scholarly journals The XXL Survey

2018 ◽  
Vol 620 ◽  
pp. A3 ◽  
Author(s):  
Andrew Butler ◽  
Minh Huynh ◽  
Jacinta Delhaize ◽  
Vernesa Smolčić ◽  
Anna Kapińska ◽  
...  
Keyword(s):  
Radio Source ◽  
Galactic Nuclei ◽  
Spectral Energy ◽  
Radio Sources ◽  
Density Level ◽  
Energy Distributions ◽  
Sky Survey ◽  
Multiple Component ◽  
Good Agreement ◽  
Compact Array

The 2.1 GHz radio source catalogue of the 25 deg2 ultimate XMM extragalactic survey south (XXL-S) field, observed with the Australia Telescope Compact Array (ATCA), is presented. The final radio mosaic achieved a resolution of ~ 4.8″ and a median rms noise of σ ≈ 41 μJy/beam. To date, this is the largest area radio survey to reach this flux density level. A total of 6350 radio components above 5σ are included in the component catalogue, 26.4% of which are resolved. Of these components, 111 were merged together to create 48 multiple-component radio sources, resulting in a total of 6287 radio sources in the source catalogue, 25.9% of which were resolved. A survival analysis revealed that the median spectral index of the Sydney University Molonglo Sky Survey (SUMSS) 843 MHz sources in the field is α = −0.75, consistent with the values of − 0.7 to − 0.8 commonly used to characterise radio spectral energy distributions of active galactic nuclei. The 2.1 GHz and 1.4 GHz differential radio source counts are presented and compared to other 1.4 GHz radio surveys. The XXL-S source counts show good agreement with the other surveys.

scholarly journals The ATLAS 9.0 GHz survey of the extended Chandra Deep Field South: the faint 9.0 GHz radio population

2019 ◽  
Vol 491 (3) ◽  
pp. 3395-3410 ◽  
Author(s):  
M T Huynh ◽  
N Seymour ◽  
R P Norris ◽  
T Galvin
Keyword(s):  
Radio Emission ◽  
Active Galactic Nuclei ◽  
Radio Source ◽  
Galactic Nuclei ◽  
Radio Galaxies ◽  
Significant Fraction ◽  
Radio Sources ◽  
Star Forming ◽  
Source Populations ◽  
Compact Array

ABSTRACT We present a new image of the 9.0 GHz radio emission from the extended Chandra Deep Field South. A total of 181 h of integration with the Australia Telescope Compact Array has resulted in a 0.276 deg2 image with a median sensitivity of ∼20 µJy beam−1 rms, for a synthesized beam of 4.0 × 1.3 arcsec. We present a catalogue of the 9.0 GHz radio sources, identifying 70 source components and 55 individual radio galaxies. Source counts derived from this sample are consistent with those reported in the literature. The observed source counts are also generally consistent with the source counts from simulations of the faint radio population. Using the wealth of multiwavelength data available for this region, we classify the faint 9 GHz population and find that 91 per cent are radio-loud active galactic nuclei (AGNs), 7 per cent are radio-quiet AGNs, and 2 per cent are star-forming galaxies. The 9.0 GHz radio sources were matched to 5.5 and 1.4 GHz sources in the literature and we find a significant fraction of flat or inverted spectrum sources, with 36 per cent of the 9 GHz sources having $\alpha _{5.5\,\mathrm{ GHz}}^{9.0\,\mathrm{ GHz}}$ > −0.3 (for S ∝ να). This flat or inverted population is not well reproduced by current simulations of radio source populations.

scholarly journals THE SPECTRAL ENERGY DISTRIBUTIONS OF RED TWO MICRON ALL SKY SURVEY ACTIVE GALACTIC NUCLEI

2009 ◽  
Vol 692 (2) ◽  
pp. 1143-1179 ◽  
Author(s):  
Joanna Kuraszkiewicz ◽  
Belinda J. Wilkes ◽  
Gary Schmidt ◽  
Himel Ghosh ◽  
Paul S. Smith ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Sky Survey

scholarly journals Infrared colours and spectral energy distributions of hard X-ray selected obscured and Compton-thick active galactic nuclei

2020 ◽  
Vol 494 (4) ◽  
pp. 5793-5810 ◽  
Author(s):  
Ece Kilerci Eser ◽  
T Goto ◽  
T Güver ◽  
A Tuncer ◽  
O H Ataş
Keyword(s):  
Active Galactic Nuclei ◽  
Selection Criteria ◽  
Galactic Nuclei ◽  
Spectral Energy ◽  
Model Parameters ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
X Ray ◽  
Sky Survey ◽  
Combining Data

