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XMM-Newton & Chandra Observations of NGC 5044: Metal Abundances and Supernovae Fraction. Overview. Aaron D. Lewis University of California, Irvine. Previous Fe abundance measurements in groups and clusters The "Fe Bias" Chandra & XMM Observations of NGC 5044 Fe, Si, Mg, O

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  1. XMM-Newton & Chandra Observations of NGC 5044: Metal Abundances and Supernovae Fraction Overview Aaron D. Lewis University of California, Irvine • Previous Fe abundance measurements in groups and clusters • The "Fe Bias" • Chandra & XMM Observations of NGC 5044 • Fe, Si, Mg, O • SNe fractions Cooling Flow Conference, Charlottesville, Virginia

  2. Early Results for Iron Abundances in Groups and Clusters (Renzini 1997; Arimoto et al. 1997) X1.4 • Fe in groups Fe in clusters (large radius) • Groups accrete primordial gas at late times? • Fe in groups Fe in stars (small radius) • No enrichment from SNe Ia in Groups?? Is Star Formation Different in Groups and Clusters? Are Measurements Wrong?

  3. Fe Abundances from ASCA CCDs High-resolution CCD-resolution • Spatially Integrated Spectrum  R ~ 3-5 arcminutes ~ 50-100 kpc • Broad-Band Spectral Fitting

  4. ROSAT PSPC Shows Gas is NOT Isothermal in Groups NGC 1399 NGC 2563 NGC 5044 (e.g., Buote 2000) What Fe abundance will result if 1T fit to accumulated spectrum within R ~ 5 arcminutes?

  5. The Fe Bias (Buote & Fabian 1998, Buote 1999, 2000a,b) 1T Model Fitted to 2T ASCA Spectrum  1T Always Underestimates Fe Abundance ASCA Data of Centers of Bright E-Galaxies and Groups (e.g. NGC 1399) 1T+brem 2T+brem  Multi-Temperature Gas Models Fit Better!

  6. “Corrected” Fe Abundances for Groups X1.4 (Renzini 2000, astro-ph/0001312) • Remove Correlation of Fe with Temperature • <Fe> = 1.1 ± 0.3 solar  Consistent with substantial SNe Ia enrichment Multi-T Fits of Central 50-100 kpc in Groups:

  7. Chandra and XMM Observations of NGC 5044 • Brightest Group in O’Sullivan et al. Catalog • One of strongest cases for multi-T gas (Fe Bias) from ASCA • Wealth of results & comparisons from Chandra and XMM CCDs & XMM RGS Collaborators: David Buote (UC Irvine) Fabrizio Brighenti (Bologna) Bill Mathews (UC Santa Cruz) Accepted ApJ Papers: Part I: (astro-ph/0205363) Part II: (astro-ph/0303054)

  8. Chandra and XMM Images • 20 ks exposures for MOS & ACIS, 9 ks for pn • Confirm asymmetry near R~6’ (Cold Front?) • Irregularities within R~1’ (but no exceptional central radio source)

  9. Spectral Deprojection (1T) • Simultaneous fits to XMM MOS1, MOS2, pn and Chandra data (Chandra applies for R < 2.5’) • Confirms strong T-gradient for R < 30 kpc seen by ROSAT • Excellent agreement between Chandra & XMM

  10. 1T Spectral Fits • Formally poor fit ( /dof = 1368.1/689) • Residuals characteristic of Fe Bias

  11. 2T Spectral Fits • Much better fit ( /dof = 949.8/687) • Eliminates Residuals characteristic of Fe Bias

  12. 1T vs. 2T • 2T Preferred Over 1T for R < 3.5’ (34 kpc) • Evidence Weaker in Radial Bin 1 Than Bins 2-4

  13. Spectral Deprojection (2T) • Hotter Component T ~ 1.4 keV  virial T of halo • Cooler Component T ~ 0.7 keV  stellar kinetic temperature • Discrete Sources

  14. 2T Emission Measure vs. Radius • Hotter component dominates for R > ~40 kpc • Cooler component dominates for R < ~5 kpc

  15. Other Temperature Models  Limited Multi-Phase Medium?

  16. Azimuthal Temperature Variations? • No significant variations in T or Fe • 2T preferred over 1T in circles as small as R=15”  Need higher S/N!

