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Title:
The ROSAT Wide Field Camera all-sky survey of extreme-ultraviolet sources. I - The Bright Source Catalogue
Authors:
POUNDS, K. A.; ALLAN, D. J.; BARBER, C.; BARSTOW, M. A.; BERTRAM, D.; BRANDUARDI-RAYMONT, G.; BREBNER, G. E. C.; BUCKLEY, D.; BROMAGE, G. E.; COLE, R. E.; COURTIER, M.; CRUISE, A. M.; CULHANE, J. L.; DENBY, M.; DONOGHUE, D. O.; DUNFORD, E.; GEORGANTOPOULOS, I.; GOODALL, C. V.; GONDHALEKAR, P. M.; GOURLAY, J. A.; HARRIS, A. W.; HASSALL, B. J. M.; HELLIER, C.; HODGKIN, S.; JEFFRIES, R. D.; KELLETT, B. J.; KENT, B. J.; LIEU, R.; LLOYD, C.; MCGALE, P.; MASON, K. O.; MATTHEWS, L.; MITTAZ, J. P. D.; PAGE, C. G.; PANKIEWICZ, G. S.; PIKE, C. D.; PONMAN, T. J.; PUCHNAREWICZ, E. M.; PYE, J. P.; QUENBY, J. J.; RICKETTS, M. J.; ROSEN, S. R.; SANSOM, A. E.; SEMBAY, S.; SIDHER, S.; SIMS, M. R.; STEWART, B. C.; SUMNER, T. J.; VALLANCE, R. J.; WATSON, M. G.; WARWICK, R. S.; WELLS, A. A.; WILLINGALE, R.; WILLMORE, A. P.; WILLOUGHBY, G. A.; WONNACOTT, D.
Affiliation:
AA(Leicester Univ., United Kingdom) AB(Birmingham Univ., United Kingdom) AD(Leicester Univ., United Kingdom) AE(Birmingham Univ., United Kingdom) AF(London, Univ. College, Dorking, United Kingdom) AG(Birmingham Univ., United Kingdom) AH(South African Astronomical Observatory, Observatory, South Africa) AI(Rutherford Appleton Lab., Didcot, United Kingdom) AJ(Leicester Univ., United Kingdom)
Journal:
Royal Astronomical Society, Monthly Notices (ISSN 0035-8711), vol. 260, no. 1, p. 77-102.
Publication Date:
01/1993
Category:
Astronomy
Origin:
STI
NASA/STI Keywords:
FAR ULTRAVIOLET RADIATION, ROSAT MISSION, SKY SURVEYS (ASTRONOMY), ULTRAVIOLET ASTRONOMY, WHITE DWARF STARS, ACTIVE GALACTIC NUCLEI, ASTRONOMICAL CATALOGS, ASTRONOMICAL SPECTROSCOPY, LATE STARS, SPACEBORNE ASTRONOMY, STELLAR ACTIVITY, X RAY BINARIES
Bibliographic Code:
1993MNRAS.260...77P

Abstract

First comprehensive results from an initial processing of the ROSAT Wide Field Camera all-sky survey for cosmic sources of extreme-ultraviolet radiation are presented. The reduction of the survey data has yielded a catalog of 383 relatively bright EUV sources, forming the WFC Bright Source Catalogue. Details of the EUV source positions and count rates are given, as are optical identifications where known. It is found that the log N-log S distributions are unusually flat for the white dwarf stars, but almost Euclidean for the nearby main-sequence late-type stars. The sky distribution of identified white dwarfs is highly nonuniform, suggesting gross variations in the opacity of the interstellar medium within about 100 pc.

