J/ApJ/824/29 ATLASGAL clumps with IRAS flux and MALT90 data (Stephens+, 2016)
Linking dense gas from the Milky Way to external galaxies.
Stephens I.W., Jackson J.M., Whitaker J.S., Contreras Y., Guzman A.E.,
Sanhueza P., Foster J.B., Rathborne J.M.
<Astrophys. J., 824, 29-29 (2016)>
=2016ApJ...824...29S 2016ApJ...824...29S (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Radio lines ; Surveys ; Molecular clouds ;
H II regions ; Infrared sources
Keywords: galaxies: star formation; ISM: clouds; ISM: molecules;
stars: formation; stars: massive
Abstract:
In a survey of 65 galaxies, Gao & Solomon (2004ApJS..152...63G 2004ApJS..152...63G) found
a tight linear relation between the infrared luminosity (LIR, a
proxy for the star formation rate) and the HCN(1-0) luminosity
(LHCN). Wu et al. (2005ApJ...635L.173W 2005ApJ...635L.173W) found that this relation
extends from these galaxies to the much less luminous Galactic
molecular high-mass star-forming clumps (∼1pc scales), and posited
that there exists a characteristic ratio LIR/LHCN for high-mass
star-forming clumps. The Gao-Solomon relation for galaxies could then
be explained as a summation of large numbers of high-mass star-forming
clumps, resulting in the same LIR/LHCN ratio for galaxies. We test
this explanation and other possible origins of the Gao-Solomon
relation using high-density tracers (including HCN(1-0),
N2H+(1-0), HCO+(1-0), HNC(1-0), HC3N(10-9), and C2H(1-0))
for ∼300 Galactic clumps from the Millimetre Astronomy Legacy Team
90GHz (MALT90) survey. The MALT90 data show that the Gao-Solomon
relation in galaxies cannot be satisfactorily explained by the
blending of large numbers of high-mass clumps in the telescope beam.
Not only do the clumps have a large scatter in the LIR/LHCN ratio,
but also far too many high-mass clumps are required to account for the
Galactic IR and HCN luminosities. We suggest that the scatter in the
LIR/LHCN ratio converges to the scatter of the Gao-Solomon
relation at some size-scale ≳1kpc. We suggest that the Gao-Solomon
relation could instead result from of a universal large-scale star
formation efficiency, initial mass function, core mass function, and
clump mass function.
Description:
The Millimetre Astronomy Legacy Team 90GHz (MALT90) survey (Foster+
2011, J/ApJS/197/25; 2013PASA...30...38F 2013PASA...30...38F; Jackson+
2013PASA...30...57J 2013PASA...30...57J) mapped 16 lines for 3246 clumps, primarily
high-mass star-forming clumps that are >200M☉, as identified
from the ATLASGAL 870um survey (Schuller et al. 2009A&A...504..415S 2009A&A...504..415S).
In order to compare luminosities derived from IRAS (LIR) to
molecular line luminosities from MALT90 (Lmolecule), we first
matched the MALT90 clumps to the IRAS Point Source Catalog v2.1 (PSC;
see Cat. II/125). See section 2.1 for further explanations.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 116 405 *IR and molecular fluxes
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Note on table4.dat: This table shows a list of all MALT90 (Millimetre Astronomy
Legacy Team 90GHz) sources that match with an IRAS source.
