ALMA CO Observations of the Gamma-Ray Supernova Remnant RX J1713.7-3946: Discovery of Shocked Molecular Cloudlets and Filaments at 0.01 pc scales

Abstract

RX J1713.7-3946 is a unique core-collapse SNR that emits bright TeV gamma-rays and synchrotron X-rays caused by cosmic rays, in addition to interactions with interstellar gas clouds. We report here on results of ALMA ${}^{12}$CO($J$ = 1-0) observations toward the northwestern shell of the SNR. We newly found three molecular complexes consisting of dozens of shocked molecular cloudlets and filaments with typical radii of $\sim$0.03-0.05 pc and densities of $\sim$$10^4$ cm${}^{-3}$. These cloudlets and filaments are located not only along synchrotron X-ray filaments, but also in the vicinity of X-ray hotspots with month or year-scale time variations. We argue that X-ray hotspots were generated by shock-cloudlet interactions through magnetic-field amplification up to mG. The ISM density contrast of $\sim$$10^5$, coexistence of molecular cloudlets and low-density diffuse medium of $\sim$0.1 cm${}^{-3}$, is consistent with such a magnetic field amplification as well as a wind-bubble scenario. The small-scale cloud structures also affect hadronic gamma-ray spectra considering the magnetic field amplification on surface and inside clouds.

9 pages, 1 table, 4 figures, accepted for publication in The Astrophysical Journal Letters (ApJL)

References in corpus (12)

• Multi-Scale CLEAN deconvolution of radio synthesis images
• Primary particle acceleration above 100 TeV in the shell-type Supernova Remnant RX J1713.7-3946 with deep H.E.S.S. observations
• Observations of the young supernova remnant RX J1713.7-3946 with the Fermi Large Area Telescope
• Study of Nonthermal Emission from SNR RX J1713.7-3946 with Suzaku
• Hadronic gamma-rays from RX J1713.7-3946?
• A detailed study of the interstellar protons toward the TeV $\gamma$-ray SNR RX J0852.0$-$4622 (G266.2$-$1.2, Vela Jr.); a third case of the $\gamma$-rays and ISM spatial correspondence
• Expansion measurement of Supernova Remnant RX J1713.7-3946
• ALMA CO Observations of Gamma-Ray Supernova Remnant N132D in the Large Magellanic Cloud: Possible Evidence for Shocked Molecular Clouds Illuminated by Cosmic-Ray Protons
• Bell-Instability-Mediated Spectral Modulation of Hadronic Gamma Rays from a Supernova Remnant Interacting with a Molecular Cloud
• Shock-Cloud Interaction in the Southwestern Rim of RX J1713.7$-$3946 Evidenced by Chandra X-ray Observations
• NuSTAR observations of the supernova remnant RX J1713.7$-$3946
• X-ray Hotspots in the Northwest Shell of the Supernova Remnant RX J1713.7$-$3946

Cited by in corpus (16)

• Where are Milky Way's Hadronic PeVatrons?
• ALMA CO Observations of the Mixed-Morphology Supernova Remnant W49B: Efficient Production of Recombining Plasma and Hadronic Gamma-rays via Shock-Cloud Interactions
• Pursuing the origin of the gamma rays in RX J1713.7$-$3946 quantifying the hadronic and leptonic components
• The interstellar medium in young supernova remnants: key to the production of cosmic X-rays and $\gamma$-rays
• Detection of a new molecular cloud in the LHAASO J2108+5157 region supporting a hadronic PeVatron scenario
• Supernova remnant G46.8-0.3, a new case of interaction with molecular material
• Possible Detection of X-Ray Emitting Circumstellar Material in the Synchrotron-Dominated Supernova Remnant RX J 1713.7-3946
• Interaction between the Supernova Remnant W44 and the Infrared Dark Cloud G034.77-00.55: shock induced star formation?
• Large-field CO (J=1-0) observations toward SNR G150.3+4.5
• Chemical complexity in star formation induced by stellar feedback: cores shock-formed by the supernova remnant W44
• Modelling the Gamma-Ray Morphology of HESS J1804-216 from Two Supernova Remnants in a Hadronic Scenario
• Observations of ionized carbon towards the $\gamma$-ray-bright supernova remnant RX J1713.7-3946
• Survival of Molecular Complexity under Recent Supernova Feedback: Detection of Hot Cores in RX J1713.7-3946
• Associated molecular and atomic clouds with X-ray shell of superbubble 30 Doradus C in the LMC
• Discovery of CO Clouds Associated with the X-ray Jets of SS 433: Evidence for Shock-Cloud Interaction Enhancing Nonthermal X-ray Emission
• Can a single supernova remnant account for the gamma-ray emission of G106.3+2.7?