Journal articles: 'NVSS radio source catalogue'

1

Paronyan, Gurgen M., Hayk V. Abrahamyan, Gohar S. Harutyunyan, and Areg M. Mickaelian. "The ROSAT/NVSS AGN sample." Proceedings of the International Astronomical Union 9, S304 (October 2013): 164–65. http://dx.doi.org/10.1017/s1743921314003652.

Full text

Abstract:

AbstractWe attempt to create an X-ray/radio AGN catalog and make its multiwavelength studies. ROSAT Bright Source Catalogue (BSC) contains 18,806 and ROSAT Faint Source Catalogue (FSC), 105,922 X-ray sources giving the total number of ROSAT X-ray sources 124,727 (one source is listed twice). On the other hand, NVSS radio catalogue contains 1,773,484 sources. Taking into account that X-ray sources contain AGN, bright stars and galaxies, clusters, white dwarfs (WD), cataclysmic variables (CV), etc., the cross-identification with radio catalogue may distinguish the extragalactic sources. We have cross-correlated ROSAT catalogs with NVSS one with a search radius 30 arcsec. 9,193 associations have been found. To distinguish AGN from the normal bright galaxies and clusters, Veron-Cetty & Veron AGN catalog (v.13, 2010; VCV-13) containing 168,940 objects have been used. A cross-correlation of the 9,193 ROSAT/NVSS sources with the VCV-13 with a search radius 30 arcsec resulted in 3,094 associations. Thus we are left with more 6,099 X-ray/radio sources without an optical identification. Brighter objects are normal bright galaxies, while we believe that all faint ones are candidate AGN with some contamination of distant clusters. SDSS spectroscopic survey allows us classify objects by activity types, and a number of our candidate AGN is found to be present in SDSS. We attempt to find connections between the fluxes in different wavelength ranges, which will allow us to confirm AGN and blazars candidates and in some cases find new ones.

APA, Harvard, Vancouver, ISO, and other styles

2

Andernach, H., O. V. Verkhodanov, and N. V. Verkhodanova. "Radio-optical Identification of Very-Steep Spectrum Radio Sources from the UTR-2 Catalogue." Symposium - International Astronomical Union 199 (2002): 217–18. http://dx.doi.org/10.1017/s0074180900168949.

Full text

Abstract:

We used radio source catalogues accessible from the CATS database to establish radio continuum spectra for decametric radio sources in the UTR-2 catalogue. In an attempt to find further candidates for high-redshift radio galaxies, we searched the FIRST and NVSS surveys for counterparts of a sample of UTR sources with ultra-steep radio spectra (USS, α ≤ −1.2, S ∼ vα). We derived accurate positions and sizes for 23 of these USS sources. The search for optical counterparts from the APM (object) and DSS (image) databases, as well as infrared and X—ray identifications of these UTR sources are in progress.

APA, Harvard, Vancouver, ISO, and other styles

3

de Gasperin, F., H. T. Intema, and D. A. Frail. "A radio spectral index map and catalogue at 147–1400 MHz covering 80 per cent of the sky." Monthly Notices of the Royal Astronomical Society 474, no. 4 (December 5, 2017): 5008–22. http://dx.doi.org/10.1093/mnras/stx3125.

Full text

Abstract:

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. > − 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.

APA, Harvard, Vancouver, ISO, and other styles

4

Verkhodanov, O. V., and S. A. Trushkin. "Study of Objects of Low Radio Frequency Catalogues and IRAS Data — Cross-Identification." Symposium - International Astronomical Union 199 (2002): 221–24. http://dx.doi.org/10.1017/s0074180900168962.

Full text

Abstract:

We present results of cross—identifications of the objects from two large catalogues, IRAS and the low radio frequency Texas catalogue at 365 MHz in the database CATS. The resulting list consists of 715 pairs of sources within a circle of radius of 60 arcsec. It has been cross—identified with the GB6 4.85 GHz, NVSS 1.4 GHz, FIRST 1.4 GHz, WENSS 325 MHz radio catalogues, ROSAT catalogues and different optical data lists, including APM catalogue. We selected 3 subsamples: objects matching in 3″radius, ultra steep spectrum (USS) radio sources, inverse spectrum radio sources, galactic sources. Several objects have radio spectral index α < −2, some of them in Galactic plane.

APA, Harvard, Vancouver, ISO, and other styles

5

Flesch, E. "An All-Sky Atlas of Radio/X-ray Associations." Publications of the Astronomical Society of Australia 27, no. 3 (2010): 283–89. http://dx.doi.org/10.1071/as09060.

Full text

Abstract:

AbstractAn all-sky comprehensive catalogue of calculated radio and X-ray associations to optical objects is presented. Included are X-ray sources from XMM-Newton, Chandra and ROSAT catalogues, radio sources from NVSS, FIRST and SUMSS catalogues, and optical data, identifications and redshifts from the APM, USNO-A, SDSS-DR7 and the extant literature. This ‘Atlas of Radio/X-ray Associations’ inherits many techniques from the predecessor Quasars.org (2004) catalogue, but object selection is changed and processing tweaked. Optical objects presented are those which are calculated with ≥40% confidence to be associated with radio/X-ray detections, totalling 602 570 objects in all, including 23 681 double radio lobe detections. For each of these optical objects I display the calculated percentage probabilities of its being a QSO, galaxy, star, or erroneous radio/X-ray association, plus any identification from the literature. The catalogue includes 105 568 uninvestigated objects listed as 40% to >99% likely to be a QSO. The catalogue is available at http://quasars.org/arxa.htm.

APA, Harvard, Vancouver, ISO, and other styles

6

Chan, B. H. P., and L. E. Cram. "Image Processing for the Sydney University Molonglo Sky Survey (SUMSS)." Publications of the Astronomical Society of Australia 19, no. 2 (2002): 201–6. http://dx.doi.org/10.1071/as01060.

Full text

Abstract:

AbstractThe Sydney University Molonglo Sky Survey (SUMSS) is a deep radio survey at 843 MHz, covering the region south of −30° declination. Designed to be a southern counterpart of the northern NRAO VLA Sky Survey (NVSS), SUMSS is over 40% complete, and it is now time to devise ways to generate the source catalogue for the survey. We describe here new methods to deal with image artifacts to minimise spurious fits by automatic source fitting algorithms. With the new techniques, an automatically generated, objective catalogue can be made to a 10 mJy cutoff. Catalogues can be made to a 5 mJy cutoff provided that special care is taken and certain artifacts are avoided.

APA, Harvard, Vancouver, ISO, and other styles

7

Żywucka, Natalia, Dorota Koziel-Wierzbowska, and Arti Goyal. "Catalogue with visual morphological classification of 32,616 radio galaxies with optical hosts." Proceedings of the International Astronomical Union 15, S356 (October 2019): 361–63. http://dx.doi.org/10.1017/s174392132000335x.

