J/ApJ/938/135 Pressure estimates around SFRs in nearby galaxies (Murphy, 2022)
The relative importance of thermal gas, radiation, and magnetic pressures around
star-forming regions in normal galaxies and dusty starbursts.
Murphy E.J.
<Astrophys. J., 938, 135 (2022)>
=2022ApJ...938..135M 2022ApJ...938..135M
ADC_Keywords: Galaxies, nearby; Star Forming Region; Magnetic fields;
Infrared sources; Radio sources
Keywords: Star formation ; Star forming regions ; Radio continuum emission ;
Extragalactic magnetic fields ; Galaxies ; Stellar feedback ;
Magnetic fields ; Luminous infrared galaxies ;
Galaxy evolution ; Dust continuum emission ; Disk galaxies
Abstract:
In this paper, an investigation on the relative importance of the
thermal gas, radiation, and (minimum-energy) magnetic pressures around
∼200 star-forming regions in a sample of nearby normal and luminous
infrared galaxies is presented. Given the range of galaxy distances,
pressure estimates are made on spatial scales spanning ∼0.1-3kpc. The
ratio of thermal gas-to-radiation pressures does not appear to
significantly depend on star formation rate surface density
(ΣSFR), but exhibits a steady decrease with increasing
physical size of the aperture over which the quantities are measured.
The ratio of magnetic-to-radiation pressures appears to be relatively
flat as a function of ΣSFR and similar in value for both
nuclear and extranuclear regions, but, unlike the ratio of thermal
gas-to-radiation pressures, exhibits a steady increase with increasing
aperture size. Furthermore, it seems that the magnetic pressure is
typically weaker than the radiation pressure on subkiloparsec scales,
and only starts to play a significant role on few-kiloparsec scales.
When the internal pressure terms are summed, their ratio to the
(ΣSFR-inferred) kiloparsec-scale dynamical equilibrium
pressure estimates is roughly constant. Consequently, it appears that
the physical area of the galaxy disk, and not necessarily environment
(e.g., nuclear versus extranuclear regions) or star formation
activity, may play the dominant role in determining which pressure
term is most active around star-forming regions. These results are
consistent with a scenario in which a combination of processes acting
primarily on different physical scales work collectively to regulate
the star formation process in galaxy disks.
Description:
In this paper, a combination of mid-infrared and multifrequency radio
data are used to investigate the relative strengths of thermal gas,
radiation, and magnetic pressures on ∼100pc to ∼3kpc scales around
star-forming regions within a sample of nearby galaxies included in
the Star Formation in Radio Survey (SFRS; Murphy+ 2012, J/ApJ/761/97
and 2018, J/ApJS/234/24) and luminous infrared galaxies (LIRGs;
LIR>1011L☉) in the Great Observatories All-Sky LIRG Survey
(GOALS; Armus+ 2009PASP..121..559A 2009PASP..121..559A).
The Star Formation in Radio Survey (SFRS) galaxy sample is derived
from the Spitzer Infrared Nearby Galaxies Survey (SINGS; Kennicutt+
2003PASP..115..928K 2003PASP..115..928K) and Key Insights on Nearby Galaxies: a
Far-Infrared Survey with Herschel (KINGFISH; Kennicutt+
2011PASP..123.1347K 2011PASP..123.1347K) legacy programs. Consequently, all sources are
well studied and have a wealth of ancillary data available. Radio data
were collected for a total of 112 star-forming complexes (50 nuclei
and 62 extranuclear regions) easily observable with the Very Large
Array (VLA; i.e., having δ>-35°).
See Section 2.1.
The Great Observatories All-Sky LIRG Survey (GOALS) galaxy sample
includes over 200 LIRGs included in the flux-density-limited
(S60um>5.24Jy) IRAS Revised Bright Galaxy Sample (RBGS;
Sanders+ 2003, J/AJ/126/1607). A subset of 68 GOALS galaxies within
the decl. range spanning -20°<δ<20° were observed with
the VLA as part of the GOALS "equatorial" survey and included in the
present study.
