J/ApJ/902/39 GBT HI obs. of ultradiffuse galaxies (Karunakaran+, 2020)
Systematically measuring ultradiffuse galaxies in HI: results from the pilot
survey.
Karunakaran A., Spekkens K., Zaritsky D., Donnerstein R.L.,
Kadowaki J., Dey A.
<Astrophys. J., 902, 39 (2020)>
=2020ApJ...902...39K 2020ApJ...902...39K
ADC_Keywords: H I data; Galaxies, photometry; Optical; Morphology; Colors;
Rotational velocities
Keywords: H I line emission ; Low surface brightness galaxies ;
Galaxy evolution ; Galaxy formation ; Dwarf galaxies
Abstract:
We present neutral hydrogen (HI) observations using the Robert C. Byrd
Green Bank Telescope (GBT) of 70 optically detected UDG candidates in
the Coma region from the Systematically Measuring Ultra-Diffuse
Galaxies survey (SMUDGes). We detect HI in 18 targets, confirming nine
to be gas-rich UDGs and the remainder to be foreground dwarfs. None of
our HI-detected UDGs are Coma Cluster members and all but one are in
low-density environments. The HI-detected UDGs are bluer and have more
irregular morphologies than the redder, smoother candidates not
detected in HI, with the combination of optical color and morphology
being a better predictor of gas richness than either parameter alone.
There is little visual difference between the gas-rich UDGs and the
foreground dwarfs in the SMUDGes imaging, and distances are needed to
distinguish between them. We find that the gas richnesses of our
HI-confirmed UDGs and those from other samples scale with their
effective radii in two stellar mass bins, possibly providing clues to
their formation. We attempt to place our UDGs on the baryonic
Tully-Fisher relation (BTFR) using optical ellipticities and
turbulence-corrected HI line widths to estimate rotation velocities,
but the potential systematics associated with fitting smooth Sersic
profiles to clumpy, low-inclination disks of low surface brightness
precludes a meaningful analysis of potential BTFR offsets. These
observations are a pilot for a large campaign now under way at the GBT
to use the HI properties of gas-rich UDGs to quantitatively constrain
how these galaxies form and evolve.
Description:
We performed 88hr of position-switched HI observations between 2018
February and 2018 August using the Robert C. Byrd Green Bank Telescope
(GBT) along the lines of sight (LOSs) to the 70 ultra-diffuse galaxy
(UDG) candidates in Table 1 (program AGBT18B-239). Nine objects were
observed with an offset between the optical centroid and the LOS in
order to minimize contamination from known nearby objects
(see Section 4.1).
We used the L-band receiver and the Versatile GBT Astronomical
Spectrometer (VEGAS) with a spectral resolution of 3.1kHz and a wide
bandpass of 100MHz.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 139 70 Target ultra-diffuse galaxy (UDG) candidate properties
table2.dat 96 9 Properties of UDG with HI detections
table3.dat 96 9 HI properties of dwarfs
table4.dat 38 52 HI properties of non-detections
table5.dat 30 18 Inclinations and rotation velocities
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See also:
VIII/77 : HI spectral properties of galaxies (Springob+, 2005)
J/AJ/113/22 : Tully-Fisher Relation. I. (Giovanelli+ 1997)
J/A+AS/131/73 : Catalogue of HI maps of galaxies. I. (Martin 1998)
J/A+A/370/765 : HI synthesis observations in UMa cluster (Verheijen+, 2001)
J/ApJ/588/218 : i*g* photometry of SDSS EDR galaxies (Abraham+, 2003)
J/ApJS/147/1 : Classification of nearby galaxies (Conselice+, 2003)
J/A+A/506/677 : HI in Local Supercluster dwarf galaxies (Huchtmeier+, 2009)
J/AJ/142/170 : ALFALFA survey: α.40 HI source catalog (Haynes+, 2011)
