A high resolution X-ray A high resolution X-ray spectrum of the nearby LINER spectrum of the nearby LINER

M81M81

M. J. PageM. J. Page11, A. A. Breeveld, A. A. Breeveld11 and the RGS and the RGS ConsortiumConsortium

11 Mullard Space Science Laboratory, University College LondonMullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, , Holmbury St. Mary, Dorking, Surrey, RH5 6NTSurrey, RH5 6NT

Fig 2. Spatially extended emission line gas: emission lines are seen an arcminute away from the nucleus in the cross dispersion direction.

Fig 1. The RGS spectrum with a power law + 3 temp Mekal model in red. Prominent emission lines are marked.

Fig 3. Fit to the O VII triplet. The line ratios (confidence contours) are consistent with collisional ionization.

Here we present results Here we present results from the analysis of the from the analysis of the XMM-Newton RGS XMM-Newton RGS observations of the spiral observations of the spiral LINER galaxy M81. The LINER galaxy M81. The excellent RGS data clearly excellent RGS data clearly show the presence of show the presence of emission lines, as well as emission lines, as well as continuum emission from continuum emission from the active nucleus. The the active nucleus. The emission lines are emission lines are significantly broader than significantly broader than the RGS point-source the RGS point-source spectral resolution, and spectral resolution, and appear to originate from appear to originate from multi-temperature (0.15-0.8 multi-temperature (0.15-0.8 keV) collisionally ionized gas keV) collisionally ionized gas in a region of at least an in a region of at least an arcminute across.arcminute across.

M81 is a nearby spiral galaxy hosting a M81 is a nearby spiral galaxy hosting a low luminosity Seyfert nucleus. ROSAT low luminosity Seyfert nucleus. ROSAT and Chandra data show apparently and Chandra data show apparently diffuse emission associated with the diffuse emission associated with the bulge, extending over a few bulge, extending over a few arcminutes. Later, ROSAT, BBXRT, arcminutes. Later, ROSAT, BBXRT, ASCA and SAX spectra suggested a ASCA and SAX spectra suggested a soft thermal component at <1keV in soft thermal component at <1keV in addition to the absorbed power law addition to the absorbed power law from the nucleus.from the nucleus.

M81 was observed by XMM in April M81 was observed by XMM in April 2001 for 138ks; the RGS data are 2001 for 138ks; the RGS data are shown in Fig.1. The continuum from shown in Fig.1. The continuum from the AGN at the heart of M81 dominates the AGN at the heart of M81 dominates the spectrum. A good fit is obtained the spectrum. A good fit is obtained with a simple power law model with a simple power law model absorbed by an intrinsic cold column of absorbed by an intrinsic cold column of 6.106.102020cmcm-2-2. .

The lines, and in particular O VIII LyThe lines, and in particular O VIII Ly, are , are considerably broader than one expects considerably broader than one expects from the RGS line spread function from a from the RGS line spread function from a point source. Figure 2 shows that the point source. Figure 2 shows that the emission line gas is actually spatially emission line gas is actually spatially extended by more than an arcminute.extended by more than an arcminute.

Fig 3. shows a fit to the He-like Oxygen Fig 3. shows a fit to the He-like Oxygen triplet. These lines are consistent with a triplet. These lines are consistent with a purely collisionally ionized, low density purely collisionally ionized, low density plasma (nplasma (nee~10~101010 cm cm-3-3 ). A 3-temperature ). A 3-temperature Mekal plasma model provides a good fit Mekal plasma model provides a good fit to the emission lines (see Fig. 1).to the emission lines (see Fig. 1).

These data show that the emission lines These data show that the emission lines come from the hot interstellar medium in come from the hot interstellar medium in the bulge region of M81, and are not the bulge region of M81, and are not powered by the nucleus.powered by the nucleus.