Full text

Abstract:

AbstractWe present the catalogue of Radio sources associated with Optical Galaxies and having Unresolved or Extended morphologies I (ROGUE I). It was generated by cross-matching galaxies from the Sloan Digital Sky Survey Data Release 7 (SDSS DR 7) as well as radio sources from the First Images of Radio Sky at Twenty Centimetre (FIRST) and the National Radio Astronomical Observatory VLA Sky Survey (NVSS) catalogues. We created the largest handmade catalogue of visually classified radio objects and associated with them optical host galaxies, containing 32,616 galaxies with a FIRST core within 3 arcsec of the optical position. All listed objects possess the good quality SDSS DR 7 spectra with the signal-to-noise ratio > 10 and spectroscopic redshifts up to z = 0.6. The radio morphology classification was performed by a visual examination of the FIRST and the NVSS contour maps overlaid on a DSS image, while an optical morphology classification was based on the 120 arcsec snapshot images from SDSS DR 7.The majority of radio galaxies in ROGUE I, i.e. ∼ 93%, are unresolved (compact or elongated), while the rest of them exhibit extended morphologies, such as Fanaroff-Riley (FR) type I, II, and hybrid, wide-angle tail, narrow-angle tail, head-tail sources, and sources with intermittent or reoriented jet activity, i.e. double–double, X–shaped, and Z–shaped. Most of FR IIs have low radio luminosities, comparable to the luminosities of FR Is. Moreover, due to visual check of all radio maps and optical images, we were able to discover or reclassify a number of radio objects as giant, double–double, X–shaped, and Z–shaped radio galaxies. The presented sample can serve as a database for training automatic methods of identification and classification of optical and radio galaxies.

APA, Harvard, Vancouver, ISO, and other styles

8

Siewert, Thilo M., Matthias Schmidt-Rubart, and Dominik J. Schwarz. "Cosmic radio dipole: Estimators and frequency dependence." Astronomy & Astrophysics 653 (September 2021): A9. http://dx.doi.org/10.1051/0004-6361/202039840.

Full text

Abstract:

The cosmic radio dipole is of fundamental interest to studies of cosmology. Recent works have put forth open questions about the nature of the observed cosmic radio dipole. In the current work, we use simulated source count maps to test a linear and a quadratic estimator for possible biases in the estimated dipole amplitude with respect to the masking procedure. We find a superiority on the part of the quadratic estimator, which we used to analyse the TGSS-ADR1, WENSS, SUMSS, and NVSS radio source catalogues, spread over a decade of frequencies. We applied the same masking strategy to all four surveys to produce comparable results. In order to address the differences in the observed dipole amplitudes, we cross-matched the two surveys located at both ends of the analysed frequency range. For the linear estimator, we identified a general bias in the estimated dipole directions. The positional offsets of the quadratic estimator to the cosmic microwave background (CMB) dipole for skies with 107 simulated sources is found to be below one degree and the absolute accuracy of the estimated dipole amplitudes is better than 10−3. For the four radio source catalogues, we find an increasing dipole amplitude with decreasing frequency, which is consistent with results from the literature and the results of the cross-matched catalogue. We conclude that for all analysed surveys, the observed cosmic radio dipole amplitudes exceed the expectations derived from the CMB dipole, which cannot strictly be explained by a kinematic dipole alone.

APA, Harvard, Vancouver, ISO, and other styles

9

Et al., Rashed. "Studying the Flux Density of Bright Active Galaxies at Different Spectral Bands." Baghdad Science Journal 16, no. 1 (March 17, 2019): 0230. http://dx.doi.org/10.21123/bsj.16.1.(suppl.).0230.

Full text

Abstract:

Statistical studies are reported in this article for an active galactic nuclei sample of different type of active galaxies Seyferts 1, Seyferts 2, and Quasars. These sources have been selected from a Catalogue for bright X-ray galaxies. The name of this index is ROSAT Bright Source Catalogue (RBSC) and the NRAO VLA Sky Survey (NVSS). In this research, multi-wavelength observational bands Radio at 1.4 GHz, Optical at 4400 A0, and X-ray at energy 0.1-2.4 KeV have been adopted in this study. The behavior of flux density ratios has been studied , with respect to the absolute magnitude . Furthermore, the Seyfert1 and Seyfert 2 objects are combined in one group and the QSOs are collectest in another group. Also, it has been found that the ratios , are increasing towards fainter optical absolute magnitude especially in Quasars.

APA, Harvard, Vancouver, ISO, and other styles

10

Et al., Rashed. "Studying the Flux Density of Bright Active Galaxies at Different Spectral Bands." Baghdad Science Journal 16, no. 1(Suppl.) (March 17, 2019): 0230. http://dx.doi.org/10.21123/bsj.2019.16.1(suppl.).0230.

Full text

Abstract:

Statistical studies are reported in this article for an active galactic nuclei sample of different type of active galaxies Seyferts 1, Seyferts 2, and Quasars. These sources have been selected from a Catalogue for bright X-ray galaxies. The name of this index is ROSAT Bright Source Catalogue (RBSC) and the NRAO VLA Sky Survey (NVSS). In this research, multi-wavelength observational bands Radio at 1.4 GHz, Optical at 4400 A0, and X-ray at energy 0.1-2.4 KeV have been adopted in this study. The behavior of flux density ratios has been studied , with respect to the absolute magnitude . Furthermore, the Seyfert1 and Seyfert 2 objects are combined in one group and the QSOs are collectest in another group. Also, it has been found that the ratios , are increasing towards fainter optical absolute magnitude especially in Quasars.

APA, Harvard, Vancouver, ISO, and other styles

11

Harutyunyan, Gohar S., and Areg M. Mickaelian. "Study of Starburst/Activity/Interaction Phenomena based on the Multiple Byurakan-IRAS Galaxies." Proceedings of the International Astronomical Union 9, S304 (October 2013): 383–84. http://dx.doi.org/10.1017/s1743921314004360.

Full text

Abstract:

AbstractThe Byurakan-IRAS Galaxy (BIG) sample is the result of optical identifications of IRAS PSC sources at high-galactic latitudes using the First Byurakan Survey (FBS) low-dispersion spectra. Among the 1178 objects most are spiral galaxies and many have been proved to be AGN and starburst by spectroscopic observations, as well as there is a number of ULIRGs among these objects. BIG objects contain galaxy pairs, multiples, and small groups that are subject for study on the matter of the real IR-emitter in these systems. Given that these objects are powerful IR sources, they are considered as young systems indicating high rate of evolution and starburst activity exceeding 100 Mo/yr. Spectroscopic observations show that all these systems are physical ones and we were able to measure the mutual distances and sizes for all components. Cross-correlations with the recent more accurate IR catalogues, such as 2MASS and WISE, as well as radio ones (NVSS, FIRST), provided accurate coordinates of the IR source and possibility to find the individual galaxy responsible for the IR. However, in almost half of the cases, IR position indicates the intermediate region between the components, which means that it comes from the system as a whole. Some more MW data have been matched to IR and radio to have an overall understanding on these systems. Given that these systems are mostly interacting/merging ones often containing AGN and most of them may be considered as powerful starbursts, it is possible to study starburst/activity/interaction phenomena and their interrelationship.

