scholarly journals The Rapid ASKAP Continuum Survey I: Design and first results

2020 ◽  
Vol 37 ◽  
Author(s):  
D. McConnell ◽  
C. L. Hale ◽  
E. Lenc ◽  
J. K. Banfield ◽  
George Heald ◽  
...  
Keyword(s):  
Spectral Index ◽  
Spatial Resolution ◽  
Western Australia ◽  
Large Area ◽  
Square Kilometre Array ◽  
Sky Survey ◽  
Data Release ◽  
First Results ◽  
Area Survey

Abstract The Rapid ASKAP Continuum Survey (RACS) is the first large-area survey to be conducted with the full 36-antenna Australian Square Kilometre Array Pathfinder (ASKAP) telescope. RACS will provide a shallow model of the ASKAP sky that will aid the calibration of future deep ASKAP surveys. RACS will cover the whole sky visible from the ASKAP site in Western Australia and will cover the full ASKAP band of 700–1800 MHz. The RACS images are generally deeper than the existing NRAO VLA Sky Survey and Sydney University Molonglo Sky Survey radio surveys and have better spatial resolution. All RACS survey products will be public, including radio images (with $\sim$ 15 arcsec resolution) and catalogues of about three million source components with spectral index and polarisation information. In this paper, we present a description of the RACS survey and the first data release of 903 images covering the sky south of declination $+41^\circ$ made over a 288-MHz band centred at 887.5 MHz.

scholarly journals Giant radio galaxies in the LOFAR Two-metre Sky Survey

2020 ◽  
Vol 635 ◽  
pp. A5 ◽  
Author(s):  
P. Dabhade ◽  
H. J. A. Röttgering ◽  
J. Bagchi ◽  
T. W. Shimwell ◽  
M. J. Hardcastle ◽  
...  
Keyword(s):  
Spectral Index ◽  
Radio Galaxy ◽  
Radio Galaxies ◽  
Large Sample ◽  
Search Techniques ◽  
Sky Survey ◽  
Data Release ◽  
Cluster Environment ◽  
First Time

Giant radio galaxies (GRGs) are a subclass of radio galaxies, which have grown to megaparsec scales. GRGs are much rarer than normal-sized radio galaxies (< 0.7 Mpc) and the reason for their gigantic sizes is still debated. Here, we report on the biggest sample of GRGs identified to date. These objects were found in the LOFAR Two-metre Sky Survey first data release images, which cover a 424 deg2 region. Of the 239 GRGs found, 225 are new discoveries. The GRGs in our sample have sizes ranging from 0.7 Mpc to 3.5 Mpc and have redshifts (z) between 0.1 and 2.3. Seven GRGs have sizes above 2 Mpc and one has a size of ∼3.5 Mpc. The sample contains 40 GRGs hosted by spectroscopically confirmed quasars. Here, we present the search techniques employed and the resulting catalogue of the newly discovered large sample of GRGs along with their radio properties. In this paper, we also show for the first time that the spectral index of GRGs is similar to that of normal-sized radio galaxies, indicating that most of the GRG population is not dead or is not similar to a remnant-type radio galaxy. We find that 20 out of 239 GRGs in our sample are located at the centres of clusters and we present our analysis on their cluster environment and radio morphology.

scholarly journals ATLASGAL, the APEX Telescope Large Area Survey of the Galaxy

2009 ◽  
Vol 5 (H15) ◽  
pp. 780-780
Author(s):  
F. Schuller ◽  
K. M. Menten ◽  
F. Wyrowski ◽  
H. Beuther ◽  
S. Bontemps ◽  
...  
Keyword(s):  
Galactic Plane ◽  
High Mass ◽  
Current Status ◽  
Continuum Emission ◽  
Mass Star ◽  
Large Area ◽  
Submillimeter Wavelengths ◽  
The Galaxy ◽  
First Results ◽  
Area Survey

