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Interstellar anatomy of the TeV gamma-ray peak in the IC443 supernova remnant
Context. Supernova remnants (SNRs) represent a major feedback source from stars in the interstellar medium of galaxies. During the latest stage of supernova explosions, shock waves produced by the initial blast modify the chemistry of gas and dust, inject kinetic energy into the surroundings, and ma...
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Published in: | Astronomy and astrophysics (Berlin) 2020-12, Vol.644, p.A64 |
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Main Authors: | , , , , , , , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Context.
Supernova remnants (SNRs) represent a major feedback source from stars in the interstellar medium of galaxies. During the latest stage of supernova explosions, shock waves produced by the initial blast modify the chemistry of gas and dust, inject kinetic energy into the surroundings, and may alter star formation characteristics. Simultaneously,
γ
-ray emission is generated by the interaction between the ambient medium and cosmic rays (CRs), including those accelerated in the early stages of the explosion.
Aims.
We study the stellar and interstellar contents of IC443, an evolved shell-type SNR at a distance of 1.9 kpc with an estimated age of 30 kyr. We aim to measure the mass of the gas and characterize the nature of infrared point sources within the extended G region, which corresponds to the peak of
γ
-ray emission detected by VERITAS and
Fermi
.
Methods.
We performed 10′ × 10′ mapped observations of
12
CO,
13
CO
J
= 1–0,
J
= 2–1, and
J
= 3–2 pure rotational lines, as well as C
18
O
J
= 1–0 and
J
= 2–1 obtained with the IRAM 30 m and APEX telescopes over the extent of the
γ
-ray peak to reveal the molecular structure of the region. We first compared our data with local thermodynamic equilibrium models. We estimated the optical depth of each line from the emission of the isotopologs
13
CO and C
18
O. We used the population diagram and large velocity gradient assumption to measure the column density, mass, and kinetic temperature of the gas using
12
CO and
13
CO lines. We used complementary data (stars, gas, and dust at multiple wavelengths) and infrared point source catalogs to search for protostar candidates.
Results.
Our observations reveal four molecular structures: a shocked molecular clump associated with emission lines extending between −31 and 16 km s
−1
, a quiescent, dark cloudlet associated with a line width of ~2 km s
−1
, a narrow ring-like structure associated with a line width of ~1.5 km s
−1
, and a shocked knot. We measured a total mass of ~230, ~90, ~210, and ~4
M
⊙
, respectively, for the cloudlet, ring-like structure, shocked clump, and shocked knot. We measured a mass of ~1100
M
⊙
throughout the rest of the field of observations where an ambient cloud is detected. We found 144 protostar candidates in the region.
Conclusions.
Our results emphasize how the mass associated with the ring-like structure and the cloudlet cannot be overlooked when quantifying the interaction of CRs with the dense local medium. Additionally, the prese |
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ISSN: | 0004-6361 1432-0746 1432-0756 |
DOI: | 10.1051/0004-6361/202038339 |