J/A+A/544/A65 : GALEX Arecibo SDSS survey. VI. (Catinella+, 2012)
J/AJ/144/134 : LITTLE THINGS survey of nearby dwarf galaxies (Hunter+, 2012)
J/AJ/147/13 : Disturbers of nearby giant galaxies (Karachentsev+, 2014)
J/ApJS/215/22 : The Extended Virgo Cluster Catalog (EVCC) (Kim+, 2014)
J/ApJ/809/146 : SDSS-DR8 isolated low-mass galaxies (Bradford+, 2015)
J/ApJ/816/L14 : Tully-Fisher relation in disk gal. from SPARC (Lelli+, 2016)
J/MNRAS/456/1359 : IAC Stripe 82 Legacy Project: Photometry (Fliri+, 2016)
J/ApJS/225/11 : Subaru-UDGs in the Coma cluster (Yagi+, 2016)
J/ApJ/842/133 : HI-bearing ultra-diffuse ALFALFA galaxies (Leisman+, 2017)
J/A+A/608/A142 : Fornax Deep Survey with VST. III. LSB gal. (Venhola+, 2017)
J/ApJ/857/104 : Low surface brightness galaxies from HSC-SSP (Greco+, 2018)
J/AJ/156/18 : Binary companions of evolved stars (Price-Whelan+, 2018)
J/ApJ/861/49 : ALFALFA extragalactic HI source catalog (Haynes+, 2018)
J/ApJS/240/1 : SMUDGes. I. First results in Coma Cluster (Zaritsky+, 2019)
J/AJ/157/212 : Ultra-diffuse galaxies at UV wavelengths (Singh+, 2019)
J/ApJS/247/46 : Opt. phot. of SMUDGes ultra-diffuse galaxies (Barbosa+, 2020)
J/ApJ/894/75 : Ultra-diffuse & LSB dwarf gal. in A370 from HFF (Lee+, 2020)
J/ApJ/923/257 : Ultra-diffuse galaxies with sp. redshifts (Kadowaki+, 2021)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SMDG]
5- 18 A14 --- SMDG Adopted SMUDGes UDG candidate name
(HHMMSSs+DDMMSS; J2000)
20- 21 I2 h RAh [11/13] Hour of Right Ascension (J2000) (1)
23- 24 I2 min RAm Minute of Right Ascension (J2000)
26- 29 F4.1 s RAs Second of Right Ascension (J2000)
30 A1 --- f_pos Offset flag (2)
32 A1 --- DE- [+] Sign of Declination (J2000) (1)
33- 34 I2 deg DEd [18/33] Degree of Declination (J2000) (1)
36- 37 I2 arcmin DEm Arcminute of Declination (J2000)
39- 40 I2 arcsec DEs Arcsecond of Declination (J2000)
42- 46 F5.2 mag gtmag [16.5/20.3] CTIO/DECam g band total apparent
AB magnitude (3)
48- 51 F4.2 mag e_gtmag [0.01/0.05] 1 sigma uncertainty in gtmag (3)
53- 57 F5.2 mag/arcsec2 mu0g [23.78/26.04] Central surface brightness,
g-band (3)
59- 62 F4.2 mag/arcsec2 e_mu0g [0.02/0.2] 1 sigma uncertainty in mu0g (3)
64- 67 F4.2 mag g-r [0.03/0.84] g-r color index (3)
69- 72 F4.2 mag e_g-r [0.01/0.07] 1 sigma uncertainty in g-r (3)
74- 77 F4.2 mag g-z [0.06/1.24] g-z color index (3)
79- 82 F4.2 mag e_g-z [0.01/0.08] 1 sigma uncertainty in g-z (3)
84- 87 F4.1 arcsec re [4.7/25.8] Effective radius
89- 91 F3.1 arcsec e_re [0.1/1.2] 1 sigma uncertainty in re
93- 96 F4.2 --- b/a [0.38/0.97] Axial ratio
98- 101 F4.2 --- e_b/a [0.01/0.03] 1 sigma uncertainty in b/a
103- 105 I3 deg PA [-87/84] Position angle, θ
107- 108 I2 deg e_PA [1/29] 1 sigma uncertainty in PA
110- 113 F4.2 --- n [0.29/1.36] Sersic index
115- 118 F4.2 --- e_n [0.01/0.07] 1 sigma uncertainty in n
120- 122 F3.1 h Time [0.2/3.9] Total effective GBT integration
time (4)
124- 127 F4.2 mJy RMS [0.22/2.29] Representative RMS noise (5)
129- 131 A3 --- Ref Reference from which UDG candidate is
selected (6)
133 A1 --- --- [(]
134- 136 A3 --- Ref2 Alternative reference (7)
137 A1 --- --- [)]
139 A1 --- HI HI detection
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Note (1): J2000 position of optical centroid, which corresponds to our
GBT line of sight R.A. values.
Note (2): Flag as follows:
* = offset (in RA and/or Dec) in the GBT pointing position.
Note (3): Magnitudes, surface brightnesses, and colors are not extinction
corrected.
Note (4): The total effective integration time, including the ON+OFF positions
and subtracting any time lost due to RFI.
