A detailed observation of a LMC supernova remnant DEM L241 with XMM-Newton

¹ RIKEN (The Institute of Physical and Chemical Research) 2-1, Hirosawa, Wako, Saitama 351-0198, Japan e-mail: bamba@crab.riken.jp
² Department of physics, Faculty of Science, Tokyo Institute of Technology 2-12-1, Oo-okayama, Meguro-ku, Tokyo 152-8551, Japan e-mail: masaru@hp.phys.titech.ac.jp
³ Department of Physics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan e-mail: [nakajima;koyama]@cr.scphys.kyoto-u.ac.jp
⁴ Department of Applied Physics, Faculty of Engineering University of Miyazaki, 1-1 Gakuen Kibana-dai Nishi Miyazaki, 889-2192, Japan e-mail: mori@astro.miyazaki-u.ac.jp

Received: 24 August 2005
Accepted: 22 December 2005

Abstract

We report on an XMM-Newton observation of the supernova remnant (SNR) DEM L241 in the Large Magellanic Cloud. In the soft band image, the emission shows an elongated structure, like a killifish, with a central compact source. The compact source is point-like, and named XMMU J053559.3-673509. The source spectrum is reproduced well by a power-law model with a photon index of (1.51–1.62); and the intrinsic luminosity is 2.2 in the 0.5–10.0 keV band, with an assumed distance of 50 kpc. The source has neither significant coherent pulsations in 2.0 10^-3–8.0 Hz nor time variabilities. Its luminosity and spectrum suggest that the source might be a pulsar wind nebula (PWN) in DEM L241. The spectral feature classifies this source as rather bright and hard PWN, which is similar to those in Kes 75 and B0540-693. The elongated diffuse structure can be divided into a “Head” and “Tail”, and both have soft and line-rich spectra. Their spectra are reproduced well by a plane-parallel shock plasma (vpshock) model with a temperature of 0.3–0.4 keV, over-abundance in O and Ne, and a relative under-abundance in Fe. Such an abundance pattern and the morphology imply both that the emission is from the ejecta of the SNR and that the progenitor of DEM L241 is a very massive star, more than 20 . This result is also supported by the existence of the central point source and an OB star association, LH 88. The total thermal energy and plasma mass are ~4 10⁵⁰ erg and ~, respectively.