- ID:
- ivo://CDS.VizieR/J/MNRAS/468/196
- Title:
- The invisible AGN catalogue
- Short Name:
- J/MNRAS/468/196
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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 (IR)-bright AGN is predicted by models of galaxy-supermassive black hole coevolution and is required to explain the observed X-ray and IR backgrounds. Recently, IR colour cuts with Wide-field Infrared Survey Explorer 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 IR emission originating from the AGN and from its host galaxy. As a solution, we have developed a new method to select obscured AGN using their 20-cm continuum emission to identify the objects as AGN. We created the resulting invisible AGN catalogue by selecting objects that are detected in AllWISE (mid-IR) and FIRST (20 cm), but are not detected in SDSS (optical) or 2MASS (near-IR), producing a final catalogue of 46 258 objects. 30 per cent of the objects are selected by existing selection methods, while the remaining 70 per cent represent a potential previously unidentified population of candidate AGN that are missed by mid-IR colour cuts. Additionally, by relying on a radio continuum detection, this technique is efficient at detecting radio-loud AGN at z>=0.29, regardless of their level of dust obscuration or their host galaxy's relative brightness.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/900/55
- Title:
- The SPT-SZ catalog at 95, 150, and 220GHz
- Short Name:
- J/ApJ/900/55
- Date:
- 21 Mar 2022 09:29:14
- Publisher:
- CDS
- Description:
- We present a catalog of emissive point sources detected in the SPT-SZ survey, a contiguous 2530 square degree area surveyed with the South Pole Telescope (SPT) from 2008-2011 in three bands centered at 95, 150, and 220GHz. The catalog contains 4845 sources measured at a significance of 4.5{sigma} or greater in at least one band, corresponding to detections above approximately 9.8, 5.8, and 20.4mJy in 95, 150, and 220GHz, respectively. The spectral behavior in the SPT bands is used for source classification into two populations based on the underlying physical mechanisms of compact, emissive sources that are bright at millimeter wavelengths: synchrotron radiation from active galactic nuclei and thermal emission from dust. The latter population includes a component of high-redshift sources often referred to as submillimeter galaxies (SMGs). In the relatively bright flux ranges probed by the survey, these sources are expected to be magnified by strong gravitational lensing. The survey also contains sources consistent with protoclusters, groups of dusty galaxies at high redshift undergoing collapse. We cross-match the SPT-SZ catalog with external catalogs at radio, infrared, and X-ray wavelengths and identify available redshift information. The catalog splits into 3980 synchrotron-dominated and 865 dust-dominated sources, and we determine a list of 506 SMGs. Ten sources in the catalog are identified as stars. We calculate number counts for the full catalog, and synchrotron and dusty components, using a bootstrap method and compare our measured counts with models. This paper represents the third and final catalog of point sources in the SPT-SZ survey.
- ID:
- ivo://CDS.VizieR/J/A+A/563/A137
- Title:
- THz spectrum of methylamine
- Short Name:
- J/A+A/563/A137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Methylamine (CH_3_NH_2_) is the simplest primary alkylamine and has been detected in the interstellar medium. The molecule is relatively light, with the 50K Boltzmann peak appearing near 800GHz. However, reliable predictions for its rotational spectrum are available only up to 500GHz. Spectroscopic analyses have been complicated by the two large amplitude motions: internal rotation of the methyl top and inversion of the amino group. The aims is to provide reliable predictions of the methylamine ground state rotational spectrum above 500GHz we studied its rotational spectrum in the frequency range from 500 to 2650GHz. The spectra of methylamine were recorded using the spectrometers based on Schottky diode frequency multiplication chains in the Lille laboratory (500-945GHz) and in JPL (1060-2660GHz). The analysis of the rotational spectrum of methylamine in the ground vibrational state was performed on the basis of the group-theoretical high barrier tunneling Hamiltonian developed for methylamine by Ohashi and Hougen. In the recorded spectra we have assigned 1849 new rotational transitions of methylamine. They were fitted together with previously published data to a Hamiltonian model that uses 76 parameters with overall weighted rms deviation of 0.87. On the basis of the new spectroscopic results, predictions of transition frequencies in the frequency range up to 3THz with J<50 and Ka<20 are presented.
- ID:
- ivo://CDS.VizieR/J/ApJ/712/925
- Title:
- Transition circumstellar disks in Ophiuchus
- Short Name:
- J/ApJ/712/925
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained millimeter-wavelength photometry, high-resolution optical spectroscopy, and adaptive optics near-infrared imaging for a sample of 26 Spitzer-selected transition circumstellar disks. All of our targets are located in the Ophiuchus molecular cloud (d~125pc) and have spectral energy distributions (SEDs) suggesting the presence of inner opacity holes. We use these ground-based data to estimate the disk mass, multiplicity, and accretion rate for each object in our sample in order to investigate the mechanisms potentially responsible for their inner holes. We find that transition disks are a heterogeneous group of objects, with disk masses ranging from <0.6 to 40M_JUP_ and accretion rates ranging from <10^-11^ to 10^-7^M_{sun}_/yr, but most tend to have much lower masses and accretion rates than "full disks" (i.e., disks without opacity holes). Eight of our targets have stellar companions: six of them are binaries and the other two are triple systems. In four cases, the stellar companions are close enough to suspect they are responsible for the inferred inner holes. We find that nine of our 26 targets have low disk mass (<2.5M_JUP_) and negligible accretion (<10^-11^M_{sun}_/yr), and are thus consistent with photoevaporating (or photoevaporated) disks. Four of these nine non-accreting objects have fractional disk luminosities <10^-3^ and could already be in a debris disk stage. Seventeen of our transition disks are accreting. Thirteen of these accreting objects are consistent with grain growth. The remaining four accreting objects have SEDs suggesting the presence of sharp inner holes, and thus are excellent candidates for harboring giant planets.
