Mid-infrared spectroscopy of candidate AGN-dominated submillimeter galaxies
K. Coppin, A. Pope, K. Menendez-Delmestre, D. M. Alexander, J. S. Dunlop, E. Egami, J. Gabor, Edo Ibar, R. J. Ivison, J. E. Austermann, A. W. Blain, S. C. Chapm… 展开作者
K. Coppin, A. Pope, K. Menendez-Delmestre, D. M. Alexander, J. S. Dunlop, E. Egami, J. Gabor, Edo Ibar, R. J. Ivison, J. E. Austermann, A. W. Blain, S. C. Chapman, D. L. Clements, L. Dunne, S. Dye, D. Farrah, D. H. Hughes, A. M. J. Mortier, M. J. Page, M. Rowan-Robinson, D. Scott, C. Simpson, Ian Smail, A. M. Swinbank, M. Vaccari, M. S. Yun
备注：
Accepted for publication in ApJ. 17 pages, 10 figures
Spitzer spectroscopy has revealed that ~80% of submm galaxies (SMGs) are starburst (SB) dominated in the mid-infrared. Here we focus on the remaining ~20% that show signs of harboring powerful active galactic nuclei (AGN). We have obtained Spitzer-IRS spectroscopy of a sample of eight SMGs which are candidates for harboring powerful AGN on the basis of IRAC color-selection (S8/S4.5>2; i.e. likely power-law mid-infrared SEDs). SMGs with an AGN dominating (>50%) their mid-infrared emission could represent `missing link' sources in an evolutionary sequence involving a major merger. First of all, we detect PAH features in all of the SMGs, indicating redshifts from 2.5-3.4, demonstrating the power of the mid-infrared to determine redshifts for these optically faint dusty galaxies. Secondly, we see signs of both star-formation (from the PAH features) and AGN activity (from continuum emission) in our sample: 62% of the sample are AGN-dominated in the mid-infrared with a median AGN content of 56%, compared with <30% on average for typical SMGs, revealing that our IRAC color selection has successfully singled out sources with proportionately more AGN emission than typical SB-dominated SMGs. However, we find that only about 10% of these AGN dominate the bolometric emission of the SMG when the results are extrapolated to longer infrared wavelengths, implying that AGN are not a significant power source to the SMG population overall, even when there is evidence in the mid-infrared for substantial AGN activity. When existing samples of mid-infrared AGN-dominated SMGs are considered, we find that S8/S4.5>1.65 works well at selecting mid-infrared energetically dominant AGN in SMGs, implying a duty cycle of ~15% if all SMGs go through a subsequent mid-infrared AGN-dominated phase in the proposed evolutionary sequence.
The large gas and dust reservoirs of submm galaxies (SMGs) could potentially provide ample fuel to trigger an Active Galactic Nucleus (AGN), but previous studies of the AGN fraction in SMGs have been controversial largely due to the inhomogeneity and limited angular resolution of the available submillimeter surveys. Here we set improved constraints on the AGN fraction and X-ray properties of the SMGs with ALMA and Chandra observations in the Extended Chandra Deep Field-South (E-CDF-S). This study is the first among similar works to have unambiguously identified the X-ray counterparts of SMGs; …
A two-parameter semi-empirical model is presented for the spectral energy distributions of galaxies with contributions to their infrared-submillimeter-radio emission from both star formation and accretion disk-powered activity. This model builds upon a previous one-parameter family of models for star-forming galaxies, and includes an update to the mid-infrared emission using an average template obtained from Spitzer Space Telescope observations of normal galaxies. Star-forming/AGN diagnostics based on PAH equivalent widths and broadband infrared colors are presented, and example mid-infrared A…
We present radiative transfer models for submillimeter galaxies with spectroscopic redshifts and mid-infrared spectroscopy from Spitzer/IRS and analyze available Spitzer/MIPS 24, 70 and 160mu data. We use two types of starburst models, a cirrus model and a model for the emission of an AGN torus in order to investigate the nature of these objects. We find that for three of the objects (25%) cirrus emission alone can account for the mid-infrared spectrum and the MIPS and submillimeter data. For the remaining objects we find that we need a combination of starburst and cirrus in order to fit simul…