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Title:
THE U.K. DEEP AND MEDIUM SURVEYS WITH ROSAT - LOG/N-LOG/S RELATION
Authors:
BRANDUARDI RAYMONT, G.; MASON, K. O.; WARWICK, R. S.; CARRERA, F. J.; GRAFFAGNINO, V. G.; MITTAZ, J. P. D.; PUCHNAREWICZ, E. M.; SMITH, P. J.; BARBER, C. R.; POUNDS, K. A.; STEWART, G. C.; MCHARDY, I. M.; JONES, L. R.; MERRIFIELD, M. R.; FABIAN, A. C.; MCMAHON, R. G.; WARD, M. J.; GEORGE, I. M.; JONES, M. H.; LAWRENCE, A.; ROWAN-ROBINSON, M.
Journal:
R.A.S. MONTHLY NOTICES V.270, NO. 4/OCT15, P. 947, 1994
Publication Date:
10/1994
Origin:
KNUDSEN; NED
Bibliographic Code:
1994MNRAS.270..947B

Abstract

We have carried out a soft X-ray survey of the sky using the ROSAT Position Sensitive Proportional Counter (PSPC) in a region of very low Galactic column density (N_H_ = 6-9 x 10^19^ cm^-2^). The data consist of a deep >70 ks pointing (the Deep Survey) and six pointings at lower sensitivity (13-20 ks; the Medium Survey). We detect a total of 141 sources over the 0.9 deg^2^ of sky area used. The faintest source detected has a flux of 3.2 x 10^-15^ erg cm^-2^ s^-1^ (0.5-2.0 keV). We present the source number-flux distribution, and we compare it with the distributions constructed from other ROSAT observations and from surveys carried out with X-ray instruments operating at higher energies. We estimate the contribution of the resolved sources to the soft X-ray background by direct comparison of their integrated spectrum with that of the diffuse background: 44 per cent of the extragalactic X-ray background between 0.5 and 2.0 keV is resolved directly into discrete sources whose average spectrum is steeper than that of the background. Integration of our number-flux relation to infinite flux produces a background resolved fraction of 44+/- _5_^56^ per cent (0.5-2.0 keV). Limits on the slope of the log N-log S curve at very faint fluxes are set by the measured value of the X-ray background.

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Title:
Discovery of a major new contributor to the X-ray background at very faint X-ray fluxes
Authors:
JONES, L. R.; MCHARDY, I.; MERRIFIELD, M.; MASON, K. O.; BRANDUARDI-RAYMONT, G.; SMITH, P.; ABRAHAM, R.; LUPPINO, G.
Affiliation:
AA(NASA/GSFC), AB(University of Southampton, UK), AD(MSSL, UK), AG(DAO, Canada), AH(IOA, Hawaii)
Journal:
Bull. American Astron. Soc., 185, #119.04
Publication Date:
12/1994
Origin:
AAS
Abstract Copyright:
(c) 1994: American Astronomical Society
Bibliographic Code:
1994AAS...18511904J

Abstract

We describe results from the deepest optically identified ROSAT survey yet performed, designed to resolve as much of the soft X-ray background as possible. The ROSAT PSPC exposure of 110 ksec reaches a limiting X-ray flux of 2x10(-15) erg cm(-2) s(-1) (0.5-2 keV). At this flux limit we have currently optically identified a total of 84 sources, representing 82% completeness. At relatively bright fluxes (>10(-14) erg cm(-2) s(-1) ) QSOs dominate the survey. However below a flux of 5x10(-15) erg cm(-2) s(-1) a population of narrow emission line galaxies dominates. The number counts of these faint galaxies rise steeply at faint X-ray fluxes and they are clearly a major new contributor to the X-ray background. They contribute 9-20% of the X-ray background at our flux limit. Optical emission line diagnostics indicate that they are a mixture of Sy2 galaxies, possible starburst galaxies and relatively normal galaxies at their redshifts of z~0.2-0.5.

