We present analysis of spectral energy distributions (SEDs) from mid-infrared
through X-ray of a sample of 420 hard X-ray selected, z-band and Spitzer/IRAC
detected active galactic nuclei (AGN) and ...AGN candidates from the GOODS
multiwavelength survey. We fit local empirical SED templates of both normal and
active galaxies to the rest-frame luminosities calculated from spectroscopic
(where available) and photometric redshifts. The majority of the optically
stellar-dominated (with early-type galaxy fits) sources are moderately luminous
(L_X,2-10 keV ~ 10^43 erg/s) hard X-ray sources with high X-ray hardness ratios
(HR > 0.2), high MIR luminosities and red MIR colors in excess of a typical
stellar dominated elliptical galaxy. These sources likely harbor heavily
obscured (though Compton-thin) AGN. The observed ratio of obscured to
unobscured AGN has an integrated mean of ~3.4:1 but declines with increasing
redshift. This effect has been explained by Treister et al. (2004) as an
observational bias triggered by the lack of spectroscopic redshifts at R > 24
which are predominantly higher redshift obscured sources.
We present a detailed X-ray study of the Broad Line Radio Galaxy 3C382,
observed with the BeppoSAX satellite in a very bright state. The continuum
emission is well modeled with a power law that ...steepens at high energies, with
an e-folding energy of about 120 keV. At soft energies a clear excess of
emission is detected, which can not be explained solely by the extended thermal
halo seen in a ROSAT HRI image. A second, more intense soft X-ray component,
possibly related to an accretion disk, is required by the data. Both a
reflection component (R=0.3) and an iron line (EW \sim 50) are detected, at
levels much weaker than in Seyfert galaxies, suggesting a common origin.
Combining our measurements with results from the literature we find that the
iron line has remained approximately constant over 9 years while the continuum
varied by a factor of 5. Thus the fluorescent gas does not respond promptly to
the variations of the X-ray primary source, suggesting that the reprocessing
site is located away, likely at parsec distances. While the continuum shape
indicates that X-rays derive from a thermal Comptonization process, the
weakness of other spectral features implies that either the upper layers of the
optically thick accretion disk are completely ionized or the corona above the
disk is outflowing with mildly relativistic velocity.
We briefly review BeppoSAX observations of X-ray bright radio-galaxies. Their X-ray spectra are quite varied, and perhaps surprisingly, any similarity between radio-loud AGN and Seyfert galaxies is ...the exception rather than the rule. When detected, reprocessing features (iron line and reflection) are generally weak, suggesting two possible scenarios: either: (1) non-thermal (jet?) radiation dilutes the X-ray emission from the disk in radio-loud objects, or (2) the solid angle subtended by the X-ray reprocessing material is smaller in radio-loud than in radio-quiet AGN due to different characteristics of the accretion disk itself.
We investigate the optical and Wide-field Survey Explorer (WISE) colors of "E+A" identified post-starburst galaxies, including a deep analysis of 190 post-starbursts detected in the 2 mu m All Sky ...Survey Extended Source Catalog. The post-starburst galaxies appear in both the optical green valley and the WISE Infrared Transition Zone. Furthermore, we find that post-starbursts occupy a distinct region of 3.4-4.6 versus 4.6-12 WISE colors, enabling the identification of this class of transitioning galaxies through the use of broadband photometric criteria alone. We have investigated possible causes for the WISE colors of post-starbursts by constructing a composite spectral energy distribution (SED), finding that the mid-infrared (4-12 mu m) properties of post-starbursts are consistent with either 11.3 mu m polycyclic aromatic hydrocarbon emission, or thermally pulsating asymptotic giant branch (TP-AGB) and post-AGB stars. The composite SED of extended post-starburst galaxies with 22 mu m emission detected with signal-to-noise ratio >= 3 requires a hot dust component to produce their observed rising mid-infrared SED between 12 and 22 mu m. The composite SED of WISE. 22 mu m non-detections (S/N < 3), created by stacking 22 mu m images, is also flat, requiring a hot dust component. The most likely source of the mid-infrared emission of these E+A galaxies is a buried active galactic nucleus (AGN). The inferred upper limits to the Eddington ratios of post-starbursts are 10(-2)-10(-4), with an average of 10(-3). This suggests that AGNs are not radiatively dominant in these systems. This could mean that including selections capable of identifying AGNs as part of a search for transitioning and post-starburst galaxies would create a more complete census of the transition pathways taken as a galaxy quenches its star formation.
