J/MNRAS/510/4998 ATOMS IV Gas clumps properties and SFRs (Zhang+, 2022)
ATOMS ALMA Three-millimeter Observations of Massive Star-forming regions.
IV. Radio recombination lines and evolution of star formation efficiencies.
Zhang C., Evans N.J., Liu T., Wu J.-W., Wang K., Liu H.-L., Zhu F.-Y.,
Ren Z.-Y., Dewangan L.K., Lee C.W., Li S., Bronfman L., Tej A., Li D.
<Mon. Not. R. Astron. Soc., 510, 4998-5008 (2022)>
=2022MNRAS.510.4998Z 2022MNRAS.510.4998Z (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Molecular clouds ; Molecular data ; Radio lines ;
Star Forming Region ; Millimetric/submm sources ; Radio sources ;
Positional data ; Photometry ; Spectroscopy
Keywords: stars: formation - ISM: clouds - H II regions - radio lines: ISM
Abstract:
We report the detection of radio recombination line (RRL) H40α
towards 75 sources, with data obtained from ACA (Atacama Compact 7 m
Array) observations in the ATOMS (ALMA Three-millimeter Observations
of Massive Star-forming regions) survey of 146 active Galactic
star-forming regions. We calculated ionized gas mass and star
formation rate (SFR) with H40α line emission. The mass of
ionized gas is significantly smaller than molecular gas mass,
indicating that ionized gas is negligible in the star-forming clumps
of the ATOMS sample. The SFR estimated with RRL H40α agrees
well with that calculated with the total bolometric luminosity
(Lbol) when SFR => 5 M☉.Myr-1, suggesting that millimetre
RRLs could well sample the upper part of the initial mass function and
thus be good tracers of SFR. We also study the relationships between
Lbol and the molecular line luminosities (L'mol) of CS J = 2-1 and
HC3N J = 11-10 for all the 146 ATOMS sources. The Lbol - L'mol
correlations of both the CS J = 2-1 and HC3N J = 11-10 lines appear
approximately linear and these transitions have success in predicting
Lbol similar to that of more commonly used transitions. The Lbol
-to- L'mol ratios or SFR-to-mass ratios (star formation efficiency)
do not change with galactocentric distances (RGC). Sources with
H40α emission (or H II regions) show higher Lbol -to-
L'mol ratios than those without H40α emission, which may be
an evolutionary effect.
Description:
We made the ALMA observations for 146 active Galactic star-forming
regions as the ATOMS survey (ALMA 3 mm observations of massive SFRs).
Most (139) of the targets are located in the first and fourth Galactic
quadrants of the inner Galactic plane. The properties and ALMA
observations of these sources have been described in detail in Liu et
al. (2016ApJ...829...59L 2016ApJ...829...59L; 2020MNRAS.496.2790L 2020MNRAS.496.2790L, Cat. J/MNRAS/496/2790;
2020MNRAS.496.2821L 2020MNRAS.496.2821L, Cat. J/MNRAS/496/2821; 2021MNRAS.505.2801L 2021MNRAS.505.2801L, Cat.
J/MNRAS/505/2801). The data on (CS J = 2-1 97.9 GHz, HC3N J = 11-10
100 GHz, and H40α 99.02 GHz) RRL were obtained from the ACA
(Morita Array) observations in the ATOMS survey. We use only the ACA
data to obtain a larger field of view than we would have with the 12-m
array data and the ACA data can match clump-scale luminosity
information and better trace the overall spatial distribution of gas
within these star-forming regions. The ACA observations were performed
between September and mid-November in 2019 in band 3 (Project ID:
2019.1.00685.S), (i.e refer to section 2 Observations).
As explained in the section 3.1 Extraction of compact objects, we
extracted compact objects from the integrated intensity maps of the
three lines (CS J = 2-1, HC3N J = 11-10, and H40α) using an
elliptical Gaussian fit. The objects in molecular line emission can be
easily identified by eye. In total, we detected 177, 185, and 75
sources in emission from CS J = 2-1, HC3N J = 11-10, and H40α,
respectively. These gaussian fits provide line fluxes, object sizes
and velocities which are used to compute properties of the ionized gas
such as molecular and bolometric luminosities, Q0, ne, gas masses
and SFRs as well (i.e refer to the sections 3 Results, 4.1 SFRs. and
appendix A and B).
