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Metallicity in intra-cluster medium of clusters and groups of galaxies observed with Suzaku

This article discusses the measurements of metal abundances (Oxygen, Magnesium, Iron) in the intra-cluster medium of clusters and groups of galaxies using the Suzaku X-ray satellite. The results are compared with nucleosynthesis models to estimate the numbers of Type II and Type Ia supernovae in the past. The study also explores the mass-to-light ratios and metal distributions in different systems.

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Metallicity in intra-cluster medium of clusters and groups of galaxies observed with Suzaku

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  1. Metallicity in intra-cluster medium of clusters and groups of galaxies observed with Suzaku ApJ , vol. 667, L41, 2007 PASJ, vol. 59, 299, 2007 PASJ, vol. 60, 333, 2008 PASJ, vol. 60, 317, 2008 astro-ph/arXiv0805.2771 Kosuke Sato1, K. Matsushita2, Y. Ishisaki3, N.Y. Yamasaki4, M. Ishida4, and T. Ohashi3 1 Kanazawa Univ., 2 Tokyo Univ. of Science, 3 Tokyo Metropolitan Univ., 4 ISAS/JAXA

  2. Introduction– past X-ray observations – “ ASCA ” ⇒ Dupke & White (2000), Baumgartner et al. (2005) “ XMM ” ⇒ de Plaa et al. (2006,2007), Werner et al. (2006) XMM • 22clusters • O & Mg measurements • in the only central region de Plaa et al. (2007) SNe II/Ia ratio~3.5 More information needed from SNe II products Suzaku • Low & stable background level • Higher sensitivity below ~1 keV Determination of O & Mg synthesized in SNe II

  3. Selected clusters and groups • Nearby and Bright objects in early Suzaku observations • Moderate low temperature (kT<4 keV) for O measurement Obs.redshiftkT (keV)date 23.Jan.2006 28.Jul.2006 17.Aug.2007 22.Nov.2005 5.Aug.2006 HCG62 NGC507 A262 A1060 AWM7 0.0145 0.0165 0.0163 0.0114 0.0172 ~1.5 ~1.5 ~2.0 ~3.0 ~3.5 Sampling ranging: Groups (~1.5 keV) ~ Clusters (~4 keV) Not including in de Plaa et al. (2007) Measurements of the metal abundances and distributions to ~0.3 – 0.4 r180 Analysis methods : See in Sato et al. (2007, 2008)& Tokoi et al. (2008)

  4. O & Mg measurements with Suzaku A1060 OVII OVIII O Mg Galactic emission

  5. Metal distributions AWM7A262 A1060HCG62 NGC507 • From O to Fe radial profiles • （solar: Anders & Grevesse 1989） • Comparison the metals to Fe ratio • Si, S / Fe :fairly flat ~1 – 2 • O, Mg / Fe :increase with radius? • ⇒ Difference from SNe Ia or II ? 1 （solar） 0.1 Radial profiles of Fe r / r180 Fornax: Matsushita et al. (2007) O/Fe 1 1 1 Mg/Fe Si/Fe r / r180 r / r180 r / r180

  6. SNe nucleosynthesis model SNe Ia ： W7 model （Nomoto et al. 1984） WDD1 or 2 model（Iwamoto et al. 1999） SNe II : 10 – 50 M (Salpeter Initial Mass Function) Progenitor Metallicity Z = 0.02（Nomoto et al. 2006） ψ（M） ∝ M -2.35 Numbers of Type Ia and II supernovae How each metal is synthesized with SN Ia & II ? ⇒ Estimation of the numbers of SN Ia& II （NSNe Ia, NSNe II） Fit the amount of metals with nucleosynthesis model

  7. Fitting results AWM7 χ2 / d.o.f. = 15.9 / 3 NSNe II / NSNe Ia = 4.0 ± 1.2 (Ne) O W7 model Fe Mg S Si • ~75% of Fe, • ~40% of Si and S • from SNe Ia Ne is excluded in the fits.

  8. Numbers and Ratio of SNe Ia & II W7 model SNe II SNe Ia（W7） ＋ 3.5 SNe II/Ia ratio Numbers of SNe Ia & II Gas mass（M） Gas mass（M） • Numbers of SNe Ia & II ∝ the gas mass • SNe II/Ia Ratio: ~3.5 (W7 and WDD2), ~2.5 (WDD1) cf. Clusters (XMM ; de Plaa et al. 2007): ~3.5 Our Galaxy (Tsujimoto et al. 1995): ~6.7 LMC & SMC (Tsujimoto et al. 1995): 3.3 – 5

  9. M L Mass-to-Light Ratio: MLR Metals are synthesized in stars (galaxies): Compare Mmetal, < R ( in units of M ) with B-bandluminosity LB, < R ( in units of L) Also use K-band luminosity because of the comparison of galaxy type Fe mass / B-band Luminosity Makishima et al. (2001) Mmetal, < R Temperature (keV) ∝ size of system MLR = LB or K, < R Oxygen Mass-to-Light Ratio: OMLR Magnesium Mass-to-Light Ratio: MMLR Iron Mass-to-Light Ratio: IMLR First time

  10. IMLR（B-band vs. K-band） • We use 2MASS data set for K-band. • r > ~1º ~ rvir data as a background B-band K-band IMLR Better correlation r / r180 r / r180 For all systems, a small dispersion with K-band rather than B-band

  11. OMLR & MMLR OMLR OMLR OMLR K-band B-band Metal enrichment process in the ICM seem to be quite similar for different clusters and groups Small dispersion MMLR MMLR MMLR r / r180 r / r180

  12. Comparison of Numbers of SNe II • Number of SNe II expected from Star Formation Rate • of Hubble Deep Field (Madau et al. 1998) • Numbers of SNe II expected from the metal mass • observed with Suzaku Normalized by K-band（2MASS） luminosities NSNe II normalized by LK between field galaxy and clusters from our obs. is consistent . AWM7 r < 0.1 r180 HDF NSNeII / LK（LK-1） A262 A1060 However, we consider now only the metals in the ICM, not including in the stars (galaxies) Numbers of SNe II（Mpc-3）

  13. Summary • Suzaku has conducted spatially resolved spectral analysis • of clusters & groups. • Measurements of the metals (O to Fe)to ~0.3 r180 • were carried out. • Assuming nucleosynthesis models, we determined • the numbers of SNe II in the past using the metal • masses of O, Mg, Si, S, and Fe. • SNe II / Ia number ratio: ~3.5 (W7 and WDD2) • Measurements of O & Mg mass to light ratios for the first time. • Metal-mass to light ratios with K-band are close • between clusters & groups • X-ray and HDF observations imply consistent number • of the total SNe II explosions.

  14. Merits of Suzaku XIS Tsunemi et al. (2006) A1060 Oxygen Suzaku XMM XMM XMM Suzaku BI Superior O Line sensitivity FI • Low intrinsic non X-ray Background (NXB) & Good reproducibility (～5%） due to low orbit satellite & short focal length • High line sensitivity below ～1 keV Suitable for extended objects, like clusters & groups

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