J/ApJ/860/172 Cloud-scale molecular gas properties in 15 galaxies (Sun+, 2018)
Cloud-scale molecular gas properties in 15 nearby galaxies.
Sun J., Leroy A.K., Schruba A., Rosolowsky E., Hughes A., Kruijssen J.M.D.,
Meidt S., Schinnerer E., Blanc G.A., Bigiel F., Bolatto A.D., Chevance M.,
Groves B., Herrera C.N., Hygate A.P.S., Pety J., Querejeta M., Usero A.,
Utomo D.
<Astrophys. J., 860, 172 (2018)>
=2018ApJ...860..172S 2018ApJ...860..172S
ADC_Keywords: Galaxies, nearby; Interstellar medium; Velocity dispersion;
Molecular data; Carbon monoxide
Keywords: galaxies: ISM; galaxies: spiral; galaxies: star formation;
ISM: clouds; ISM: molecules; ISM: structure
Abstract:
We measure the velocity dispersion, σ, and surface density,
Σ, of the molecular gas in nearby galaxies from CO spectral line
cubes with spatial resolution 45-120pc, matched to the size of
individual giant molecular clouds. Combining 11 galaxies from the
PHANGS-ALMA survey with four targets from the literature, we
characterize ∼30000 independent sightlines where CO is detected at
good significance. Σ and σ show a strong positive
correlation, with the best-fit power-law slope close to the expected
value for resolved, self-gravitating clouds. This indicates only a
weak variation in the virial parameter
αvir∝σ2/Σ, which is ∼1.5-3.0 for most
galaxies. We do, however, observe enormous variation in the internal
turbulent pressure Pturb∝Σσ2, which spans ∼5dex
across our sample. We find Σ, σ, and Pturb to be
systematically larger in more massive galaxies. The same quantities
appear enhanced in the central kiloparsec of strongly barred galaxies
relative to their disks. Based on sensitive maps of M31 and M33, the
slope of the σ-Σ relation flattens at
Σ≲10M☉/pc2, leading to high σ for a given Σ
and high apparent αvir. This echoes results found in the Milky
Way and likely originates from a combination of lower beam-filling
factors and a stronger influence of local environment on the dynamical
state of molecular gas in the low-density regime.
Description:
Our sample consists of 15 nearby galaxies with high-resolution maps of
low-J carbon monoxide (CO) rotational line emission.
Our sample includes 11 targets from the PHANGS-ALMA survey (Physics at
High Angular resolution in Nearby GalaxieS with ALMA; A. K. Leroy+, in
preparation). These targets were observed by ALMA in CO(2-1) using the
12m and 7m interferometric arrays as well as the total-power antennas.
Observations of the full PHANGS-ALMA sample are currently underway,
but the first 11 targets analyzed here were already observed in 2016
during ALMA's Cycle 3.
To supplement these first PHANGS-ALMA targets, we include the PdBI
Arcsecond Whirlpool Survey (PAWS) CO(1-0) map of M51 (Pety+
2013ApJ...779...43P 2013ApJ...779...43P ; Schinnerer+ 2013ApJ...779...42S 2013ApJ...779...42S), which
incorporates short-spacing data from the IRAM 30m telescope.
We also analyze the Local Group galaxies M31 and M33. For M31, we use
the CARMA CO(1-0) survey by A. Schruba et al. (in preparation), which
includes short- and zero-spacing data from the IRAM 30m telescope
(Nieten+ 2006A&A...453..459N 2006A&A...453..459N). For M33, we use the IRAM 30m CO(2-1)
survey by Gratier+ (2010, J/A+A/522/A3) and
Druard+ (2014A&A...567A.118D 2014A&A...567A.118D).