To resume all the results, compact gas clumps detected with
CS J = 2-1, HC3N J = 11-10, H40α are presented the table2.dat,
table3.dat, table4.dat respectively. Next, molecular and bolometric
luminosities of the 146 sources shown in the table5.dat. Finally, the
SFRs are thus exhibited in the table7.dat as well as Mclump and
Mion of each ATOMS sources.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 52 177 Gas clumps identified in CS J = 2-1
table3.dat 52 185 Gas clumps identified in HC3N J = 11-10
table4.dat 73 75 Gas clumps identified in H40α
table5.dat 66 146 Luminosities of ATOMS sources
table7.dat 43 146 SFRs and gas masses of ATOMS sources
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See also:
J/MNRAS/496/2790 : ATOMS I Description and a first look at G9.62+0.19
(Liu+, 2020)
J/MNRAS/496/2821 : ATOMS II Compact objects in ACA observations (Liu+, 2020)
J/MNRAS/505/2801 : ATOMS Paper III, massive star-forming regions (Liu+, 2021)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- IRAS IRAS source identifier (IHHMMm±DDMM)
(IRAS)
13 I1 --- ID [1/4] Relative ID number to IRAS source
identifier (ID)
15- 20 F6.2 arcsec OffsetRA Offset in right ascension relative to IRAS
RAdeg position (OffsetRA)
22- 27 F6.2 arcsec OffsetDE Offset in declination relative to IRAS
DEdeg position (OffsetDec)
29- 32 F4.2 --- Rasp The aspect ratio is defined as the ratio
between de-convolved semimajor size a and
semiminor size b (rasp)
34- 37 F4.2 pc Reff The effective radius is defined as
sqrt(ab) (Reff)
39- 44 F6.2 Jy.km/beam/s Speak Peak integrated intensity (Speak)
46- 52 F7.2 Jy.km/s Stotal Total flux intensity (Stotal)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- IRAS IRAS source identifier (IHHMMm±DDMM)
(IRAS)
13 I1 --- ID [1/5] Relative ID number to IRAS source
identifier (ID)
15- 20 F6.2 arcsec OffsetRA Offset in right ascension relative to IRAS
RAdeg position (OffsetRA)
22- 27 F6.2 arcsec OffsetDE Offset in declination relative to IRAS
DEdeg position (OffsetDec)
29- 32 F4.2 --- Rasp The aspect ratio is defined as the ratio
between de-convolved semimajor size a and
semiminor size b (rasp)
34- 37 F4.2 pc Reff The effective radius is defined as
sqrt(ab) (Reff)
39- 44 F6.2 Jy.km/beam/s Speak Peak integrated intensity (Speak)
46- 52 F7.2 Jy.km/s Stotal Total flux intensity (Stotal)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- IRAS IRAS source identifier (IHHMMm±DDMM)
(IRAS)
13 I1 --- ID [1/5] Relative ID number to IRAS source
identifier (ID)
15- 20 F6.2 arcsec OffsetRA Offset in right ascension relative to
IRAS RAdeg position (OffsetRA)
22- 27 F6.2 arcsec OffsetDE Offset in declination relative to IRAS
DEdeg position (OffsetDec)
29- 32 F4.2 --- Rasp The aspect ratio is defined as the ratio
between de-convolved semimajor size a and
semiminor size b (rasp)
34- 37 F4.2 pc Reff The effective radius is defined as
sqrt(ab) (Reff)
39- 44 F6.2 Jy.km/beam/s Speak Peak integrated intensity (Speak)
46- 51 F6.2 Jy.km/s Stotal Total flux intensity (Stotal)
53- 56 F4.2 Jy.km/s e_Stotal Mean error of Stotal (errStotal)
58- 62 F5.2 [s-1] logQ0 The rate of ionizations as computed with
equation A5 in the section APPENDIX A
From rrls to sfrs (logQ0)
64- 67 F4.2 [cm-3] logne The electron density according to
equation B1 in the section APPENDIX B
Derivation of electron density and
ionized gas mass (logne)
69- 73 F5.2 [Msun] logMion The mass of ionized gas in computed with
equation B2 in the section APPENDIX B
Derivation of electron density and
ionized gas mass (logMion)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- ID Identifier source number (ID)
5- 15 A11 --- IRAS IRAS source identifier
(IHHMMm±DDMM) (IRAS)
17- 18 I2 h RAh Right ascension (J2000)
20- 21 I2 min RAm Right ascension (J2000)
23- 27 F5.2 s RAs Right ascension (J2000)
29 A1 --- DE- Declination sign (J2000)
30- 31 I2 deg DEd Declination (J2000)
33- 34 I2 arcmin DEm Declination (J2000)
36- 39 F4.1 arcsec DEs Declination (J2000)
41- 44 F4.1 kpc D Distance of the source (Distance)
46- 49 F4.1 kpc RGC Galactocentric distance (RGC)
51- 54 F4.2 [Lsun] logLbol Logarithm of the bolometric luminosity are
calculated from integrating the whole SED
(logLbol)
56- 60 F5.2 [K.km/s/pc2] logL'CS ? The molecular carbon monosulfide CS line
luminosity from equation 1 of the
section 3.3 The Lbol-L'mol scaling
relations (logL'CS)
62- 66 F5.2 [K.km/s/pc2] logL'HC3N ? The molecular cyanoacetylene HC3N line
luminosity from equation 1 of the
section 3.3 The Lbol-L'mol scaling
relations (logL'HC3N)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- ID Identifier source number (ID)
5- 15 A11 --- IRAS IRAS source identifier
(IHHMMm±DDMM) (IRAS)
17- 20 F4.2 [Jy.kpc2.km/s] logLH40a ? Logarithm of line H40α
luminosity computed with equation
A1 of the section APPENDIX A From
rrls to sfrs (logLH40a)
22- 26 F5.2 [Msun/Myr] logSFRbol ? Logarithm of the bolometric SFR
derived from the Lbol as in
equation 2 of the section 4.1 SFRs
(logSFRbol)
28- 32 F5.2 [Msun/Myr] logSFRH40a ? Logarithm of the H40α SFR
derived as equation A6 of the
section APPENDIX A From rrls to
sfrs (logSFRH40a)
34- 37 F4.2 [Msun] logMclump Logarithm of the molecular gas in
clumps from Liu et al.
2020MNRAS.496.2790L 2020MNRAS.496.2790L
Cat. J/MNRAS/496/2790 (logMclump)
39- 43 F5.2 [Msun] logMion ? The mass of ionized gas in
computed with equation B2 in the
section APPENDIX B Derivation of
electron density and ionized gas
mass (logMion)
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History:
From electronic version of the journal
(End) Luc Trabelsi [CDS] 26-Nov-2024