J/MNRAS/482/1618 Molecular gas tracers in star-forming galaxies (Cortzen+, 2019)
PAHs as tracers of the molecular gas in star-forming galaxies.
Cortzen I., Garrett J., Magdis G., Rigopoulou D., Valentino F.,
Pereira-Santaella M., Combes F., Alonso-Herrero A., Toft S., Daddi E.,
Elbaz D., Gomez-Guijarro C., Stockmann M., Huang J., Kramer C.
<Mon. Not. R. Astron. Soc., 482, 1618-1633 (2019)>
=2019MNRAS.482.1618C 2019MNRAS.482.1618C (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies ; Star Forming Region ; Interstellar medium
Keywords: galaxies: active - galaxies: evolution - galaxies: ISM -
galaxies: star formation
Abstract:
We combine new CO(1-0) line observations of 24 intermediate redshift
galaxies (0.03<z<0.28) along with literature data of galaxies at 0<z<4
to explore scaling relations between the dust and gas content using
polycyclic aromatic hydrocarbon (PAH) 6.2µm (L6.2), CO(L'CO),
and infrared (LIR) luminosities for a wide range of redshifts and
physical environments. Our analysis confirms the existence of a
universal L6.2-L'CO correlation followed by normal star-forming
galaxies (SFGs) and starbursts (SBs) at all redshifts. This relation
is also followed by local ultraluminous infrared galaxies that appear
as outliers in the L6.2-LIR and LIR-L'CO relations defined by
normal SFGs. The emerging tight (σ∼0.26dex) and linear
(α=1.03) relation between L6.2 and L'CO indicates a L6.2
to molecular gas (MH2) conversion factor of
α6.2=MH2/L6.2= (2.7±1.3)xαCO, where αCO
is the L'CO to MH2 conversion factor. We also find that on galaxy
integrated scales, PAH emission is better correlated with cold rather
than with warm dust emission, suggesting that PAHs are associated with
the diffuse cold dust, which is another proxy for MH2. Focusing on
normal SFGs among our sample, we employ the dust continuum emission to
derive MH2 estimates and find a constant MH2/L6.2 ratio of
α6.2=12.3M☉/L_☉ (σ∼0.3dex). This ratio is in
excellent agreement with the L'CO-based MH2/L6.2 values for
αCO=4.5M☉/(K km/s/pc2) which is typical of normal
SFGs. We propose that the presented L6.2-L'CO and L6.2-MH2
relations will serve as useful tools for the determination of the
physical properties of high-z SFGs, for which PAH emission will be
routinely detected by the James Webb Space Telescope.
Description:
We have selected 34 star-forming targets from the 5 mJy Unbiased
Spitzer Extragalactic Survey (5MUSES; Wu et al. 2010ApJ...723..895W 2010ApJ...723..895W,
Cat. J/ApJ/723/895) in order to examine the gas and ISM properties of
star-formation dominated galaxies at intermediate redshift
(0.03<z<0.28) by detecting CO(1-0) emission and using existing
observations. 5MUSES is a 24µm flux-limited (f24µm>5mJy)
spectroscopic survey with Spitzer IRS, containing 330 galaxies with
LIR∼1010-1012L☉ located in the SWIRE (Lonsdale et al.
2003PASP..115..897L 2003PASP..115..897L) and Extragalactic First Look Survey (XFLS) fields
(Fadda et al. 2006AJ....131.2859F 2006AJ....131.2859F, Cat. J/AJ/131/2859).