APA, Harvard, Vancouver, ISO, and other styles

12

Yang, Chen, Han Jin-lin, and He Xiang-tao. "Radio quasars identified from the NVSS catalogue." Chinese Astronomy and Astrophysics 25, no. 1 (January 2001): 6–22. http://dx.doi.org/10.1016/s0275-1062(01)00038-8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Bruni, G., F. Ursini, F. Panessa, L. Bassani, A. Bazzano, A. J. Bird, E. Chiaraluce, et al. "Probing restarting activity in hard X-ray selected giant radio galaxies." Proceedings of the International Astronomical Union 14, A30 (August 2018): 66–69. http://dx.doi.org/10.1017/s1743921319003478.

Full text

Abstract:

AbstractWith their sizes larger than 0.7 Mpc, Giant Radio Galaxies (GRGs) are the largest individual objects in the Universe. To date, the reason why they reach such enormous extensions is still unclear. One of the proposed scenarios suggests that they are the result of multiple episodes of jet activity. Cross-correlating the INTEGRAL+Swift AGN population with radio catalogues (NVSS, FIRST, SUMSS), we found that 22% of the sources are GRG (a factor four higher than those selected from radio catalogues). Remarkably, all of the sources in the sample show signs of restarting radio activity. The X-ray properties are consistent with this scenario, the sources being in a high-accretion, high-luminosity state with respect to the previous activity responsible for the radio lobes.

APA, Harvard, Vancouver, ISO, and other styles

14

Verkhodanov, O. V., S. A. Trushkin, and H. Andernach. "Low Frequency Catalogues of the CATS Database." Symposium - International Astronomical Union 199 (2002): 245–46. http://dx.doi.org/10.1017/s0074180900169037.

Full text

Abstract:

We describe the most complete, publicly accessible database of radio sources, CATS (“astrophysical CATalogues Support system”). It contains more than 300 catalogues of objects detected in various (mostly radio) wavelength ranges. Apart from catalogues drawn from the most important existing surveys and compilations (e.g. NVSS, FIRST, GB6, IRAS, ROSAT, PGC, MCG), CATS includes the largest low-frequency catalogues published so far: UTR, Culgoora, Cambridge, Miyun, WENSS, TXS, Bologna and Molonglo etc., CATS allows one to operate with these, and to draw samples of objects for the study of a large variety of astrophysical problems. Some modes of access are described here.

APA, Harvard, Vancouver, ISO, and other styles

15

Mickaelian, A. M., H. V. Abrahamyan, M. V. Gyulzadyan, G. A. Mikayelyan, and G. M. Paronyan. "Multi-wavelength studies of the statistical properties of active galaxies using Big Data." Proceedings of the International Astronomical Union 12, S325 (October 2016): 32–38. http://dx.doi.org/10.1017/s1743921316012916.

Full text

Abstract:

AbstractStatistical studies of active galaxies (both AGN and Starburst) using large multi-wavelength data are presented, including new studies of Markarian galaxies, large sample of IR galaxies, variable radio sources, and large homogeneous sample of X-ray selected AGN. Markarian survey (the First Byurakan Survey) was digitized and the DFBS database was created, as the biggest spectroscopic database by the number of objects involved ( ~ 20 million). This database provides both 2D images and 1D spectra. We have carried out a number of projects aimed at revealing and multi-wavelength studies of active galaxies among optical, X-ray, IR and radio sources. Thousands of X-ray sources were identified from ROSAT, including many AGN (52% among all identified sources). IRAS PSC/FSC sources were studied having accurate positions from WISE and a large extragalactic sample was created for further search for AGNs. The fraction of active galaxies among IR-selected galaxies was estimated as 24%. Variable radio sources at 1.4 GHz were revealed by cross-correlation of NVSS and FIRST catalogues using the method introduced by us for optical variability. Radio-X-ray sources were revealed from NVSS and ROSAT for detection of new active galaxies. Big Data in astronomy is described that provide new possibilities for statistical research of active galaxies and other objects.

APA, Harvard, Vancouver, ISO, and other styles

16

Han, J. L., R. N. Manchester, A. G. Lyne, and G. J. Qiao. "Searching for Submillisecond Pulsars from Highly Polarized Radio Sources." Symposium - International Astronomical Union 218 (2004): 135–36. http://dx.doi.org/10.1017/s0074180900180805.

Full text

Abstract:

Pulsars are among the most highly polarized sources in the universe. The NVSS has cataloged 2 million radio sources with linear polarization measurements, from which we have selected 253 sources, with polarization percentage greater than 25%, as targets for pulsar searches. We believe that such a sample is not biased by selection effects against ultra-short spin or orbit periods. Using the Parkes 64-m telescope, we conducted searches with sample intervals of 50 μs and 80 μs, sensitive to submillisecond pulsars. Unfortunately we did not find any new pulsars.

APA, Harvard, Vancouver, ISO, and other styles

17

Sadler, Elaine M., V. J. McIntyre, C. A. Jackson, and R. D. Cannon. "Radio Sources in the 2dF Galaxy Redshift Survey I. Radio Source Populations." Publications of the Astronomical Society of Australia 16, no. 3 (1999): 247–56. http://dx.doi.org/10.1071/as99247.

Full text

Abstract:

AbstractWe present the first results from a study of the radio continuum properties of galaxies in the 2dF Galaxy Redshift Survey, (2dFGRS) based on thirty 2dF fields covering a total area of about 100 deg2. About 1·5% of galaxies with bJ < 19·4 mag. are detected as radio continuum sources in the NRAO VLA Sky Survey (NVSS). Of these, roughly 40% are star-forming galaxies and 60% are active galaxies (mostly low-power radio galaxies and a few Seyferts). The combination of 2dFGRS and NVSS will eventually yield a homogeneous set of around 4000 radio-galaxy spectra, which will be a powerful tool for studying the distribution and evolution of both AGN and starburst galaxies out to z ∼ 0·3.

APA, Harvard, Vancouver, ISO, and other styles

18

Pal, Sabyasachi, Dusmanta Patra, Monique Hollick, and Sandip K. Chakrabarti. "Transient nature of radio source NVSS J1957+35." Advances in Space Research 64, no. 3 (August 2019): 765–78. http://dx.doi.org/10.1016/j.asr.2019.05.014.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Lew, Bartosz. "Constraints on radio source clustering towards galaxy clusters: application for cm-wavelength simulations of blind sky surveys." Proceedings of the International Astronomical Union 11, S308 (June 2014): 301–2. http://dx.doi.org/10.1017/s1743921316010048.

