The ASCA View on Cooling Flows and its Implications

1. The ASCA View on Cooling Flows and its Implications K. Max Makishima (U. Tokyo /RIKEN) in collaboration with Yasusi Ikebe, Yasusi Fukazawa, Kyoko Matsushita, Haiguan Xu, Takayuki Tamura, Isao Takahashi, and Madoka Kawaharada Makishima et al. PASJ, 53, 401 (2001) 1. ASCA and the Gas Imaging Spectrometer 2. Summary of the ASCA Results 3. Physics in the “post-CF” Era 4. The Prospect for ASTRO-E2 Cooling Flow, 31 May 2003

2. Sunlit earth (solar X-ray+ NXB) 45 arcmin 0.1 1e-2 1e-3 1e-4 Mg Si S cts/sec/cm2/keV Ar Cu Night earth (NXB) 0.5 1 2 5 10 Energy (keV) Fornax Cluster with the GIS 1. ASCA and the GIS Ohashi et al. PASJ48, 157 (1996) Makishima et al. PASJ48, 171 (1996) GIS background spectra Blanck sky (CXB+NXB) Cooling Flow, 31 May 2003

3. hot Virgo /EM Cen 1 3A0335 A2634 A262 A496 cool A1795 AWM7 Hydra-A EM A2199 A2063 0.1 AWM4 A539 A2147 MKW3s A4059 A119 A400 A3558 2 3 4 5 6 A1060 0.01 2. Summary of the ASCA Results 2a.The central cool emission is exclusively associated with cD galaxies cD clusters (B-M I, I-II, or II) non-cD clusters (B-M II or III) From 2T fits Consistent with previous knowledge Hot component temperature (keV) Cooling Flow, 31 May 2003

4. 1 cD clusters 0.8 Non-cD clusters Centaurus 0.6 A262 Central iron abundance (solar) 0.4 AWM7 Virgo A2199 0.2 A496 A2063 0 A1060 A539 0.01 0.1 1 A400 EM /EM cool hot 2b: The cool ICM phase is metal-enriched • According to the CF scenario, a metal-rich portion would cool and disappear quickly -- a contradiction. • The chemical abundance of ICM differs between the central and outer regions (Fukazawa et al. MNRAS313, 21, 2000) • The cool component appear to be associated with the cD galaxy, rather than with cooling portion of the ICM. Cooling Flow, 31 May 2003

5. A1795 100 3A0335 Hydra-A A496 A2199 Centaurus MKW3s 10 AWM7 Virgo A262 1 2c. The CF rate was previously overestimated - Ikebe et al. (1997) - Xu et al. (1998) - Ikebe et al. (1999) - Makishima et al (2001) - Hot emission from the cluster core was mistaken for the cool emission. - The central potential “dimple” was not properly considered. CF rate with ASCA (M0 /yr) Reconfirmed with Chandra and XMM-Newton CF rate before ASCA (M0 /yr) A good example will be given by the next speaker 10 100 Cooling Flow, 31 May 2003

6. 1-beta fits (95 clusters) 15 10 5 0 60 kpc Number 2-beta fits (26 clusters) 220 kpc 8 6 4 2 0 ASCA GIS 0.7-3 keV ASCA GIS 3-10 keV 1 10 1 10 0.03 0.1 0.3 1 Core radius (Mpc) 2d. The centrally peaked surface brightness is due to central potential deepening The ICM profile involvetwo spatial scales (ROSAT+ASCA; Ota et al. ApJL567, L23, 2002) . The central excess surface brightness is nearly color-independent(A1795; Xu et al. ApJ500,738, 1998). Surface brightness (a.u.) Beta model (convolved) 100 kpc Projected radius (arcmin) Cooling Flow, 31 May 2003

7. Ikebe astroph/0112132 A1795 ASCA EPIC-MOS 44 43 42 41 40 EPIC-PN Log LX (erg/s) Cool component obeys the same Lx-T relation as the entire cluster sample 1 2 5 10 Temperature (keV) 2e. The central cool component traces the central potential deepening Most detailed 2T analysis:Ikebe et al. ApJ 525, 58 (1999) Tcool may simply reflect the central potential depth 8 6 4 2 Temperature (keV) 0.1 0.2 0.5 1 2 5 10 Projected radius (arcmin) Tcool ~ Thot /2, with a common radial temperature profile (Ikebe astro-ph/0112132 ; Allen et al. MNRAS328, L37, 2001) Cooling Flow, 31 May 2003

8. 2f. The ASCA view of a cD cluster -- “Double-beta” and “2T” (Ikebe et al. ApJ, 525, 58,1999) A hierarchical potential is formed by the cluster and the cD galaxy. An isothermal hot ICM fills the entire potential well. A two-phase region is produced within the central potential dimple, by an admixture of metal-rich cool plasma.

