Enhanced CO<i>J</i>= 2–1/<i>J</i>= 1–0 Ratio as a Marker of Supernova Remnant–Molecular Cloud Interactions: The Cases of W44 and IC 443

Seta, Masumichi; Hasegawa, Tetsuo; Dame, T. M.; Sakamoto, Seiichi; Oka, Tomoharu; Handa, Toshihiro; Hayashi, Masahiko; Morino, Jun Ichi; Saito, Kazuo; Usuda, K. S.

doi:10.1086/306141

Cited by 142 publications

(129 citation statements)

References 52 publications

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“…This parameter is a useful tool to trace shocked gas. Large values in the ratio R 2−1/1−0 are expected to be found in shocked molecular clouds, as observed in the clouds related with the SNRs G349.7+0.2 (R 2−1/1−0 ∼ 1.5; Dubner et al 2004), W44 (R 2−1/1−0 ∼ 1.3), IC443 (R 2−1/1−0 ∼ 1.3−4) and HB 21 (R 2−1/1−0 ∼ 1.6−2.3) (Seta et al 1998;Koo et al 2001). For the observed molecular clump we obtained R 2−1/1−0 ∼ 0.6, a low value that suggests that it is quiescent gas.…”

Section: Discussionmentioning

confidence: 66%

High-resolution CO observations towards the bright eastern knot of the SNR Puppis A

Paron

Dubner

Reynoso

et al. 2008

A&A

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Aims. This paper reports molecular observations towards the bright eastern knot (BEK) in the SNR Puppis A, a feature where radio and X-ray studies suggest that the shock front is interacting with a dense molecular clump. Methods. We performed high-resolution millimetric observations towards the BEK of Puppis A using the SEST telescope in the 12 CO J = 1-0 and 2-1 lines (beams of 45 and 23 , respectively). More extended, lower angular resolution 12 CO J = 1-0 observations taken from NANTEN archival data were also analyzed to obtain a complete picture. Results. In the velocity range near 16 km s −1 , which is the Puppis A systemic velocity, our study revealed two important properties: (i) no dense molecular gas is detected immediately adjacent to the eastern border of the BEK and (ii) the molecular clump detected very close to the radiocontinuum maximum is probably located in the foreground along the line of sight and has not yet been reached by the SNR shock front. We propose two possible scenarios for explaining the absence of molecular emission eastwards of the BEK border of Puppis A. Either the shock front has completely engulfed and destroyed a molecular clump or the shock front is interacting with part of a larger cloud, and we do not detect CO emission immediately beyond it because the molecules have been dissociated by photodissociation and by reactions with photoionized material due to the radiative precursor.

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Section: Discussionmentioning

confidence: 66%

High-resolution CO observations towards the bright eastern knot of the SNR Puppis A

Paron

Dubner

Reynoso

et al. 2008

A&A

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“…In particular, millimeter and submillimeter wave observations of dense molecular gas have proved to be a powerful probe of the shocked gas and the interactions; broad wings of several ;10 km s À1 accelerated by the shocks are observed in several SNRs in the millimeter and submillimeter spectra of interstellar CO and other molecules (e.g., W44, Seta et al 1998;W28, Arikawa et al 1999;IC 443, White et al 1987). Note also that observations of molecular gas are extremely useful in constraining the kinematic distance of SNRs owing to the better angular resolutions of millimeter-wave telescopes and the intrinsic smaller velocity dispersions of the molecular gas compared to atomic gas.…”

Section: Introductionmentioning

confidence: 99%

A Detailed Study of Molecular Clouds toward the TeV Gamma‐Ray Supernova Remnant G347.3−0.5

