J/ApJ/879/22 GALFA-HI search for local dwarf galaxies (Defelippis+, 2019)
A correlated search for local dwarf galaxies in GALFA-H I and Pan-STARRS.
Defelippis D., Putman M., Tollerud E.
<Astrophys. J., 879, 22-22 (2019)>
=2019ApJ...879...22D 2019ApJ...879...22D (SIMBAD/NED BibCode)
ADC_Keywords: Radio sources; H I data; Surveys
Keywords: galaxies: dwarf; Local Group; radio lines: ISM; surveys
Abstract:
In recent years, ultrafaint dwarf (UFD) galaxies have been found
through systematic searches of large optical surveys. However, the
existence of Leo T, a nearby gas-rich dwarf, suggests that there could
be other nearby UFDs that are optically obscured but have gas
detectable at nonoptical wavelengths. With this in mind, we perform a
search of the full Galactic Arecibo L-band Feed Array HI (GALFA-HI)
survey, a radio survey that covers one-third of the sky at velocities
-650<VLSR<+650km/s, for neutral hydrogen sources. We are able to
probe regions of the sky at lower Galactic latitudes and smaller
|VLSR| compared to previous explorations. We use the Source Finding
Application on GALFA-HI and select all sources with similar properties
to Leo T and other local dwarf galaxies. We find 690 dwarf galaxy
candidates, one of which is particularly promising and likely a new
galaxy near the Galactic plane (b=-8°) that is comparable in
velocity width and HI-flux to other recently discovered local volume
galaxies. We find we are sensitive to Leo T-like objects out to 1Mpc
at velocities clear from background HI emission. We check each
candidate's corresponding optical fields from Pan-STARRS and fit stars
drawn from isochrones, but find no evidence of stellar populations. We
thus find no other Leo T-like dwarfs within 500 kpc of the Milky Way
in the one-third of the sky covered by the GALFA-HI footprint, and
discuss our nondetection in a cosmological context.
Description:
The GALFA-HI survey is a high spatial (4') and spectral (0.74km/s,
smoothed) resolution survey of HI in the Milky Way (MW) environment.
It comprises 225 data cubes with 1' pixels that cover declinations
between -1° and 38° across all right ascensions, and covers
velocities from -650<Vlsr<+650km/s. For this study, we utilize
GALFA-HI DR2 (Peek+ 2018, J/ApJS/234/2).
To correlate objects found in GALFA-HI with optical observations, we
require an optical survey with an overlapping footprint. The
Pan-STARRS survey fits this need. Pan-STARRS was run using the 1.8m
telescope at the University of Hawaii that mapped the sky in five
optical and infrared bands: g, r, i, z, and y.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 62 690 HI dwarf galaxy candidates
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See also:
J/AJ/136/713 : Arecibo legacy fast ALFA survey. VI. (Kent+, 2008)
J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)
J/ApJ/758/44 : The GALFA-HI compact cloud catalog (Saul+, 2012)
J/ApJ/768/77 : Ultra-compact high velocity clouds from ALFALFA (Adams+, 2013)
J/ApJ/808/136 : UV xids in HI clouds using ALFA surveys (Donovan+, 2015)
J/ApJ/812/158 : Leo P RR Lyrae candidates & cumulative SFH (McQuinn+, 2015)
J/ApJ/827/89 : HST imaging of Pisces A and B (Tollerud+, 2016)
J/ApJS/234/2 : The GALFA-HI survey data release 2 (Peek+, 2018)
J/A+A/612/A26 : Deep HI observations of Leo T with WSRT (Adams+, 2018)
J/AJ/156/18 : APOGEE DR14: companions of evolved stars (Price-Whelan+, 2018)
J/ApJ/861/49 : ALFALFA extragalactic HI source catalog (Haynes+, 2018)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- ID Galaxy identifier (LLL.ll+BB.bb+NNN;
with +NNN=Vlsr)
18- 19 I2 h RAh Hour of Right Ascension (J2000) (1)
21- 22 I2 min RAm Minute of Right Ascension (J2000)
24- 25 I2 s RAs Second of Right Ascension (J2000)
27 A1 - DE- Sign of Declination (J2000) (1)
28- 29 I2 deg DEd Degree of Declination (J2000) (1)
31- 32 I2 arcmin DEm Arcminute of Declination (J2000)
34- 35 I2 arcsec DEs Arcsecond of Declination (J2000)
37- 39 F3.1 arcmin Size [4/8] Major axis of fitted ellipse (2)
41- 43 I3 --- SNR [30/226] Signal to noise ratio (3)
45- 49 F5.2 Jy.km/s Fint [0.5/15.7] Integrated source HI flux (3)
51- 54 F4.2 K TB [0.4/3.1] Peak brightness temperature
(identical to f_peak in the Source Finding
Application (SoFiA))
56- 57 I2 km/s w50 [10/49] Line width at 50% peak flux density
59- 62 I4 km/s Vlsr [-415/358] Local Standard of Rest velocity
at the source's flux-weighted center
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Note (1): The RA and DEC in J2000 coordinates of the source's flux-weighted
center (in other words, the "center of flux" of all pixels defined
to be part of the source). Previous work in the ALFALFA group has
found the HI positions to be accurate to within 30"
(Kent+ 2008, J/AJ/136/713).
Note (2): Fitted to all pixels in the source that are ≥3-sigma above the
local noise level (identical to ell3s_maj in the Source Finding
Application (SoFiA, Serra+ 2015MNRAS.448.1922S 2015MNRAS.448.1922S)).
Note (3): Integrated over the entire velocity spectrum.
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History:
* 11-Jan-2021: From electronic version of the journal
* 30-Sep-2021: unit of Size corrected
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 08-Dec-2020