We present measurements of the mean mid-infrared-to-submillimeter flux densities of massive (M\ast \approx 2 \times 10^11 Msun) galaxies at redshifts 1.7 < z < 2.9, obtained by stacking positions of known objects taken from the GOODS NICMOS Survey (GNS) catalog on maps: at 24 μm (Spitzer/MIPS); 70, 100, and 160μm (Herschel/PACS); 250, 350, 500μm (BLAST); and 870μm (LABOCA). A modified blackbody spectrum fit to the stacked flux densities indicates a median [interquartile] star-formation rate of SFR = 63 [48, 81] Msun yr^-1 . We note that not properly accounting for correlations between bands wh…
We report the detection of 6.2um polycyclic aromatic hydrocarbon (PAH) and rest-frame 4-7um continuum emission in the z=4.055 submillimeter galaxy GN20, using the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope. This represents the first detection of PAH emission at z>4. The strength of the PAH emission feature is consistent with a very high star formation rate of ~1600Msun/yr. We find that this intense starburst powers at least ~1/3 of the faint underlying 6um continuum emission, with an additional, significant (and perhaps dominant) contribution due to a power-law-like hot d…
We present the results of a program of optical and near-infrared spectroscopic follow-up of candidate Active Galactic Nuclei (AGN) selected in the mid-infrared. This survey selects both normal and obscured AGN closely matched in luminosity across a wide range, from Seyfert galaxies with bolometric luminosities L_bol~10^10L_sun, to highly luminous quasars (L_bol~10^14L_sun), and with redshifts from 0-4.3. Samples of candidate AGN were selected through mid-infrared color cuts at several different 24 micron flux density limits to ensure a range of luminosities at a given redshift. The survey cons…
We describe a mid-infrared (MIR) survey of local AGN to be conducted with the CanariCam instrument on the Gran Telescopio Canarias (GTC). We will obtain MIR imaging and spectroscopy of a sample of ~100 AGN covering six orders of magnitude in AGN luminosity, and including different AGN classes (e.g., LINERs, Seyfert 1s and 2s, QSO). The main goals are: (1) to test unification of Type 1 and Type 2 AGN, (2) to study the star formation activity around AGN, and (3) to explore the role of the dusty torus in low-luminosity AGN.
Using the Herschel ATLAS science demonstration phase data crossidentified with SDSS DR7 spectra, we select 297 galaxies with F250μm > 5σ. The sample galaxies are classified into five morphological types, and more than 40% of the galaxies are peculiar/compact galaxies. The peculiar galaxies show higher far-infrared/submillimeter luminosity-to-mass ratios than the other types. We perform and analyze the correlations of far-infrared/submillimeter and Hα luminosities for different morphological types and different spectral types. The Spearman rank coefficient decreases and the scatter increases wi…
The Wide-field Infrared Survey Explorer (WISE) is an extremely capable and efficient black hole finder. We present a simple mid-infrared color criterion, W1-W2 \geq 0.8 (i.e., [3.4]-[4.6] \geq 0.8, Vega), which identifies 61.9 \pm 5.4 AGN candidates per deg2 to a depth of W2 = 15.0. This implies a much larger census of luminous AGN than found by typical wide-area surveys, attributable to the fact that mid-infrared selection identifies both unobscured (type 1) and obscured (type 2) AGN. Optical and soft X-ray surveys alone are highly biased towards only unobscured AGN, while this simple WISE se…
We compare the relative merits of AGN 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 optical follow-up are drawn from the SEXSI program. Mid-infrared data in these fields are derived from Spitzer imaging, and mid-infrared AGN selection is accomplished primarily through application of the 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 …