9. 3. Physics in the “Post-CF” Era 3a. Conclusion from Makishima et al. (2001) Through the ASCA study, we have arrived at a novel view on central regions of galaxy clusters. It describes the region around a cD galaxy as a site of significant and active evolution, where plenty of heavy elements are produced, a self-gravitating core develops, the stellar component condensates to the center, and the liberated energy is deposited onto the X-ray emitting plasmas. The scenario makes a sharp contrast to the previous view which emphasized the role of radiative plasma cooling. Novel X-ray information to be available with Chandra, XMM-Newton, and hopefully the rebuilt ASTRO-E will be utilized for further examination of our scenario. Through the ASCA study, we have arrived at a novel view on central regions of galaxy clusters. It describes the region around a cD galaxy as a site of significant and active evolution, where plenty of heavy elements are produced, a self-gravitating core develops, the stellar component condensates to the center, and the liberated energy is deposited onto the X-ray emitting plasmas. The scenario makes a sharp contrast to the previous view which emphasized the role of radiative plasma cooling. Novel X-ray information to be available with Chandra, XMM-Newton, and hopefully the rebuilt ASTRO-E will be utilized for further examination of our scenario. 3b. Simple-minded considerations Cooling Flow, 31 May 2003

10. Evolution? High z Low z 3b. A simple idea (Makishima 1994) - ICM, DM, and galaxies have ~ the same specific energy. - Since alaxies have much lower specific entropy than ICM, the free energy will be transferred from galaxies to ICM. - Galaxies will lose energy and fall to the cluster center. Cooling Flow, 31 May 2003

11. Radial IMLR profiles IMLR Centaurus 0.01 A1060 3D radius (kpc) 1e-3 1e-4 20 50 100 200 300 3c. Supporting evidence - In angular extent, stars < DM < ICM -- Energy of the galaxies was transferred to the ICM. - Evidence for gradual galaxy mergers in the cluster center -- Dynamical energy of galaxies was extracted, and was deposited on the ICM. --> Poster #17. “The Dark Group Candidate, RXJ 0419+2225” by Kawaharada et al. - The central decrease in Iron-Mass-to-Light -Ratio (IMLR) -- Galaxies gradually fell to the center while ejecting metals. - The O-profile is flatter than the Fe-profile -- Early SNe II occurred over an extended region, while subsequent SNe Ia occurred closer to the center. Cooling Flow, 31 May 2003

12. 3d. Numerical estimates - The expected galaxy-to-ICM energy transfer rate ; -dE/dt ~ NpRi2 n mpv3(Sazazin 1988, p.152) ~ 2x1044(N/300) (Ri /10kpc)2(n/10-3) (v/500 kms-1)3 erg/s (N=galaxy number; Ri= interaction radius; n=ICM density; v=galaxy velocity dispersion) - The intra-cluster magnetic fields are easily “pushed away” by moving galaxies that are good electrical conductors. This makes Ri ~ DM halo of each galaxy. - The available total dynamical energy in galaxies; E ~ 5x1062 (Mgal /1014M0) (v/500 kms-1)2ergs E/(dE/dt) ~ 80 Gyr Cooling Flow, 31 May 2003

13. Galaxy motion/rotation Magnetic field lines Reconnection sites Hot phase Cool phase 3c. A speculative view -- the “cD corona” - Ordered magnetic fields separate the hot and cool phases. - Galaxies’ kinetic energy -->MHD turbulence -->reconnection -->plasma heating & particle acceleration - The loop-like structure stabilizes the heating/cooling. Cooling Flow, 31 May 2003

14. The recovery mission ASTRO-E2 will be launched in 2005. • - The XRS (D measures the expected ICM turbulence. • The HXD (10-600 keV) searches for particle acceleration. • The XIS (CCD camera) studies the ICM heating process. The first improved version of the M-5 rocket has been launched successfully on 2003 May 9, putting “Sample-Return” mission into an interplanetary orbit. 4. The Prospect for ASTRO-E2 We are re-building the Hard X-ray Detector (HXD).

15. Conclusion • - Using ASCA, we have pointed out for the first time that the CF hypothesis needs a significant revision. • - The view has been reinforced by XMM-Newton and Chandra. • - We propose that the dynamical energy in the galaxy motion is dissipated onto the ICM. • - ASTRO-E2 will open the new era of such post-CF physics. Cooling Flow, 31 May 2003

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