See Section 2.2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 160 204 Estimated physical quantities for each region
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See also:
J/ApJ/554/803 : New VLA Sky Survey (NVSS) Cat of IRAS 2Jy Galaxies (Yun+ 2001)
J/AJ/126/1607 : IRAS Revised Bright Galaxy Sample (Sanders+, 2003)
J/ApJ/671/333 : Aperture photometry in NGC 5194 (Kennicutt+, 2007)
J/AJ/133/2559 : Compact radio sources in spiral galaxies. II. (Maddox+, 2007)
J/AJ/136/2782 : Star formation efficiency in nearby galaxies (Leroy+, 2008)
J/ApJ/703/517 : The Spitzer Local Volume Legacy: IR photometry (Dale+, 2009)
J/ApJS/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009)
J/ApJS/190/233 : Spectroscopy & abundances of SINGS galaxies (Moustakas+, 2010)
J/A+A/533/A119 : GOODS-Herschel North and South catalogs (Elbaz+, 2011)
J/ApJ/761/97 : Star Formation in Radio Survey (SFRS): 33GHz (Murphy+, 2012)
J/ApJS/234/24 : VLA 33GHz obs. of star-forming regions (Murphy+, 2018)
J/ApJS/248/25 : SFRS: 3-33GHz VLA obs. of star-forming regions (Linden+, 2020)
J/ApJ/892/148 : Molecular ISM in nearby star-forming galaxies (Sun+, 2020)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Set Sample origin (1)
8- 21 A14 --- Gal Galaxy name
23- 30 A8 --- Enuc Extranuclear identifier within Gal
32 A1 --- m_Gal Source component identifier
34- 35 I2 h RAh Hour of right ascension (J2000)
37- 38 I2 min RAm Minute of right ascension (J2000)
40- 44 F5.2 s RAs Second of right ascension (J2000)
46 A1 --- DE- Sign of declination (J2000)
47- 48 I2 deg DEd Degree of declination (J2000)
50- 51 I2 arcmin DEm Arcminute of declination (J2000)
53- 56 F4.1 arcsec DEs Arcsecond of declination (J2000)
58- 62 F5.3 kpc Dap [0.1/2.8] Aperture diameter, DAp
64- 68 F5.2 Msun/yr/kpc2 SigSFR [0.02/45] Star formation rate surface
density, ΣSFR
70- 73 F4.2 Msun/yr/kpc2 e_SigSFR [0.01/3] SigSFR uncertainty
75- 80 F6.2 10-12dyn/cm2 Pb [1.4/227] The magnetic pressure, PB;
see Equation 2 (2)
82- 86 F5.2 10-12dyn/cm2 e_Pb [0.4/96] Pb uncertainty
88- 93 F6.2 10-12dyn/cm2 Pcr [0.5/227] The cosmic ray (CR) pressure;
see Equation 4 (2)
95- 99 F5.2 10-12dyn/cm2 e_Pcr [0.16/67] Pcr uncertainty
101-106 F6.2 10-12dyn/cm2 Prad [1.2/807]? The radiation pressure;
see Equation 8 (2)
108-113 F6.2 10-12dyn/cm2 e_Prad [0.06/760]? Prad uncertainty
115-120 F6.2 dyn/cm2 Pth [3/140] The thermal gas pressure (2) (3)
122-126 F5.2 dyn/cm2 e_Pth [1.9/37] Pth uncertainty
128-135 F8.2 10-12dyn/cm2 Pde [8.9/26451] The dynamical equilibrium
pressure; see Equation 13 (4)
137-143 F7.2 10-12dyn/cm2 e_Pde [7/1532] Pde uncertainty
145-152 F8.2 10-12dyn/cm2 Pturb [11/27946] The turbulent gas pressure (4)
154-160 F7.2 10-12dyn/cm2 e_Pturb [8.4/1619] Pturb uncertainty
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Note (1): Sample origin as follows:
SFRSn = The Star Formation in Radio Survey (SFRS;
Murphy+ 2012, J/ApJ/761/97 and 2018, J/ApJS/234/24)
Nuclear Regions (31 occurrences)
SFRSe = The Star Formation in Radio Survey (SFRS;
Murphy+ 2012, J/ApJ/761/97 and 2018, J/ApJS/234/24)
Extranuclear Regions (<[MBM2012] NGCNNNN Enuc. NN> in Simbad)
(107 occurrences)
GOALSn = The Great Observatories All-Sky LIRG Survey (GOALS;
Armus+ 2009PASP..121..559A 2009PASP..121..559A) Nuclear Regions (22 occurrences)
GOALSe = The Great Observatories All-Sky LIRG Survey (GOALS) Extranuclear
Regions (44 occurrences)
Note (2): Total internal pressures are calculated as
Pint=Pth+Prad+PCR+PB; see Section 3.2.
Note (3): Thermal gas pressure in Equation 11:
Pth=2x104nekB(Te/104K)
Where kB=1.38x10-16cm2.g/s2/K is Boltzmann's constant.
Note (4): Pressure estimates derived using empirical relations between
PDE, Pturb, and ΣSFR given in Sun+ 2020, J/ApJ/892/148.
Associated uncertainties provided here do not include the intrinsic
scatter of these empirical relations.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 04-Sep-2024