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Title:
A study of the interstellar dust distribution in regions of low total column density
Authors:
JONES, M. H.; ROWAN-ROBINSON, M.; BRANDUARDI-RAYMONT, G.; SMITH, P.; PEDLAR, A.; WILLACY, K.
Affiliation:
AA(Astronomy Unit, School of Mathematical Sciences, Queen Mary and Westfield College, Mile End Road, London E1 4NS, UK ), AB(Astronomy Unit, School of Mathematical Sciences, Queen Mary and Westfield College, Mile End Road, London E1 4NS, UK ), AC(Mullard Space Science Laboratory, University College London, Holmbury Saint Mary, Dorking, Surrey RH5 6NT, UK ), AD(Mullard Space Science Laboratory, University College London, Holmbury Saint Mary, Dorking, Surrey RH5 6NT, UK ), AE(Nuffield Radio Astronomy Laboratories, Jodrell Bank, Macclesfield, Cheshire SK11 9DL, UK ), AF(Nuffield Radio Astronomy Laboratories, Jodrell Bank, Macclesfield, Cheshire SK11 9DL, UK )
Journal:
Monthly Notices of the Royal Astronomical Society, Volume 277, Issue 4, pp. 1587-1598.
Publication Date:
12/1995
Origin:
MNRAS; KNUDSEN
MNRAS Keywords:
ISM: CLOUDS, DUST, EXTINCTION, INFRARED: ISM: CONTINUUM, RADIO LINES: ISM
Abstract Copyright:
(c) 1995 The Royal Astronomical Society
Bibliographic Code:
1995MNRAS.277.1587J

Abstract

We present a study of the distribution of interstellar dust and HI, using 100-mum and 21-cm measurements, for two regions of very low total column density. We find that down to the spatial resolution of the HI data (12 arcmin), there is good agreement between dust and neutral gas features. Although the 100-mum data show substantial variance on scales corresponding to the detector resolution (5 arcmin), it is found that this is consistent with that expected from an extrapolation of the 100-mum luminosity function to faint (<1 Jy) sources. We find no evidence for structure in the cirrus on scales of ~5-10 arcmin. The effect on the transmission of soft X-rays arising from such structure that may be present is found to be negligible.

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Title:
X-ray QSO evolution from a very deep ROSAT survey
Authors:
JONES, L. R.; MCHARDY, I. M.; MERRIFIELD, M. R.; MASON, K. O.; SMITH, P. J.; ABRAHAM, R. G.; BRANDUARDI-RAYMONT, G.; NEWSAM, A. M.; ROMERO-COLMENERO, E.
Journal:
Proc. 'Röntgenstrahlung from the Universe', eds. Zimmermann, H.U.; Trümper, J.; and Yorke, H.; MPE Report 263, p. 457-458
Publication Date:
02/1996
Origin:
MPE
Bibliographic Code:
1996rftu.proc..457J

Abstract

Not Available

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Title:
X-ray QSO evolution from a very deep ROSAT survey
Authors:
JONES, L. R.; MCHARDY, I. M.; MERRIFIELD, M. R.; MASON, K. O.; SMITH, P. J.; ABRAHAM, R. G.; BRANDUARDI-RAYMONT, G.; NEWSAM, A. M.; DALTON, G.; ROWAN-ROBINSON, M.; LUPPINO, G.
Affiliation:
AA(Code 660.2, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA ), AB(Department of Physics, The University, Southampton SO17 1BJ ), AC(Department of Physics, The University, Southampton SO17 1BJ ), AD(Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking RH5 6NT ), AE(Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking RH5 6NT ), AF(Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0EZ ), AG(Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking RH5 6NT ), AH(Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking RH5 6NT ), AI(Department of Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH ), AJ(Astrophysics Group, Blackett Laboratory, Imperial College, London SW7 2BZ ), AK(Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA )
Journal:
Monthly Notices of the Royal Astronomical Society, Volume 285, Issue 3, pp. 547-560.
Publication Date:
03/1997
Origin:
MNRAS
MNRAS Keywords:
SURVEYS, GALAXIES: ACTIVE, QUASARS: GENERAL, COSMOLOGY: OBSERVATIONS, DIFFUSE RADIATION, X-RAYS: GALAXIES
Abstract Copyright:
(c) 1997 The Royal Astronomical Society
Bibliographic Code:
1997MNRAS.285..547J