We present a new study of the stellar mass in a sample of ~ 70 submillimeter-selected galaxies (SMGs) with accurate spectroscopic redshifts. We fit combinations of stellar population synthesis models and power laws to the galaxies' observed-frame optical through mid-IR spectral energy distributions to separate stellar emission from non-stellar near-IR continuum. By separating the stellar emission from the non-stellar near-IR continuum, we find that ~ 50% of our sample have non-stellar continuum contributions of less than 10% in rest-frame H-band, but ~ 10% of our sample have non-stellar contri…
We used the Spitzer Infrared Spectrograph (IRS) to study the mid-IR properties and investigate the energetics of 24 Submillimeter Galaxies (SMGs). This is the largest sample of SMGs observed with Spitzer IRS and covers the full extent of properties of the radio-identified population of SMGs in the redshift range of z ~ 0.65-3.2. We observe broad emission features from Polycyclic Aromatic Hydrocarbons (PAHs) in more than 80% of our sample. We find that the median mid-IR spectrum is well described by a starburst component with an additional power law, Fnu ~ nu^-2, likely representing a < 32% AGN…
The AGN-heated dust distribution (the "torus") is increasingly recognized not only as the absorber required in unifying models, but as a tracer for the reservoir that feeds the nuclear Super-Massive Black Hole. Yet, even its most basic structural properties (such as its extent, geometry and elongation) are unknown for all but a few archetypal objects. Since most AGNs are unresolved in the mid-infrared, we utilize the MID-infrared interferometric Instrument (MIDI) at the Very Large Telescope Interferometer (VLTI) that is sensitive to structures as small as a few milli-arcseconds (mas). We prese…
We present the first integral-field spectroscopic observations of high-redshift submillimeter-selected galaxies (SMGs) using Laser Guide Star Adaptive Optics (LGS-AO). We target H-alpha emission of three SMGs at redshifts z~1.4-2.4 with the OH-Suppressing Infrared Imaging Spectrograph (OSIRIS) on Keck. The spatially-resolved spectroscopy of these galaxies reveals unresolved broad H-alpha line regions (FWHM>1000 km/s) likely associated with an AGN and regions of diffuse star formation traced by narrow-line H-alpha emission (FWHM<500 km/s) dominated by multiple Halpha-bright stellar clumps, each…
Over the course of two flights, the Balloon-borne Large Aperture Submillimeter Telescope (BLAST) made resolved maps of seven nearby (<25 Mpc) galaxies at 250, 350, and 500 microns. During its June 2005 flight from Sweden, BLAST observed a single nearby galaxy, NGC 4565. During the December 2006 flight from Antarctica, BLAST observed the nearby galaxies NGC 1097, NGC 1291, NGC 1365, NGC 1512, NGC 1566, and NGC 1808. We fit physical dust models to a combination of BLAST observations and other available data for the galaxies observed by Spitzer. We fit a modified blackbody to the remaining galaxi…
We compare mid-infrared emission-line properties, from high-resolution Spitzer spectra of a hard X-ray (14 -- 195 keV) selected sample of nearby (z < 0.05) AGN detected by the Burst Alert Telescope (BAT) aboard Swift. The luminosity distribution for the mid-infrared emission-lines, [O IV] 25.89 micron, [Ne II] 12.81 micron, [Ne III] 15.56 micron and [Ne V] 14.32/24.32 micron, and hard X-ray continuum show no differences between Seyfert 1 and Seyfert 2 populations, however six newly discovered BAT AGNs are under-luminous in [O IV], most likely the result of dust extinction in the host galaxy. T…
The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) has made one square degree, deep, confusion limited maps at three different bands, centered on the Great Observatories Origins Deep Survey South field. By calculating the covariance of these maps with catalogs of 24 micron sources from the Far-Infrared Deep Extragalactic Legacy Survey (FIDEL), we have determined that the total submillimeter intensities are 8.60 +/- 0.59, 4.93 +/- 0.34, and 2.27 +/- 0.20 nW m^2 sr^(-1) at 250, 350, and 500 micron, respectively. These numbers are more precise than previous estimates of the cosmic i…