- ID:
- ivo://CDS.VizieR/J/ApJ/749/79
- Title:
- Transition disks. II. Southern MoC
- Short Name:
- J/ApJ/749/79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Transition disk objects are pre-main-sequence stars with little or no near-IR excess and significant far-IR excess, implying inner opacity holes in their disks. Here we present a multifrequency study of transition disk candidates located in Lupus I, III, IV, V, VI, Corona Australis, and Scorpius. Complementing the information provided by Spitzer with adaptive optics (AO) imaging (NaCo, VLT), submillimeter photometry (APEX), and echelle spectroscopy (Magellan, Du Pont Telescopes), we estimate the multiplicity, disk mass, and accretion rate for each object in our sample in order to identify the mechanism potentially responsible for its inner hole. We find that our transition disks show a rich diversity in their spectral energy distribution morphology, have disk masses ranging from <~1 to 10M_JUP_, and accretion rates ranging from <~10^-11^ to 10^-7.7^M_{sun}_/yr. Of the 17 bona fide transition disks in our sample, three, nine, three, and two objects are consistent with giant planet formation, grain growth, photoevaporation, and debris disks, respectively. Two disks could be circumbinary, which offers tidal truncation as an alternative origin of the inner hole.
- ID:
- ivo://CDS.VizieR/J/A+A/592/A126
- Title:
- Transition disk survey
- Short Name:
- J/A+A/592/A126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Understanding disk evolution and dissipation is essential for studies of planet formation. Transition disks, i.e., disks with large dust cavities and gaps, are promising candidates of active evolution. About two dozen candidates, selected by their Spectral Energy Distribution (SED), have been confirmed to have dust cavities through millimeter interferometric imaging, but this sample is biased toward the brightest disks. The Spitzer surveys of nearby low-mass star-forming regions have resulted in more than 4000 young stellar objects (YSOs). Using color criteria, we selected a sample of ~150 candidates and an additional 40 candidates and known transition disks from the literature. The Spitzer data were complemented by new observations at longer wavelengths, including new JCMT and APEX submillimeter photometry, and WISE and Herschel-PACS mid- and far-infrared photometry. Furthermore, optical spectroscopy was obtained and stellar types were derived for 85% of the sample, including information from the literature. The SEDs were fit to a grid of RADMC-3D disk models with a limited number of parameters: disk mass, inner disk mass, scale height and flaring, and disk cavity radius, where the latter is the main parameter of interest. About 72% of our targets possibly have dust cavities based on the SED. The derived cavity sizes are consistent with imaging/modeling results in the literature, where available. Trends are found with the L_disk_ over L_*_ ratio and stellar mass and a possible connection with exoplanet orbital radii. A comparison with a previous study where color observables are used (Cieza et al., 2010, Cat. J/ApJ/712/925) reveals large overlap between their category of planet-forming disks and our transition disks with cavities. A large number of the new transition disk candidates are suitable for follow-up observations with ALMA.
- ID:
- ivo://CDS.VizieR/J/A+A/518/A25
- Title:
- Transits of HD40307b by Spitzer
- Short Name:
- J/A+A/518/A25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used Spitzer and its IRAC camera to search for the transit of the super-Earth HD 40307b. The hypothesis that the planet transits could not be firmly discarded from our first photometric monitoring of a transit window because of the uncertainty coming from the modeling of the photometric baseline. To obtain a firm result, two more transit windows were observed and a global Bayesian analysis of the three IRAC time series and the HARPS radial velocities was performed. Unfortunately, the hypothesis that the planet transited during the observed phase window is firmly rejected, while the probability that the planet does transit but that the eclipse was missed by our observations is nearly negligible (0.26%)
- ID:
- ivo://CDS.VizieR/J/MNRAS/396/964
- Title:
- T Tauri in and around bright-rimmed clouds
- Short Name:
- J/MNRAS/396/964
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of this paper is to quantitatively testify the 'small-scale sequential star formation' hypothesis in and around bright-rimmed clouds (BRCs). As a continuation of the recent attempt by Ogura et al. (2007PASJ...59..199O), we have carried out BVIc photometry of four more BRC aggregates along with deeper re-observations of two previously observed BRCs. Again, quantitative age gradients are found in almost all the BRCs studied in the present work. Archival Spitzer/Infrared Array Camera data also support this result.
- ID:
- ivo://CDS.VizieR/J/A+A/525/A47
- Title:
- U-band photometry in sigma Orionis region
- Short Name:
- J/A+A/525/A47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents the results of an U band survey with FORS1/VLT of a large area in the sigma Ori star-forming region. We combine the U-band photometry with literature data to compute accretion luminosity and mass accretion rates from the U-band excess emission for all objects (187) detected by Spitzer in the FORS1 field and classified by Hernandez et al. (2007, Cat. J/ApJ/662/1067) as likely members of the cluster.
- ID:
- ivo://CDS.VizieR/J/A+A/561/A49
- Title:
- 867um image of SBS 0335-052 with ALMA
- Short Name:
- J/A+A/561/A49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 0 Band 7 observations of an extremely metal-poor dwarf starburst galaxy in the Local Universe, SBS 0335-052 (12+log(O/H)~7.2). With these observations, dust is detected at 870um (ALMA Band 7), but 87% of the flux in this band is due to free-free emission from the starburst.
