J/ApJ/855/49 ALMA astrochemical obs. of the merger NGC 3256 (Harada+, 2018)
ALMA astrochemical observations of the infrared-luminous merger NGC 3256.
Harada N., Sakamoto K., Martin S., Aalto S., Aladro R., Sliwa K.
<Astrophys. J., 855, 49 (2018)>
=2018ApJ...855...49H 2018ApJ...855...49H
ADC_Keywords: Galaxies, radio; Millimetric/submm sources; Molecular data
Keywords: astrochemistry ; galaxies: abundances ;
galaxies: individual (NGC 3256, Arp 220, NGC 253) ; galaxies: ISM ;
galaxies: starburst ; ISM: molecules
Abstract:
In external galaxies, molecular composition may be influenced by
extreme environments such as starbursts and galaxy mergers. To study
such molecular chemistry, we observed the luminous infrared galaxy and
merger NGC 3256 using the Atacama Large Millimeter/submillimeter
Array. We covered most of the 3 and 1.3mm bands for a multispecies,
multitransition analysis. We first analyzed intensity ratio maps of
selected lines such as HCN/HCO+, which shows no enhancement at an
active galactic nucleus. We then compared the chemical compositions
within NGC 3256 at the two nuclei, tidal arms, and positions with
influence from galactic outflows. We found the largest variation in
SiO and CH3OH, species that are likely to be enhanced by shocks.
Next, we compared the chemical compositions in the nuclei of NGC 3256,
NGC 253, and Arp 220; these galactic nuclei have varying star
formation efficiencies. Arp 220 shows higher abundances of SiO and
HC3N than NGC 3256 and NGC 253. Abundances of most species do not
show a strong correlation with star formation efficiencies, although
the CH3CCH abundance seems to have a weak positive correlation with
the star formation efficiency. Lastly, the chemistry of spiral arm
positions in NGC 3256 is compared with that of W51, a Galactic
molecular cloud complex in a spiral arm. We found higher fractional
abundances of shock tracers, and possibly also a higher dense gas
fraction in NGC 3256 compared with W51.
Description:
Our ALMA observations (project code 2015.1.00412.S and 2016.1.00965.S)
span through Cycles 3 and 4 using the 12m array and Atacama Compact
Array (ACA) for higher-frequency observations.
For better signal-to-noise ratio (S/N), we also used ALMA data
2015.1.00993.S in the archive for frequency ranges overlapping with
ours. To get the data on the CN (1-0) line, we also used ALMA data
2011.0.00525.S, whose observational parameters are described in
Sakamoto+ (2014ApJ...797...90S 2014ApJ...797...90S). Our observations covered most of
Bands 3 (3mm) and 6 (1.3mm).
Objects:
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RA (ICRS) DE Designation(s)
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10 27 51.28 -43 54 13.6 NGC 3256 = MCG-07-22-010
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 64 327 Observed peak intensities and velocity-integrated
intensities for detected lines
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See also:
J/A+A/361/1079 : HNCO in massive galactic dense cores (Zinchenko, 2000)
J/AJ/126/1607 : IRAS Revised Bright Galaxy Sample (Sanders+, 2003)
J/A+A/432/369 : Leiden Atomic and Molecular Database (LAMDA) (Schoeier+, 2005)
J/ApJ/720/1055 : VBLA observations of W51 Main/South (Sato+, 2010)
J/ApJS/206/1 : Mid-IR properties of GOALS nearby LIRGs (Stierwalt+, 2013)
J/AJ/146/86 : Cosmicflows-2 catalog (Tully+, 2013)
J/A+A/572/A40 : Outflow of H2 gas from NGC3256 (Emonts+, 2014)
J/A+A/579/A101 : 3mm molecular line survey of 8 AGN (Aladro+, 2015)
J/ApJ/799/10 : Arp 220 6 and 33GHz images (Barcos-Munoz+, 2015)
J/A+A/582/A91 : NGC 4418 ALMA mm-wave spectral scan (Costagliola+, 2015)
J/ApJ/822/105 : Chemical evolution in the SMC (Acharyya+, 2016)
J/A+A/590/A25 : Arp 220 HCN and HCO+ data cubes (Martin+, 2016)
J/ApJ/845/116 : Spectral line survey toward W51 in 3mm (Watanabe+, 2017)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Pos Position (1)
5- 14 A10 --- Species Detected species
16- 30 A15 --- Transition Transition
32- 38 F7.3 GHz Freq [86.7/273.5] Rest Frequency
40- 46 F7.2 mK Ipeak [12/1174] Peak intensity
48- 52 F5.2 mK e_Ipeak [5/25] Uncertainty in Ipeak
54- 59 F6.2 K.km/s Idv [-0.3/205.3] Velocity integrated intensity
61- 64 F4.2 K.km/s e_Idv [0.4/2.3] Uncertainty in Idv
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Note (1): Position (see also Figure 1) as follows:
N = northern nucleus;
S = southern nucleus;
C = central peak;
TNE = tidal arm northeast;
TSE = tidal arm southeast;
TSW = tidal arm southwest;
OS = outflow south;
SW = southern galaxy west.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 16-Nov-2018