2011ApJ...732...11L

We propose that a nonthermal X-ray arc inside the remnant of Tycho's supernova (SN) represents the interaction between the SN ejecta and the companion star's envelope lost in the impact of the explosion. The X-ray emission of the remnant further shows an apparent shadow casted by the arc in the opposite direction of the explosion site, consistent with the blocking of the SN ejecta by the envelope. This scenario supports the single degenerate binary origin of Tycho's SN. The properties of the X-ray arc, together with the previous detection of the companion candidate and its space velocity by Ruiz-Lapuente et al. and Hernández et al., enable us to further infer that (1) the progenitor binary has a period of 4.9^+5.3_–3.0days, (2) the companion gained a kick velocity of 42±30 km/s, and (3) the stripped envelope mass is about 0.0016 ( ≤ 0.0083) M_☉. However, we note that the nature of the companion candidate is still under debate, and the above parameters need to be revised according to the actual properties of the companion candidate. Further work to measure the proper motion of the arc and to check the capability of the interaction to emit the amount of X-rays observed from the arc is also needed to validate the current scenario.