ABSTRACT We investigate the infrared colours and spectral energy distributions (SEDs) of 338 X-ray selected active galactic nuclei (AGNs) from the Swift/Burst Alert Telescope (BAT) 105-month survey catalogue, which have been detected using AKARI, in order to find new selection criteria for Compton-thick AGNs. By combining data from the Galaxy Evolution Explorer (GALEX), the Sloan Digital Sky Survey (SDSS) Data Release 14 (DR14), the Two-Micron All Sky Survey (2MASS), the Wide-field Infrared Survey Explorer (WISE), AKARI and Herschel for the first time, we perform ultraviolet (UV) to far-infrared (FIR) SEDs, fitting 158 Swift/BAT AGNs using cigale and constraining the AGN model parameters of obscured and Compton-thick AGNs. The comparison of average SEDs shows that while the mid-infrared (MIR) SEDs are similar for the three AGN populations, the optical/UV and FIR regions have differences. We measure the dust luminosity, the pure AGN luminosity and the total infrared luminosity. We examine the relationships between the measured infrared luminosities and the hard X-ray luminosity in the 14–195 keV band. We show that the average covering factor of Compton-thick AGNs is higher compared with the obscured and unobscured AGNs. We present new infrared selection criteria for Compton-thick AGNs based on MIR and FIR colours ([9–22 μm] > 3.0 and [22–90 μm] < 2.7) from WISE and AKARI. We find two known Compton-thick AGNs that are not included in the Swift/BAT sample. We conclude that MIR colours covering 9.7-μm silicate absorption and the MIR continuum could be promising new tools to identify Compton-thick AGNs.

scholarly journals The Optical/Near-IR Colours of Red Quasars

2000 ◽  
Vol 17 (1) ◽  
pp. 56-71 ◽  
Author(s):  
Paul J. Francis ◽  
Matthew T. Whiting ◽  
Rachel L. Webster
Keyword(s):  
Power Law ◽  
High Redshift ◽  
Sloan Digital Sky Survey ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Red Power ◽  
Near Ir ◽  
Sky Survey ◽  
Ir Photometry

AbstractWe present quasi-simultaneous multi-colour optical/near-IR photometry for 157 radio selected quasars, forming an unbiassed sub-sample of the Parkes Flat-Spectrum Sample. Data are also presented for 12 optically selected QSOs, drawn from the Large Bright QSO Survey. The spectral energy distributions of the radio- and optically-selected sources are quite different. The optically selected QSOs are all very similar: they have blue spectral energy distributions curving downwards at shorter wavelengths. Roughly 90% of the radio-selected quasars have roughly power-law spectral energy distributions, with slopes ranging from Fv∝v0 to Fv∝v−2. The remaining 10% have spectral energy distributions showing sharp peaks: these are radio galaxies and highly reddened quasars. Four radio sources were not detected down to magnitude limits of H ∼ 19·6. These are probably high redshift (z > 3) galaxies or quasars. We show that the colours of our red quasars lie close to the stellar locus in the optical: they will be hard to identify in surveys such as the Sloan Digital Sky Survey. If near-IR photometry is added, however, the red power-law sources can be clearly separated from the stellar locus: IR surveys such as 2MASS should be capable of finding these sources on the basis of their excess flux in the K-band.

scholarly journals The spectral energy distributions of active galactic nuclei

2019 ◽  
Vol 15 (S341) ◽  
pp. 21-25
Author(s):  
M. J. I. Brown ◽  
K. J. Duncan ◽  
H. Landt ◽  
M. Kirk ◽  
C. Ricci ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Spectral Energy ◽  
Wide Field ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Photometric Redshifts ◽  
X Ray ◽  
Ongoing Work ◽  
Prior Literature

AbstarctWe present ongoing work on the spectral energy distributions (SEDs) of active galactic nuclei (AGNs), derived from X-ray, ultraviolet, optical, infrared and radio photometry and spectroscopy. Our work is motivated by new wide-field imaging surveys that will identify vast numbers of AGNs, and by the need to benchmark AGN SED fitting codes. We have constructed 41 SEDs of individual AGNs and 80 additional SEDs that mimic Seyfert spectra. All of our SEDs span 0.09 to 30μm, while some extend into the X-ray and/or radio. We have tested the utility of the SEDs by using them to generate AGN photometric redshifts, and they outperform SEDs from the prior literature, including reduced redshift errors and flux density residuals.

scholarly journals Fitting Spectral Energy Distributions of AGN A Markov Chain Monte Carlo Approach

2013 ◽  
Vol 9 (S304) ◽  
pp. 228-229
Author(s):  
Gabriela Calistro Rivera ◽  
Elisabeta Lusso ◽  
Joseph F. Hennawi ◽  
David W. Hogg
Keyword(s):  
Monte Carlo ◽  
Markov Chain ◽  
Markov Chain Monte Carlo ◽  
Galactic Nuclei ◽  
Physical Models ◽  
Monte Carlo Algorithm ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Multiple Parameters

