The Australia Telescope Large Area Survey (ATLAS) is the widest deep radio survey ever attempted, covering 7 square degrees of sky in two separate fields, with extensive multi-wavelength data. The primary aim of this research is to investigate all possible discriminants between active galactic nuclei (AGN) and star-formation (SF) in ATLAS, with the goal of comparing discriminants, identifying the strengths and weaknesses, and establishing an optimum technique given the available data. Ultimately, all possible discriminants will be utilized, including optical/infrared SEDs, spectroscopic line widths, optical line ratios, radio spectral indices, variability, morphology, polarization and the radio/FIR correlation. A preliminary investigation using only the available spectroscopic data in ATLAS is ongoing. Results from this investigation are presented, exploring the proportion of AGN/SF galaxies as a function of radio flux density down to 150 microJy. Three faint GPS candidates are also presented, as a preliminary result from ATLAS.
We present an optical spectroscopic atlas at intermediate resolution (8-15A) for 123 core-dominated radio-loud active galactic nuclei with relativistic jets, drawn from the MOJAVE/2cm sample at 15GHz. It is the first time that spectroscopic and photometric parameters for a large sample of such type of AGN are presented. The atlas includes spectral parameters for the emission lines Hb, [O III] 5007, Mg II 2798 and/or C IV 1549 and corresponding data for the continuum, as well as the luminosities and equivalent widths of the Fe II UV/optical. It also contains the homogeneous photometric informat…
We present the first subarcsecond-resolution mid-infrared (MIR) atlas of local active galactic nuclei (AGN). Our atlas contains 253 AGN with a median redshift of z=0.016, and includes all publicly available MIR imaging performed to date with ground-based 8-m class telescopes, a total of 895 independent measurements. Of these, more than 60% are published here for the first time. We detect extended nuclear emission in at least 21% of the objects, while another 19% appear clearly point-like, and the remaining objects cannot be constrained. Where present, elongated nuclear emission aligns with the…
We examine the relationship between star formation and AGN activity by constructing matched samples of local ($0<z<0.6$) radio-loud and radio-quiet AGN in the $\textit{Herschel}$-ATLAS fields. Radio-loud AGN are classified as high-excitation and low-excitation radio galaxies (HERGs, LERGs) using their emission lines and $\textit{WISE}$ 22-$μ$m luminosity. AGN accretion and jet powers in these active galaxies are traced by [OIII] emission-line and radio luminosity, respectively. Star formation rates (SFRs) and specific star formation rates (SSFRs) were derived using $\textit{Herschel}$ 250-$μ$m…
We discuss the possible origin of the double-peaked profiles recently observed in Lyman-Alpha Emitters (LAEs) at the epoch of reionization ($z \gtrsim 6.5$) from obscured active galactic nuclei (AGN). Combining the extent of the Lyman-$α$ near-zones estimated from the blue peak velocity offset in these galaxies, with the ionizing emissivity of quasars at $z \gtrsim 6$, we forecast the intrinsic UV and X-ray luminosities of the AGN needed to give rise to their double-peaked profiles. We also estimate the extent of the obscuration of the AGN by comparing their luminosities to those of similar qu…
We present the largest mid-infrared atlas of active galactic nuclei at sub-arcsecond spatial scales containing 249 objects. It comprises all ground-based HR MIR observations performed to date. This catalog includes a large number of new observations. The photometry in multiple filters allows for characterizing the properties of the dust emission for most objects. Because of its size and characteristics, this sample is very well-suited for AGN unification studies. In particular, we discuss the enlarged MIR--X-ray correlation which extends over six orders of magnitude in luminosity and potential…
ATLAS (Australia Telescope Large Area Survey) is a wide deep radio survey which is distinguished by its comprehensive multi-wavelength approach. ATLAS is creating a large dataset of radio-selected galaxies for studying the evolution and inter-relationship of star-forming and active galaxies. Although the project is far from complete, we are already starting to answer some of these questions, and have stumbled across three surprises along the way: * FRI/FRII radio-loud AGN embedded within spiral galaxies, * radio-bright AGN which are unexpectedly faint in the infrared, and which may be at high …