Clusters of galaxies have long been used as laboratories for the study of galaxy evolution, but despite intense, recent interest in feedback between AGNs and their hosts, the impact of environment on these relationships remains poorly constrained. We present results from a study of AGNs and their host galaxies found in low-redshift galaxy clusters. We fit model spectral energy distributions (SEDs) to the combined visible and mid-infrared (MIR) photometry of cluster members and use these model SEDs to determine stellar masses and star-formation rates (SFRs). We identify two populations of AGNs,…
We present Spitzer 7-38um spectra for a 24um flux limited sample of galaxies at z~0.7 in the COSMOS field. The detailed high-quality spectra allow us to cleanly separate star formation (SF) and active galactic nucleus (AGN) in individual galaxies. We first decompose mid-infrared Luminosity Functions (LFs). We find that the SF 8um and 15um LFs are well described by Schechter functions. AGNs dominate the space density at high luminosities, which leads to the shallow bright-end slope of the overall mid-infrared LFs. The total infrared (8-1000um) LF from 70um selected galaxies shows a shallower br…
We report a highly significant Submillimeter Array (SMA) detection of the prototypical submillimeter source HDF 850.1, which is the brightest submillimeter source in the Hubble Deep Field-North proper. The detection yields an extremely precise position of RA(2000)=12:36:51.99 and Dec(2000)=+62:12:25.83 with a 1-sigma positional uncertainty of 0.17 arcsec. The position is consistent with the location of a millimeter wavelength interferometric detection and with the locations of weak VLA detections at 1.4 and 8.4 GHz, but it is not consistent with any previous optical/near-infrared identificatio…
We apply a simple model, tested on local ULIRGs, to disentangle the active galactic nucleus (AGN) and starburst contributions in submillimiter and 24um-selected ULIRGs observed with the Spitzer-IRS spectrometer. We quantitatively estimate the average AGN contribution to the stacked 6-8um rest-frame spectra of these sources in different luminosity and redshift ranges, and, under the assumption of similar infrared-to-bolometric ratios as in local ULIRGs, the relative AGN/starburst contributions to the total infrared luminosity. Though the starburst component is always dominant in submillimeter-s…
We present Spitzer InfraRed Spectrograph (IRS) low-resolution spectra of 16 spectroscopically selected post-starburst quasars (PSQs) at z ~ 0.3. The optical spectra of these broad-lined active galactic nuclei (AGNs) simultaneously show spectral signatures of massive intermediate-aged stellar populations making them good candidates for studying the connections between AGNs and their hosts. The resulting spectra show relatively strong polycyclic aromatic hydrocarbon (PAH) emission features at 6.2 and 11.3\micron and a very weak silicate feature, indicative of ongoing star formation and low dust …
We have used the Caltech Submillimeter Observatory (CSO) to follow-up a sample of WISE-selected, hyperluminous galaxies, so called W1W2-dropout galaxies. This is a rare (~ 1000 all-sky) population of galaxies at high redshift (peaks at z=2-3), that are faint or undetected by WISE at 3.4 and 4.6 um, yet are clearly detected at 12 and 22 um. The optical spectra of most of these galaxies show significant AGN activity. We observed 14 high-redshift (z > 1.7) W1W2-dropout galaxies with SHARC-II at 350 to 850 um, with 9 detections; and observed 18 with Bolocam at 1.1 mm, with five detections. Warm Sp…
We present an Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 0 survey of 126 submillimeter sources from the LABOCA ECDFS Submillimeter Survey (LESS). Our 870 micron survey with ALMA (ALESS) has produced maps ~3X deeper and with a beam area ~200X smaller than the original LESS observations, doubling the current number of interferometrically-observed submillimeter sources. The high resolution of these maps allows us to resolve sources that were previously blended and accurately identify the origin of the submillimeter emission. We discuss the creation of the ALESS submillimeter galaxy…
