3 research outputs found
HI Selected Galaxies in the Sloan Digital Sky Survey I: Optical Data
We present the optical data for 195 HI-selected galaxies that fall within
both the Sloan Digital Sky Survey (SDSS) and the Parkes Equatorial Survey (ES).
The photometric quantities have been independently recomputed for our sample
using a new photometric pipeline optimized for large galaxies, thus correcting
for SDSS's limited reliability for automatic photometry of angularly large or
low surface brightness (LSB) galaxies. We outline the magnitude of the
uncertainty in the SDSS catalog-level photometry and derive a quantitative
method for correcting the over-sky subtraction in the SDSS photometric
pipeline. The main thrust of this paper is to present the ES/SDSS sample and
discuss the methods behind the improved photometry, which will be used in
future scientific analysis. We present the overall optical properties of the
sample and briefly compare to a volume-limited, optically-selected sample.
Compared to the optically-selected SDSS sample (in the similar volume),
HI-selected galaxies are bluer and more luminous (fewer dwarf ellipticals and
more star formation). However, compared to typical SDSS galaxy studies, which
have their own selection effects, our sample is bluer, fainter and less
massive.Comment: 14 pages, 8 Figures, accepted for publication in AJ. Complete tables
will be available in the AJ electronic version and on the Vizier sit
HI Selected Galaxies in the Sloan Digital Sky Survey II: The Colors of Gas-Rich Galaxies
We utilize color information for an HI-selected sample of 195 galaxies to
explore the star formation histories and physical conditions that produce the
observed colors. We show that the HI selection creates a significant offset
towards bluer colors that can be explained by enhanced recent bursts of star
formation. There is also no obvious color bimodality, because the HI selection
restricts the sample to bluer, actively star forming systems, diminishing the
importance of the red sequence. Rising star formation rates are still required
to explain the colors of galaxies bluer than g-r < 0.3. We also demonstrate
that the colors of the bluest galaxies in our sample are dominated by emission
lines and that stellar population synthesis models alone (without emission
lines) are not adequate for reproducing many of the galaxy colors. These
emission lines produce large changes in the r-i colors but leave the g-r color
largely unchanged. In addition, we find an increase in the dispersion of galaxy
colors at low masses that may be the result of a change in the star formation
process in low-mass galaxies.Comment: 12 pages, 16 figures, published in AJ (138, 796); replaced Figure 16
with higher resolution versio
The Northern HIPASS catalogue - Data presentation, completeness and reliability measures
The Northern HIPASS catalogue (NHICAT) is the northern extension of the
HIPASS catalogue, HICAT (Meyer et al. 2004). This extension adds the sky area
between the declination range of +2 deg < dec. < +25.5 deg to HICAT's
declination range of -90 deg < dec. < +2 deg. HIPASS is a blind HI survey using
the Parkes Radio Telescope covering 71% of the sky (including this northern
extension) and a heliocentric velocity range of -1,280 km/s to 12,700 km/s .
The entire Virgo Cluster region has been observed in the Northern HIPASS. The
galaxy catalogue, NHICAT, contains 1002 sources with v_hel > 300 km/s . Sources
with -300 km/s < v_hel < 300 km/s were excluded to avoid contamination by
Galactic emission. In total, the entire HIPASS survey has found 5317 galaxies
identified purely by their HI content. The full galaxy catalogue is
publicly-available at .Comment: 12 pages, accepted for publication by MNRA