Submillimeter/millimeter observations of the molecular clouds associated with the Tycho' Supernova Remnant

TL;DR

This study uses submillimeter/millimeter observations to identify and analyze molecular clouds around Tycho's supernova remnant, revealing interactions, possible cloud collisions, and shock propagation directions.

Contribution

First detection of a small molecular cloud near Tycho's SNR and detailed analysis of cloud interactions and shock effects using CO line observations.

Findings

Three molecular clouds identified around Tycho's SNR.

Evidence of SNR-MC interaction through broad emission lines.

Indications of cloud-cloud collision and shock propagation direction.

Abstract

We have carried out CO J=2-1 and CO J=3-2 observations toward Tycho's supernova remnant (SNR) using the KOSMA 3m-Telescope. From these observations we identified three molecular clouds (MCs) around the SNR. The small cloud in the southwest was discovered for the first time. In the north and east, two MCs (cloud A and cloud B) adjacent in space display a bow-shaped morphology, and have broad emission lines, which provide some direct evidences of the SNR-MCs interaction. The MCs is revealed at -69~-59 km \s, well coincident with the Tycho's SNR. The MCs associated with Tycho's SNR have a mass of ~2130 sun masses. Position-velocity diagrams show the two clouds adjacent in velocity which means possible cloud-cloud collision in this region. The maximum value (0.66) of integrated CO line intensity ratio I(CO J=3-2/CO J=2-1) for the three MCs agrees well with the previous measurement of individual Galactic MCs, implying that the SNR shock just drove into the MCs. The two MCs have a line intensity ratio gradient. The distribution of the ratio appears to indicate that the shock propagates from the southwest to the northeast.