Note (5): Representative RMS noise of the spectrum at a velocity resolution
of DeltaV=50km/s
Note (6): Reference as follows:
Z19 = Zaritsky+ 2019, J/ApJS/240/1
K20 = This work (see Zaritsky et al. 2021ApJS..257...60Z 2021ApJS..257...60Z for SMUDGes
pipeline improvements)
Note (7): Alternative references for UDG candidates that have either been
presented in other work and/or previously detected in HI as follows:
S97 = Schombert+ 1997ApJS..111..233S 1997ApJS..111..233S
M98 = Martin M.C. 1998, J/A+AS/131/73
H18 = Haynes+ 2018, J/ApJ/861/49
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Byte-by-byte Description of file: table[23].dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- --- [SMDG]
5- 18 A14 --- SMDG Adopted SMUDGes UDG candidate name
(HHMMSSs+DDMMSS; J2000)
20- 21 I2 km/s DV [5/25] Velocity resolution of spectrum
used to compute H I properties
23- 26 F4.2 mJy rmsDV [0.45/4.76] RMS noise of spectrum at ΔV
28- 32 I5 km/s Vsys [420/11585] Heliocentric systemic velocity
34 I1 km/s e_Vsys [1/6] Uncertainty in Vsys
36- 38 I3 km/s W50c [8/102] Velocity width of the HI
detection (1)
40 I1 km/s e_W50c [2/8] Uncertainty in W50c
42- 45 F4.2 Jy.km/s SHI [0.13/4.37] Integrated H I flux
47- 50 F4.2 Jy.km/s e_SHI [0.04/0.21] Uncertainty in SHI
52- 56 F5.1 Mpc DHI [6/165.5] Distance estimate (2)
58- 61 F4.2 [Msun] logMHI [6.45/9.22] Log, H I mass (3)
63- 66 F4.2 [Msun] e_logMHI [0.08/0.72] Uncertainty in logMHI
68- 71 F4.2 [Msun] logMstar [5.64/8.57] Log, stellar mass (4)
73- 76 F4.2 [Msun] e_logMstar [0.2/0.75] Uncertainty in logMstar
78- 81 F4.2 [Msun] logMbary [6.68/9.41] Log, baryonic mass,
1.33*MHI+Mstar
83- 86 F4.2 [Msun] e_logMbary [0.08/0.72] Uncertainty in logMbary
88- 91 F4.2 kpc Reff [0.2/5.85] Effective radius using reff
(Table 1) and DHI
93- 96 F4.2 kpc e_Reff [0.02/0.62] Uncertainty in Reff
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Note (1): Velocity width of the HI detection, corrected for cosmological
redshift and instrumental broadening.
Note (2): Distance estimated using the Hubble-Lemaitre Law, Vsys and
H0=70km/s/Mpc. We adopt distance uncertainties of 5Mpc.
Note (3): Logarithm of HI mass calculated from Eq.1:
MHI=2.356x105(DHI)2SHIM☉
Note (4): Logarithm of stellar mass calculated using gtmag and g-r
from Table 1 and DHI.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- --- [SMDG]
5- 18 A14 --- SMDG Adopted SMUDGes UDG candidate name
(HHMMSSs+DDMMSS; J2000)
20- 20 A1 --- f_SMDG Flag on upper limit,
*= Offset in GBT pointing (see Table 1)
22- 26 F5.1 Mpc Dlim [3.8/100.0] Adopted distance (1)
28- 28 A1 --- r_Dlim Source for Dlim (2)
30- 33 F4.2 [Msun] logMHIlim [5.94/8.8] 5σ upper limit on MHI
35- 38 F4.2 Msun/Lsun MHIlim/Lg [0.25/3.5] Upper limit on the gas richness
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Note (1): The adopted distance is used in Equation 2:
MHIlim=5.89x107(Dlim)2σ50M☉
Note (2): References for adopted distance as follows:
a = Kadowaki+ 2021, J/ApJ/923/257
b = Kadowaki+ 2017ApJ...838L..21K 2017ApJ...838L..21K
c = Kim+ 2014, J/ApJS/215/22
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- --- [SMDG]
5- 18 A14 --- SMDG Adopted SMUDGes UDG candidate name
(HHMMSSs+DDMMSS; J2000)
20- 20 I1 --- sSet [1/2] Object type (1)
22- 23 I2 deg iGF [33/69] Inclination calculated using Eq.4 (2)
25- 26 I2 km/s VGF [3/53] Rotational velocity (3)
28- 30 I3 deg iBTFR [4/20]? Inclination required to lie on the BTFR (4)
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Note (1): Subsets as follows:
1 = H I-confirmed UDGs (9 occurrences);
2 = Foreground dwarfs (9 occurrences).
Note (2): Inclination calculated using Eq.4:
cos2(iGF)=((b/a)2-q02)/(1-q02)
with, b/a from Table 1, and an intrinsic axial ratio of q0=0.2.
Given the systematics associated with measuring inclinations of clumpy
low-inclination objects from smooth models, we consider iGF to be
rough estimates (see text).
Note (3): Rotational velocity calculated using W50c corrected for turbulence
and iGF. Given the systematics associated with measuring inclinations
of clumpy low-inclination objects from smooth models, we consider VGF
to be rough estimates (see text).
Note (4): Inclinations required to lie on the baryonic Tully-Fisher relation
(BTFR) for UDGs and dwarfs with VGF lower than expected from the BTFR
at their measured Mbary.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 21-Jan-2022