We present high spatial resolution MIR observations for several nearby radio loud active galactic nuclei (RLAGN), which were obtained using the Gemini North and South telescopes. Of the six observed objects, we detected five in the Si-2 (8.7 microns) and Si-6 (12.3 microns) filters, of which two objects show some evidence of low level extended emission surrounding the unresolved nucleus. In Pictor A, we also obtained an image in Qs (18.3 microns) that has a flux of only half that seen in the Spitzer image, suggesting structure on arcsecond scales. We also used the Si-6 (12.3 microns) flux meas…
We quantify the active galactic nucleus (AGN) contribution to the mid-infrared (mid-IR) and the total infrared (IR, 8-1000micron) emission in a complete volume-limited sample of 53 local luminous infrared galaxies (LIRGs). We decompose the Spitzer Infrared Spectrograph (IRS) low-resolution 5-38micron spectra of the LIRGs into AGN and starburst components using clumpy torus models and star-forming galaxy templates, respectively. We find that 50% (25/50) of local LIRGs have an AGN component detected with this method. There is good agreement between these AGN detections through mid-IR spectral de…
We investigate the optical morphologies of candidate active galaxies identified at radio, X-ray, and mid-infrared wavelengths. We use the Advanced Camera for Surveys General Catalog (ACS-GC) to identify 372, 1360, and 1238 AGN host galaxies from the VLA, XMM-Newton and Spitzer Space Telescope observations of the COSMOS field, respectively. We investigate both quantitative (GALFIT) and qualitative (visual) morphologies of these AGN host galaxies, split by brightness in their selection band. We find that the radio-selected AGN are most distinct, with a very low incidence of having unresolved opt…
We report interferometric imaging of CO(J=3-2) emission toward the z=2.846 submillimeter-selected galaxy SMM J04135+10277, using the Combined Array for Research in Millimeter-wave Astronomy (CARMA). SMM J04135+10277 was previously thought to be a gas-rich, submillimeter-selected quasar, with the highest molecular gas mass among high-z quasars reported in the literature. Our maps at ~6x improved linear resolution relative to earlier observations spatially resolve the emission on ~1.7" scales, corresponding to a (lensing-corrected) source radius of ~5.2 kpc. They also reveal that the molecular g…
We study a combined sample of 264 star-forming, 51 composite, and 73 active galaxies using optical spectra from SDSS and mid-infrared (mid-IR) spectra from the Spitzer Infrared Spectrograph. We examine optical and mid-IR spectroscopic diagnostics that probe the amount of star formation and relative energetic contributions from star formation and an active galactic nucleus (AGN). Overall we find good agreement between optical and mid-IR diagnostics. Misclassifications of galaxies based on the SDSS spectra are rare despite the presence of dust obscuration. The luminosity of the [NeII] 12.8 μm em…
Advancements in infrared IR open up the possibility to spatially resolve AGN on the parsec-scale level and study the circumnuclear dust distribution, commonly referred to as the "dust torus", that is held responsible for the type 1/type 2 dichotomy of AGN. We used the mid-IR beam combiner MIDI together with the 8m telescopes at the VLTI to observe the nucleus of the Seyfert 2 galaxy NGC 424, achieving an almost complete coverage of the uv-plane accessible by the available telescope configurations. We detect extended mid-IR emission with a relatively baseline- and model-independent mid-IR half-…
We have developed an efficient Active Galactic Nucleus (AGN) selection method using 18-band Spectral Energy Distribution (SED) fitting in mid-infrared (mid-IR). AGNs are often obscured by gas and dust, and those obscured AGNs tend to be missed in optical, UV and soft X-ray observations. Mid-IR light can help us to recover them in an obscuration free way using their thermal emission. On the other hand, Star-Forming Galaxies (SFG) also have strong PAH emission features in mid-IR. Hence, establishing an accurate method to separate populations of AGN and SFG is important. However, in previous mid-…