Moriguchi

Tamura

Tawara

et al. 2005

ApJ

108

134

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The supernova remnant G347.3À0.5 (J1713.7À3946) is known as one of the unique SNRs that emit TeV -rays, as well as nonthermal X-rays. We present a detailed study of molecular gas toward this SNR obtained with the 4 m millimeter and submillimeter telescope NANTEN at an angular resolution of 2A6. This study has revealed that several intensity peaks and the overall distribution of the molecular gas with radial velocities from À12 to À3 km s À1 show a remarkably good correlation with the X-ray features, strongly supporting the recently derived kinematic distance around 1 kpc, as opposed to the 6 kpc previously claimed. In addition, we show that absorption of X-rays is caused by local molecular gas at softer X-ray bands. Subsequent measurements of the submillimeter J ¼ 3 2 transition of CO made with the ASTE 10 m and CSO 10.4 m submillimeter telescopes toward three of the molecular intensity peaks have revealed higher excitation conditions, most likely higher temperatures above $30 K , in contrast to the typical gas temperature, 10 K, in low-mass dark clouds. This temperature rise is most likely caused by enhanced heating by the high-energy events in the SNR, where possible mechanisms include heating by X-rays, -rays, and/or cosmic-ray protons, although we admit that additional radiative heating by young protostars embedded may be working as well. In one of the CO peaks, we have confirmed the presence of broad molecular wings of $20 km s À1 velocity extent in the CO J ¼ 3 2 transition. Two alternative interpretations for the wings are presented; one is shock acceleration by the blast wave, and the other is molecular outflow driven by an embedded protostar. The SNR evolution is well explained as the free expansion phase based on the distance of 1 kpc. The molecular data set should be valuable for making a further detailed comparison with the -ray and X-ray distributions in order to examine the cosmic-ray acceleration quantitatively. Subject headingg s: cosmic rays -ISM: individual (SNR J1713.37À3946) -ISM: kinematics and dynamicssupernova remnants

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“…Line broadening is present in 18 SNRs listed in our table. The third kind of evidence is high high-to-low excitation line ratio in line wings (Seta et al 1998). In the broad wings of the shocked 12 CO, where both the J=2-1 and J=1-0 emissions are optically thin, their ratio can be > ∼ 1.…”

Section: Census Of Snr-mc Associationsmentioning

confidence: 97%

“…After a survey of 1720 MHz OH maser emission towards Galactic SNRs, Frail et al (1996) and Green et al (1997) revealed the unique diagnostic relation between such masers and the SNR shocks in MCs and identified nearly a score of SNRs interacting with MCs. Seta et al (1998) listed 26 SNRs detected in CO-and H 2 -line emissions along the line of sight, but no physical evidence of shock-MC interaction was given for them.…”

Section: Census Of Snr-mc Associationsmentioning

confidence: 99%

Molecular Environments of Supernova Remnants

Chen

Jiang²,

Zhou³

et al. 2013

Proc. IAU

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Abstract. There are about 70 Galactic supernova remnants (SNRs) that are now confirmed or suggested to be in physical contact with molecular clouds (MCs) with six kinds of evidence of multiwavelength observations. Recent detailed CO-line spectroscopic mappings of a series of SNRs reveal them to be in cavities of molecular gas, implying the roles the progenitors may have played. We predict a linear correlation between the wind bubble sizes of main-sequence OB stars in a molecular environment and the stellar masses and discuss its implication for supernova progenitors. The molecular environments of SNRs can serve as a good probe for the γ-rays arising from the hadronic interaction of the accelerated protons, and this paper also discusses the γ-ray emission from MCs illuminated by diffusive protons that escape from SNR shocks.

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Enhanced COJ= 2–1/J= 1–0 Ratio as a Marker of Supernova Remnant–Molecular Cloud Interactions: The Cases of W44 and IC 443

Cited by 142 publications

References 52 publications

High-resolution CO observations towards the bright eastern knot of the SNR Puppis A

High-resolution CO observations towards the bright eastern knot of the SNR Puppis A

A Detailed Study of Molecular Clouds toward the TeV Gamma‐Ray Supernova Remnant G347.3−0.5

Molecular Environments of Supernova Remnants

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