AbstractSubmillimeter continuum emission traces high molecular column densities and, thus, dense cloud regions in which new stars are forming. Surveys of the Galactic plane in such emission have the potential of delivering an unbiased view of high-mass star formation throughout the Milky Way. Here we present the scope, current status and first results of ATLASGAL, an ongoing survey of the Galactic plane using the Large APEX Bolometer Camera (LABOCA) on the Atacama Pathfinder Experiment (APEX) telescope at the Chajnantor plateau in Chile. Aimed at mapping 360 square degrees at 870 μm, with a uniform sensitivity of 50 mJy/beam, this survey will provide the first unbiased sample of cold dusty clumps in the Galaxy at submillimeter wavelengths. These will be targets for molecular line follow-up observations and high resolution studies with ALMA and the EVLA.

scholarly journals OH as a Probe of The Milky Way's Hidden Gas: First Results from SPLASH

2015 ◽  
Vol 11 (S315) ◽  
Author(s):  
J. R. Dawson ◽  
A. J. Walsh ◽  
Keyword(s):  
Ground State ◽  
Galactic Plane ◽  
Thermal Excitation ◽  
Large Area ◽  
Early Results ◽  
First Results ◽  
Area Survey ◽  
Deep Survey ◽  
Maser Sources ◽  
Future Plans

AbstractSPLASH (the Southern Parkes Large-Area Survey in Hydroxyl) is a deep survey of ground-state OH absorption and emission from the Galactic Plane, as well as an unbiased search for OH masers. Key early results include the detection of a rich and complex distribution of diffuse, optically thin OH with strongly non-thermal excitation temperatures, and the detection of numerous new maser sources. The survey aims to use OH as a probe of CO-dark H2 ISM Galactic scales, with future plans including comprehensive comparisons with CO and Hi, as well as non-LTE excitation modelling of the four ground-state lines.

scholarly journals The Sloan Digital Sky Survey Quasar Catalog: Fourteenth data release

2018 ◽  
Vol 613 ◽  
pp. A51 ◽  
Author(s):  
Isabelle Pâris ◽  
Patrick Petitjean ◽  
Éric Aubourg ◽  
Adam D. Myers ◽  
Alina Streblyanska ◽  
...  
Keyword(s):  
Emission Line ◽  
Near Infrared ◽  
Wavelength Region ◽  
Principal Component ◽  
Sloan Digital Sky Survey ◽  
Large Area ◽  
Robust Identification ◽  
Broad Absorption Line ◽  
Sky Survey ◽  
Data Release

We present the data release 14 Quasar catalog (DR14Q) from the extended Baryon Oscillation Spectroscopic Survey (eBOSS) of the Sloan Digital Sky Survey IV (SDSS-IV). This catalog includes all SDSS-IV/eBOSS objects that were spectroscopically targeted as quasar candidates and that are confirmed as quasars via a new automated procedure combined with a partial visual inspection of spectra, have luminosities Mi [z = 2] < −20.5 (in a Λ CDM cosmology with H0 = 70 km s−1 Mpc−1, Ω M =0.3, and Ω Λ = 0.7), and either display at least one emission line with a full width at half maximum larger than 500 km s−1 or, if not, have interesting/complex absorption features. The catalog also includes previously spectroscopically-confirmed quasars from SDSS-I, II, and III. The catalog contains 526 356 quasars (144 046 are new discoveries since the beginning of SDSS-IV) detected over 9376 deg2 (2044 deg2 having new spectroscopic data available) with robust identification and redshift measured by a combination of principal component eigenspectra. The catalog is estimated to have about 0.5% contamination. Redshifts are provided for the Mg II emission line. The catalog identifies 21 877 broad absorption line quasars and lists their characteristics. For each object, the catalog presents five-band (u, g, r, i, z) CCD-based photometry with typical accuracy of 0.03 mag. The catalog also contains X-ray, ultraviolet, near-infrared, and radio emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra, covering the wavelength region 3610–10 140 Å at a spectral resolution in the range 1300 < R < 2500, can be retrieved from the SDSS Science Archiver Server.

scholarly journals Blazars in the LOFAR Two-Metre Sky Survey first data release

2019 ◽  
Vol 622 ◽  
pp. A14 ◽  
Author(s):  
S. Mooney ◽  
J. Quinn ◽  
J. R. Callingham ◽  
R. Morganti ◽  
K. Duncan ◽  
...  
Keyword(s):  
Spectral Index ◽  
Low Frequency ◽  
Value Added ◽  
Low Frequencies ◽  
Sample Distribution ◽  
Sky Survey ◽  
Data Release ◽  
Frequency Regime ◽  
Source Confusion ◽  
Bl Lacs