  17. Iron Abundance • 1T models biased low in central ~ 50 kpc • Fe ~ 1 solar within central ~50 kpc (central dip?) • Fe ~ 0.4 solar near 100 kpc

  18. XMM RGS (Tamura et al. 2003) • 2T preferred over 1T • Fitted parameters of RGS 2T model agree with our CCD results when we fit same model with same free parameters over same energy range

  19. Intrinsic Absorption • Multi-Temperature models still preferred even with intrinsic absorption • Large fitted column densities imply absorbing masses comparable to the mass of hot gas  We do not emphasize these models

  20. Selected Abundances • Si ~ 0.8 solar within 40 kpc • S ~ 0.7 solar within 30 kpc • O profile is flat (~0.4 solar) • Mg ~ 1 solar (?)

  21. Si/Fe • 1T & 2T values similar for most radii • ~0.8 solar • Weak evidence for decline with radius

  22. Average Abundances Within R=5’-10’=48-96 kpc

  23. Implications for SNe Enrichment • Si/Fe and S/Fe  SNe Ia fraction 70%-80%  Preference for “Convective Deflagration” models (W7) as opposed to “Delayed Detonation” models (WDD) of SNe Ia • No evidence for different star formation in groups and clusters • “Iron Discrepancy” in elliptical galaxies resolved?

  24. Hot Gas Evolution Models • If no cooling flow, then central iron abundance is over-predicted • Inhomogeneous metal enrichment? (Morris & Fabian) NGC 5044 (Brighenti & Mathews)

  25. XMM Observation of NGC 1399 (Buote 2002)

  26. Fe & Si in NGC 1399 • Fe & Si > 1 solar for R < ~20 kpc • Si/Fe ~ 0.8 solar (just like NGC 5044)  SNe Ia fraction ~ 80%

  27. Chandra & XMM Observations of NGC 4636 XMM RGS (Xu et al. 2002) Chandra ACIS-S (Jones et al. 2002) • Highly disturbed central ~1.5’ ~ 7 kpc (shocks?) • RGS finds range of temperatures 0.53-0.71 keV which may be consistent with 1-phase gradient • Fe = 1.3 ± 0.1 solar (consistent with ASCA -- Buote 1999)

  28. Chandra & XMM Observations of Other Groups • NGC 533: Fe = 1.3 ± 0.2 solar (XMM RGS, Peterson et al. 2003, astro-ph/0210662) also fully consistent with ASCA (Buote 2000) • NGC 507: Fe poorly constrained (Chandra, Paolillo et al. 2003) • NGC 2563, NGC 4325: Fe ~ 0.5 solar using 1T models (XMM, Mushotzky et al. 2003, astro-ph/0302267)

  29. Summary of Chandra & XMM Observations of Metals in Groups • Abundances UNDERESTIMATED (esp. Fe & Si) if 1T used indiscriminately (Fe Bias) • Limited multi-phase medium in cores of many systems • Fe gradients common -- Fe ~ 1 solar at center and ~ 0.4-0.5 solar at largest radii investigated - clusters too! • (esp. Si/Fe & S/Fe) imply SNIa fraction 60%-80% for BOTH clusters and groups • Star formation similar in clusters & groups • Star formation similar to Milky Way (e.g., Renzini et al. 1993)

  30. Future Directions • Abundance mapping of many more systems (esp. groups): /Fe from cores to near virial radius • Verify limited multi-phase medium & find its cause: cooling flow, AGN heating, “cold fronts”? • Map star formation history with gas dynamical evolution models (esp. groups) • Constrain SNe explosion models & yields (as in M87)

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