J/MNRAS/494/1276 MALATANG survey NGC253 dense gas & SFR formation (Jiang+, 2020)
The MALATANG survey:
Dense gas and star formation from high transition HCN and HCO+ maps of NGC 253.
Jiang X.-J., Greve T.R., Gao Y., Zhang Z.-Y., Tan Q., de Grijs R., Ho L.C.,
Michalowski M.J., Currie M.J., Wilson C.D., Brinks E., Ao Y., Zhao Y.,
He J., Harada N., Yang C., Jiao Q., Chung A., Lee B., Smith M.W.L., Liu D.,
Matsushita S., Shi Y., Imanishi M., Rawlings M.G., Zhu M., Eden D.,
Davis T.A., Li X.
<Mon. Not. R. Astron. Soc. 494, 1276-1296 (2020)>
=2020MNRAS.494.1276J 2020MNRAS.494.1276J (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Galaxies, nearby ; Interstellar medium
Keywords: galaxies: ISM - galaxies: individual: NGC 253 -
galaxies: star formation - ISM: molecules - submillimetre: ISM
Abstract:
In order to study the high-transition dense-gas tracers and their
relationships to the star formation of the inner ∼2kpc circumnuclear
region of NGC 253, we present HCN J=4-3 and HCO+ J=4-3 maps
obtained with the James Clerk Maxwell Telescope(JCMT). With the
spatially resolved data, we compute the concentration indices r90/r50
for the different tracers. HCN and HCO+ 4-3 emission features tend
to be centrally concentrated, which is in contrast to the shallower
distribution of CO 1-0 and the stellar component. The dense-gas
fraction (fdense, traced by the velocity-integrated-intensity ratios
of HCN/CO and HCO+/CO) and the ratio R31 (CO 3-2/1-0) decline
towards larger galactocentric distances, but increase with higher SFR
surface density. The radial variation and the large scatter of fdense
and R31 imply distinct physical conditions in different regions of the
galactic disc. The relationships of fdense versus Sigma_stellar, and
SFE_dense versus Sigma_stellar are explored. SFE_dense increases with
higher Sigma_stellar in this galaxy, which is inconsistent with
previous work that used HCN 1-0 data. This implies that existing
stellar components might have different effects on the high-J HCN and
HCO+ than their low-J emission. We also find that SFE_dense seems to
be decreasing with higher f_dense which is consistent with previous
works, and it suggests that the ability of the dense gas to form stars
diminishes when the average density of the gas increases. This is
expected in a scenario where only the regions with high-density
contrast collapse and form stars.
Description:
All temperature units are in main beam temperature (Tmb). The HCN and
HCO+ data are obtained with the James Clerk Maxwell Telescope (JCMT).
The CO 1-0 data are from the Nobeyama CO Atlas of Nearby Spiral
Galaxies (Sorai et al. 2000PASJ...52..785S 2000PASJ...52..785S; Kuno et al.
