J/AJ/157/212 Ultra-diffuse galaxies at ultraviolet wavelengths (Singh+, 2019)
Ultra-diffuse galaxies at ultraviolet wavelengths.
Singh P.R., Zaritsky D., Donnerstein R., Spekkens K.
<Astron. J., 157, 212 (2019)>
=2019AJ....157..212S 2019AJ....157..212S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, photometry ; Photometry, ultraviolet ; Extinction
Keywords: galaxies: photometry - galaxies: star formation
Abstract:
We measure near-ultraviolet (NUV) aperture magnitudes from Galaxy Evolution
Explorer images for 258 ultra-diffuse galaxy (UDG) candidates drawn from
the initial Systematically Measuring Ultra-Diffuse Galaxies (SMUDGes)
survey of ∼300 square degrees surrounding, and including, the Coma galaxy
cluster. For the vast majority, 242 of them, we present flux upper limits
due either to a lack of significant flux in the aperture or confusion with
other objects projected within the aperture. These limits often place
interesting constraints on the UDG candidates, indicating that they are
non-star-forming or quiescent. In particular, we identify field, quiescent
UDG candidates, which are a challenge for formation models and are,
therefore, compelling prospects for spectroscopic follow-up and distance
determinations. We present far-ultraviolet (FUV) and NUV magnitudes for
16 detected UDG candidates and compare those galaxies to the local
population of galaxies on color-magnitude and specific star formation rate
diagrams. The NUV-detected UDG candidates form mostly an extension toward
lower stellar masses of the star-forming galaxy sequence, and none of these
lie within regions of high local galaxy density. UDG candidates span a
range of properties, although almost all are consistent with being
quiescent, low surface brightness galaxies, regardless of environment.
Description:
We begin with the UDG catalog from Zaritsky et al. (2019, J/ApJS/240/1)
of 275 UDG candidates with half light radii, rh≳5.3" that lie
within roughly a 10° projected radius from the Coma galaxy cluster.
The NUV data come from the NASA public archive portal MAST
(http://archive.stsci.edu/) of the GALEX mission (Martin et al.
2005ApJ...619L...1M 2005ApJ...619L...1M). GALEX was a 50 cm diameter UV telescope capable
of imaging the sky in far-ultraviolet (FUV) (1350-1750 Å) and NUV
(1750-2750 Å) bands simultaneously. We exclude UDG candidates without
the available r band or that lie outside available GALEX images, and
our final sample consists of 258 candidates. After rejecting 53 candidates
on the basis of our initial contamination criterion and 17 candidates
without either NUV images or r-band data, we have 16 detections and
189 nondetections.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 57 16 NUV-detected UDG candidates photometry
table3.dat 43 189 NUV-undetected UDG candidates photometry
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See also:
J/ApJS/225/11 : Subaru-UDGs in the Coma cluster (Yagi+, 2016)
J/ApJS/240/1 : SMUDGes. I. First results in the Coma Cluster (Zaritsky+, 2019)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SMDG]
5- 18 A14 --- SMDG Galaxy name (HHMMSSs+DDMMSS) (G1)
20- 23 F4.1 arcsec Rad [5.3/22.5] Half-light radius (G1)
25- 29 F5.2 mag rmag [16.47/21.06] r-band magnitude, extinction
corrected (G1)
31- 35 F5.2 mag NUVmag [20.18/22.56] GALEX NUV AB magnitude, extinction
corrected
37- 40 F4.2 mag e_NUVmag [0.1/0.55] Uncertainty in NUVmag
42 A1 --- l_FUVmag [>] Limit flag on FUVmag (1)
43- 47 F5.2 mag FUVmag [21.34/25.59] GALEX FUV AB magnitude, extinction
corrected
49- 52 F4.2 mag e_FUVmag [0.07/2.13] Uncertainty in FUVmag
54- 57 F4.2 mag E(B-V) [0.01/0.03] Adopted color excess, Galactic
extinction (G2)
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Note (1): Lower limits on FUVmag provided for the objects that are not visually
discernable in the FUV band.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SMDG]
5- 18 A14 --- SMDG Galaxy name (HHMMSSs+DDMMSS) (G1)
20- 23 F4.1 arcsec Rad [5.3/75.2] Half-light radius (G1)
25- 28 F4.1 mag NUVmag [17.1/27.1] Limit, GALEX NUV AB magnitude,
extinction corrected
30- 33 F4.1 mag rmag [15.0/22.2] r-band magnitude, extinction corrected
(G1)
35- 38 F4.2 mag E(B-V) [0.01/0.07] Adopted color excess, Galactic
extinction (G2)
40- 43 F4.1 --- S/N [-2.8/23.1] Signal-to-noise ratio
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Global notes:
Note (G1): Galaxy name, effective radius and r-band magnitude from the
Zaritsky et al. (2019, J/ApJS/240/1) catalog.
Note (G2): Magnitudes extinction corrected using reddening maps from
Schlafly & Finkbeiner (2011ApJ...737..103S 2011ApJ...737..103S).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 08-Aug-2019