We present a detailed X-ray study of the Broad Line Radio Galaxy 3C382, observed with the BeppoSAX satellite in a very bright state. The continuum emission is well modeled with a power law that ...steepens at high energies, with an e-folding energy of about 120 keV. At soft energies a clear excess of emission is detected, which can not be explained solely by the extended thermal halo seen in a ROSAT HRI image. A second, more intense soft X-ray component, possibly related to an accretion disk, is required by the data. Both a reflection component (R=0.3) and an iron line (EW \sim 50) are detected, at levels much weaker than in Seyfert galaxies, suggesting a common origin. Combining our measurements with results from the literature we find that the iron line has remained approximately constant over 9 years while the continuum varied by a factor of 5. Thus the fluorescent gas does not respond promptly to the variations of the X-ray primary source, suggesting that the reprocessing site is located away, likely at parsec distances. While the continuum shape indicates that X-rays derive from a thermal Comptonization process, the weakness of other spectral features implies that either the upper layers of the optically thick accretion disk are completely ionized or the corona above the disk is outflowing with mildly relativistic velocity.
We present analysis of spectral energy distributions (SEDs) from mid-infrared through X-ray of a sample of 420 hard X-ray selected, z-band and Spitzer/IRAC detected active galactic nuclei (AGN) and ...AGN candidates from the GOODS multiwavelength survey. We fit local empirical SED templates of both normal and active galaxies to the rest-frame luminosities calculated from spectroscopic (where available) and photometric redshifts. The majority of the optically stellar-dominated (with early-type galaxy fits) sources are moderately luminous (L_X,2-10 keV ~ 10^43 erg/s) hard X-ray sources with high X-ray hardness ratios (HR > 0.2), high MIR luminosities and red MIR colors in excess of a typical stellar dominated elliptical galaxy. These sources likely harbor heavily obscured (though Compton-thin) AGN. The observed ratio of obscured to unobscured AGN has an integrated mean of ~3.4:1 but declines with increasing redshift. This effect has been explained by Treister et al. (2004) as an observational bias triggered by the lack of spectroscopic redshifts at R > 24 which are predominantly higher redshift obscured sources.
We present a catalog of the millimeter-wave (mm-wave) continuum properties of
98 nearby ($z <$ 0.05) active galactic nuclei (AGNs) selected from the 70-month
Swift/BAT hard X-ray catalog that have ...precisely determined X-ray spectral
properties and subarcsec-resolution ALMA Band-6 (211--275 GHz) observations as
of 2021 April. Due to the hard-X-ray ($>$ 10 keV) selection, the sample is
nearly unbiased for obscured systems at least up to Compton-thick-level
obscuration, and provides the largest number of AGNs with high physical
resolution mm-wave data ($\lesssim$ 100--200 pc). Our catalog reports emission
peak coordinates, spectral indices, and peak fluxes and luminosities at 1.3 mm
(230 GHz). Additionally, high-resolution mm-wave images are provided. Using the
images and creating radial surface brightness profiles of mm-wave emission, we
identify emission extending from the central source and isolated blob-like
emission. Flags indicating the presence of these emission features are
tabulated. Among 90 AGNs with significant detections of nuclear emission, 37
AGNs ($\approx$ 41%) appear to have both or one of extended or blob-like
components. We, in particular, investigate AGNs that show well-resolved mm-wave
components and find that these seem to have a variety of origins (i.e., a jet,
radio lobes, a secondary AGN, stellar clusters, a narrow line region, galaxy
disk, active star-formation regions, and AGN-driven outflows), and some
components have currently unclear origins.