Full text

Abstract:

AbstractWe derive constraints on radio source clustering towards Planck-selected galaxy clusters using the NVSS point source catalog. The constraint can be used for making a more realistic Sunyaev-Zeldovich effect (SZE) mocks, calculating predictions of detectable clusters count and for quantifying source confusion in radio surveys.

APA, Harvard, Vancouver, ISO, and other styles

20

Jackson, C. A., and J. V. Wall. "Radio Source Evolution Derived from Low Frequency Surveys." Symposium - International Astronomical Union 199 (2002): 50–53. http://dx.doi.org/10.1017/s0074180900168524.

Full text

Abstract:

We find simple parametric models to describe the space density evolution of radio-loud AGN, treating FRI and FRII radio galaxies separately as the two parent populations in our dual-population unified scheme. In this we use low frequency radio data (v < 500 MHz), where radio samples are unbiased by Doppler beaming. Incorporated into this latest analysis is a new determination of the local radio luminosity function at 1.4 GHz from galaxies common to both the 2dFGRS and NVSS surveys.

APA, Harvard, Vancouver, ISO, and other styles

21

Sadler, Elaine M., Richard W. Hunstead, Thomas Mauch, Duncan Campbell-Wilson, Carole A. Jackson, Carlos De Breuck, and Chris Blake. "Mapping the Local and Distant Universe with SUMSS." Symposium - International Astronomical Union 216 (2005): 211–18. http://dx.doi.org/10.1017/s0074180900196652.

Full text

Abstract:

The Sydney University Molonglo Sky Survey (SUMSS) is a radio continuum imaging survey of the southern sky at 843 MHz, with similar sensitivity and resolution to the northern NRAO VLA Sky Survey (NVSS). We have combined radio data from SUMSS and NVSS with optical spectra from the 2dF Galaxy Redshift Survey and 6dF Galaxy Survey to study the space distribution and properties of both AGN and star-forming galaxies in the local universe (redshift range 0 < z < 0.3). We also discuss new results on radio-source clustering in the more distant universe (z ∼ 1) and present the first results from a search for the most distant (z > 3) southern radio galaxies.

APA, Harvard, Vancouver, ISO, and other styles

22

Narang, Mayank. "The nature of the radio source detected towards the exoplanet system 1RXS1609.1−210524." Monthly Notices of the Royal Astronomical Society 515, no. 2 (July 22, 2022): 2015–19. http://dx.doi.org/10.1093/mnras/stac1902.

Full text

Abstract:

ABSTRACT Several studies have been carried out to detect radio emissions from known exoplanets. Some of these studies have resulted in tentative detections of radio sources near the position of known exoplanets. One such planet/brown dwarf around which a radio source was detected is 1RXS1609.1−210524 (hereafter 1RX) b. A radio source near 1RX was detected with the TIFR GMRT Sky Survey (TGSS) at 150 MHz and the NRAO VLA Sky Survey (NVSS) at 1.4 GHz. However, since these surveys’ spatial resolution was low, it was not possible to ascertain whether the radio emission originated from the system or a background source. This work presents results from the 1RX field’s targeted observations at 150, 325, and 610 MHz with Giant Meterwave Radio Telescope (GMRT). These observations have a higher angular resolution as compared to TGSS and NVSS. I detected the radio source near the position of 1RX at all frequencies with GMRT. I further used the Very Large Array Sky Survey (VLASS) data at 3 GHz to determine the flux density and position at high frequency. With the targeted GMRT observations and observations from VLASS, I show that the radio emission does not originate from the 1RX b but is from a background source about ∼13 arcsec away from the host star. Further, no radio emission was detected from the position of 1RX.

APA, Harvard, Vancouver, ISO, and other styles

23

Verkhodanov, O. V., N. V. Verkhodanova, and H. Andernach. "Decametric AGNs: FIRST and NVSS Maps and Radio Spectra." International Astronomical Union Colloquium 184 (2002): 306–7. http://dx.doi.org/10.1017/s025292110003092x.

Full text

Abstract:

AbstractRadio sources from the decametric UTR-2 catalog were cross-identified with other radiocatalogs at higher frequencies. We used the CATS database to extract all sources within the UTR beam size (~40’) to find candidate radio identifications. Using the least squares method, we fitted the spectrum of each source with one of a set of curves. We extracted NVSS and FIRST radio images for the radio-identified sources, and looked for a possible relation between size and spectral index.

APA, Harvard, Vancouver, ISO, and other styles

24

Veres, Patrik Milán, Krisztina Éva Gabányi, and Sándor Frey. "Very Long Baseline Interferometry Observations of the Proposed Radio Counterpart of an EGRET Source." Symmetry 12, no. 9 (September 15, 2020): 1516. http://dx.doi.org/10.3390/sym12091516.

Full text

Abstract:

We present high-resolution radio interferometric imaging observations of the radio source NVSS J182659+343113 (hereafter J1826+3431), the proposed radio counterpart of the γ-ray source, 3EG J1824+3441 detected by the Energetic Gamma Ray Experiment Telescope (EGRET) on board the Compton Gamma Ray Observatory satellite. We analyzed eight epochs of archival multi-frequency very long baseline interferometry data. We imaged the asymmetric core–jet structure of the source, and detected apparent superluminal motion in the jet. At the highest observing frequency, 15.3 GHz, the core shows high brightness temperature indicating Doppler boosting. Additionally, the radio features undergo substantial flux density variability. These findings strengthen the previous claim of the association of the blazar J1826+3431 with the possible γ-ray source, 3EG J1824+3441.

APA, Harvard, Vancouver, ISO, and other styles

25

Patil, Pallavi, Mark Whittle, Kristina Nyland, Carol Lonsdale, Mark Lacy, Amy E. Kimball, Colin Lonsdale, et al. "Radio Spectra of Luminous, Heavily Obscured WISE-NVSS Selected Quasars." Astrophysical Journal 934, no. 1 (July 1, 2022): 26. http://dx.doi.org/10.3847/1538-4357/ac71b0.

