5 research outputs found
Searching for Intragroup Light in Deep U-band Imaging of the COSMOS Field
We present the results of deep, ground based U-band imaging with the Large
Binocular Telescope of the Cosmic Evolution Survey (COSMOS) field as part of
the near-UV imaging program, UVCANDELS. We utilize a seeing sorted stacking
method along with night-to-night relative transparency corrections to create
optimal depth and optimal resolution mosaics in the U-band, which are capable
of reaching point source magnitudes of AB 26.5 mag at 3 sigma. These ground
based mosaics bridge the wavelength gap between the HST WFC3 F27W and ACS F435W
images and are necessary to understand galaxy assembly in the last 9-10 Gyr. We
use the depth of these mosaics to search for the presence of U-band intragroup
light (IGrL) beyond the local Universe. Regardless of how groups are scaled and
stacked, we do not detect any U-band IGrL to unprecedented U-band depths of
29.1-29.6 mag/arcsec2, which corresponds to an IGrL fraction of less than 1% of
the total group light. This stringent upper limit suggests that IGrL does not
contribute significantly to the Extragalactic Background Light at short
wavelengths. Furthermore, the lack of UV IGrL observed in these stacks suggests
that the atomic gas observed in the intragroup medium (IGrM) is likely not
dense enough to trigger star formation on large scales. Future studies may
detect IGrL by creating similar stacks at longer wavelengths or by
pre-selecting groups which are older and/or more dynamically evolved similar to
past IGrL observations of compact groups and loose groups with signs of
gravitational interactions.Comment: Accepted to PAS
Seeing-sorted Visible Multi-Object Spectrograph U-band Imaging of the GOODS-south Field*
We present the optimal resolution and optimal depth U-filter mosaics using the seeing-sorted method of Ashcraft et al. on deep, ground-based U-bandimaging of the Great Observatories Origins Deep Survey South field as part of the near-UV imaging program UVCANDELS. We use the U-bandimages obtained with the VIsible Multi-Object Spectrograph on the European Southern Observatory Very Large Telescope by Nonino et al. Our best resolution mosaic includes images with a seeing full-width half maximum (FWHM) ā¤ 0"8, and encompasses 50% of the data. Our best depth mosaic includes images with FWHM ā¤ 1"5, corresponding to 100% of the data. Prior to being combined, the source fluxes in each individual background-subtracted image are corrected to match a 3D-HST photometric catalog of the same field to correct variations in the U-band zero-points. These mosaics provide deep U-banddata complementary to the UVCANDELS HST WFC3 F275W and ACS F435W images. We assess the depth of both U-bandmosaics. * Based on data acquired using the Very Large Telescope (VLT) of the European Southern Observatory (ESO)
The Lyman Continuum Escape Fraction of Star-forming Galaxies at from UVCANDELS
The UltraViolet Imaging of the Cosmic Assembly Near-infrared Deep
Extragalactic Legacy Survey Fields (UVCANDELS) survey is a Hubble Space
Telescope (HST) Cycle-26 Treasury Program, allocated in total 164 orbits of
primary Wide-Field Camera 3 Ultraviolet and Visible light F275W imaging with
coordinated parallel Advanced Camera for Surveys F435W imaging, on four of the
five premier extragalactic survey fields: GOODS-N, GOODS-S, EGS, and COSMOS. We
introduce this survey by presenting a thorough search for galaxies at
that leak significant Lyman continuum (LyC) radiation, as well as
a stringent constraint on the LyC escape fraction () from stacking
the UV images of a population of star-forming galaxies with secure redshifts.
Our extensive search for LyC emission and stacking analysis benefit from the
catalogs of high-quality spectroscopic redshifts compiled from archival
ground-based data and HST slitless spectroscopy, carefully vetted by dedicated
visual inspection efforts. We report a sample of five galaxies as individual
LyC leaker candidates, showing estimated
using detailed Monte Carlo analysis of intergalactic medium attenuation. We
develop a robust stacking method to apply to five samples of in total 85
non-detection galaxies in the redshift range of . Most stacks
give tight 2- upper limits below . A stack
for a subset of 32 emission-line galaxies shows tentative LyC leakage detected
at 2.9-, indicating at ,
supporting the key role of such galaxies in contributing to the cosmic
reionization and maintaining the UV ionization background. These new F275W and
F435W imaging mosaics from UVCANDELS have been made publicly available on the
Barbara A. Mikulski Archive for Space Telescopes.Comment: 33 pages, 21 figures, and 5 tables. Resubmitted after addressing the
referee repor
The Ultraviolet Luminosity Function at 0.6 < z < 1 from UVCANDELS
UVCANDELS is a Hubble Space Telescope Cycle-26 Treasury Program awarded 164 orbits of primary ultraviolet (UV) F275W imaging and coordinated parallel optical F435W imaging in four CANDELS fieldsāGOODS-N, GOODS-S, EGS, and COSMOSācovering a total area of ā¼426 arcmin2. This is ā¼2.7 times larger than the area covered by previous deep-field space UV data combined, reaching a depth of about 27 and 28 ABmag (5Ļ in 0.ā2 apertures) for F275W and F435W, respectively. Along with new photometric catalogs, we present an analysis of the rest-frame UV luminosity function (LF), relying on our UV-optimized aperture photometry method, yielding a factor of 1.5 increase over H-isophot aperture photometry in the signal-to-noise ratios of galaxies in our F275W imaging. Using well-tested photometric redshift measurements, we identify 5810 galaxies at redshifts 0.6 < z < 1, down to an absolute magnitude of M UV = ā14.2. In order to minimize the effect of uncertainties in estimating the completeness function, especially at the faint end, we restrict our analysis to sources above 30% completeness, which provides a final sample of 4726 galaxies at ā21.5 < M UV < ā15.5. We performed a maximum likelihood estimate to derive the best-fit parameters of the UV LF. We report a best-fit faint-end slope of Ī±=ā1.359ā0.041+0.041 at z ā¼ 0.8. Creating subsamples at z ā¼ 0.7 and z ā¼ 0.9, we observe a possible evolution of Ī± with redshift. The unobscured UV luminosity density at M UV < ā10 is derived as ĻUV=1.339ā0.030+0.027(Ć1026ergsā1Hzā1Mpcā3) using our best-fit LF parameters. The new F275W and F435 photometric catalogs from UVCANDELS have been made publicly available on the Barbara A. Mikulski Archive for Space Telescopes
Ultraviolet and Blue Optical Imaging of UVCANDELS
The UltraViolet Imaging of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey Fields (UVCANDELS) survey provided ultraviolet F275W imaging with coordinated parallel optical F435W imaging in four of the five CANDELS fields: GOODS-N, GOODS-S, EGS, and COSMOS, covering a total area of ā¼426 arcmin2. UVCANDELS takes primary WFC3/UVIS F275W exposures at a uniform 3-orbit depth and ACS F435W exposures (in parallel) at slightly varying depth due to the roll angle constraints and the overlap from the increased field of view of the ACS camera, reaching a limiting magnitude of ā¼27 and ā¼28 ABmag (5Ļ in 0.ā³2 apertures) for F275W and F435W, respectively. We present the results of the UVCANDELS observations, custom calibrations, and the creation of F275W and F435W imaging mosaics, which have been made publicly available on the Barbara A. Mikulski Archive for Space Telescopes