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

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 $\Gamma = 1.57$ (1.51–1.62); and the intrinsic luminosity is 2.2 $\times$ $10^{35}~{\rm erg~s^{-1}}$ 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 $\times$ 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 $M_\odot$. 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 $\times$ 10 50 erg and ~$200~M_\odot$, respectively.