The Australia Telescope Large Area Survey (ATLAS) has surveyed seven square degrees of sky around the Chandra Deep Field South (CDFS) and the European Large Area ISO Survey - South 1 (ELAIS-S1) fields at 1.4 GHz. ATLAS aims to reach a uniform sensitivity of $10 μ$Jy beam$^{-1}$ rms over the entire region with data release 1 currently reaching $\sim30 μ$Jy beam$^{-1}$ rms. Here we present 466 new spectroscopic redshifts for radio sources in ATLAS as part of our optical follow-up program. Of the 466 radio sources with new spectroscopic redshifts, 142 have star-forming optical spectra, 282 show e…
We use the Herschel-ATLAS science demonstration data to investigate the star-formation properties of radio-selected galaxies in the GAMA-9h field as a function of radio luminosity and redshift. Radio selection at the lowest radio luminosities, as expected, selects mostly starburst galaxies. At higher radio luminosities, where the population is dominated by AGN, we find that some individual objects are associated with high far-infrared luminosities. However, the far-infrared properties of the radio-loud population are statistically indistinguishable from those of a comparison population of radi…
Automatically distinguishing Rubin transients from AGN using variability metrics
Queen’s University Belfast（贝尔法斯特女王大学）；University of Southampton（南安普顿大学）；University of Birmingham（伯明翰大学）；University of Portsmouth（朴茨茅斯大学）；Leiden University（莱顿大学）；University of Manchester（曼彻斯特大学）
We present an atlas of Spitzer/IRS high resolution (R~600) 10-37um spectra for 24 well known starburst galaxies. The spectra are dominated by fine-structure lines, molecular hydrogen lines, and emission bands of polycyclic aromatic hydrocarbons. Six out of the eight objects with a known AGN component show emission of the high excitation [NeV] line. This line is also seen in one other object (NGC4194) with, a priori, no known AGN component. In addition to strong polycyclic aromatic hydrocarbon emission features in this wavelength range (11.3, 12.7, 16.4um), the spectra reveal other weak hydroca…
We present Herschel-SPIRE Fourier Transform Spectrometer (FTS) and radio follow-up observations of two Herschel-ATLAS (H-ATLAS) detected strongly lensed distant galaxies. In one of the targeted galaxies H-ATLAS J090311.6+003906 (SDP.81) we detect [OIII] 88\mum and [CII] 158\mum lines at a signal-to-noise ratio of ~5. We do not have any positive line identification in the other fainter target H-ATLAS J091305.0-005343 (SDP.130). Currently SDP.81 is the faintest sub-mm galaxy with positive line detections with the FTS, with continuum flux just below 200 mJy in the 200-600 \mum wavelength range. T…
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…
Infrared-Faint Radio Sources (IFRSs) are a class of radio objects found in the Australia Telescope Large Area Survey (ATLAS) which have no observable mid-infrared counterpart in the Spitzer Wide-area Infrared Extragalactic (SWIRE) survey. The extended Chandra Deep Field South now has even deeper Spitzer imaging (3.6 to 70 micron) from a number of Legacy surveys. We report the detections of two IFRS sources in IRAC images. The non-detection of two other IFRSs allows us to constrain the source type. Detailed modeling of the SED of these objects shows that they are consistent with high redshift (…
The Herschel survey, H-ATLAS, with its large areal coverage, has recently discovered a number of bright, strongly lensed high-z submillimeter galaxies. The strong magnification makes it possible to study molecular species other than CO, which are otherwise difficult to observe in high-z galaxies. Among the lensed galaxies already identified by H-ATLAS, the source J090302.9-014127B (SDP.17b) at z = 2.305 is remarkable due to its excitation conditions and a tentative detection of the H2O 202-111 emission line (Lupu et al. 2010). We report observations of this line in SDP.17b using the IRAM inter…
Continuum Reverberation in Bright Quasars Using NASA/ATLAS
Research School of Astronomy and Astrophysics, Australian National University（澳大利亚国立大学天文与天体物理研究学院）；Centre for Gravitational Astrophysics (CGA), Australian National University（澳大利亚国立大学引力天体物理学中心）；Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast（贝尔法斯特女王大学数学与物理学院天体物理研究中心）；Research Center for Space and Cosmic Evolution, Ehime University（爱媛大学宇宙演化研究中心）；University of Belgrade-Faculty of Mathematics, Department of Astronomy（贝尔格莱德大学数学系天文学系）；Millennium Institute of Astrophysics (MAS)（天体物理学千年研究所）；Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile（智利天主教Pontificia大学物理学院天体物理研究所）
Star forming galaxies are thought to dominate the sub-mJy radio population, but recent work has shown that low luminosity AGN can still make a significant contribution to the faint radio source population. Spectral indices are an important tool for understanding the emission mechanism of the faint radio sources. We have observed the extended Chandra Deep Field South at 5.5 GHz using a mosaic of 42 pointings with the Australia Telescope Compact Array (ATCA). Our image reaches an almost uniform sensitivity of ~12 microJy rms over 0.25 deg^2 with a restoring beam of 4.9 x 2.0 arcsec, making it on…
