J/ApJ/908/61 Revisiting Integrated Star Formation Law. II. (Kennicutt+, 2021)
Revisiting the Integrated Star Formation Law.
II. Starbursts and the Combined Global Schmidt Law.
Kennicutt R.C., De Los Reyes M.A.C.
<Astrophys. J., 908, 61 (2021)>
=2021ApJ...908...61K 2021ApJ...908...61K
ADC_Keywords: Star Forming Region; Interstellar medium; Galaxies, IR
Keywords: Disk galaxies ; Galaxy evolution ; Spiral galaxies ;
Interacting galaxies ; Luminous infrared galaxies ; Starburst
galaxies ; Blue compact dwarf galaxies ; Star formation ;
Interstellar dust
Abstract:
We compile observations of molecular gas contents and infrared-based
star formation rates (SFRs) for 112 circumnuclear star-forming
regions, in order to reinvestigate the form of the disk-averaged
Schmidt surface density star-formation law in starbursts. We then
combine these results with total gas and SFR surface densities for 153
nearby nonstarbursting disk galaxies from de los Reyes & Kennicutt
(Paper I), to investigate the properties of the combined star
formation law, following Kennicutt (1998ApJ...498..541K 1998ApJ...498..541K). We confirm
that the combined Schmidt law can be fitted with a single power law
with slope n=1.5±0.05 (including fitting method uncertainties),
somewhat steeper than the value n=1.4±0.15 found by Kennicutt.
Fitting separate power laws to the nonstarbursting and starburst
galaxies, however, produces very different slopes (n=1.34±0.07 and
0.98±0.07, respectively), with a pronounced offset in the
zero-point (∼0.6dex) of the starburst relation to higher SFR surface
densities. This offset is seen even when a common conversion factor
between CO intensity and molecular hydrogen surface density is
applied, and it is confirmed when disk surface densities of
interstellar dust are used as proxies for gas measurements. Tests for
possible systematic biases in the starburst data fail to uncover any
spurious sources for such a large offset. We tentatively conclude that
the global Schmidt law in galaxies, at least as it is conventionally
measured, is bimodal or possibly multimodal. Possible causes may
include changes in the small-scale structure of the molecular
interstellar medium or the stellar initial mass function. A single n
∼1.5 power law still remains as a credible approximation or "recipe"
for analytical or numerical models of galaxy formation and evolution.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 108 112 Basic properties of starburst sample
table2.dat 51 112 Derived properties of starburst sample
table3.dat 20 76 *Dust surface densities for spiral galaxies
refs.dat 55 37 References used for table1
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Note on table3.dat: From Paper I; de los Reyes+, 2019, J/ApJ/872/16.
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See also:
J/A+AS/126/3 : CO and HI in interacting galaxies (Horellou+ 1997)
J/AJ/136/2782 : Star formation efficiency in nearby galaxies (Leroy+, 2008)
J/ApJ/674/172 : Oxygen abundances of LIRGs and ULIRGs (Rupke+, 2008)
J/ApJ/723/993 : Spatial extent of (U)LIRGs in the MIR. I. (Diaz-Santos+, 2010)
J/ApJ/715/572 : GOALS UV and FIR properties (Howell+, 2010)
J/ApJ/733/87 : Star formation efficiency in galaxies (Shi+, 2011)
J/ApJ/777/156 : Spitzer/IRS spectra GOALS luminous IR galaxies (Inami+, 2013)
J/ApJ/805/31 : IR-radio luminosities & surface densities galaxies (Liu+, 2015)
J/A+A/591/A136 : Galaxies and QSOs FIR size & surface brightness (Lutz+, 2016)
J/ApJS/229/25 : GOALS sample PACS and SPIRE fluxes (Chu+, 2017)
J/A+A/609/A37 : 875 nearby galaxies multiwavelength photometry (Clark+, 2018)
J/ApJ/872/16 : Integrated star formation law revisited I (de los Reyes+, 2019)
J/ApJ/870/104 : 1-500um obs. of nearby luminous IR galaxies (Shangguan+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/112] Running index number (1)
5- 23 A19 --- Name Galaxy ID preferred by NED
25- 26 I2 h RAh [0/23] Hour of Right Ascension (J2000)
28- 29 I2 min RAm Minute of Right Ascension (J2000)
31- 36 F6.3 s RAs Second of Right Ascension (J2000)
38 A1 --- DE- [±] Sign of the Declination (J2000)
40- 41 I2 deg DEd Degree of Declination (J2000)
43- 44 I2 arcmin DEm Arcminute of Declination (J2000)
46- 50 F5.2 arcsec DEs Arcsecond of Declination (J2000)
52- 56 F5.1 Mpc Dist [3/395] Distance
58- 61 F4.1 arcsec Diam [1.8/66] Diameter
63- 67 F5.2 arcsec DiamRad [0.13/22]? Diameter measured from radio
continuum
69- 73 F5.2 [Lsun] IRLum [9.97/12.5]? Log total IR luminosity
75- 79 F5.2 [Msun/yr] SFR [-0.49/2.64] Log star formation rate
81- 84 F4.2 --- fExt [0/0.58] Fraction of IR emission outside
diameter
86- 90 F5.2 [Msun] MassH2 [7.78/10.7] Log H2 mass
92-100 A9 --- r_MassH2 Reference logMassH2
102-105 F4.2 [Msun] MassDust [7.34/8.67]? Log dust mass
107-108 I2 --- MapFlag [0/1] Flag denoting availability of
interferometric maps; 1=yes, 0=no
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Note (1): Index numbers 1-23 are local circumnuclear disks while the rest,
24-112, are LIRGs.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/112] Running index number (1)
5- 23 A19 --- Name Galaxy ID preferred by NED
25- 28 F4.2 [Msun/pc2] logSigmaH2 [1.96/4.49] LogΣ H2 surface
density
30- 34 F5.2 [Msun/yr/kpc2] logSigmaSFR [-0.57/2.48] LogΣ SFR surface
density
36- 40 F5.2 [Msun/pc2] logSigmaDust [-0.16/2.88]? LogΣ dust mass
surface density
42- 44 I3 km/s vRot [60/350]? Rotational velocity
46- 51 F6.4 10+8yr tDyn [0.082/1.2]? Dynamical time
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Note (1): Index numbers 1-23 are local circumnuclear disks while the rest,
24-112, are LIRGs.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/76] Running index number (1)
4- 14 A11 --- Name Galaxy ID preferred by NED
16- 20 F5.2 [Msun/pc2] logSigmaDust [-2.1/0.18] LogΣ dust mass
surface density
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Note (1): Index numbers 1-23 are local circumnuclear disks while the rest,
24-112, are LIRGs.
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Ref [1/37] Reference code
4- 22 A19 --- Autor Main autor
24- 42 A19 --- BIB BIBcode
44- 55 A12 --- Cat. Catalog in Vizier
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History:
From electronic version of the journal
References:
de los Reyes et al. Paper I : 2019ApJ...872...16D 2019ApJ...872...16D Cat. J/ApJ/872/16
(End) Prepared by [AAS], Coralie Fix [CDS], 27-Jun-2022