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See also:
II/125 : IRAS catalogue of Point Sources, Version 2.0 (IPAC 1986)
J/ApJ/815/130 : High-mass molecular clumps from MALT90 (Guzman+, 2015)
J/AJ/148/124 : Herschel key program Heritage (Seale+, 2014)
J/A+A/568/A41 : ATLASGAL Compact Source Catalog: 280<l<60 (Urquhart+, 2014)
J/A+A/565/A75 : ATLASGAL Dust condensations in Galactic plane (Csengeri+, 2014)
J/ApJ/783/130 : Parallaxes of high mass star forming regions (Reid+, 2014)
J/ApJ/780/173 : Masses of giant molecular clouds in MW (Battisti+, 2014)
J/ApJ/777/157 : 90GHz obs. of high-mass star-forming regions (Hoq+, 2013)
J/AJ/146/62 : HERschel HERITAGE in Magellanic Clouds (Meixner+, 2013)
J/A+A/549/A45 : ATLASGAL Compact Source Catalog: 330<l<21 (Contreras+, 2013)
J/ApJS/197/25 : MALT90 pilot survey (Foster+, 2011)
J/ApJS/184/172 : High- and intermediate-mass YSOs in the LMC (Gruendl+, 2009)
J/ApJS/178/56 : CO observations of LMC Giant Molecular clouds (Fukui+, 2008)
J/ApJ/674/172 : Oxygen abundances of LIRGs and ULIRGs (Rupke+, 2008)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [AGAL]
5- 18 A14 --- AGAL ATLASGAL identifier
(LLL.lll+BB.bbb; G) (1)
19- 20 A2 --- m_AGAL Component identifier (if _A or _B) (2)
22- 33 A12 --- Class Mid-IR classification (3)
35- 39 F5.2 kpc Dist [0.06/24]? Distance (4)
41- 44 F4.2 [Lsun/kpc2] logFIR [1.5/5] Log IR flux (5)
46- 50 F5.2 [K.km/s.pc2/kpc2] FHCO+ [-0.6/1.7]? Log HCO+ line flux
52- 56 F5.2 [K.km/s.pc2/kpc2] FHNC [-0.4/1.4]? Log HNC line flux
58- 62 F5.2 [K.km/s.pc2/kpc2] FN2H+ [-0.7/1.3]? Log N2H+ line flux
64- 68 F5.2 [K.km/s.pc2/kpc2] FHCN [-0.5/1.8]? Log HCN line flux
70- 74 F5.2 [K.km/s.pc2/kpc2] FH13CO+ [-0.2/0.7]? Log H13CO+ line flux
76- 80 F5.2 [K.km/s.pc2/kpc2] FHN13C [-0.3/0.7]? Log HN13C line flux
82- 86 F5.2 [K.km/s.pc2/kpc2] F13CS [-0.2/0.7]? Log 13CS line flux
88- 92 F5.2 [K.km/s.pc2/kpc2] FHNCO4 [-0.08/0.8]? Log HNCO40,4 line flux
94- 98 F5.2 [K.km/s.pc2/kpc2] FCH3CN [-0.4/1.1]? Log CH3CN line flux
100-104 F5.2 [K.km/s.pc2/kpc2] FSiO [-0.7/0.7]? Log SiO line flux
106-110 F5.2 [K.km/s.pc2/kpc2] FHC3N [-0.6/1.5]? Log HC3N line flux
112-116 F5.2 [K.km/s.pc2/kpc2] FC2H [-0.2/1.1]? Log C2H line flux
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Note (1): GAL344.582-00.024_S and AGAL346.418+00.279_S luminosities were not
used in this paper because the distances are unrealistically close
for H II regions.
Note (2): ATLASGAL clumps have either "_S", "_A", or "_B" after their names, as
per Rathborne+ (2016PASA...33...30R 2016PASA...33...30R). Those with the nomenclature "_S"
are not likely to have multiple clumps along the line of sight.
Those with "_A" and "_B" are likely to have confusion along the
line of sight (i.e., they have two velocity components separated
by >15km/s). For all numbers, fits, and figures within the bulk of
the paper, "_A" and "_B" components are not used since the IRAS
continuum contributed to each the "_A" and "_B" components cannot be
deduced. We report the fluxes here for completeness.
Note (3): Classification based on Spitzer three-color images (see Section 4.1):
254 "HII Region", 110 "Protostellar", 23 "Compact HII",
11 "PDR" (photodissociation region), 5 "Uncertain" and 2 "Quiescent".
Note (4): These are kinematic distances from J. Whitaker et al. (in prep).
Note (5): The fluxes reported in this paper are simply the luminosities divided
by the square of the distance in kpc2, i.e., for FIR:
FIR=0.56(13.48F12+5.16F25+2.58F60+F100) (equation 3).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 10-Aug-2016