The single-dish observations were carried out with the IRAM 30m
telescope at Pico Veleta, Spain, in 2015 July, 2015 June, and 2016
September. All galaxies were observed at 3mm using the spectral line
receiver band E0 of EMIR with WILMA as backends in order to observe
the CO(1-0) emission line. The receiver was tuned to the expected
frequency of the targets (in the range 95GHz<ν<107GHz) and the
wobbler switching mode was used. We spent one to eight hours on each
galaxy. During observations the pointing of the telescope was checked
every two hours using a bright nearby source.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 141 283 General properties of the 5MUSES sample
table4.dat 166 132 Galaxies from the literature with PAH, IR,
and/or CO emission
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See also:
J/ApJ/723/895 : IR luminosities and aromatic features of 5MUSES (Wu+, 2010)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Source name (5MUSES NNN)
12- 13 I2 h RAh Right ascension (J2000)
15- 16 I2 min RAm Right ascension (J2000)
18- 21 F4.1 s RAs Right ascension (J2000)
23 A1 --- DE- Declination sign (J2000)
24- 25 I2 deg DEd Declination (J2000)
27- 28 I2 arcmin DEm Declination (J2000)
30- 36 F7.4 arcsec DEs Declination (J2000)
38- 42 F5.3 --- z Redshift
44- 49 F6.3 [Lsun] L6.2 ? PAH 6.2um luminosity (1)
51- 56 F6.3 [Lsun] e_L6.2 ? Error on L6.2 (1)
58- 63 F6.3 [Lsun] L7.7 ? PAH 7.7um luminosity (1)
65- 70 F6.3 [Lsun] e_L7.7 ? Error on L7.7 (1)
72- 76 F5.3 um EW6.2 ? Equivalent width of the PAH 6.2um feature
78- 82 F5.3 um e_EW6.2 ? Error on EW6.2
84- 89 F6.3 [Msun] Mstar ? Stellar mass (2)
91- 96 F6.3 [Lsun] LIR Infrared luminosity (integrated from 8 to
1000um)
98-102 F5.3 [Lsun] e_LIR Error on LIR
104-108 F5.3 [Msun] Mdust ? Dust mass
110-114 F5.3 [Msun] e_Mdust ? Lower error on Mdust
116-134 F19.16 [Msun] E_Mdust ? Upper error on Mdust
136-141 F6.3 [Msun] MH2 ? Molecular gas mass derived using the
Mdust-δGDR method (3)
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Note (1): PAH luminosity from Magdis et al. (2013A&A...558A.136M 2013A&A...558A.136M)
Note (2): Stellar masses from Shi et al. (2011ApJ...733...87S 2011ApJ...733...87S,
Cat. J/ApJ/733/87)
Note (3): We derive molecular gas mass estimates using the FIR dust continuum
observations. This method relies on the fact that Mgas can be derived
from the dust mass by exploiting the well-calibrated gas-to-dust mass
ratio (δGDR(Z)): δGDRxMdust=Mgas∼MH2
Current models suggest MH2 dominates over MHI at high-z and high
stellar surface densities (Blitz & Rosolowsky 2006ApJ...650..933B 2006ApJ...650..933B;
Obreschkow et al. 2009ApJ...698.1467O 2009ApJ...698.1467O) and thus Mgas∼MH2.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 20 A20 --- Name Source name
22- 23 I2 h RAh Right ascension (J2000)
25- 26 I2 min RAm Right ascension (J2000)
28- 34 F7.4 s RAs Right ascension (J2000)
36 A1 --- DE- Declination sign (J2000)
37- 38 I2 deg DEd Declination (J2000)
40- 41 I2 arcmin DEm Declination (J2000)
43- 49 F7.4 arcsec DEs Declination (J2000)
51- 62 A12 --- Sample Galaxy sample or selection
64- 68 F5.3 --- z ? Redshift
70- 75 F6.3 [Lsun] L6.2 ? PAH 6.2um luminosity
77- 81 F5.3 [Lsun] e_L6.2 ? Error on L6.2
83- 88 F6.3 [Lsun] L7.7 ? PAH 7.7um luminosity
90- 94 F5.3 [Lsun] e_L7.7 ? Error on L7.7
96-100 F5.3 um EW6.2 ? Equivalent width of the PAH 6.2um feature
102-106 F5.3 um e_EW6.2 ? Error on EW6.2
108-113 F6.3 [Msun] Mstar ? Stellar mass
115-120 F6.3 [Lsun] LIR Aperture corrected infrared luminosity
(integrated from 8 to 1000um)
122-126 F5.3 [Lsun] e_LIR Error on LIR
128-134 A7 --- Line Observed CO line
136-141 F6.3 [Lsun] LCO ? CO(1-0) luminosity
143-147 F5.3 [Lsun] e_LCO ? Error on LCO
149-154 F6.3 [Msun] Mdust ? Dust mass
156-160 F5.3 [Msun] e_Mdust ? Lower error on Mdust
162-166 F5.3 [Msun] E_Mdust ? Upper error on Mdust
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 28-Jun-2022