Abstract

In the deepest optically identified X-ray survey yet performed, we have identified 32 X-ray-selected QSOs to a flux limit of 2x10^-15 erg cm^-2 s^-1 (0.5-2keV). The survey, performed with the ROSAT Position Sensitive Proportional Counter (PSPC), has 89 per cent spectroscopic completeness. The QSO log(N)-log(S) relation is found to have a break to a flat slope at faint fluxes. The surface density of QSOs at the survey limit is 230+/-40 per square degree, the largest so far of any QSO survey. We use this survey to measure the QSO X-ray luminosity function at low luminosities (L_X<10^44.5 ergs^-1) and high redshifts (1<z<2.5). The highest redshift QSO in the survey has z=3.4. Combined with the QSOs from the Einstein Extended Medium Sensitivity Survey (EMSS) at bright fluxes, we find pure luminosity evolution of the form L_X~(1+z)^3.0(+0.2,-0.3) is an adequate description of the evolution of the X-ray luminosity function at low redshifts. A redshift cut-off in the evolution is required at z=1.4^+0.4_-0.17 (for q_0=0.5). We discuss the form of this evolution, its dependence on the model assumed and the errors on the derived parameters. We show that most previous X-ray surveys, including the EMSS, are consistent with a power-law luminosity evolution index of 3.0. The contribution of QSOs to the 1-2keV cosmic X-ray background is found to be between 31 and 51 per cent.

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Title:
The UK ROSAT Deep Survey
Authors:
MCHARDY, I. M.; JONES, L. R.; MERRIFIELD, M. R.; MASON, K. O.; NEWSAM, A. M.; ABRAHAM, R. G.; DALTON, G. B.; CARRERA, F.; SMITH, P. J.; ROWAN-ROBINSON, M.; WEGNER, G. A.; PONMAN, T. J.; LEHTO, H. J.; BRANDUARDI-RAYMONT, G.; LUPPINO, G. A.; EFSTATHIOU, G.; ALLAN, D. J.; QUENBY, J. J.
Journal:
Astronomische Nachrichten, vol. 319, no. 1, p. 51.
Publication Date:
00/1998
Origin:
AN
Abstract Copyright:
(c) 1998: Astronomische Nachrichten
Bibliographic Code:
1998AN....319...51M

Abstract

We present a summary of the identification content of the UK ROSAT Deep Survey. The survey is based on a 115ksec PSPC observation and comprises a sample of 70 sources to a flux limit of 2 x 10(-15) ergs cm(-2) s(-1) (0.5-2 keV). At bright fluxes the survey is dominated by broad line QSOs, at intermediate fluxes it contains a number of groups and clusters of galaxies, but at faint fluxes the survey contains many galaxies with narrow optical emission lines (NELGs). The average X-ray spectrum of the NELGs is harder than that of the QSOs and similar to that of the X-ray background. The NELGs have optical spectra similar to the majority of the field galaxy population in the same redshift range and may simply be the more luminous members of the emission line field galaxy population. Based on optical line ratios and X-ray/optical ratios, the NELGs, both as a sample and within individual galaxies, appear to be a mixture of starburst galaxies and true AGN.

