J/A+A/689/A122 12CO and HCN datacubes of NGC 253 (Beslic+, 2024)
The properties and kinematics of HCN emission across the closest starburst
galaxy NGC 253 observed with ALMA.
Beslic I., Barnes A.T., Bigiel F., Jimenez-Donaire M.J., Usero A.,
Henshaw J.D., Faesi C., Leroy A.K., Rosolowsky E., den Brok J.S.,
Chevance M., Eibensteiner C., Grasha K., Klessen R.S., Kruijssen J.M.D.,
Liu D., Meidt S., Neumann J., Neumann L., Pan H., Puschnig J., Querejeta M.,
Schinnerer E., Williams T.G.
<Astron. Astrophys. 689, A122 (2024)>
=2024A&A...689A.122B 2024A&A...689A.122B (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, Seyfert ; Radio lines ; Interstellar medium ;
Carbon monoxide
Keywords: stars: formation - ISM: molecules - galaxies: starburst -
radio lines: ISM
Abstract:
Investigating molecular gas tracers, such as hydrogen cyanide (HCN),
to probe higher densities than CO emission across nearby galaxies
remains challenging. This is due to the large observing times required
to detect HCN at a high sensitivity and spatial resolution. Although
approximate kiloparsec scales of HCN maps are available for tens of
galaxies, higher-resolution maps still need to be available. We aim to
study the properties of molecular gas, the contrast in intensity
between two tracers that probe different density regimes (the
HCN(1-0)/CO(2-1), ratio), and their kinematics across NGC 253, one of
the closest starburst galaxies. With its advanced capabilities, the
Atacama Large Millimeter/submillimeter Array (ALMA) can map these
features at a high resolution across a large field of view and uncover
the nature of such dense gas in extragalactic systems. We present new
ALMA Atacama Compact Array and Total Power (ACA+TP) observations of
the HCN emission across NGC 253. The observations cover the inner 8.6'
of the galaxy disk at a spatial resolution of 300pc. Our study
examines the distribution and kinematics of the HCN- traced gas and
its relationship with the bulk molecular gas traced by CO(2-1). We
analyze the integrated intensity and mean velocity of HCN and CO along
each line of sight. We also used the SCOUSE software to perform
spectral decomposition, which considers each velocity component
separately. We find that the denser molecular gas traced by HCN piles
up in a ring-like structure at a radius of 2kpc. The HCN emission is
enhanced by two orders of magnitude in the central 2kpc regions,
beyond which its intensity decreases with increasing galactocentric
distance. The number of components in the HCN spectra shows a robust
environmental dependence, with multiple velocity features across the
center and bar. The HCN spectra exhibit multiple velocity features
across the center and bar, which shows a robust environmental
dependence. We have identified an increase in the HCN/CO ratio in
these regions, corresponding to a velocity component likely associated
with a molecular outflow. We have also discovered that the ratio
between the total infrared luminosity and dense gas mass, which is an
indicator of the star formation efficiency of dense gas, is
anticorrelated with the molecular gas surface density up to
approximately 200M☉/pc2. However, beyond this point, the ratio
starts to increase. We argue that using information about
spectroscopic features of molecular emission is an important aspect of
understanding molecular properties in galaxies.
Description:
We provide two data cubes of HCN(1-0) and CO(2-1) at 22 arcsecond
resolution with a channel width of 10 km/s of NGC 253.
Objects:
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RA (2000) DE Designation(s)
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00 47 33.13 -25 17 19.6 NGC 253 = NAME Sculptor Filament
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 159 2 List of fits datacubes
fits/* . 2 Individual fits datacubes
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 21 I2 --- Nx Number of pixels along X-axis
23- 24 I2 --- Ny Number of pixels along Y-axis
26- 27 I2 --- Nz Number of slices
29- 37 F9.4 km/s bVRAD Lower value of VRAD interval
39- 45 F7.3 km/s BVRAD Upper value of VRAD interval
47- 53 F7.5 km/s dVRAD VRAD resolution
55- 58 I4 Kibyte size Size of FITS file
60- 78 A19 --- FileName Name of FITS file, in subdirectory fits
80-159 A80 --- Title Title of the FITS file
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Acknowledgements:
Ivana Beslic, astro.beslijica(at)gmail.com
(End) Patricia Vannier [CDS] 09-Jul-2024