Historically, the blazar population has been poorly understood at low frequencies because survey sensitivity and angular resolution limitations have made it difficult to identify megahertz counterparts. We used the LOFAR Two-Metre Sky Survey (LoTSS) first data release value-added catalogue (LDR1) to study blazars in the low-frequency regime with unprecedented sensitivity and resolution. We identified radio counterparts to all 98 known sources from the Third Fermi-LAT Point Source Catalogue (3FGL) or Roma-BZCAT Multi-frequency Catalogue of Blazars (5th edition) that fall within the LDR1 footprint. Only the 3FGL unidentified γ-ray sources (UGS) could not be firmly associated with an LDR1 source; this was due to source confusion. We examined the redshift and radio luminosity distributions of our sample, finding flat-spectrum radio quasars (FSRQs) to be more distant and more luminous than BL Lacertae objects (BL Lacs) on average. Blazars are known to have flat spectra in the gigahertz regime but we found this to extend down to 144 MHz, where the radio spectral index, α, of our sample is −0.17 ± 0.14. For BL Lacs, α = −0.13 ± 0.16 and for FSRQs, α = −0.15 ± 0.17. We also investigated the radio-to-γ-ray connection for the 30 γ-ray-detected sources in our sample. We find Pearson’s correlation coefficient is 0.45 (p = 0.069). This tentative correlation and the flatness of the spectral index suggest that the beamed core emission contributes to the low-frequency flux density. We compare our sample distribution with that of the full LDR1 on colour-colour diagrams, and we use this information to identify possible radio counterparts to two of the four UGS within the LDR1 field. We will refine our results as LoTSS continues.

scholarly journals White dwarfs in the UKIRT Infrared Deep Sky Survey Large Area Survey: the substellar companion fraction

2011 ◽  
Vol 416 (4) ◽  
pp. 2768-2791 ◽  
Author(s):  
P. R. Steele ◽  
M. R. Burleigh ◽  
P. D. Dobbie ◽  
R. F. Jameson ◽  
M. A. Barstow ◽  
...  
Keyword(s):  
White Dwarfs ◽  
Large Area ◽  
Sky Survey ◽  
Area Survey

scholarly journals A radio spectral index map and catalogue at 147–1400 MHz covering 80 per cent of the sky

2017 ◽  
Vol 474 (4) ◽  
pp. 5008-5022 ◽  
Author(s):  
F de Gasperin ◽  
H T Intema ◽  
D A Frail
Keyword(s):  
Galaxy Evolution ◽  
Spectral Index ◽  
Radio Galaxy ◽  
Galactic Plane ◽  
Cosmic Radio ◽  
Large Area ◽  
Sky Survey ◽  
Combining Data ◽  
Extended Sources ◽  
Lower Limits

Abstract The radio spectral index is a powerful probe for classifying cosmic radio sources and understanding the origin of the radio emission. Combining data at 147 MHz and 1.4 GHz from the TIFR GMRT Sky Survey (TGSS) and the NRAO VLA Sky Survey (NVSS), we produced a large-area radio spectral index map of ∼80 per cent of the sky (Dec. &gt; − 40 deg), as well as a radio spectral index catalogue containing 1396 515 sources, of which 503 647 are not upper or lower limits. Almost every TGSS source has a detected counterpart, while this is true only for 36 per cent of NVSS sources. We released both the map and the catalogue to the astronomical community. The catalogue is analysed to discover systematic behaviours in the cosmic radio population. We find a differential spectral behaviour between faint and bright sources as well as between compact and extended sources. These trends are explained in terms of radio galaxy evolution. We also confirm earlier reports of an excess of steep-spectrum sources along the galactic plane. This corresponds to 86 compact and steep-spectrum source in excess compared to expectations. The properties of this excess are consistent with normal non-recycled pulsars, which may have been missed by pulsation searches due to larger than average scattering along the line of sight.

scholarly journals Constraints on running of non-Gaussianity from large-scale structure probes

2019 ◽  
Vol 491 (1) ◽  
pp. L61-L65 ◽  
Author(s):  
Ji-Ping Dai ◽  
Jun-Qing Xia
Keyword(s):  
Spectral Index ◽  
Large Scale ◽  
Cross Correlation ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Sloan Digital Sky Survey ◽  
Microwave Background ◽  
Sky Survey ◽  
Data Release ◽  
Clustering Data