Finally, we include the ALMA CO(3-2) map of the interacting region of
the Antennae galaxies presented by Whitmore+ (2014ApJ...795..156W 2014ApJ...795..156W) and
analyzed by Johnson+ (2015ApJ...806...35J 2015ApJ...806...35J) and
Leroy+ (2016ApJ...831...16L 2016ApJ...831...16L).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 69 15 Sample of galaxies
table2.dat 56 15 CO detection statistics
table3.dat 67 299559 Cloud-scale molecular gas measurements for
all 15 galaxies
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See also:
J/ApJ/428/693 : Rosette Nebula & Maddalena Cloud structures (Williams+ 1994)
J/ApJ/551/852 : FCRAO CO survey of the outer Galaxy (Heyer+, 2001)
J/ApJS/149/343 : Giant molecular clouds in M33 (Engargiola+, 2003)
J/ApJ/599/1049 : Supergiant molecular complexes in Antennae (Wilson+, 2003)
J/A+A/466/905 : HII regions in NGC 628 (Fathi+, 2007)
J/ApJ/654/240 : Giant molecular clouds in M31 (Rosolowsky+, 2007)
J/ApJ/661/830 : Giant molecular clouds of M33 (Rosolowsky+, 2007)
J/ApJ/686/948 : CO in extragalactic giant molecular clouds (Bolatto+, 2008)
J/AJ/136/2782 : Star formation efficiency in nearby galaxies (Leroy+, 2008)
J/ApJ/699/1092 : Giant molecular clouds (SRBY) (Heyer+, 2009)
J/A+A/522/A3 : M33 CO(2-1) and HI integrated intensity maps (Gratier+, 2010)
J/PASP/122/1397 : Spitzer Survey of Stellar Structure in Gal. (Sheth+, 2010)
J/ApJS/197/16 : CO obs. of LMC molecular clouds (MAGMA). (Wong+, 2011)
J/ApJ/750/136 : Molecular clouds in the Antennae from CO(2-1) (Wei+, 2012)
J/ApJ/772/107 : Giant molecular clouds in nearby gal. (Donovan Meyer+, 2013)
J/ApJ/784/3 : The PAWS catalogs of GMCs and islands in M51 (Colombo+, 2014)
J/A+A/580/A112 : THOR. The HI, OH, Recombination Line Survey (Bihr+, 2015)
J/ApJ/803/16 : Giant MoCs in NGC4526 based on 12CO (Utomo+, 2015)
J/ApJ/846/71 : M51 ISM structures from the CO maps of PAWS (Leroy+, 2017)
J/ApJ/834/57 : MW molecular clouds from 12CO (Miville-Deschenes+, 2017)
J/ApJ/835/278 : Molecular clouds in the dwarf galaxy NGC6822 (Schruba+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Galaxy name
10- 15 A6 --- TType Morphological type
17- 21 F5.2 Mpc Dist [0.7/22] Distance
from Tully+, 2009AJ....138..323T 2009AJ....138..323T
23- 26 F4.1 deg Inc [6.5/77.7]? Inclination
27 A1 --- r_Inc [a-hkrs] Reference for the inclination (1)
29- 35 A7 10+10Msun Mass Stellar mass (2)
37- 44 A8 --- Tel Telescope
46- 52 A7 --- Line Line
54- 60 A7 arcsec/pc Res Resolution
62- 64 F3.1 km/s Width [2.5/5] Channel width
66- 69 F4.2 K Sens [0.04/0.4] Sensitivity
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Note (1): References for the inclination angle values as follows:
a = Corbelli et al. (2010A&A...511A..89C 2010A&A...511A..89C)
b = de Blok et al. (2008AJ....136.2648D 2008AJ....136.2648D)
c = Colombo et al. (2014ApJ...784....4C 2014ApJ...784....4C)
d = Diaz et al. (1999ApJ...512..623D 1999ApJ...512..623D)
e = Dicaire et al. (2008MNRAS.385..553D 2008MNRAS.385..553D)
f = Fathi et al. (2007, J/A+A/466/905)
g = Guhathakurta et al. (1988AJ.....96..851G 1988AJ.....96..851G)
h = HyperLeda database (Makarov+ 2014A&A...570A..13M 2014A&A...570A..13M ; see VII/237 and VII/238)
k = E. Koch et al. (in preparation)
r = Ryder et al. (1999PASA...16...84R 1999PASA...16...84R)
s = Schinnerer et al. (2002ApJ...575..826S 2002ApJ...575..826S)
