in the type 2 AGNs allows us to determine redshifts of host galaxies through stellar absorption lines. We typically find that one peak is redshifted and another is blueshifted relative to the host galaxy. We find a strong correlation between the ratios of the shifts and the double peak fluxes. The correlation can be naturally explained by the Keplerian relation predicted by models of co-rotating dual AGNs. The current sample statistically favors that most of the [OIII] double-peaked sources are dual AGNs and disfavors other explanations, such as rotating disk and outflows. These dual AGNs have a separation distance at ~1kpc scale, showing an intermediate phase of merging systems. The appearance of dual AGNs is about ~10^-2^, impacting on the current observational deficit of binary supermassive black holes with a probability of ~10^-4^ (Boroson & Lauer, 2009Natur.458...53B).
89. AGN with WISE. II. The NDWFS Bootes field
ID:
ivo://CDS.VizieR/J/ApJ/772/26
Title:
AGN with WISE. II. The NDWFS Bootes field
Short Name:
J/ApJ/772/26
Date:
21 Oct 2021
Publisher:
CDS
Description:
Stern et al. (2012ApJ...753...30S, Paper I) presented a study of Wide-field Infrared Survey Explorer (WISE) selection of active galactic nuclei (AGNs) in the 2deg^2^ COSMOS field, finding that a simple criterion W1-W2>=0.8 provides a highly reliable and complete AGN sample for W2<15.05, where the W1 and W2 passbands are centered at 3.4{mu}m and 4.6{mu}m, respectively. Here we extend this study using the larger 9deg^2^ NOAO Deep Wide-Field Survey Bootes field which also has considerably deeper WISE observations than the COSMOS field, and find that this simple color cut significantly loses reliability at fainter fluxes. We define a modified selection criterion combining the W1-W2 color and the W2 magnitude to provide highly reliable or highly complete AGN samples for fainter WISE sources. In particular, we define a color-magnitude cut that finds 130+/-4deg^-2^ AGN candidates for W2<17.11 with 90% reliability. Using the extensive UV through mid-IR broadband photometry available in this field, we study the spectral energy distributions of WISE AGN candidates. We find that, as expected, the WISE AGN selection can identify highly obscured AGNs, but that it is biased toward objects where the AGN dominates the bolometric luminosity output. We study the distribution of reddening in the AGN sample and discuss a formalism to account for sample incompleteness based on the step-wise maximum-likelihood method of Efstathiou et al. The resulting dust obscuration distributions depend strongly on AGN luminosity, consistent with the trend expected for a receding torus. At L_AGN_~3x10^44^erg/s, 29%+/-7% of AGNs are observed as Type 1, while at ~4x10^45^erg/s the fraction is 64%+/-13%. The distribution of obscuration values suggests that dust in the torus is present as both a diffuse medium and in optically thick clouds.
90. AKARI-LMC Near-infrared Spectroscopic Catalog
ID:
ivo://CDS.VizieR/J/AJ/145/32
Title:
AKARI-LMC Near-infrared Spectroscopic Catalog
Short Name:
J/AJ/145/32
Date:
21 Oct 2021
Publisher:
CDS
Description:
We performed a near-infrared spectroscopic survey toward an area of ~10deg^2^ of the Large Magellanic Cloud (LMC) with the infrared satellite AKARI. Observations were carried out as part of the AKARI Large-area Survey of the Large Magellanic Cloud (LSLMC). The slitless multi-object spectroscopic capability of the AKARI/IRC enabled us to obtain low-resolution (R~20) spectra in 2-5{mu}m for a large number of point sources in the LMC. As a result of the survey, we extracted about 2000 infrared spectra of point sources. The data are organized as a near-infrared spectroscopic catalog. The catalog includes various infrared objects such as young stellar objects (YSOs), asymptotic giant branch (AGB) stars, supergiants, and so on. It is shown that 97% of the catalog sources have corresponding photometric data in the wavelength range from 1.2 to 11{mu}m, and 67% of the sources also have photometric data up to 24{mu}m. The catalog allows us to investigate near-infrared spectral features of sources by comparison with their infrared spectral energy distributions. In addition, it is estimated that about 10% of the catalog sources are observed at more than two different epochs. This enables us to study a spectroscopic variability of sources by using the present catalog. Initial results of source classifications for the LSLMC samples are presented. We classified 659 LSLMC spectra based on their near-infrared spectral features by visual inspection. As a result, it is shown that the present catalog includes 7 YSOs, 160 C-rich AGBs, 8 C-rich AGB candidates, 85 O-rich AGBs, 122 blue and yellow supergiants, 150 red super giants, and 128 unclassified sources. Distributions of the classified sources on the color-color and color-magnitude diagrams are discussed in the text. Continuous wavelength coverage and high spectroscopic sensitivity in 2-5{mu}m can only be achieved by space observations. This is an unprecedented large-scale spectroscopic survey toward the LMC in the near-infrared. A large number of near-infrared spectral data provided by the survey possess scientific potential that can be applied to various studies. In this paper, we present the details of the spectroscopic survey and the catalog, and discuss its scientific applications.