Revealing what fraction of galaxies harbor AGN is central in understanding black hole accretion history of the Universe. However, optical and soft X-ray surveys miss the most highly obscured AGNs. Infrared (IR), instead, is more robust against absorption. Previous IR photometric surveys, however, only had 4 or 5 filters in mid-IR. Our AKARI North Ecliptic Pole (NEP) wide field sample has 18 filters in mid-IR (9 from AKARI, 4 from WISE, and 5 from Spitzer), for the first time, allowing a sophisticated mid-IR SED fitting diagnosis for a statistical number of sources (89178 over 5.4 deg$^2$). By …
The emission of warm dust dominates the mid-infrared spectra of active galactic nuclei (AGN). Only interferometric observations provide the necessary angular resolution to resolve the nuclear dust and to study its distribution and properties. The investigation of dust in AGN cores is hence one of the main science goals for the MID-infrared Interferometric instrument MIDI at the VLTI. As the first step, the feasibility of AGN observations was verified and the most promising sources for detailed studies were identified. This was carried out in a "snapshot survey" with MIDI using Guaranteed Time …
The goal of this work is to study the obscuration properties of mid-infrared (mid-IR) selected AGN. For that purpose, we use {\it{WISE}} sources in the Stripe 82-XMM area to identify mid-IR AGN candidates, applying the Assef et al. criteria. Stripe 82 has optical photometry $\approx$\,2 times deeper than any single-epoch SDSS region. XMM-Newton observations cover $\sim$26\,deg$^2$. Applying the aforementioned criteria, 1946 IR AGN are selected. $\sim 78\%$ have SDSS detection, while 1/3 of them is detected in X-rays, at a flux limit of $\rm \sim 5 \times 10^{-15}\,erg\,s^{-1}\,cm^{-2}$. Our fi…
A large fraction of active galactic nuclei (AGN) are "invisible" in extant optical surveys due to either distance or dust-obscuration. The existence of this large population of dust-obscured, infrared-bright AGN is predicted by models of galaxy - supermassive black hole coevolution and is required to explain the observed X-ray and infrared backgrounds. Recently, infrared colour-cuts with WISE have identified a portion of this missing population. However, as the host galaxy brightness relative to that of the AGN increases, it becomes increasingly difficult to differentiate between infrared emis…
The role of galaxy mergers in fueling active galactic nuclei (AGN) is still debated, owing partly to selection effects inherent to studies of the merger/AGN connection. In particular, luminous AGN are often heavily obscured in late-stage mergers. Mid-infrared (IR) color selection of dust-enshrouded AGN with, e.g., the Wide-field Infrared Survey Explorer (WISE) has uncovered large new populations of obscured AGN. However, this method is sensitive mainly to AGN that dominate emission from the host. To understand how these selection biases affect mid-IR studies of the merger/AGN connection, we si…
In this research, we provide a new, efficient method to select infrared (IR) active galatic nucleus (AGN). In the past, AGN selection in IR had been established by many studies using color-color diagrams. However, those methods have a problem in common that the number of bands is limited. The AKARI North Ecliptic Pole (NEP) survey was carried out by the AKARI Infrared Camera (IRC), which has 9 filters in mid-IR with a continuous wavelength coverage from 2 to 24$μ$m$^{-1}$. Based on the intrinsic different mid-IR features of AGN and star-forming galaxies (SFGs), we performed SED fitting to sepa…
In contrast to massive, bulge hosting galaxies, very few supermassive black holes (SMBHs) are known in either low mass, or bulgeless galaxies. Such a population could provide clues to the origins of SMBHs and to secular pathways for their growth. Using the all-sky Wide-Field Infrared Survey Explorer (WISE) survey, and bulge-to-disk decompositions from the Sloan Digital Sky Survey (SDSS) Data Release 7, we report the discovery of a population of local (z<0.3) bulgeless disk galaxies with extremely red mid-infrared colors highly suggestive of a dominant active galactic nucleus (AGN), despite hav…
