J/A+A/618/A126 CO in group-dominant ellipticals (O'Sullivan+, 2018)
Cold gas in a complete sample of group-dominant early-type galaxies.
O'Sullivan E., Combes F., Salome P., David L.P., Babul A., Vrtilek J.M.,
Lim J., Olivares V., Raychaudhury S., Schellenberger G.
<Astron. Astrophys. 618, A126 (2018)>
=2018A&A...618A.126O 2018A&A...618A.126O (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Galaxies, spectra ; Carbon monoxide
Keywords: galaxies: elliptical and lenticular, cD - galaxies: groups: general -
galaxies: star formation - radio lines: galaxies
Abstract:
We present IRAM 30m and APEX telescope observations of CO(1-0) and
CO(2-1) lines in 36 group-dominant early-type galaxies, completing our
molecular gas survey of dominant galaxies in the Complete Local-volume
Groups Sample. We detect CO emission in 12 of the galaxies at
>4σ significance, with molecular gas masses in the range
0.01-6x108M☉, as well as CO in absorption in the non-dominant
group member galaxy NGC 5354. In total 21 of the 53 CLoGS dominant
galaxies are detected in CO and we confirm our previous findings that
they have low star formation rates (0.01-1M☉/yr) but short
depletion times (<1Gyr) implying rapid replenishment of their gas
reservoirs. Comparing molecular gas mass with radio luminosity, we
find that a much higher fraction of our group-dominant galaxies
(60±16%) are AGN-dominated than is the case for the general
population of ellipticals, but that there is no clear connection
between radio luminosity and the molecular gas mass. Using data from
the literature, we find that at least 27 of the 53 CLoGS dominant
galaxies contain HI, comparable to the fraction of nearby non-cluster
early type galaxies detected in HI and significantly higher that the
fraction in the Virgo cluster. We see no correlation between the
presence of an X-ray detected intra-group medium and molecular gas in
the dominant galaxy, but find that the HI-richest galaxies are located
in X-ray faint groups. Morphological data from the literature suggests
the cold gas component most commonly takes the form of a disk, but
many systems show evidence of galaxy-galaxy interactions, indicating
that they may have acquired their gas through stripping or mergers. We
provide improved molecular gas mass estimates for two galaxies
previously identified as being in the centres of cooling flows, NGC
4636 and NGC5846, and find that they are relatively molecular gas poor
compared to our other detected systems.
Description:
IRAM 30m CO(1-0) and CO(2-1), and APEX CO(2-1) spectra for the
detected galaxies in this paper. The telescope beam targeted the
optical centroid of the galaxy and velocities are given relative to
the systemic velocity of the galaxy, with the exception of NGC128,
where the position and velocity of the detected HI cloud were used
instead.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 98 36 Basic data for the newly observed or processed
group-dominant galaxies
table2.dat 114 23 Molecular data and stellar mass of the newly
detected galaxies
sp/* . 23 Individual spectra
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See also:
J/A+A/573/A111 : Group-dominant elliptical galaxies CO spectra
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- Case [A-D] sample (1)
3- 13 A11 --- Galaxy Galaxy name
16- 23 F8.6 --- z Redshift
25- 29 F5.2 Mpc DL Luminosity distance
31- 34 F4.2 kpc Beam FWHM CO(1-0) beam for IRAM observations,
CO(2-1) beam for APEX observations
36- 40 F5.2 [Lsun] logLB B-band luminosity (2)
42- 46 F5.2 kpc D25 Apparent major isophotal diameter at
muB=25mag/arcsec2 (2)
48- 51 F4.2 [Msun] logMdust ?=- Dust mass (3)
53 A1 --- l_logM(HI) Limit flag on logM(HI)
54- 58 F5.2 [Msun] logM(HI) ?=- HI mass (4)
59 A1 --- n_logM(HI) [i] Note on logM(HI) (5)
61- 65 F5.2 [Lsun] logLFIR ?=- FIR luminosity (2)
67- 70 F4.2 [Lsun] e_logLFIR ? rms uncertainty on LFIR
72- 76 F5.2 [Msun] logM* Stellar mass (6)
78 A1 --- l_M(H2) Limit flag on M(H2)
79- 83 F5.3 [10+8Msun] M(H2) H2 mass (7)
85- 89 F5.3 [10+8Msun] e_M(H2) ? rms uncertainty on H2 mass
90 A1 --- n_M(H2) [h] Note on M(H2 (5)
91 A1 --- l_F1.4GHz Limit flag on F1.4GHz
92- 98 F7.1 mJy F1.4GHz ?=- 1.4GHz flux (8)
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Note (1): Cases as follows:
A = IRAM 30m CLoGS survey observations
B = IRAM 30m deep observations
C = APEX CLoGS survey observations
D = APEX archival observations
Note (2): Computed from HYPERLEDA (http://leda.univlyon1.fr/).