Full text

Abstract:

Abstract We present radio spectra spanning 0.1–10 GHz for the sample of heavily obscured luminous quasars with extremely red mid-infrared-optical colors and compact radio emission. The spectra are constructed from targeted 10 GHz observations and archival radio survey data that together yield 6–11 flux-density measurements for each object. Our primary result is that most (62%) of the sample have peaked or curved radio spectra and many (37%) could be classified as Gigahertz-Peaked Spectrum (GPS) sources. This indicates compact emission regions likely arising from recently triggered radio jets. Assuming synchrotron self-absorption (SSA) generates the peaks, we infer compact source sizes (3–100 pc) with strong magnetic fields (6–100 mG) and young ages (30–104 yr). Conversely, free-free absorption (FFA) could also create peaks due to the high column densities associated with the deeply embedded nature of the sample. However, we find no correlations between the existence or frequency of the peaks and any parameters of the MIR emission. The high-frequency spectral indices are steep (α ≈ −1) and correlate, weakly, with the ratio of MIR photon energy density to magnetic energy density, suggesting that the spectral steepening could arise from inverse Compton scattering off the intense MIR photon field. This study provides a foundation for combining multifrequency and mixed-resolution radio survey data for understanding the impact of young radio jets on the ISM and star-formation rates of their host galaxies. faGithub

APA, Harvard, Vancouver, ISO, and other styles

26

Parnovsky, S., and I. Izotova. "Spectral index in the radio continuum 140 MHz – 1.4 GHz emission for compact star-forming galaxies." Bulletin of Taras Shevchenko National University of Kyiv. Astronomy, no. 62 (2020): 12–16. http://dx.doi.org/10.17721/btsnua.2020.62.12-16.

Full text

Abstract:

The sample of compact star-forming galaxies (CSFGs) has been identified with sources in the catalogues of radio sources. It includes only galaxies with active star formation without objects with spectral signs of active galactic nuclei. For CSFGs with known flux densities in radiocontinuum at frequencies of 1.4 GHz from the FIRST or the NVSS and in the range of 120–168 MHz from the LOFAR, as well as in hydrogen emission lines from the SDSS, the spectral index and the spectral index of non-thermal emission component for these frequencies have been estimated. Note that obtaining the spectral index of nonthermal emission component is a much more difficult task than determining the spectral index of total emission. It is shown that the approximation by the model dependence using the least squares method can lead to unreliable estimates of the fraction of thermal (free-free) emission. Therefore, the flux densities of the thermal component are derived from the extinction- and aperture corrected fluxes of the Hα emission line. This method of estimation without using a fitting is more reliable. It is shown that the fact that derived spectra in radio range are quite flat is due, in particular, to the influence of selection effects caused by limited sensitivity of radio telescopes. For the same reason, only galaxies with a small fraction of thermal emission were included in the sample. Therefore, the spectral index is not much different from the spectral index of non-thermal emission.

APA, Harvard, Vancouver, ISO, and other styles

27

Tiwari, Prabhakar, Rahul Kothari, Abhishek Naskar, Sharvari Nadkarni-Ghosh, and Pankaj Jain. "Dipole anisotropy in sky brightness and source count distribution in radio NVSS data." Astroparticle Physics 61 (February 2015): 1–11. http://dx.doi.org/10.1016/j.astropartphys.2014.06.004.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Abrahamyan, Hayk V., and Areg M. Mickaelian. "Radio Properties of AGN." Proceedings of the International Astronomical Union 9, S304 (October 2013): 102–3. http://dx.doi.org/10.1017/s1743921314003469.

Full text

Abstract:

AbstractTo study the radio properties of AGN, we cross-correlate and investigate Veron-Cetty & Veron catalog of QSOs and Active Galaxies (v.13, 2010) with a number of radio catalogs: NVSS, FIRST, GB6, 87GB, SUMSS, WISH, WENSS, and 7C. This catalog contains 168,940 objects with positional accuracy of mostly 1 arcsec, though many positions have larger errors. We use new cross-correlation software based on accuracy of each object independently. In this software we take into account errors for each source and take identifications with errors within 3 sigma. Altogether, we find ~16,000 AGN having radio detection in any of the listed catalogs. Using all data from radio catalogs, we derive a homogeneous sample of radio AGN. The sample allows accomplish several tasks, including study of the distribution of radio sources by activity types, differences in physical properties of radio-loud and radio-quiet AGN, luminosity functions for various types of radio AGN, study of the q parameter by AGN types and its evolution, etc.

APA, Harvard, Vancouver, ISO, and other styles

29

Zhelenkova, O. P., and E. K. Majorova. "Study of RCR Catalogue Radio Source Integral Spectra." Astrophysical Bulletin 73, no. 2 (April 2018): 142–61. http://dx.doi.org/10.1134/s1990341318020037.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Fan, Dongwei, Tamás Budavári, Ray P. Norris, and Amitabh Basu. "Optimal probabilistic catalogue matching for radio sources." Monthly Notices of the Royal Astronomical Society 498, no. 1 (August 17, 2020): 565–73. http://dx.doi.org/10.1093/mnras/staa2447.

Full text

Abstract:

ABSTRACT Cross-matching catalogues from radio surveys to catalogues of sources at other wavelengths is extremely hard, because radio sources are often extended, often consist of several spatially separated components, and often no radio component is coincident with the optical/infrared host galaxy. Traditionally, the cross-matching is done by eye, but this does not scale to the millions of radio sources expected from the next generation of radio surveys. We present an innovative automated procedure, using Bayesian hypothesis testing, that models trial radio-source morphologies with putative positions of the host galaxy. This new algorithm differs from an earlier version by allowing more complex radio-source morphologies, and performing a simultaneous fit over a large field. We show that this technique performs well in an unsupervised mode.

APA, Harvard, Vancouver, ISO, and other styles

31

Otrupcek, Robina E., and Alan E. Wright. "PKSCAT90: the Southern Radio Source Database." Publications of the Astronomical Society of Australia 9, no. 1 (1991): 170. http://dx.doi.org/10.1017/s1323358000025443.

Full text

Abstract:

AbstractThe PKSCAT90 database consists of radio and optical data for 8264 radio sources. It covers all the sky south of declination +27 degrees. Most of the galactic plane and the Magellanic Cloud regions are excluded from this catalogue but have been the subject of other specialised surveys. A few data errors in the initial PKSCAT90 version 1.00 released in March 1990 have been corrected in the current version 1.01 edition.

APA, Harvard, Vancouver, ISO, and other styles

32

Butler, Andrew, Minh Huynh, Jacinta Delhaize, Vernesa Smolčić, Anna Kapińska, Dinko Milaković, Mladen Novak, et al. "The XXL Survey." Astronomy & Astrophysics 620 (November 20, 2018): A3. http://dx.doi.org/10.1051/0004-6361/201630129.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

33

Randriamanakoto, Z., C. H. Ishwara-Chandra, and A. R. Taylor. "J1615+5452: a remnant radio galaxy in the ELAIS-N1 field." Monthly Notices of the Royal Astronomical Society 496, no. 3 (June 23, 2020): 3381–89. http://dx.doi.org/10.1093/mnras/staa1782.

