Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/43377

Download PDF (Accepted manuscript) (Adobe Acrobat PDF, -1 bytes)

Title

The morphological identification of the rapidly evolving population of faint galaxies

Author(s)

Glazebrook, Karl;  Ellis, Richard S.;  Santiago, Basilio X.;  Griffiths, Richard

Abstract

The excess numbers of blue galaxies at faint magnitudes are a long-standing cosmological puzzle. We present new number-magnitude counts as a function of galactic morphology from the first deep fields of the Cycle 4 Hubble Space Telescope Medium Deep Survey project. From a sample of 301 galaxies we define counts for elliptical, spiral and irregular/peculiar galaxies to I=22. We find two principal results. Firstly the elliptical and spiral galaxy counts both follow the predictions of high-normalisation no-evolution models at all magnitudes, indicating that regular Hubble types evolve only slowly to z∼ 0.5. Secondly we find that irregular/peculiar galaxies, including multiple-peaked, possibly merging, objects, have a very steep number-magnitude relation and greatly exceed predictions based on proportions in local surveys. These systems make up half the total counts by I=22 and imply the rapidly-evolving component of the faint galaxy population has been identified.

Publication type

Journal article

Source

Monthly Notices of the Royal Astronomical Society, Vol. 275, no. 2 (Jul 1995), pp. L19-L22

Publication year

1995

Keyword(s)

APM redshift survey;  Cosmology;  Counts;  Evolution;  Galaxies;  Luminosity function;  Number;  Observations;  Peculiar;  Structure;  Surveys;  Universe

Publisher

Wiley-Blackwell Publishing

ISSN

0035-8711

Publisher URL

http://www.wiley.com/

Copyright

Copyright © 1995 RAS. The accepted manuscript of the paper is reproduced here in accordance with the copyright policy of the publisher. The definitive publication is available at www.interscience.wiley.com.

Full text

Peer reviewed