6,446 research outputs found
The Star Formation Across Cosmic Time (SFACT) Survey. II. The First Catalog from a New Narrow-Band Survey for Emission-Line Objects
Star Formation Across Cosmic Time (SFACT) is a new narrowband survey designed
to detect faint emission-line galaxies and QSOs over a broad range of
redshifts. Here we present the first list of SFACT candidates from our
pilot-study fields. Using the WIYN 3.5m telescope, we are able to achieve good
image quality with excellent depth and routinely detect ELGs to r = 25.0. The
limiting line flux of the survey is ~1.0 x 10^16 erg/s/cm^2. SFACT targets
three primary emission lines: H-alpha, [O III]5007, and [O II]3727. The
corresponding redshift windows allow for the detection of objects at z ~ 0-1.
With a coverage of 1.50 square degrees in our three pilot-study fields, a total
of 533 SFACT candidates have been detected (355 candidates per square degree).
We detail the process by which these candidates are selected in an efficient
and primarily automated manner, then tabulate accurate coordinates, broadband
photometry, and narrowband fluxes for each source.Comment: 26 pages, 12 figures. Accepted for publication in the Astronomical
Journa
Metal Abundances of KISS Galaxies. VI. New Metallicity Relations for the KISS Sample of Star-Forming Galaxies
We present updated metallicity relations for the spectral database of
star-forming galaxies (SFGs) found in the KPNO International Spectroscopic
Survey (KISS). New spectral observations of emission-line galaxies (ELGs)
obtained from a variety of telescope facilities provide oxygen abundance
information. A nearly four-fold increase in the number of KISS objects with
robust metallicities relative to our previous analysis provides for an
empirical abundance calibration to compute self-consistent metallicity
estimates for all SFGs in the sample with adequate spectral data. In addition,
a sophisticated spectral energy distribution (SED) fitting routine has provided
robust calculations of stellar mass. With these new and/or improved galaxy
characteristics, we have developed luminosity-metallicity (-) relations,
mass-metallicity (-) relations, and the so-called Fundamental
Metallicity Relation (FMR) for over 1,450 galaxies from the KISS sample. This
KISS - relation is presented for the first time and demonstrates
markedly lower scatter than the KISS - relation. We find that our
relations agree reasonably well with previous publications, modulo modest
offsets due to differences in the SEL metallicity calibrations used. We
illustrate an important bias present in previous - and -
studies involving direct-method () abundances that may result in
systematically lower slopes in these relations. Our KISS FMR shows consistency
with those found in the literature, albeit with a larger scatter. This is
likely a consequence of the KISS sample being biased toward galaxies with high
levels of activity.Comment: Accepted for publication in The Astronomical Journal; 27 pages, 15
figures, 7 tables (with Appendix
The Star Formation Across Cosmic Time (SFACT) Survey. I. Survey Description and Early Results from a New Narrow-Band Emission-Line Galaxy Survey
We introduce the Star Formation Across Cosmic Time (SFACT) survey. SFACT is a
new narrow-band survey for emission-line galaxies (ELGs) and QSOs being carried
out using the wide-field imager on the WIYN 3.5 m telescope. Because of the
superior depth and excellent image quality afforded by WIYN, we routinely
detect ELGs to r = 25.0. Our survey observations are made using three custom
narrow-band filters centered on 6590 A, 6950 A, and 7460 A. Due to the
sensitivity of the survey, we are able to simultaneously detect sources via a
number of different emission lines over a wide range of redshifts. The
principal lines detected in SFACT are H-alpha (redshifts up to 0.144), [O
III]5007 (redshifts up to 0.500) and [O II]3727 (redshifts up to 1.015). In
this paper we detail the properties of the survey as well as present initial
results obtained by analyzing our three pilot-study fields. These fields have
yielded a total of 533 ELG candidates in an area of 1.50 square degrees
(surface density of 355 ELGs per square degree). Follow-up spectra for a subset
of the ELG candidates are also presented. One of the key attributes of the
SFACT survey is that the ELGs are detected in discrete redshift windows that
will allow us to robustly quantify the properties of the star-forming and AGN
populations as a function of redshift to z = 1 and beyond. The planned
acquisition of additional narrow-band filters will allow us to expand our
survey to substantially higher redshifts.Comment: 27 pages, 13 figures. Accepted for publication in the Astronomical
Journa
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CP Violation in Hadronic Penguins at BABAR
The authors present preliminary measurements of time-dependent CP-violation parameters in the decay B{sup 0} {yields} {omega}K{sub S}{sup 0}, B{sup 0} {yields} {eta}{prime}K{sup 0}, B{sup 0} {yields} {pi}{sup 0}K{sub S}{sup 0}, B{sup 0} {yields} {phi}K{sub S}{sup 0}{pi}{sup 0}, and B{sup 0} {yields} K{sup +}K{sup -}K{sub S}{sup 0}, which includes the resonant final states {phi}K{sub S}{sup 0} and f{sub 0}(980)K{sub S}{sup 0}. The data sample corresponds to the full BABAR dataset of 467 x 10{sup 6} B{bar B} pairs produced at the PEP-II asymmetric-energy E{sup +}e{sup -} collider at the Stanford Linear Accelerator Center
Searches for Extremely Metal Poor Galaxies using ALFALFA-selected Dwarf Galaxies
We present a study of nearby dwarf galaxies selected from the ALFALFA blind
HI survey. A primary goal of the project was to utilize a non-standard
selection method with the hope of detecting previously unrecognized extremely
metal-poor (XMP) galaxies. The study was motivated by the recent discovery of
two XMP galaxies Leo P and Leoncino which were both originally found
via the ALFALFA survey. We have obtained narrowband H images for 42
dwarf systems, many of which are located in the local void in front of the
Pisces-Perseus Supercluster. Spectra for eleven of the best candidates resulted
in the determination of metal abundances for ten of the systems. None were
found to be extremely metal poor, although one system (AGC 123350) was found to
have an oxygen abundance of log(O/H)+12 = 7.46, or 6\% solar. One of the
galaxies in our sample exhibits a high oxygen abundance for its luminosity,
suggesting the possibility that it may have a tidal origin.Comment: 21 pages, 11 figures, 4 table
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