AbstractWe present AGNfitter: a Markov Chain Monte Carlo algorithm developed to fit the spectral energy distributions (SEDs) of active galactic nuclei (AGN) with different physical models of AGN components. This code is well suited to determine in a robust way multiple parameters and their uncertainties, which quantify the physical processes responsible for the panchromatic nature of active galaxies and quasars. We describe the technicalities of the code and test its capabilities in the context of X-ray selected obscured AGN using multiwavelength data from the XMM-COSMOS survey.

scholarly journals Clustering properties of TGSS radio sources

2019 ◽  
Vol 623 ◽  
pp. A148 ◽  
Author(s):  
Arianna Dolfi ◽  
Enzo Branchini ◽  
Maciej Bilicki ◽  
Andrés Balaguera-Antolínez ◽  
Isabella Prandoni ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Large Scale ◽  
Angular Spectrum ◽  
Radio Sources ◽  
Angular Power Spectrum ◽  
Sky Survey ◽  
Systematic Effects ◽  
Angular Correlation Function ◽  
Multiple Component ◽  
Anomalous Nature

We investigate the clustering properties of radio sources in the Alternative Data Release 1 of the TIFR GMRT Sky Survey (TGSS), focusing on large angular scales, where previous analyses have detected a large clustering signal. After appropriate data selection, the TGSS sample we use contains ∼110 000 sources selected at 150 MHz over ∼70% of the sky. The survey footprint is largely superimposed on that of the NRAO VLA Sky Survey (NVSS) with the majority of TGSS sources having a counterpart in the NVSS sample. These characteristics make TGSS suitable for large-scale clustering analyses and facilitate the comparison with the results of previous studies. In this analysis we focus on the angular power spectrum, although the angular correlation function is also computed to quantify the contribution of multiple-component radio sources. We find that on large angular scales, corresponding to multipoles 2 ≤ ℓ ≤ 30, the amplitude of the TGSS angular power spectrum is significantly larger than that of the NVSS. We do not identify any observational systematic effects that may explain this mismatch. We have produced a number of physically motivated models for the TGSS angular power spectrum and found that all of them fail to match observations, even when taking into account observational and theoretical uncertainties. The same models provide a good fit to the angular spectrum of the NVSS sources. These results confirm the anomalous nature of the TGSS large-scale power, which has no obvious physical origin and seems to indicate that unknown systematic errors are present in the TGSS dataset.

scholarly journals A Comparison of the Structures of 3CR Quasars and Blank Field Radio Sources

1982 ◽  
Vol 97 ◽  
pp. 435-436 ◽  
Author(s):  
F. N. Owen ◽  
J. J. Puschell ◽  
R. A. Laing
Keyword(s):  
Radio Source ◽  
Structural Properties ◽  
Low Frequency ◽  
Radio Sources ◽  
Blank Field ◽  
Sky Survey

The purpose of this communication is to update our knowledge of the radio structural properties of quasars and blank field radio sources (blank field ≡ any radio source without an identification on the Palomar Sky Survey prints). The quasar sample consists of all sources (25) with angular sizes greater than 10 arcsec in the list of Jodrell Bank quasars observed by Owen, Porcas and Neff (1978). The blank fields consist of 16 3CR sources also with structures >10 arcsec based on Cambridge 5 km telescope observations. The sources were selected in low-frequency surveys; their emission at ν < 1 GHz is dominated by extended components with steep spectra. Thus, both samples should be oriented randomly in space except for a slight bias to be in the plane of the sky.

scholarly journals Interferometry meets the third and fourth dimensions in galaxies

2014 ◽  
Vol 10 (S309) ◽  
pp. 1-10
Author(s):  
Virginia Trimble
Keyword(s):  
Radio Astronomy ◽  
Earth Rotation ◽  
Milky Way ◽  
Thermal Emission ◽  
Spectral Energy ◽  
Radio Sources ◽  
Energy Distributions ◽  
The Third ◽  
Grey Scale ◽  
Paraboloid Of Revolution

AbstractRadio astronomy began with one array (Jansky's) and one paraboloid of revolution (Reber's) as collecting areas and has now reached the point where a large number of facilities are arrays of paraboloids, each of which would have looked enormous to Reber in 1932. In the process, interferometry has contributed to the counting of radio sources, establishing superluminal velocities in AGN jets, mapping of sources from the bipolar cow shape on up to full grey-scale and colored images, determining spectral energy distributions requiring non-thermal emission processes, and much else. The process has not been free of competition and controversy, at least partly because it is just a little difficult to understand how earth-rotation, aperture-synthesis interferometry works. Some very important results, for instance the mapping of HI in the Milky Way to reveal spiral arms, warping, and flaring, actually came from single moderate-sized paraboloids. The entry of China into the radio astronomy community has given large (40-110 meter) paraboloids a new lease on life.

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