Full text

Abstract:

ABSTRACT We report the discovery of a remnant radio active galactic nucleus (AGN) J1615+5452 in the field of ELAIS-N1. GMRT continuum observations at 150, 325, and 610 MHz combined with archival data from the 1.4 GHz NVSS survey were used to derive the radio spectrum of the source. At a redshift z ∼ 0.33, J1615+5452 has a linear size of ∼100 kpc and spectral indices ranging between $\alpha ^{1400}_{610} \lt -1.5$ and $\alpha ^{325}_{150} = -0.61 \pm 0.12$. While the source has a diffuse radio emission at low frequencies, we do not find evidence of core, jets, or hotspots in the 1.4 GHz VLA data of ∼5 arcsec angular resolution. Such morphological properties coupled with a curved radio spectrum suggest that the AGN fueling mechanisms undergo a shortage of energy supply which is typical of a dying radio AGN. This is consistent with the observed steep curvature in the spectrum Δα ≈ −1, the estimated synchrotron age of $t_{\rm s}=76.0\, ^{+7.4}_{-8.7}$ Myr and a toff/ts ratio of ∼0.3.

APA, Harvard, Vancouver, ISO, and other styles

34

Sokolova, Yu R., and Z. M. Malkin. "Pulkovo combined catalogue of radio source positions PUL 2013." Astronomy Letters 40, no. 5 (May 2014): 268–77. http://dx.doi.org/10.1134/s1063773714050041.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Labiano, Alvaro, Matteo Guainazzi, and Stefano Bianchi. "Radio Loud AGN in the 2XMMi catalogue." Proceedings of the International Astronomical Union 6, S275 (September 2010): 200–201. http://dx.doi.org/10.1017/s1743921310016042.

Full text

Abstract:

AbstractWe are carrying out a search for all radio loud Active Galactic Nuclei observed with XMM-Newton, including targeted and field sources to perform a multi-wavelength study of these objects. We have cross-correlated the Verón-Cetty & Verón (2010) catalogue with the XMM-Newton Serendipitous Source Catalogue (2XMMi) and found around 4000 sources. A literature search provided radio, optical, and X-ray data for 403 sources. This poster summarizes the first results of our study.

APA, Harvard, Vancouver, ISO, and other styles

36

Westerlund, S., C. Harris, and T. Westmeier. "Assessing the Accuracy of Radio Astronomy Source-Finding Algorithms." Publications of the Astronomical Society of Australia 29, no. 3 (2012): 301–8. http://dx.doi.org/10.1071/as11049.

Full text

Abstract:

AbstractThis work presents a method for determining the accuracy of a source finder algorithm for spectral line radio astronomy data and the Source Finder Accuracy Evaluator (SFAE), a program that implements this method. The accuracy of a source finder is defined in terms of its completeness, reliability, and accuracy of the parameterisation of the sources that were found. These values are calculated by executing the source finder on an image with a known source catalogue, then comparing the output of the source finder to the known catalogue. The intended uses of SFAE include determining the most accurate source finders for use in a survey, determining the types of radio sources a particular source finder is capable of accurately locating, and identifying optimum parameters and areas of improvement for these algorithms. This paper demonstrates a sample of accuracy information that can be obtained through this method, using a simulated ASKAP data cube and the duchamp source finder.

APA, Harvard, Vancouver, ISO, and other styles

37

W Hunstead, Richard. "Accurate Optical Positions for Radio Source Identifications." Australian Journal of Physics 47, no. 5 (1994): 657. http://dx.doi.org/10.1071/ph940657.

Full text

Abstract:

The optical identification of strong radio sources was a key step in establishing a grid of southern hemisphere calibrators, both for Parkes and for Molonglo. However, the measurement of precise positions for these optical counterparts presented some special astrometric problems and led to some novel solutions. This paper summarises the progress of optical position measurement from a radio astronomer's viewpoint and examines the role of the COSMOS database against this background. The source 0007-44, from the first Parkes catalogue, is used as a case study to illustrate the present-day approach to optical identifications.

APA, Harvard, Vancouver, ISO, and other styles

38

Pasetto, Alice, Carlos Carrasco-González, Shane O’Sullivan, Aritra Basu, Gabriele Bruni, Alex Kraus, Salvador Curiel, and Karl-Heinz Mack. "Broadband radio spectro-polarimetric observations of high-Faraday-rotation-measure AGN." Astronomy & Astrophysics 613 (May 2018): A74. http://dx.doi.org/10.1051/0004-6361/201731804.

Full text

Abstract:

We present broadband polarimetric observations of a sample of high-Faraday-rotation-measure (high-RM) active galactic nuclei (AGN) using the Karl. G. Jansky Very Large Array (JVLA) telescope from 1 to 2 GHz, and 4 to 12 GHz. The sample (14 sources) consists of very compact sources (linear resolution smaller than ≈5 kpc) that are unpolarized at 1.4 GHz in the NRAO VLA Sky Survey (NVSS). Total intensity data have been modeled using a combination of synchrotron components, revealing complex structure in their radio spectra. Depolarization modeling, through the so-called qu-fitting (the modeling of the fractional quantities of the Stokes Q and U parameters), has been performed on the polarized data using an equation that attempts to simplify the process of fitting many different depolarization models. These models can be divided into two major categories: external depolarization (ED) and internal depolarization (ID) models. Understanding which of the two mechanisms is the most representative would help the qualitative understanding of the AGN jet environment and whether it is embedded in a dense external magneto-ionic medium or if it is the jet-wind that causes the high RM and strong depolarization. This could help to probe the jet magnetic field geometry (e.g., helical or otherwise). This new high-sensitivity data shows a complicated behavior in the total intensity and polarization radio spectrum of individual sources. We observed the presence of several synchrotron components and Faraday components in their total intensity and polarized spectra. For the majority of our targets (12 sources), the depolarization seems to be caused by a turbulent magnetic field. Thus, our main selection criteria (lack of polarization at 1.4 GHz in the NVSS) result in a sample of sources with very large RMs and depolarization due to turbulent magnetic fields local to the source. These broadband JVLA data reveal the complexity of the polarization properties of this class of radio sources. We show how the new qu-fitting technique can be used to probe the magnetized radio source environment and to spectrally resolve the polarized components of unresolved radio sources.

APA, Harvard, Vancouver, ISO, and other styles

39

Dey, Arjun, Wil van Breugel, and Joseph C. Shields. "Radio Loud Far-Infrared Galaxies." International Astronomical Union Colloquium 124 (1990): 309–14. http://dx.doi.org/10.1017/s0252921100005273.

Full text

Abstract:

AbstractWe present the first results of a multiwavelength study of IRAS galaxies with excess radio emission. The sample was selected by cross-correlating the IRAS Faint Source Survey (for |b| ≥ 50°) and the Point Source Catalogue (for 10° < |b| < 50°) with the Texas radio survey. Recent optical (imaging and spectroscopic) and radio (VLA) observations are discussed. These observations will be used to investigate possible connections between radio galaxy activity, star formation and galaxy interactions.