We describe a 325-MHz survey, undertaken with the Giant Metrewave Radio Telescope (GMRT), which covers a large part of the three equatorial fields at 9, 12 and 14.5 h of right ascension from the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS) in the area also covered by the Galaxy And Mass Assembly survey (GAMA). The full dataset, after some observed pointings were removed during the data reduction process, comprises 212 GMRT pointings covering ~90 deg^2 of sky. We have imaged and catalogued the data using a pipeline that automates the process of flagging, calibration, self-calibr…
We have used data from the Herschel-ATLAS at 250, 350 and 500 μm to determine the far-infrared (FIR) properties of 50 Broad Absorption Line Quasars (BAL QSOs). Our sample contains 49 high-ionization BAL QSOs (HiBALs) and 1 low-ionization BAL QSO (LoBAL) which are compared against a sample of 329 non-BAL QSOs. These samples are matched over the redshift range 1.5 \leq z < 2.3 and in absolute i-band magnitude over the range -28 \leq M_{i} \leq -24. Of these, 3 BAL QSOs (HiBALs) and 27 non-BAL QSOs are detected at the > 5 sigma level. We calculate star-formation rates (SFR) for our individually d…
We have constructed a sample of radio-loud objects with optical spectroscopy from the Galaxy and Mass Assembly (GAMA) project over the Herschel-ATLAS Phase 1 fields. Classifying the radio sources in terms of their optical spectra, we find that strong-emission-line sources (`high-excitation radio galaxies') have, on average, a factor ~4 higher 250-micron Herschel luminosity than weak-line (`low-excitation') radio galaxies and are also more luminous than magnitude-matched radio-quiet galaxies at the same redshift. Using all five H-ATLAS bands, we show that this difference in luminosity between t…
We describe the infrared properties of sources detected over ~36 deg^2 of sky in the GAMA 15-hr equatorial field, using data from both the Herschel Astrophysical Terahertz Large-Area Survey (H-ATLAS) and Wide-field Infrared Survey (WISE). With 5-sigma point-source depths of 34 and 0.048 mJy at 250 micron and 3.4 micron, respectively, we are able to identify 50.6% of the H-ATLAS sources in the WISE survey, corresponding to a surface density of ~630 deg^{-2}. Approximately two-thirds of these sources have measured spectroscopic or optical/near-IR photometric redshifts of z<1. For sources with sp…
We report the detection of a significant excess in the surface density of far-infrared sources from the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS) within ~1 Mpc of the centres of 66 optically-selected clusters of galaxies in the SDSS with <z>~0.25. From the analysis of the multiwavelength properties of their counterparts we conclude that the far-infrared emission is associated with dust-obscured star formation and/or active galactic nuclei within galaxies in the clusters themselves. The excess reaches a maximum at a radius of ~0.8 Mpc, where we find 1.0\pm0.3 S_250um>34 mJy s…
Recent observations of AGN activity in massive galaxies (log Mstar / Msun > 10.4) show that: 1) at z < 1, AGN-hosting galaxies do not show enhanced merger signatures compared to normal galaxies, 2) also at z < 1, most AGNs are hosted by quiescent galaxies; and 3) at z > 1, percentage of AGNs in star forming galaxies increases and becomes comparable to AGN percentage in quiescent galaxies at z ~ 2. How can major mergers explain AGN activity in massive quiescent galaxies which have no merger features and no star formation to indicate recent galaxy merger? By matching merger events in a cosmologi…
We produce an atlas of homogeneously reduced and calibrated low resolution IRS spectra of the nuclear regions of nearby early-type galaxies (i.e. Es and S0s, ETGs), in order to build a reference sample in the mid-infrared window. From the Spitzer Heritage Archive we extract ETGs in the "Revised Shapley-Ames Catalog of Bright Galaxies" having an IRS SL and/or LL spectrum. We recover 91 spectra out of 363 galaxies classified as ETGs in the catalog: 56 E (E0-E6), 8 mixed E/S0+S0/E, 27 S0 (both normal and barred - SB0) plus mixed types SB0/Sa+SB0/SBa. For each galaxy, we provide the fully reduced …
We perform a stacking analysis of H-ATLAS data in order to obtain isothermal dust temperatures and rest-frame luminosities at 250um (L250), for 1599 radio sources over the H-ATLAS P1 GAMA area. The radio sample is generated using a combination of NVSS data and K-band UKIDSS-LAS data, over 0.01<z<0.8. The FIR properties of the sample are investigated as a function of L_1.4 GHz, z, projected radio-source size and radio spectral index. In order to search for stellar-mass dependent relations, we split the parent sample into those sources which are below and above 1.5 L_{K}^{*}. Correcting for stel…