Using data from the Wide-field Infrared Survey Explorer (WISE) we show that the mid infrared (MIR) colors of low-luminosity AGNs (LLAGNs) are significanlty different from those of post-asymptotic giant branch stars (PAGBs). This is due to a difference in spectral energy distribution (SEDs), the LLAGNs showing a flat component due to an AGN. Consistent with this interpretation we show that in a MIR color-color diagram the LINERs and the Seyfert~2s follow a power law with specific colors that allow to distinguish them from each other, and from star forming galaxies, according to their present le…
We present luminosity functions derived from a spectroscopic survey of AGN selected from Spitzer Space Telescope imaging surveys. Selection in the mid-infrared is significantly less affected by dust obscuration. We can thus compare the luminosity functions of the obscured and unobscured AGN in a more reliable fashion than by using optical or X-ray data alone. We find that the AGN luminosity function can be well described by a broken power-law model in which the break luminosity decreases with redshift. At high redshifts ($z>1.6$), we find significantly more AGN at a given bolometric luminosity…
We present a highly reliable and efficient mid-infrared colour-based selection technique for luminous active galactic nuclei (AGN) using the Wide-field Infrared Survey Explorer (WISE) survey. Our technique is designed to identify objects with red mid-infrared power-law spectral energy distributions. We studied the dependency of our mid-infrared selection on the AGN intrinsic luminosity and the effectiveness of our technique to uncover obscured AGN missed in X-ray surveys. To do so we used two samples of luminous AGN independently selected in hard X-ray and optical surveys. We used the largest …
We classify the spectral energy distributions (SEDs) of 431,038 sources in the 9 sq. deg Bootes field of the NOAO Deep Wide-Field Survey (NDWFS). There are up to 17 bands of data available per source, including ultraviolet (GALEX), optical (NDWFS), near-IR (NEWFIRM), and mid-infrared (IRAC/MIPS) data, as well as spectroscopic redshifts for ~20,000 objects, primarily from the AGN and Galaxy Evolution Survey (AGES). We fit galaxy, AGN, stellar, and brown dwarf templates to the observed SEDs, which yield spectral classes for the Galactic sources and photometric redshifts and galaxy/AGN luminositi…
Past studies of compact active galactic nuclei (AGNs), the dominant population at high radio frequencies, selected them using flat spectral index criteria. This biases the sample due to the steepening of AGN spectra at high radio frequencies. We improve upon this by selecting 3610 compact AGNs using their angular size information ($\sim$0.15 arcsec scale) from the Australia Telescope 20 GHz (AT20G) high-angular-resolution catalogue. We cross-match these against the Wide-field Infrared Survey Explorer All-WISE catalogue and present a catalogue with 3300 (91%) matches, 91 (3%) rejects and 219 (6…
We present results from Submillimeter Array (SMA) 860-micron sub-arcsec astrometry and multiwavelength observations of the brightest millimeter (S_1.1mm = 8.4 mJy) source, SSA22-AzTEC1, found near the core of the SSA22 protocluster that is traced by Lyαemitting galaxies at z = 3.09. We identify a 860-micron counterpart with a flux density of S_860um = 12.2 +/- 2.3 mJy and absolute positional accuracy that is better than 0.3". At the SMA position, we find radio to mid-infrared counterparts, whilst no object is found in Subaru optical and near-infrared deep images at wavelengths \le 1 micron (J …
In order to understand the interaction between the central black hole and the whole galaxy or their co-evolution history along with cosmic time, a complete census of active galactic nuclei (AGN) is crucial. However, AGNs are often missed in optical, UV and soft X-ray observations since they could be obscured by gas and dust. A mid-infrared (mid-IR) survey supported by multiwavelength data is one of the best ways to find obscured AGN activities because it suffers less from extinction. Previous large IR photometric surveys, e.g., $WISE$ and $Spitzer$, have gaps between the mid-IR filters. Theref…