To understand the origin of nuclear ($\lesssim$ 100 pc) millimeter-wave
(mm-wave) continuum emission in active galactic nuclei (AGNs), we
systematically analyzed sub-arcsec resolution Band-6 (211-275 ...GHz) ALMA data of
98 nearby AGNs ($z <$ 0.05) from the 70-month Swift/BAT catalog. The sample,
almost unbiased for obscured systems, provides the largest number of AGNs to
date with high mm-wave spatial resolution sampling ($\sim$ 1-200 pc), and spans
broad ranges of 14-150 keV luminosity {$40 < \logL_{\rm 14-150}/({\rm
erg\,s^{-1}}) < 45$}, black hole mass $5 < \log(M_{\rm BH}/M_\odot) < 10$,
and Eddington ratio ($-4 < \log \lambda_{\rm Edd} < 2$). We find a significant
correlation between 1.3 mm (230 GHz) and 14-150 keV luminosities. Its scatter
is $\approx$ 0.36 dex, and the mm-wave emission may serve as a good proxy of
the AGN luminosity, free of dust extinction up to $N_{\rm H} \sim 10^{26}$
cm$^{-2}$. While the mm-wave emission could be self-absorbed synchrotron
radiation around the X-ray corona according to past works, we also discuss
different possible origins of the mm-wave emission; AGN-related dust emission,
outflow-driven shocks, and a small-scale ($<$ 200 pc) jet. The dust emission is
unlikely to be dominant, as the mm-wave slope is generally flatter than
expected. Also, due to no increase in the mm-wave luminosity with the Eddington
ratio, a radiation-driven outflow model is possibly not the common mechanism.
Furthermore, we find independence of the mm-wave luminosity on indicators of
the inclination angle from the polar axis of the nuclear structure, which is
inconsistent with a jet model whose luminosity depends only on the angle.
We present a catalog of the millimeter-wave (mm-wave) continuum properties of 98 nearby (\(z <\) 0.05) active galactic nuclei (AGNs) selected from the 70-month Swift/BAT hard X-ray catalog that have ...precisely determined X-ray spectral properties and subarcsec-resolution ALMA Band-6 (211--275 GHz) observations as of 2021 April. Due to the hard-X-ray (\(>\) 10 keV) selection, the sample is nearly unbiased for obscured systems at least up to Compton-thick-level obscuration, and provides the largest number of AGNs with high physical resolution mm-wave data (\(\lesssim\) 100--200 pc). Our catalog reports emission peak coordinates, spectral indices, and peak fluxes and luminosities at 1.3 mm (230 GHz). Additionally, high-resolution mm-wave images are provided. Using the images and creating radial surface brightness profiles of mm-wave emission, we identify emission extending from the central source and isolated blob-like emission. Flags indicating the presence of these emission features are tabulated. Among 90 AGNs with significant detections of nuclear emission, 37 AGNs (\(\approx\) 41%) appear to have both or one of extended or blob-like components. We, in particular, investigate AGNs that show well-resolved mm-wave components and find that these seem to have a variety of origins (i.e., a jet, radio lobes, a secondary AGN, stellar clusters, a narrow line region, galaxy disk, active star-formation regions, and AGN-driven outflows), and some components have currently unclear origins.
To understand the origin of nuclear (\(\lesssim\) 100 pc) millimeter-wave (mm-wave) continuum emission in active galactic nuclei (AGNs), we systematically analyzed sub-arcsec resolution Band-6 ...(211-275 GHz) ALMA data of 98 nearby AGNs (\(z <\) 0.05) from the 70-month Swift/BAT catalog. The sample, almost unbiased for obscured systems, provides the largest number of AGNs to date with high mm-wave spatial resolution sampling (\(\sim\) 1-200 pc), and spans broad ranges of 14-150 keV luminosity {\(40 < \logL_{\rm 14-150}/({\rm erg\,s^{-1}}) < 45\)}, black hole mass \(5 < \log(M_{\rm BH}/M_\odot) < 10\), and Eddington ratio (\(-4 < \log \lambda_{\rm Edd} < 2\)). We find a significant correlation between 1.3 mm (230 GHz) and 14-150 keV luminosities. Its scatter is \(\approx\) 0.36 dex, and the mm-wave emission may serve as a good proxy of the AGN luminosity, free of dust extinction up to \(N_{\rm H} \sim 10^{26}\) cm\(^{-2}\). While the mm-wave emission could be self-absorbed synchrotron radiation around the X-ray corona according to past works, we also discuss different possible origins of the mm-wave emission; AGN-related dust emission, outflow-driven shocks, and a small-scale (\(<\) 200 pc) jet. The dust emission is unlikely to be dominant, as the mm-wave slope is generally flatter than expected. Also, due to no increase in the mm-wave luminosity with the Eddington ratio, a radiation-driven outflow model is possibly not the common mechanism. Furthermore, we find independence of the mm-wave luminosity on indicators of the inclination angle from the polar axis of the nuclear structure, which is inconsistent with a jet model whose luminosity depends only on the angle.
