The radio source population at high frequency: follow-up of the 15-GHz 9C survey     

R. C. Bolton  G. Cotter  G. G. Pooley  J. M. Riley  E. M. Waldram  C. J. Chandler  B. S. Mason  T. J. Pearson  A. C. S. Readhead 《Monthly notices of the Royal Astronomical Society》2004,354(2):485-521

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Color-Redshift Relations and Photometric Redshift Estimations of Quasars in Large Sky Surveys     

Xue-Bing Wu  Wei Zhang  Xu Zhou Department of Astronomy  School of Physics  Peking University  Beijing  National Astronomical Observatories  Chinese Academy of Sciences  Beijing 《中国天文和天体物理学报》2004,4(1):17-27

With a recently constructed composite quasar spectrum and the X2 minimization technique, we describe a general method for estimating the photometric redshifts of a large sample of quasars by deriving theoretical color-redshift relations and comparing the theoretical colors with the observed ones. We estimated the photometric redshifts from the 5-band SDSS photometric data of 18678 quasars in the first major data release of SDSS and compared them with their spectroscopic redshifts. The difference is less than 0.1 for 47% of the quasars and less than 0.2 for 68%. Based on the calculation of the theoretical color-color diagrams of stars, galaxies and quasars both on the SDSS system and on the BATC system, we expect that we would be able to select candidates of high redshift quasars more efficaciously with the latter than with the former, provided the BATC survey can detect objects with magnitudes fainter than 21.  相似文献   

Intercluster Filaments of Galaxies Programme: pilot study survey and results     

Kevin A. Pimbblet  Michael J. Drinkwater 《Monthly notices of the Royal Astronomical Society》2004,347(1):137-143

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A new algorithm for the detection of intercluster galaxy filaments using galaxy orientation alignments     

Kevin A. Pimbblet 《Monthly notices of the Royal Astronomical Society》2005,358(1):256-262

We present a new algorithm for detecting intercluster galaxy filaments based upon the assumption that the orientations of constituent galaxies along such filaments are non-isotropic. We apply the algorithm to the 2dF Galaxy Redshift Survey catalogue and find that it readily detects many straight filaments between close cluster pairs. At large intercluster separations  (≫15  h ⁻¹ Mpc)  , we find that the detection efficiency falls quickly, as it also does with more complex filament morphologies. We explore the underlying assumptions and suggest that it is only in the case of close cluster pairs that we can expect galaxy orientations to be significantly correlated with filament direction.  相似文献   

Short time-scale variability in the Faint Sky Variability Survey     

L. Morales-Rueda  P. J. Groot  T. Augusteijn  G. Nelemans  P. M. Vreeswijk  E. J. M. van den Besselaar 《Monthly notices of the Royal Astronomical Society》2006,371(4):1681-1692

We present the V -band variability analysis of the point sources in the Faint Sky Variability Survey on time-scales from 24 min to tens of days. We find that about one per cent of the point sources down to   V = 24  are variables. We discuss the variability-detection probabilities for each field depending on field sampling, amplitude and time-scale of the variability. The combination of colour and variability information allows us to explore the fraction of variable sources for different spectral types. We find that about 50 per cent of the variables show variability time-scales shorter than 6 h. The total number of variables is dominated by main-sequence sources. The distribution of variables with spectral type is fairly constant along the main sequence, with 1 per cent of the sources being variable, except at the blue end of the main sequence, between spectral types F0 and F5, where the fraction of variable sources increases to about 2 per cent. For bluer sources, above the main sequence, this percentage increases to about 3.5. We find that the combination of the sampling and the number of observations allows us to determine the variability time-scales and amplitudes for a maximum of 40 per cent of the variables found. About a third of the total number of short time-scale variables found in the survey were not detected in either B or/and I band. These show a similar variability time-scale distribution to that found for the variables detected in all three bands.  相似文献   

Cleaning sky survey data bases using Hough transform and renewal string approaches     

A. J. Storkey  N. C. Hambly  C. K. I. Williams  R. G. Mann 《Monthly notices of the Royal Astronomical Society》2004,347(1):36-51

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Erratum: Near-infrared and optical luminosity functions from the 6dF Galaxy Survey     

《Monthly notices of the Royal Astronomical Society》2006,370(3):1583-1584

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A deep Giant Metre-wave Radio Telescope 610-MHz survey of the 1^HXMM–Newton/Chandra survey field     

D. Moss  N. Seymour  I. M. McHardy  T. Dwelly  M. J. Page  N. S. Loaring 《Monthly notices of the Royal Astronomical Society》2007,378(3):995-1006

We present the results of a deep 610-MHz survey of the 1 ^H XMM–Newton / Chandra survey area with the Giant Metre-wave Radio Telescope. The resulting maps have a resolution of ∼7 arcsec and an rms noise limit of 60 μJy. To a 5σ detection limit of 300 μJy, we detect 223 sources within a survey area of 64 arcmin in diameter. We compute the 610-MHz source counts and compare them to those measured at other radio wavelengths. The well-known flattening of the Euclidean-normalized 1.4-GHz source counts below ∼2 mJy, usually explained by a population of starburst galaxies undergoing luminosity evolution, is seen at 610 MHz. The 610-MHz source counts can be modelled by the same populations that explain the 1.4-GHz source counts, assuming a spectral index of −0.7 for the starburst galaxies and the steep spectrum active galactic nucleus (AGN) population. We find a similar dependence of luminosity evolution on redshift for the starburst galaxies at 610 MHz as is found at 1.4 GHz (i.e.  ' Q '= 2.45^+0.3_−0.4  ).  相似文献   

The local hole in the galaxy distribution: evidence from 2MASS     

W. J. Frith  G. S. Busswell  R. Fong  N. Metcalfe  T. Shanks 《Monthly notices of the Royal Astronomical Society》2003,345(3):1049-1056

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BOOK REVIEWS     

《The Professional geographer》1988,40(1):116-131

Books reviewed in this article: Boundary Control and Legal Priniciples . Curtis M. Brown , Walter G. Robillard and Donald A. Wilson . Lost Initiatives: Canada's Forest Industries, Forest Policy, and Forest Conservation . R. Peter Gillis and Thomas R. Roach . The Navajo Atlas: Resources, People, and History of the Dine Bikeyah . James M. Goodman . The City and the Sign . M. Gottdiener AND Alexandros Ph . Lagopoulos , EDS. The Comfortable House: North American Suburban Architecture 1890–1930 . Alan Gowans . Arabic-Islamic Cities. Building and Planning Principles . Besim Salim Hakim . Contemporary Climatology . Ann Henderson -Sellers and Peter J. Robinson . A Trace of Desert Waters . Samuel G. Houghton . Geography, Resources and Environment. Vol. 1: Selected Writings of Gilbert F. White. Vol. 2: Themes from the Work of Gilbert F. White . Robert W. Kates AND Ian Burton , ED. Spatial Dimensions of Unemployment and Underemployment (A Case Study of Rural Punjab) . Gopal Krishan . Maps of the Holy Land: Cartobibliography of Printed Maps, 1475–1900 . Compiled by Eran Laor , assisted by Shoshana Klein . The Geography of Third World Cities . Stella Lowder . A Perspective on U.S. Farm Problems and Agricultural Policy . Lance Mc Kinzie , Timothy G. Baker AND Wallace E. Tyner . Soil Erosion and Its Control. R.P.C . Morgan , ED Geopolitics . Patrick O'Sullivan . Landscape, Meanings and Values . Edmund C. Penning -Rowsell AND David Lowenthal , EDS.  相似文献