I present a review of X-ray and mid-IR surveys for Compton-thick Active Galactic Nuclei (AGN). These are the most highly obscured sources having hydrogen column densities >1.5x10^24 cm-2. Key surveys in the local Universe are presented including the high energy SWIFT/BAT and INTEGRAL surveys, mid-IR and also optical surveys. Recently, deep X-ray surveys with Chandra and XMM-Newton have produced a number of candidate Compton-thick AGN at higher redshift primarily in the Chandra Deep Field South region. In addition, mid-IR surveys with Spitzer have helped to develop novel complementary technique…
We investigate the mid- (MIR) to far-infrared (FIR) properties of a nearly complete sample of local Active Galactic Nuclei (AGNs) detected in the Swift/BAT all sky hard X-ray (14-195 keV) survey, based on the cross correlation with the AKARI infrared survey catalogs complemented by those with IRAS and WISE. Out of 135 non-blazer AGNs in the Swift/BAT 9 month catalog, we obtain the MIR photometric data for 128 sources either in the 9, 12, 18, 22, and/or 25 um band. We find good correlation between their hard X-ray and MIR luminosities over 3 orders of magnitude (42< log lambda L_{lambda}(9, 18 …
Submillimeter-emitting galaxies (SMGs) are z~2 bolometrically luminous systems hosting energetic starburst and AGN activity. SMGs may represent a rapid growth phase that every massive galaxy undergoes before lying on the well-established black-hole-spheroid mass relationship in the local Universe. Here we briefly discuss our recent results from Alexander et al. (2008) where we estimated the masses of the black holes in SMGs using the black-hole virial mass estimator, finding M_BH~6x10^7 M_solar for typical SMGs. We show that the black-hole-spheroid mass ratio for SMGs at z~2 was suggestively b…
Interferometric measurements in the mid-infrared have shown that the sizes of the warm dust distributions in active galactic nuclei are consistent with their scaling with the square root of their luminosity. We carry out a more detailed analysis of this size-luminosity relation to investigate which of the general properties of the dusty tori in active galactic nuclei can be derived from this relation. We improve the accuracy of the size-luminosity relation by adding a few additional size measurements from more recent interferometric observations and compare the measured sizes to those derived …
We investigate the use of mid-infrared PAH bands, continuum and emission lines as probes of star-formation and AGN activity in a sample of 100 `normal' and local (z~0.1) galaxies. The MIR spectra were obtained with the Spitzer IRS as part of the Spitzer-SDSS-GALEX Spectroscopic Survey (SSGSS) which includes multi-wavelength photometry from the UV to the FIR and optical spectroscopy. The spectra were decomposed using PAHFIT (Smith et al. 2007), which we find to yield PAH equivalent widths (EW) up to ~30 times larger than the commonly used spline methods. Based on correlations between PAH, conti…
We present new estimates of redshift-dependent luminosity functions of IR lines detectable by SPICA/SAFARI and excited both by star formation and by AGN activity. The new estimates improve over previous work by using updated evolutionary models and dealing in a self consistent way with emission of galaxies as a whole, including both the starburst and the AGN component. New relationships between line and AGN bolometric luminosity have been derived and those between line and IR luminosities of the starburst component have been updated. These ingredients were used to work out predictions for the …
Despite the hypothesized similar face-on viewing angles, the infrared emission of type-1 AGNs has diverse spectral energy distribution (SED) shapes that deviate substantially from the well-characterized quasar templates. Motivated by the commonly-seen UV-optical obscuration and the discovery of parsec-scale mid-IR polar dust emission in some nearby AGNs, we develop semi-empirical SED libraries for reddened type-1 AGNs built on the quasar intrinsic templates, assuming low-level extinction caused by an extended distribution of large dust grains. We demonstrate that this model can reproduce the n…