2007PASJ...59..117K 2007PASJ...59..117K), and the CO 3-2 data from the JCMT archive
(project ID: M08AU14). See Section 2 of our paper for more details.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 99 98 Integrated intensities and line ratios
table2.dat 110 98 Luminosities and dense gas masses calculated
based on Table 1
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See also:
J/MNRAS/388/849 : NGC253 XMM observations (Barnard+, 2008)
J/A+A/550/A12 : NGC253 near-infrared H2 emission (Rosenberg+, 2013)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 arcsec offsetx Offset along the major axis of NGC253
5- 7 I3 arcsec offsety Offset along the major axis of NGC253
9 A1 --- l_IHCN43 Upper limit flag on IHCN43
11- 14 F4.1 K.km/s IHCN43 ? Integrated intensity of HCN(4-3)
16- 18 F3.1 K.km/s e_IHCN43 ? Error of IHCN43 (1)
20 A1 --- l_IHCO+43 Upper limit flag on IHCO+43
22- 25 F4.1 K.km/s IHCO+43 ? Integrated intensity of HCO+(4-3)
27- 29 F3.1 K.km/s e_IHCO+43 ? Error on IHCO+43 (1)
31- 34 I4 K.km/s IHCO10 ? Integrated intensity of CO(1-0)
36- 38 I3 K.km/s e_IHCO10 ? Error on ICO10 (1)
40- 45 F6.1 K.km/s ICO32 ? Integrated intensity of CO(3-2)
47- 51 F5.1 K.km/s e_ICO32 ? Error on ICO32 (1)
53- 57 F5.2 --- ICO32/ICO10 ? Ratio between ICO32 and ICO10
60- 63 F4.2 --- e_ICO32/ICO10 ? Error on CO32/CO10 (1)
65- 69 F5.3 --- IHCN43/ICO10 ? Ratio between IHCN43 and ICO10
71- 75 F5.3 --- e_IHCN43/ICO10 ? Error on HCN43/CO10 (1)
77- 81 F5.3 --- IHCO+43/ICO10 ? Ratio between IHCO+43 and ICO10
83- 87 F5.3 --- e_IHCO+43/ICO10 ? Error on HCO+43/CO10 (1)
89 A1 --- l_IHCN43/IHCO+43 Limit flag on HCN43/HCO+43 ("<" and ">"
means upper limit and lower limit)
91- 94 F4.2 --- IHCN43/IHCO+43 ? Ratio between IHCN43 and IHCO+43
96- 99 F4.2 --- e_IHCN43/IHCO+43 ? Error on IHCN43 and IHCO+43 (1)
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Note (1): The errors include 10% flux calibration uncertainty.
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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 arcsec offsetx Offset along the major axis of NGC253
5- 7 I3 arcsec offsety Offset along the major axis of NGC253
9 A1 --- l_LHCN43 Upper limit flag on LHCN43
11- 15 F5.1 10+4K.km/s LHCN43 ? Line luminosity of HCN(4-3)
17- 20 F4.1 10+4K.km/s e_LHCN43 ? Error on LHCN43 (1)
22 A1 --- l_LHCO+43 Upper limit flag on LHCO+43
24- 28 F5.1 10+4K.km/s LHCO+43 ? Line luminosity of HCO+(4-3)h
30- 33 A4 10+4K.km/s e_LHCO+43 ? Error on LHCO+43 (1)
35- 40 F6.1 10+7Lsun LIR ? Total infrared luminosity
42- 46 F5.1 10+7Lsun e_LIR ? Error on LIR (1)
48- 51 I4 10-3Msun/yr SFR ? Star formation rate
53- 57 F5.1 10-3Msun/yr e_SFR ? Error on SFR (1)(2)
59 A1 --- l_MHCN43 Upper limit flag on MHCN43
61- 65 F5.1 10+6Msun MHCN43 ? HCN mass from a constant conversion
factor
67- 70 F4.1 10+6Msun e_MHCN43 ? Error on MHCN43 (1)
72 A1 --- l_MHCO+43 Upper limit flag on MHCO+43
74- 78 F5.1 10+6Msun MHCO+43 ? HCO+ mass from a constant conversion
factor
80- 83 F4.1 10+6Msun e_MHCO+43 ? Error on MHCO+43 (1)
85 A1 --- l_MHCN43G0 Upper limit flag on MHCN43G0
87- 91 F5.1 10+6Msun MHCN43G0 ? HCN mass from G0 dependent conversion
factor
93- 96 F4.1 10+6Msun e_MHCN43G0 ? Error on MHCN43 (1)
98 A1 --- l_MHCO+43G0 Upper limit flag on MassHCO+43G0
100-104 F5.1 10+6Msun MHCO+43G0 ? HCO+ mass from G0 dependent conversion
factor
106-110 F5.1 10+6Msun e_MHCO+43G0 ? Error on MHCO+43G0 (1)
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Note (1): The calibration uncertainty is included in the Errors.
Note (2): For SFR the uncertainty on the conversion from LIR is not included.
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Acknowledgements:
Xue-Jian Jiang, xjjiangnju(at)gmail.com
(End) Xue-Jian Jiang [Purple Mountain Obs.], Patricia Vannier [CDS] 24-Feb-2020