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Title:
The origin of the cosmic soft X-ray background: optical identification of an extremely deep ROSAT survey
Authors:
MCCHARDY, I. M. ; JONES, L. R.; MERRIFIELD, M. R.; MASON, K. O.; NEWSAM, A. M.; ABRAHAM, R. G.; DALTON, G. B.; CARRERA, F.; SMITH, P. J.; ROWAN-ROBINSON, M.; WEGNER, G. A.; PONMAN, T. J.; LEHTO, H. J.; BRANDUARDI-RAYMONT, G.; LUPPINO, G. A.; EFSTATHIOU, G. ; ALLAN, D. J.; QUENBY, J. J.
Affiliation:
AA(Department of Physics and Astronomy, The University, Southampton SO17 1BJ ), AB(Department of Physics and Astronomy, The University, Southampton SO17 1BJ ), AC(Department of Physics and Astronomy, The University, Southampton SO17 1BJ ), AD(Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking RH5 6NT ), AE(Department of Physics and Astronomy, The University, Southampton SO17 1BJ ), AF(Dominion Astrophysical Observatory, 5071 West Saanich Road, Victoria V8X 4M6, British Columbia, Canada ), AG(Department of Astrophysics, Keble Road, Oxford OX1 3RH ), AH(Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking RH5 6NT ), AI(Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking RH5 6NT ), AJ(Department of Physics, Imperial College, Prince Consort Road, London SW7 2BZ ), AK(Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755, USA ), AL(School of Physics and Space Research, University of Birmingham, Edgbaston, Birmingham B15 2TT ), AM(Tuorla Observatory, Turku University, Piikkio, FIN 21500, Finland ), AN(Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking RH5 6NT ), AO(University of Hawaii, Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822, USA ), AP(Instituto de Fisica de Cantabria, 39005 Santander, Spain ), AQ(School of Physics and Space Research, University of Birmingham, Edgbaston, Birmingham B15 2TT ), AR(Department of Physics, Imperial College, Prince Consort Road, London SW7 2BZ )
Journal:
Monthly Notices of the Royal Astronomical Society, Volume 295, Issue 3, pp. 641-671.
Publication Date:
04/1998
Origin:
MNRAS
MNRAS Keywords:
GALAXIES: ACTIVE, GALAXIES: CLUSTERS: GENERAL, QUASARS: EMISSION LINES, DIFFUSE RADIATION, X-RAYS: GALAXIES, X-RAYS: GENERAL
Abstract Copyright:
(c) 1998 The Royal Astronomical Society
Bibliographic Code:
1998MNRAS.295..641M

Abstract

We present the results of the deepest optically identified X-ray survey yet made. The X-ray survey was obtained with the ROSAT position-sensitive proportional counter (PSPC) and reaches a flux limit of 1.6x10^-15 erg cm^-2 s^-1 (0.5-2.0 keV). Above a flux limit of 2x10^-15 erg cm^-2 s^-1 we define a complete sample of 70 sources, of which 59 are identified. For a further five sources we have tentative identifications and for a further four the X-ray error boxes are blank to R=23 mag. At brighter fluxes (>=10^-14 erg cm^-2 s^-1) we confirm the results of previous less deep X-ray surveys, with 84 per cent of our sources being QSOs. However, at the faint flux limit the survey is dominated by a population of galaxies with narrow emission lines (NELGs). In addition, at intermediate fluxes we find a small number of groups and clusters of galaxies at redshifts generally >0.3. Most of these groups are poor systems of low X-ray luminosity and the number that we find is consistent with a zero evolutionary scenario, unlike the situation for high-luminosity clusters at the same redshift. To a flux limit of 2x10^-15 erg cm^-2 s^-1, QSOs contribute >31 per cent of the cosmic soft X-ray background (XRB), groups/clusters contribute ~10 per cent and NELGs contribute ~8 per cent. However, the QSO differential source count slope below 10^-14 erg cm^-2 s^-1 is ~-1.4, severely sub-Euclidean, as is the (poorly defined) group/cluster slope, whereas the differential NELG slope is close to Euclidean (~-2.4). If the NELG source counts continue to rise at that slope, all of the remaining cosmic soft XRB will be explained by a flux limit of ~1-2x10^-16 erg cm^-2 s^-1, with NELGs contributing about one quarter of the XRB. The average NELG X-ray spectrum is harder than that of the QSOs, and similar to that of the remaining unresolved cosmic XRB, suggesting that NELGs will also be substantial contributors to the XRB at higher energies. The observed NELGs lie in the redshift range 0.1-0.6 and have M_R=-20 to -23, approximately 3 mag more luminous than typical field galaxies. They have predominantly blue colours, and some are definitely spirals, but the presence of some ellipticals cannot yet be ruled out. Many are in interacting or disturbed systems. The NELGs have optical spectra similar to those of the majority of the field galaxy population at a similar redshift and may simply be the more luminous members of the emission-line field galaxy population. Based on optical line ratios and X-ray/optical flux ratios, the NELGs, both as a sample and within individual galaxies, appear to be a mixture of starburst galaxies and true active galactic nuclei (AGN).