We present two large, nearby (0.013$\le$z$\le$0.06) samples of Early-Type Galaxies (ETGs): a visually classified sample of 220 ETGs, created using source-matched data from the Galaxy and Mass Assembly (GAMA) database with FIR/sub-mm detections from $Herschel$-ATLAS; and a visually classified sample of 551 ETGs which are undetected with $Herschel$-ATLAS. Active galactic nuclei (AGN) are removed from our samples using optical emission line diagnostics. These samples are scrutinised to determine characteristics of sub-mm detected versus undetected ETGs. We find similarities in the stellar mass di…
We use data from the Herschel-ATLAS to investigate the evolution of the far-infrared--radio correlation over the redshift range 0<z<0.5. Using the total far-infrared luminosity of all >5sigma sources in the Herschel-ATLAS Science Demonstration Field and cross-matching these data with radio data from the Faint Images of the Radio Sky at Twenty-Centimetres (FIRST) survey and the NRAO VLA Northern Sky Survey (NVSS), we obtain 104 radio counterparts to the Herschel sources. With these data we find no evidence for evolution in the far-infrared--radio correlation over the redshift range 0<z<0.5, whe…
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…
Recoiling supermassive black holes (SMBHs) are considered one plausible physical mechanism to explain high velocity shifts between narrow and broad emission lines sometimes observed in quasar spectra. If the sphere of influence of the recoiling SMBH is such that only the accretion disc is bound, the dusty torus would be left behind, hence the SED should then present distinctive features (i.e. a mid-infrared deficit). Here we present results from fitting the Spectral Energy Distributions (SEDs) of 32 Type-1 AGN with high velocity shifts between broad and narrow lines. The aim is to find peculia…
This paper is the second in a pair of articles presenting data release 1 (DR1) of the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS), the largest single open-time key project carried out with the Herschel Space Observatory. The H-ATLAS is a wide-area imaging survey carried out in five photometric bands at 100, 160, 250, 350 and 500$μ$m covering a total area of 600deg$^2$. In this paper we describe the identification of optical counterparts to submillimetre sources in DR1, comprising an area of 161 deg$^2$ over three equatorial fields of roughly 12$^\circ$x4.5$^\circ$ centred at 9…
Recent models show that TP-AGB stars should dominate the NIR spectra of populations 0.3 to 2 Gyr old, leaving unique signatures that can be used to detect young/intermediate stellar population in galaxies. However, no homogeneous database of star-forming galaxies is available in the NIR to fully explore these results. With this in mind, we study the NIR spectra of a sample of 23 HII and starburst galaxies, aimed at characterizing the most prominent spectral features and continuum shape in the 0.8-2.4 micron region of these objects. Spectral indices are derived for the relevant absorption lines…
Context. The Australia Telescope Large Area Survey (ATLAS) aims to image a 7 deg2 region centred on the European Large Area ISO Survey - South 1 (ELAIS-S1) field and the Chandra Deep Field South (CDF-S) at 1.4 GHz with high sensitivity (up to ~10 \muJy) to study the evolution of star-forming galaxies (SFGs) and Active Galactic Nuclei (AGN) over a wide range of cosmic time. Aims. We present here ancillary radio observations at a frequency of 2.3 GHz obtained with the Australia Telescope Compact Array (ATCA). The main goal of this is to study the radio spectra of an unprecedented large sample of…
It is known that the IR and X-ray luminosities of Active Galactic Nuclei (AGN) are correlated with L_{IR} ~ L_{X}. Moreover, the IR flux ratio between the 5.8 and 3.6 μm bands is a good distinguishing characteristic of AGN or AGN-like behaviour. On the other hand, Galactic X-ray binaries (GXB) are under-luminous in the IR with L_{IR} << L_{X}. Since Ultra-luminous X-ray sources in nearby galaxies may be an intermediate class between AGN and GXB, it is interesting to study if their IR properties indicate which kind of objects they resemble. We use Spitzer IRAC images to identify mid-IR counterp…
We explore the behaviour of [CII]-157.74um forbidden fine-structure line observed in a sample of 28 galaxies selected from ~50deg^2 of the H-ATLAS survey. The sample is restricted to galaxies with flux densities higher than S_160um>150mJy and optical spectra from the GAMA survey at 0.02<z<0.2. Far-IR spectra centred on this redshifted line were taken with the PACS instrument on-board the Herschel Space Observatory. The galaxies span 10<log(L_IR/Lo)<12 (where L_IR=L_IR[8-1000um]) and 7.3<log(L_[CII]/Lo)<9.3, covering a variety of optical galaxy morphologies. The sample exhibits the so-called [C…