ABSTRACT In this letter, we present constraints on the scale-dependent ‘local’-type primordial non-Gaussianity, which is described by non-Gaussianity’s spectral index nNG, from the NRAO VLA Sky Survey and the quasar catalogue of the Sloan Digital Sky Survey (SDSS) Data Release 6, together with the SDSS Data Release 12 photo-z sample. Here, we use the autocorrelation analyses of these three probes and their cross-correlation analyses with the cosmic microwave background (CMB) temperature map, and obtain the tight constraint on the spectral index: $n_{\rm NG}=0.2 ^{+0.7}_{-1.0}$ ($1\sigma$ C.L.), which shows the first competitive constraint on the running of non-Gaussianity from current large-scale structure clustering data. Furthermore, we also perform the forecast calculations and improve the limit of nNG using the future Euclid mission, and obtain the standard deviation at a 68 per cent confidence level: ΔnNG = 1.74 when considering the fiducial value fNL = 3, which provides the complementary constraining power to those from the CMB bispectrum information.

scholarly journals X-ray Morphology of Clusters of Galaxies

1992 ◽  
Vol 9 ◽  
pp. 205-209
Author(s):  
H. Böhringer ◽  
R.A. Schwarz ◽  
U.G. Briel ◽  
H. Ebeling ◽  
W. Voges
Keyword(s):  
Physical Properties ◽  
Galaxy Clusters ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Morphological Structure ◽  
Clusters Of Galaxies ◽  
X Ray ◽  
Sky Survey ◽  
First Results

AbstractThe ROSAT observatory with its high spatial resolution X-ray telescope is an ideal instrument for the study of clusters of galaxies. In the first part of the mission an All Sky X-ray Survey was conducted with ROSAT. Here we present first results of observations of Virgo, Perseus and some other clusters of galaxies from the All Sky Survey. These data illustrate the capabilities of the ROSAT observatory for studies of the morphological structure and physical properties of galaxy clusters.

scholarly journals Investigation of the double-lobed sources of the Cygnus constellation core

2021 ◽  
Vol 38 ◽  
Author(s):  
J. Saponara ◽  
P. Benaglia ◽  
I. Andruchow ◽  
C. H. Ishwara-Chandra ◽  
H. T. Intema
Keyword(s):  
Spectral Index ◽  
Angular Resolution ◽  
Galactic Plane ◽  
Central Nucleus ◽  
Electromagnetic Spectrum ◽  
Large Area ◽  
X Ray ◽  
First Results ◽  
First Time ◽  
Better Than

Abstract We present a collection of double-lobed sources towards a $20\,\mathrm{deg}^2$ area of the Cygnus region at the northern sky, observed at 325 and 610 MHz with the Giant Metrewave Radio Telescope. The 10 $^{\prime\prime}$ resolution achieved at 325 MHz is 5.5 times better than previous studies, while at 610 MHz, these are the first results ever of such a large area, mapped with 6 $^{\prime\prime}$ angular resolution. After a thorough visual inspection of the images at the two bands, we found 43 double-lobed source candidates, proposed as such due to the presence of 2 bright peaks, within a few arcminutes apart, joined by a bridge or a central nucleus. All but two are presented here as a double-lobed candidates for the first time. Thirty nine of the candidates were covered at both bands, and we provide the spectral index information for them. We have searched for positional coincidences between the detected sources/components and other objects from the literature, along the electromagnetic spectrum. Twenty-three candidates possess radio counterpart(s), 12 present infrared counterparts, and 1 showed an overlapping X-ray source. We analysed each candidate considering morphology, counterparts, and spectral indices. Out of the 43 candidates, 37 show characteristics compatible with an extragalactic nature, 2 of probably Galactic origin, 3 remain as dubious cases, though with feature(s) compatible with an extragalactic nature, and the remaining one, evidence of physically unrelated components. The median spectral index of the 40 putative extragalactic sources is $-1.0$ . Their celestial surface density at 610 MHz resulted in $1.9\,\mathrm{per\ deg}^2$ , across a region lying at the Galactic plane.

Sign in / Sign up

Export Citation Format

Share Document