oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Search Results: 1 - 10 of 2890 matches for " Jon Loveday "
All listed articles are free for downloading (OA Articles)
Page 1 /2890
Display every page Item
The APM Bright Galaxy Catalogue
Jon Loveday
Physics , 1996, DOI: 10.1093/mnras/278.4.1025
Abstract: The APM Bright Galaxy Catalogue lists positions, magnitudes, shapes and morphological types for 14,681 galaxies brighter than $b_J$ magnitude 16.44 over a 4,180 square degree area of the southern sky. Galaxy and stellar images have been located from glass copy plates of the United Kingdom Schmidt Telescope (UKST) IIIaJ sky survey using the Automated Photographic Measuring (APM) facility in Cambridge, England. The majority of stellar images are rejected by the regularity of their image surface brightness profiles. Remaining images are inspected by eye on film copies of the survey material and classed as stellar, multiple stellar, galaxy, merger or noise. Galaxies are further classified as elliptical, lenticular, spiral, irregular or uncertain. The 180 survey fields are put onto a uniform photometric system by comparing the magnitudes of galaxies in the overlap regions between neighbouring plates. The magnitude zero-point, photometric uniformity and photographic saturation are checked with CCD photometry. Finally, the completeness and reliability of the catalogue is assessed using various internal tests and by comparing with several independently constructed galaxy catalogues.
Optical and Near-IR Field Luminosity Functions
Jon Loveday
Physics , 1998,
Abstract: We present preliminary measurements of the b_J and K-band luminosity functions (LFs) of field galaxies obtained from optical and K-band imaging of a sample of galaxies selected from the Stromlo-APM Redshift Survey. The b_J LF is consistent with that previously published from photographic data. The K-band LF has been estimated over a range of 12 magnitudes and is reasonably well fit by a Schechter function with faint-end slope alpha = -1.2.
The Sloan Digital Sky Survey and dark matter
Jon Loveday
Physics , 1998,
Abstract: The Sloan Digital Sky Survey (SDSS) will carry out a digital photometric and spectroscopic survey over pi steradians in the northern Galactic cap. An array of CCD detectors used in drift-scan mode will image the sky in five passbands to a limiting magnitude of r' ~ 23. Selected from the imaging survey, 10^6 galaxies, 10^5 quasars and selected samples of stars will be observed spectroscopically. I describe the current status of the survey, which recently saw first light, and its prospects for constraining models for dark matter in the Universe.
The Sloan Digital Sky Survey: Status and Prospects
Jon Loveday
Physics , 1996,
Abstract: The Sloan Digital Sky Survey (SDSS) is a project to definitively map $\pi$ steradians of the local Universe. An array of CCD detectors used in drift-scan mode will digitally image the sky in five passbands to a limiting magnitude of $r' \sim 23$. Selected from the imaging survey, $10^6$ galaxies and $10^5$ quasars will be observed spectroscopically. I describe the current status of the survey, which is due to begin observations early in 1997, and its prospects for constraining models for dark matter in the Universe.
The local space density of dwarf galaxies
Jon Loveday
Physics , 1997, DOI: 10.1086/304778
Abstract: We estimate the luminosity function of field galaxies over a range of ten magnitudes (-22 < M_{B_J} < -12 for H_0 = 100 km/s/Mpc) by counting the number of faint APM galaxies around Stromlo-APM redshift survey galaxies at known distance. The faint end of the luminosity function rises steeply at M_{B_J} \approx -15, implying that the space density of dwarf galaxies is at least two times larger than predicted by a Schechter function with flat faint-end slope. Such a high abundance of dwarf galaxies at low redshift can help explain the observed number counts and redshift distributions of faint galaxies without invoking exotic models for galaxy evolution.
The K-band luminosity function of nearby field galaxies
Jon Loveday
Physics , 1999, DOI: 10.1046/j.1365-8711.2000.03179.x
Abstract: We present a measurement of the K-band luminosity function (LF) of field galaxies obtained from near-infrared imaging of a sample of 345 galaxies selected from the Stromlo-APM Redshift Survey. The LF is well-fitted over the ten magnitude range -26 < M_K < -16 by a Schechter function with parameters alpha = -1.16 +- 0.19, M* = -23.58 +- 0.42, phi* = 0.012 +- 0.008 Mpc^-3 assuming a Hubble constant of H_0 = 100 km/s/Mpc. We have also estimated the LF for two subsets of galaxies subdivided by the equivalent width of the Halpha emission line at EW(Halpha) = 10A. There is no significant difference in LF shape between the two samples, although there is a hint (~1 sigma significance) that emission line galaxies (ELGs) have M* roughly one magnitude fainter than non-ELGs. Contrary to the optical LF, there is no difference in faint-end slope alpha between the two samples.
The Faint End of the Luminosity Function in the Field
Jon Loveday
Physics , 1998,
Abstract: I review the current observational status of the faint end of the optical luminosity function of field galaxies at low redshift. There is growing evidence for an excess number of dwarf galaxies that is not well fit by a single Schechter function. These dwarf galaxies tend to be of late morphological and spectral type, blue in colour, of low surface brightness and currently undergoing significant star formation.
The Sloan Digital Sky Survey
Jon Loveday,for the SDSS collaboration
Physics , 2002, DOI: 10.1080/0010751021000019166
Abstract: The Sloan Digital Sky Survey (SDSS) is making a multi-colour, three dimensional map of the nearby Universe. The survey is in two parts. The first part is imaging one quarter of the sky in five colours from the near ultraviolet to the near infrared. In this imaging survey we expect to detect around 50 million galaxies to a magnitude limit g ~ 23. The second part of the survey, taking place concurrently with the imaging, is obtaining spectra for up to 1 million galaxies and 100,000 quasars. From these spectra we obtain redshifts and hence distances, in order to map out the three-dimensional distribution of galaxies and quasars in the Universe. These observations will be used to constrain models of cosmology and of galaxy formation and evolution. This article describes the goals and methods used by the SDSS, the current status of the survey, and highlights some exciting discoveries made from data obtained in the first two years of survey operations.
Tracing luminous and dark matter with the Sloan Digital Sky Survey
Jon Loveday,for the SDSS collaboration
Physics , 2001,
Abstract: I summarize the scientific goals and current status of the Sloan Digital Sky Survey, briefly describe the Early Data Release, and discuss some recent scientific results obtained from commissioning data which are apposite to the distribution of luminous and dark matter in the Universe.
The Sloan Digital Sky Survey
Jon Loveday,Jeff Pier
Physics , 1998,
Abstract: The Sloan Digital Sky Survey (SDSS) will carry out a digital photometric and spectroscopic survey over pi steradians in the northern Galactic cap. An array of CCD detectors used in drift-scan mode will image the sky in five passbands to a limiting magnitude of r' ~ 23. Selected from the imaging survey, 10^6 galaxies, 10^5 quasars and selected samples of stars will be observed spectroscopically. In addition, a smaller (225 deg^2), deeper, southern survey will reach ~2.0 magnitudes fainter and will contain a wealth of information about variable sources, supernovae and proper motions. We describe the current status of the survey, which recently saw first light, and its prospects for constraining cosmological models.
Page 1 /2890
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.