Note (3): The derivation of LFIR and dust masses Mdust is described in Sec. 5.2.
Note (4): HI masses are drawn from NED (http://nedwww.ipac.caltech.edu/), the
extragalactic distance database all-digital HI catalog (Courtois et al.,
2009, Cat. J/AJ/138/1938), Serra & Oosterloo (2010MNRAS.401L..29S 2010MNRAS.401L..29S),
Serra et al. (2012MNRAS.422.1835S 2012MNRAS.422.1835S), Appleton et al. (1990ApJ...357..426A 1990ApJ...357..426A),
Huchtmeier (1994A&A...286..389H 1994A&A...286..389H), Barnes (1999PASA...16...77B 1999PASA...16...77B),
Serra et al. (2008A&A...483...57S 2008A&A...483...57S), Chung et al. (2012MNRAS.422.1083C 2012MNRAS.422.1083C) and
Haynes et al. (2018ApJ...861...49H 2018ApJ...861...49H).
Note (5): Notes as follows:
i = conflicting HI measurements, see text for discussion.
h = mass estimated from offset pointing, see NGC 128-HI in Table 2.
Note (6): Stellar masses were obtained through SED fitting with SDSS and/or
2MASS fluxes.
Note (7): Molecular gas masses and upper limits either derived from our data or
drawn from previous observations (see Section 3). Where CO(1-0) and CO(2-1)
estimates are available, the larger mass or upper limit is reported here.
Note (8): 1.4GHz continuum fluxes are drawn from the NRAO VLA Sky Survey
(NVSS, Condon et al. 1998AJ....115.1693C 1998AJ....115.1693C, 2002AJ....124..675C 2002AJ....124..675C, Cat. VIII/65),
the Faint Images of the Radio Sky at Twenty Centimeters survey (FIRST,
Becker et al., 2015ApJ...801...26H 2015ApJ...801...26H, Cat. VIII/92), or from Brown et al.
(2011, Cat. J/ApJ/731/L41) except in the cases of NGC 924, NGC 978 and
NGC 2563, where we extrapolate from the 610MHz flux (Kolokythas et al.,
2018, MNRAS, in prep.) assuming a spectral index alpha=0.8, and NGC 5903
where use the measured flux from O'Sullivan et al. (2018MNRAS.473.5248O 2018MNRAS.473.5248O).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- Case [A/B] Sample (1)
3- 12 A10 --- Galaxy Galaxy name
14 A1 --- n_Galaxy [d] Note on galaxy (2)
17- 23 A7 --- Line Observed line
25 A1 --- l_ICO Limit flag on ICO
26- 30 F5.2 K.km/s ICO CO intensity
32- 35 F4.2 K.km/s e_ICO ? rms uncertainty on ICO
37- 42 F6.1 km/s V ?=- Velocity
44- 48 F5.1 km/s e_V ? rms uncertainty on V
50- 54 F5.1 km/s DV FWHM (results of the Gaussian fits)
56- 60 F5.1 km/s e_DV ? rms uncertainty on DV
62- 66 F5.1 mK Tmb ? Peak brightness temperature
(results of the Gaussian fits)
68- 70 F3.1 mK e_Tmb ? rms uncertainty on Tmb
72- 75 F4.2 mK rms ? rms Tmb for 50km/s channel
77 A1 --- l_L'CO Limit flag on L'CO
(3sigma upper limit)
78- 83 F6.3 10+8K.km/s.pc+2 L'CO ? CO luminosity
85- 89 F5.3 10+8K.km/s.pc+2 e_L'CO ? rms uncertainty on L'CO
90 A1 --- l_M(H2) Limit flag on M(H2)
(3sigma upper limit)
91- 95 F5.3 10+8Msun M(H2) ?=- H2 mass (3)
97-101 F5.3 10+8Msun e_M(H2) ?=- rms uncertainty on H2 mass (3)
103-114 A12 --- FileName Name of the spectrum file in
subdirectory sp
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Note (1): Cases as follows:
A = IRAM 30m observations
B = APEX observations
Note (2): Detected values for the NGC 128 offset pointing in the HI bridge.
Note (3): obtained with the standard MW conversion ratio. In the two cases where
only one transition was detected, the table shows the rms Tmb for 50km/s
channels and 3 upper limits on other parameters, assuming V of 300km/s.
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Byte-by-byte Description of file: sp/*
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
11- 20 F10.3 km/s V Velocity relative to systemic velocity
24- 40 F17.10 mK Tmb ?=-1000 Main beam temperature
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Acknowledgements:
Ewan O'Sullivan, eosullivan(at)cfa.harvard.edu
(End) Ewan O'Sullivan [SAO], Patricia Vannier [CDS] 27-Jul-2018