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The X-ray Universe 2008

The X-ray Morphology and Spectra of Galactic Disks. R. Owen, R. Warwick. The X-ray Universe 2008. Introduction. We use XMM-Newton to analyze disk emission from a sample of nearby face-on spiral galaxies. After excluding the bright X-ray point sources, we investigate:.

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The X-ray Universe 2008

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  1. The X-ray Morphology and Spectra of Galactic Disks R. Owen, R. Warwick The X-ray Universe 2008

  2. Introduction We use XMM-Newton to analyze disk emission from a sample of nearby face-on spiral galaxies. After excluding the bright X-ray point sources, we investigate: • Spectral components in the galactic disk • Morphology of the residual X-ray emission • Correlation with NUV emission • Link between residual X-ray emission and star formation in disk. The X-ray Universe 2008

  3. Sample of galaxies *includes LLAGN The X-ray Universe 2008

  4. Exclusion of bright X-ray point sources Residual emission from M83 after exclusion of bright point sources. XMM-Newton soft band (0.3-1 keV) image of M83. Simulated PSF image of bright point sources. Source mask created from simulated image. The X-ray Universe 2008

  5. M83: spectral and radial analysis 2-temperature mekal fit : kT ~ 0.2, 0.6 keV. LX (0.3-1 keV) ≈ 1.6 x 1039 ergs-1 Radial distribution: exponential with scalelength 0.79’ (0.85 kpc) Unresolved soft X-ray emission (0.3-1 keV) in M83. Chandra log N-log S: 2/3 of residual emission truly diffuse. Owen & Warwick (2008, in prep.) The X-ray Universe 2008

  6. M83: Soft X-ray and NUV emission GALEX NUV 0.3-1 keV 12.8’ ~ 13.8 kpc XMM-Newton soft X-ray and GALEX NUV images of M83 overlaid with soft X-ray contours. The X-ray Universe 2008

  7. M83: X-ray / NUV correlation 0.3-1 keV GALEX 8’ ~ 8.6 kpc Soft X-ray residual and GALEX NUV images are shown overlaid with the bright source mask, showing areas used in correlation analysis. Correlation gradient: 18.3 ± 2.7 (arbitrary units) The X-ray Universe 2008

  8. M101: X-ray / NUV correlation GALEX 0.3-1 keV 10’ ~ 22.6 kpc Correlation gradient: 12.8 ± 1.2 (extinction corrected, arbitrary units) Warwick et al. (2007) The X-ray Universe 2008

  9. M51: X-ray / NUV correlation GALEX 0.3-1 keV 10’ ~ 24.5 kpc Correlation gradient: 18.2 ± 1.3 (extinction corrected, arbitrary units) The X-ray Universe 2008

  10. M74: X-ray / NUV correlation GALEX 0.3-1 keV 10’ ~ 25.3 kpc Correlation gradient: 12.0 ± 0.9 (extinction corrected, arbitrary units) The X-ray Universe 2008

  11. NGC300: X-ray / NUV correlation GALEX 0.3-1 keV 10’ ~ 6.2 kpc Correlation gradient: 1.7 ± 0.4 (extinction corrected, arbitrary units) The X-ray Universe 2008

  12. Radial distribution of X-ray emission M83: scalelength = 0.79’ (0.85 kpc) M101: scalelength = 2.6’ (5.4 kpc) X-ray SFR M51: scalelength = 0.72’ (1.76 kpc) M74: scalelength = 0.92’ (2.33 kpc)

  13. Spectral components of galaxy sample M101 M83 M51 M74 2-temperature fit: kT ≈ 0.2, 0.7 keV. Soft/hard component ratio = 3.8 LX (0.3-1 keV) ≈ 1.7 x 1039 ergs-1 2-temperature fit: kT ≈ 0.2, 0.6 keV. Soft/hard component ratio = 1.3 LX (0.3-1 keV) ≈ 1.6 x 1039 ergs-1 2-temperature fit: kT ≈ 0.2, 0.6 keV. Soft/ hard component ratio = 6.0 LX (0.3-1 keV) ≈ 2.1 x 1039 ergs-1 2-temperature fit: kT ≈ 0.2, 0.65 keV. Soft/hard component ratio = 1.5 LX (0.3-1 keV) ≈ 4.4 x 1039 ergs-1 The X-ray Universe 2008

  14. X-ray properties of galaxy sample *Munoz-Mateos et al (2007). The X-ray Universe 2008

  15. Results: Comparison with SFR • Radial scalelength of X-ray emission across galactic disk is shorter than SFR. • X-ray/NUV correlation shows X-ray deficit at low SFR. • Temperature of diffuse emission increases as SFR increases. Possible interpretation: The efficiency of X-ray emission from supernova shocks and stellar winds depends on density of gas in surrounding environment. Towards outside edge of disk, X-ray emission falls off faster than SFR as density of environment is lower. These trends agree with HMXB luminosity/SFR relationship derived by Grimm, Gilfanov & Sunyaev (2003). The X-ray Universe 2008

  16. Conclusions • We have used XMM-Newton to examine diffuse X-ray emission from a sample of nearby face-on spiral galaxies. • Spectral analysis of the disks gives two-temperature thermal fits at kT ~ 0.2, 0.6 keV, with higher temperature gas found in systems with higher SFR. • Diffuse X-ray emission declines with radius over a shorter scalelength than SFR. • Strong correlation is found between X-ray and NUV emission across the galactic disks, with an X-ray deficit found in systems with lower SFR. • Quantitative relationship with SFR still in development, physical explanation fits discovered trends across sample. The X-ray Universe 2008

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