J/A+A/702/A273 [CII] and [OIII] mapping in the molecular ridge (Fischer+, 2025)
LMC+: Large-scale mapping of [C II] and [O III] in the LMC molecular ridge.
I. Dataset and line ratio analyses.
Fischer C., Madden S.C., Krabbe A., Polles F.L., Fadda D., Tarantino E.,
Galliano F., Chen C.-H.R., Abel N., Beck A., Belloir L., Bigiel F.,
Bolatto A., Chevance M., Colditz S., Fischer N., Green A., Hughes A.,
Indebetouw R., Iserlohe C., Kazmierczak-Barthel M., Klein R.,
Lambert-Huyghe A., Lebouteiller V., Mikheeva E., Poglitsch A.,
Ramambason L., Reach W., Rubio M., Vacca W., Wong T., Zinnecker H.
<Astron. Astrophys. 702, A273 (2025)>
=2025A&A...702A.273F 2025A&A...702A.273F (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Molecular clouds ; Infrared sources ;
Radio lines
Keywords: methods: data analysis - ISM: general - galaxies: ISM
Abstract:
The fundamental process of star formation in galaxies involves the
intricate interplay between the fueling of star formation via
molecular gas and the feedback from recently formed massive stars that
can, in turn, hinder the conversion of gas into stars. This process,
by which galaxies evolve, is also closely connected to the intrinsic
properties of the interstellar medium (ISM), such as structure,
density, pressure, and metallicity.
To study the role that different molecular and atomic phases of the
ISM play in star formation, and to characterize their physical
conditions, we zoom into our nearest neighboring galaxy, the Large
Magellanic Cloud (LMC; 50kpc), the most convenient laboratory in which
to study the effects of the lower metal abundance on the properties of
the ISM. The LMC offers a view of the ISM and star formation
conditions in a low-metallicity (Z∼0.5Z☉) environment similar,
in that regard, to the epoch of the peak of star formation in the
earlier Universe (z∼1.5). Following up on studies carried out at
galactic scales in low-Z galaxies, we present an unprecedentedly
detailed analysis of well-known star-forming regions (SFRs) at a
spatial resolution of a few parsecs.
We mapped a 610pcx260pc region in the LMC molecular ridge in [C
II]λ158um and the [O III]λ88um using the FIFI-LS
instrument on the SOFIA telescope. We compared the data with the
distribution of the CO(2-1) emission from ALMA, the modeled total
infrared luminosity, and the Spitzer/MIPS 24um continuum and Hα.
We present new large maps of [C II] and [O III] and perform a first
comparison with CO(2-1) line and LTIR emission. We also provide a
detailed description of the observing strategy with SOFIA/FIFI-LS and
the data reduction process.
We find that [C II] and [O III] emission is associated with the SFRs
in the molecular ridge, but also extends throughout the mapped region,
and is not obviously associated with ongoing star formation. The CO
emission is clumpier than the [C II] emission and we find plentiful
[C II] present where there is little CO emission, possibly holding
important implications for "CO-dark" gas. We find a clear trend of the
L[C II]/LTIR ratio decreasing with increasing LTIR in the full range.
This suggests a strong link between the "[C II]-deficit" and the local
physical conditions instead of global properties.
Description:
We present SOFIA/FIFI-LS maps of the Large Magellanic Cloud molecular
ridge covering a 610pcx260pc region in the [CII] 157.74um and
[OIII] 88.36um fine-structure lines. We find that [CII] and [OIII]
emission is associated with the SFRs in the molecular ridge, but also
extends throughout the mapped region, not obviously associated with
ongoing star formation. We find plentiful [CII] present where there is
little CO emission, possibly holding important implications for
CO-dark gas. We find a clear trend of the [CII]/TIR ratio decreasing
with increasing TIR in the full range. This suggests a strong link
between the "[CII]-deficit" and the local physical conditions instead
of global properties. Where we detect [OIII] outside of the brightest
regions, it is not correlated with 24um, but remains high as the
24um emission decreases, indicating the high porosity of the ISM in
this environment.
SOFIA/FIFI-LS maps of [CII] 157.7um and [OIII] 88.4um emission
in the LMC molecular ridge.
Objects:
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RA (2000) DE Designation(s)
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05 39 55.0 -69 40 30. LMC molecular ridge
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 131 3 List of fits maps
fits/* . 3 Individual fits maps
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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- 22 I3 --- Nx Number of pixels along X-axis
24- 26 I3 --- Ny Number of pixels along Y-axis
28- 30 I3 Kibyte size Size of FITS file
32- 57 A26 --- FileName Name of FITS file, in subdirectory fits
59-131 A73 --- Title Title of the FITS file
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Acknowledgements:
Christian Fischer, fischer(at)iram.fr
(End) Patricia Vannier [CDS] 03-Sep-2025