Interactions between Galaxies and Plasmas in Galaxy Clusters Motivation 牧島一夫 1. How to stop cooling flows 2. How to explain the environmental effects in galaxy morphology and evoluion 3. How to explain differences between cD and non-cD clusters 4. How to understand the large amount of metals in the intra-cluster medium (ICM) Speculations 1. A cD galaxy has its own magnetosphere, while the other galaxies interact strongly with the ICM 2. The ICM is heated via MHD effects 3. Over tH, galaxies transfer their dynamical energies & ang. momenta to ICM → fall to the cent, merge, .. 2010/10/12 牧島＋中澤研ゼミ 1/10 Three Compnents of a Cluster of Galaxies 《ICM 》 《DM 》 ◆ ◆ ~85% of the total mass Subclumps 《galaxies》 ◆ ◆ ◆ 2010/10/12 ◆ ~3% of Mtot ◆ Random motion at transonic velocitie Concentrated ◆ 牧島＋中澤研ゼミ ◆ ◆ ~12% of Mtot kTe = 2 ~ 15 keV Emit only X-rays Grav. confined, but most extended Metallicity~0.3 Z◎ 2/10 Motivation 1: Cooling Flow Hypothesis Cooling ICM flows to the center, enhancing the colling; “cooling flow(CF) ASCA→much smaller amount of cooled ICM than predicted Some mechanism of ICM heating. Supernave far insufficient. A1795 100 CF rate with ASCA (M0 /yr) In many cluster centers, the radiative cooling time of ICM 〜 0.1 tH 3A0335 Hydra-A A496 A2199 Centaurus 10 AWM7 Virgo 1 MKW3s 10 A262 100 CF rate before ASCA (M0 /yr) Makishima et al. Publ Astr. Soc. Japan 53, 402 (2001) 2010/10/12 牧島＋中澤研ゼミ 3/10 Motivation 2: The environmental effects Butcher-Oemler effect Numerous disturbed blue galaxies (z＞0.5) vs. dwarf spheroidals (z~0) Fraction of spirals ↓ toward the cluster center. SFR may not be the only parameter… Motivation 3: cD and non-cD clusters At the center of a cD cluster (a cluster with a central dominant galaxy), we always observe - A cool ICM component - A centrally peaked brightness distribution - An enhancement in the ICM metallicity 2010/10/12 牧島＋中澤研ゼミ 4/10 Motivation 4: Metals in ICM In a clsuter, ICM is ×３ more massive than stars. Its metallicity ~ 0.3 solar. Metals in ICM ~ metals locked in stars (Tsuru 1991). How this large amount of metals transported to the intracluster space? 2010/10/12 牧島＋中澤研ゼミ 5/10 “cD Corona” Conjecture 1. A cD galaxy has cool/metal-rich magnetosphere. Open-field regions are filled with hot isothermal plasmas. 2. Moving galaxies interact strongly with the ICM → MHD turbulence in ICM →reconnection→ICM heating 3. Loss of dynamical energies of galaxies →ICM heating → suppression of CF 4. ICM drag → galaxy infall, galaxy mergers, metamorphosis → Major origin of the environmental effects Cool plasma Hot plasma Galaxy motion Mag.field Reconnection 2010/10/12 牧島＋中澤研ゼミ 6/10 Order Estimation ・ Kinetic energy of a galaxy E = (1/2) Mv2 = 1e60 (M/1011M0)(v/108cm/s) ergs ・ Dynamical friction -dE/dt = mpnv3πR2 = 5e42 (n/10-3) erg/s ・Time scale of energy loss τ= E/|dE/dt| 〜 2e17 sec = 0.5 tH ・Kinetic luminosity from moving galaxies L = Ngal ×|-dE/dt| 2010/10/12 〜 1044 erg/s 牧島＋中澤研ゼミ 7/10 Evidence 1a：Cool-Component Morphology Chandra image of Abell 1795 (Gu et al. 2008). The metal-enriched region (red) and the cool region (contours) coincide, and exhibit complex shapes. 2 arcmin ~ 150 kpc. 2010/10/12 牧島＋中澤研ゼミ 8/10 Evidence 1b: 2T Nature Deprojected thin shells The Centarus cluster With XMM-Newton (I. Tkaahashi et al. 2008) Summed thick shell 1T with gradT 2010/10/12 牧島＋中澤研ゼミ 2T view 9/10 Evidence 1c：MHD Simulation Numerically simulated lasma temperature (gray) and magnetic fields (arrows) in a 300 kpc squared region. MHD, radiative cooling, and thermal conduction are included. Asai et al. (2007) 2010/10/12 牧島＋中澤研ゼミ 10/10 Evidence 2a. Comet-like Structures 25 kpsc Fornax Cluster cD NGC1399 Chnandra mosaic X-ray image 2010/10/12 companion NGC1404 牧島＋中澤研ゼミ 11/10 Evidence 2b：ICM Heating by Moving Galaxies Abell 1060 Centaurus cluster プラズマ温度 Suzaku Sato et al. (2007) XMM, Takahashi (2005) Four giant galaxies at the center A tyical XD galaxy at the center 20’ 20’ Ｘ線 2010/10/12 Ｘ線 牧島＋中澤研ゼミ 12/10 Evidence 2c. Heating and Acceleration Ｘ-ray (contours) and 843 MHz (grayscale) maps of Abell 3667 (Roettinger et al. 1999) Suzaku νFν spectrum (Nakazawa et al. 2008) In addition to the known ~7 keV emission, a new component with kT>13 keV was detected radio lobes∝ueum 2010/10/12 Stringent U.L. on the inv.Compton hard Xray ∝ueuCMB → together with radio, B＞2μG → mag.press.＞0.15gas press. 牧島＋中澤研ゼミ 13/10 Evidence 3a: Radial Mass Profiles 1014 Radially integ. M profiles of Centaurus (M◎) ICM is more massive than stars at > 200 kpc 1013 ICM has two phases 1012 Stars more concentrated than DM ICM more extended than DM 1011 (Ikebe et al. Astrophys. J., 525, 58, 1999) 1010 20 2010/10/12 50 100 200 3D Radius (kpc) 400 牧島＋中澤研ゼミ 14/10 Evidence３b：Possible Galaxy Infall Iron Mas to Light Ratio 1 10 100 kpc IMLR (r) = Fe mass in the ICM within a radius r, divided by galaxy luminosity therein. --> Metals in the ICM is much concentrated (Ikebe et al. 1999; Metals expanded ---> unlikely, because huge amount of energy neede. Most of metals locked into stars --> quantitatively insufficien Galaxies must have been falling to the cluster center (Makishima et al. 2001; Kawaharada 2006; Kawaharada et al. 2008; Takahashi et al. 2008) High z 進化? Kawaharada 2006). 2010/10/12 Low z 牧島＋中澤研ゼミ 15/10 What to do Observe clusters with various z, and derive (radially integ. galaxy s. brightness profile) /(radially integ. ICM mass density profile) Does this profile evolve ? Largest difficulty-- membership definition 2010/10/12 牧島＋中澤研ゼミ 16/10
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