Note (2): Stellar masses from the S4G global stellar masses (Spitzer Survey of
Stellar Structure in Galaxies, Sheth+ 2010, J/PASP/122/1397 ; Querejeta+
2015ApJS..219....5Q 2015ApJS..219....5Q); except for NGC 2835 and 6744: A. K. Leroy et al. (in
preparation), M31: Barmby+ (2006ApJ...650L..45B 2006ApJ...650L..45B) and
M33: Corbelli (2003MNRAS.342..199C 2003MNRAS.342..199C).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Name Galaxy name
10 A1 --- f_Name m="main sample" (PHANGS-ALMA targets plus M51)
12- 15 I4 --- N45 [408/6156]? Number of independent
sightlines with confident CO detection
at 45pc resolution (3)
17- 21 F5.2 10+8Msun M45 [0.4/28]? Total recovered molecular
gas mass at 45pc resolution
23- 24 I2 % fM45 [26/80]? Fraction of the recovered gas mass
to the total gas mass inside
the same field of view a5pc resolution
26- 29 I4 --- N80 [308/4307]? Number of independent
sightlines with confident CO detection
at 80pc resolution (3)
31- 35 F5.2 10+8Msun M80 [0.5/62]? Total recovered molecular
gas mass at 80pc resolution
37- 39 I3 % fM80 [33/111]? Fraction of the recovered gas mass
to the total gas mass inside
the same field of view a0pc resolution
40 A1 --- f_fM80 a: Flag on fM80 (4)
42- 45 I4 --- N120 [183/5485] Number of independent
sightlines with confident CO detection
at 120pc resolution (3)
47- 51 F5.2 10+8Msun M120 [0.5/62] Total recovered molecular
gas mass at 120pc resolution
53- 55 I3 % fM120 [32/111] Fraction of the recovered gas mass
to the total gas mass inside
the same field of view a20pc resolution
56 A1 --- f_fM120 a: Flag on fM120 (4)
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Note (3): Number of independent sightlines with confident CO detection --
i.e., the number of all CO-detected sightlines divided by the areal
oversampling factor 4.53.
Note (4):
a = The derived fraction of recovered gas mass exceeds 100% in the Antennae
galaxies because the data cubes lack short-spacing information and
thus exhibit "clean bowls". These features show up as large regions
with unphysical negative signals adjacent to bright emission
structures. Summing over these negative signals reduces the estimated
total gas mass (see also Leroy+ 2016ApJ...831...16L 2016ApJ...831...16L).
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Name Galaxy name
10- 12 I3 pc Res [45/120] Spatial resolution (1)
14- 21 E8.2 K Tpk [0.02/15.3] Brightness temperature at the
CO line peak, see Appendix D
23- 30 E8.2 Msun/pc2 Sigma [0.7/13700] Molecular gas surface density
32- 39 E8.2 km/s sigV [0.6/116] Molecular gas velocity dispersion
41- 47 E7.1 --- aVir [0.07/92] Inferred virial parameter;
see Section 5.3
49- 55 E7.1 K/cm3 Pturb [22/3.4e+9] Inferred turbulent pressure;
see Section 5.4
57- 61 A5 --- Mask1 Bitmask for pixels in galaxy central region (2)
63- 67 A5 --- Mask2 Bitmask for pixels
above completeness threshold (3)
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Note (1): Spatial resolution of the measurement as the beam full width at half
maximum at the projected distance of the galaxy.
Note (2): Mask1: if the sightline is located in the central region of the host
galaxy; see Section 5.1.1.
Note (3): Mask2: if the CO detection is above the completeness threshold; see
Section 5.2.1.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 08-Jul-2019