APA, Harvard, Vancouver, ISO, and other styles

40

E Wright, Alan. "From the Parkes Catalogue to COMRAD." Australian Journal of Physics 47, no. 5 (1994): 585. http://dx.doi.org/10.1071/ph940585.

Full text

Abstract:

I present a brief description of John Bolton's work in establishing the Parkes Catalogue as the first of the major radio source databases. I also discuss how this Catalogue evolved over the years from a paper card format to a sophisticated computer database.

APA, Harvard, Vancouver, ISO, and other styles

41

Green, D. A., and N. Madhusudhan. "Search for radio emission from the exoplanets Qatar-1b and WASP-80b near 150 MHz using the giant metrewave radio telescope." Monthly Notices of the Royal Astronomical Society 500, no. 1 (October 15, 2020): 211–14. http://dx.doi.org/10.1093/mnras/staa3208.

Full text

Abstract:

ABSTRACT We present radio observations made towards the exoplanets Qatar-1b and WASP-80b near 150 MHz with the Giant Meterwave Radio Telescope (GMRT). These targets are relatively nearby irradiated giant exoplanets, a hot Jupiter and a hot Saturn, with sizes comparable to Jupiter but different masses and lower densities. Both the targets are expected to host extended H/He envelopes like Jupiter, with comparable or larger magnetic moments. No radio emission was detected from these exoplanets, with 3σ limits of 5.9 and 5.2 mJy for Qatar-1b and WASP-80b, respectively, from these targeted observations. These are considerably deeper limits than those available for exoplanets from wide-field surveys at similar frequencies. We also present archival Very Large Array (VLA) observations of a previously reported radio source close to 61 Vir (which has three exoplanets). The VLA observations resolve the source, which we identify as an extragalactic radio source, i.e. a chance association with 61 Vir. Additionally, we cross-match a recent exoplanet catalogue with the TIFR GMRT Sky Survey ADR1 radio catalogue, but do not find any convincing associations.

APA, Harvard, Vancouver, ISO, and other styles

42

Sokolova, Yu R., and Z. M. Malkin. "Erratum to: “Pulkovo combined catalogue of radio source positions PUL 2013”." Astronomy Letters 40, no. 12 (December 2014): 829. http://dx.doi.org/10.1134/s106377371412007x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

White, Graeme L. "A Catalogue of ‘Southern’ Radio Sources with Accurate Positions." Publications of the Astronomical Society of Australia 10, no. 2 (1992): 140–67. http://dx.doi.org/10.1017/s1323358000019500.

Full text

Abstract:

AbstractA list of 901 radio sources with positional accuracies better than 0.5 arcseconds has been prepared from seventeen lists of radio source positions found in the literature. This compilation includes all such sources south of declination + 48° (the northern declination limit of the Compact Array of the Australia Telescope National Facility). Where available, optical identifications, optical magnitudes and redshifts are given as well as total-power flux densities.

APA, Harvard, Vancouver, ISO, and other styles

44

Wong, O. Ivy, Rachel L. Webster, Meryl Waugh, Virginia A. Kilborn, and Lister Staveley-Smith. "The Northern HIPASS Optical/IR Catalogue (NOIRCAT)." Proceedings of the International Astronomical Union 3, S244 (June 2007): 391–92. http://dx.doi.org/10.1017/s1743921307014421.

Full text

Abstract:

AbstractWe present the Northern HIPASS Optical/Infrared Catalogue (NOIRCAT), an optical/near-infrared counterpart catalogue for the Northern HIPASS catalogue (NHICAT). Of the 1002 sources in NHICAT, 655 (66%) have optical counterparts with matching optical velocities. A further 87 sources have optical counterparts with matching velocities from previous radio emission line surveys. Assuming a dark galaxy to be an isolated HI source with no detectable stars, no candidate dark galaxies have been confirmed.

APA, Harvard, Vancouver, ISO, and other styles

45

Standish, E. M. "Celestial Reference Frames: Definitions and Accuracies." Symposium - International Astronomical Union 129 (1988): 309–15. http://dx.doi.org/10.1017/s0074180900134813.

Full text

Abstract:

The determination of a specific catalogue or ephemeris reference frame is a highly over-determined problem, depending on the particular selection of which coordinates, which objects and at what time(s) the determination is made. The consistency which various determinations exhibit is dependent upon the accuracy of the catalogue or ephemeris itself. This paper discusses the accuracies of the three most prominent celestial reference frames: stellar catalogues, the lunar and planetary ephemerides and the radio source catalogues.The FK4 stellar catalogue contains known systematic errors amounting to a few tenths of an arcsecond; the FK5 will yield nearly an order of magnitude improvement; HIPPARCOS and Space Telescope expectby the mid 1990's optical interferometry should approachwithin a couple of years, tens of micro(!)arcseconds after a couple of decades. Present-day lunar and planetary ephemerides have accuracies at the level offor the moon and inner four planets;for the outer planets. Further observational data will permit continued improvement. Radio source catalogues now show internal consistency of

APA, Harvard, Vancouver, ISO, and other styles

46

Mooney, S., J. Quinn, J. R. Callingham, R. Morganti, K. Duncan, L. K. Morabito, P. N. Best, et al. "Blazars in the LOFAR Two-Metre Sky Survey first data release." Astronomy & Astrophysics 622 (February 2019): A14. http://dx.doi.org/10.1051/0004-6361/201833937.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

47

López-Caniego, Marcos. "The Planck Compact Source Catalogues: present and future." Proceedings of the International Astronomical Union 11, A29B (August 2015): 61. http://dx.doi.org/10.1017/s1743921316004476.

Full text

Abstract:

AbstractThe Planck Collaboration has produced catalogues of radio and sub-millimeter compact sources at the nine Planck frequencies in total intensity and polarization. In particular, the 2015 Second Planck Catalogue of Compact Sources (PCCS2) contains over 45.000 sources detected in the Planck full mission maps. Since the Planck instruments have polarization capabilities in seven of its nine detectors, we were able to measure the polarized flux density of over 600 sources between 30 and 353 GHz. But we are searching not only for compact sources in single frequency maps, and we take advantage of the large frequency coverage of Planck to search for objects with specific emission laws. This is the case of the SZ catalogue of cluster of galaxies (PSZ2), that lists 1653 clusters, 1203 of which are confirmed clusters with clear associations in external data-sets, and the Galactic cold clump catalogue (PGCC) with 13188 objects. The Planck Collaboration has also published a list of high-redshift source candidates (see the report by Ludovic Montier here). These objects are rare bright sub-millimeter sources with an spectral energy distribution peaking between 353 and 857 GHz, and have been detected combining Planck and IRAS data. The colours of most of these objects are consistent with redshifts z>2, a fraction of which could be lensed objects with redshifts between 2 and 4.But new catalogues are foreseen. A multi-frequency compact source catalogue is being produced selecting sources at radio frequencies and studying them across all Planck bands. Multi-frequency catalogues can be difficult to produce in experiments like Planck that have a large frequency coverage and very different resolutions across bands. In some cases, a source can be very bright across the whole Planck frequency range and it is easy to do the associations across channels. However, it frequent to find unrelated sub-millimeter sources within the half-degree beam of the 30 GHz low frequency detector, and the association work must be done with great care. For this purpose, we are combining a multi-frequency detection procedure with a principal component analysis to produce the catalogue. In addition, for those sources where a clear identification can be made, we will attempt to include flux density information from Herschel and other experiments, in particular for those blazars that are bright in radio, sub-mm and even in gamma-ray frequencies, as seen by Fermi. Moreover, Planck has made available to the community the single survey frequency maps that allow astronomers to study the long-term variability of their favourite sources. New functionalities will be also added to the Planck Legacy Archive†, for example a timeline-cutting tool that will allow one to produce full-sky maps from the Planck timelines for specific periods of time allowing for short-term variability studies of compact sources (e.g., flares). The unique frequency coverage of Planck make these catalogues very valuable for other experiments using the Planck compact source catalogues. For example, experiments like QUIJOTE use Planck selected sources to study the impact of polarized radio source emission on their cosmological fields and other CMB experiments will use Planck polarized compact source information for calibration.

APA, Harvard, Vancouver, ISO, and other styles

48

Unewisse, A. M., and R. W. Hunstead. "Powerful Radio Sources in Clusters of Galaxies." Publications of the Astronomical Society of Australia 9, no. 1 (1991): 100–102. http://dx.doi.org/10.1017/s1323358000025054.

Full text

Abstract:

AbstractUsing a complete sample, we have looked for correlations in position between radio sources with S408 ≥ 1 Jy in the Molonglo Reference Catalogue (MRC) and rich clusters of galaxies in the Abell, Corwin and Olowin catalogue (ACO). Within a projected radius of 100 kpc of the cluster centre, we find an overdensity of radio sources similar to that seen by Robertson and Roach (1990). They attributed this feature to centrally located dominant cluster galaxies. We confirm this hypothesis by looking at the morphology of the clusters within this peak and by optically identifying galaxies associated with the radio emission. Due to the relatively high flux density limit imposed, the cluster radio sources in this sample are among the most powerful in the southern sky. The probability of a cluster containing a radio source of this power is found not to depend on cluster richness.

APA, Harvard, Vancouver, ISO, and other styles

49

Jimenez-Gallardo, A., F. Massaro, A. Capetti, M. A. Prieto, A. Paggi, R. D. Baldi, R. Grossova, L. Ostorero, A. Siemiginowska, and S. Viada. "COMP2CAT: hunting compact double radio sources in the local Universe." Astronomy & Astrophysics 627 (July 2019): A108. http://dx.doi.org/10.1051/0004-6361/201935104.

Full text

Abstract:

We present a catalog of compact double radio galaxies (hereafter COMP2CAT) listing 43 edge-brightened radio sources whose projected linear size does not exceed 60 kpc, the typical size of their host galaxies. This is the fifth in a series of radio source catalogs recently created, namely: FRICAT, FRIICAT, FR0CAT, and WATCAT, each of which focuses on a different class of radio galaxies. The main aim of our analysis is to attain a better understanding of sources with intermediate morphologies between FR IIs and FR 0s. COMP2CAT sources were selected from an existing catalog of radio sources based on NVSS, FIRST and SDSS observations because they have (i) edge-brightened morphologies typical of FR IIs, (ii) redshifts z < 0.15, and (iii) projected linear sizes smaller than 60 kpc. With radio luminosities at 1.4 GHz 1038 ≲ L1.4 ≲ 1041 erg s−1, COMP2CAT sources appear as the low radio luminosity tail of FR IIs. However, their host galaxies are indistinguishable from those of large-scale radio sources: they are luminous (−21 ≳ Mr ≳ −24), red, early-type galaxies with black hole masses in the range 107.5 ≲ MBH ≲ 109.5 M⊙. Moreover, all but one of the COMP2CAT sources are optically classifiable as low-excitation radio galaxies, in agreement with being the low radio luminosity tail of FR Is and FR IIs. This catalog of compact double sources, which is ∼47% complete at z < 0.15, can potentially be used to clarify the role of compact double sources in the general evolutionary scheme of radio galaxies.

APA, Harvard, Vancouver, ISO, and other styles

50

Gao, X. Y., P. Reich, L. G. Hou, W. Reich, and J. L. Han. "A Sino-German λ6 cm polarisation survey of the Galactic plane." Astronomy & Astrophysics 623 (March 2019): A105. http://dx.doi.org/10.1051/0004-6361/201834092.

Full text

Abstract:

Context. Large-scale radio continuum surveys provide data to get insights into the physical properties of radio sources. H II regions are prominent radio sources produced by thermal emission of ionised gas around young massive stars. Aims. We identify and analyse H II regions in the Sino-German λ6 cm polarisation survey of the Galactic plane. Methods. Objects with flat radio continuum spectra together with infrared and/or Hα emission were identified as H II regions. For H II regions with small apparent sizes, we cross-matched the λ6 cm small-diameter source catalogue with the radio H II region catalogue compiled by Paladini and the infrared H II region catalogue based on the WISE data. Effelsberg λ21 cm and λ11 cm continuum survey data were used to determine source spectra. High angular resolution data from the Canadian Galactic Plane Survey and the NRAO VLA Sky Survey were used to solve the confusion when low angular resolution observations were not sufficient. Extended H II regions were identified by eye by overlaying the Paladini and the WISE H II regions onto the λ6 cm survey images for coincidences. The TT-plot method was employed for spectral index verification. Results. A total of 401 H II regions were identified and their flux densities were determined with the Sino-German λ6 cm survey data. In the surveyed area, 76 pairs of sources are found to be duplicated in the Paladini H II region catalogue, mainly due to the non-distinction of previous observations with different angular resolutions and 78 objects in their catalogue are misclassified as H II regions, being actually planetary nebulae, supernova remnants, or extragalactic sources that have steep spectra. More than 30 H II regions and H II region candidates from our λ6 cm survey data, especially extended ones, do not have counterparts in the WISE H II region catalogue, of which 9 are identified for the first time. Our results imply that some more Galactic H II regions still await to be discovered and the combination of multi-domain observations is important for H II region identification. Based on the newly derived radio continuum spectra and the evidence of infrared emission, the previously identified SNRs G11.1−1.0, G20.4+0.1 and G16.4−0.5 are believed to be H II regions.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'NVSS radio source catalogue'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles