Status Report

The Hubble Space Telescope WFPC2 B-Band Parallel Survey: A Study of Galaxy Morphology for 18 < B < 27 mag

By SpaceRef Editor
January 13, 2003
Filed under , ,

Astrophysics, abstract

From: Seth Cohen <[email protected]>
Date: Fri, 10 Jan 2003 23:40:06 GMT (172kb)

The Hubble Space Telescope WFPC2 B-Band Parallel Survey: A Study of
Galaxy Morphology for 18 < B < 27 mag

Seth H. Cohen (1),
Rogier A. Windhorst (1),
Stephen C. Odewahn (1),
Claudia A. Chiarenza (1),
Simon P. Driver (2) ((1) Arizona State University, (2) Research School of Astronomy and Astrophysics)

Comments: Accepted by Astronomical Journal, 29 pages, 7 figs, 2 tables, uses

[Abridged] We present the results of the HST B-Band Parallel Survey (BBPS).
It covers 0.0370 sq. deg. and consists of 31 shallow (4-6 orbit), randomly
selected high latitude HST WFPC2 parallel fields with images taken in both the
B (F450W) and I (F814W) filters. The goal is to morphologically classify the
galaxies in a homogeneous manner and study galaxy properties as a function of
type and B-band magnitude for 18<b_J<23.5 mag. The B-band selected galaxies are
classified using an artificial neural network (ANN) galaxy classifier on the
higher S/N I-band images. These provide reliable types for I<24 mag (or b_J<26
mag), since these I-band classifications are less subject to the uncertain
redshifted rest-frame UV morphology. The ANN classification depends on the
shape of the surface brightness profile, but not on color. These results are
combined with deeper studies in the HDF-N and the deep WFPC2 field surrounding
the radio galaxy 53W002, for which galaxies have been classified to b_J<27 mag.
The galaxy counts for the combined B-band selected samples show adequate
statistics for a range 19<b_J<27 mag, and are in good agreement with other
studies in the flux range where they overlap, while showing improved statistics
at the bright end. The galaxies are divided into 3 morphological classes: E/S0,
Sabc and Sd/Irr, and the B-band counts are presented for each class, as well as
the total counts. The faint end of the counts is dominated by the Sd/Irr
galaxies. These type dependent counts are compared to models based on local
luminosity functions which include the effects of the Cosmological Constant.
The BBPS sample, along with the two deeper fields, is used to delineate the
general trends of effective radius and (B-I) color as a function of both
morphological type and apparent magnitude 18<b_J<27 mag.

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cited by, arXiv reformatted)

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