1. The Generation of Magnetic Fields and X-ray Observations Yutaka Fujita National Astronomical Observatory, Japan → Osaka University, Japan

2. Outline Generation of Magnetic Fields by the Weibel instability Y. Fujita & T. N. Kato Y. Fujita & T. N. Kato (2005, MNRAS in press, astro-ph/0508589) (2005, MNRAS in press, astro-ph/0508589) Japanese X-ray Missions

3. Weibel Instability The Weibel instability is driven in a collisionless plasma by the anisotropy of the particle velocity distribution function (PDF) of the plasma Shocks Strong temperature gradient Magnetic fields are generated so that the PDF becomes isotropic Particle orbits are deflected by the magnetic fields uzuz uyuy uxux

4. Example Numerical Simulation (Kato 2005) Weibel instability in a shock Weibel instability in a shock Full simulation (not MHD) Full simulation (not MHD) Motion of each particle is calculated Electron-positron plasma Electron-positron plasma Wall Shock Particles

5. DensityB Wall

6. Characteristics of the Weibel Instability Seed magnetic fields are not required Short timescale  p -1  1.8  10 -5 (n/cm -3 ) -0.5 sec  p -1  1.8  10 -5 (n/cm -3 ) -0.5 secStrong It can be saturated It can be saturated only by nonlinear effects only by nonlinear effects Okabe & Hattori (2003)

7. Evolution of Weibel Instability Velocity anisotropy creates current filaments The currents create magnetic fields The currents create magnetic fields The evolution of the instability can be described by that of the currents B Currents Medvedev et al. (2005)

8. Merger of Currents Currents with the same direction are attracted because of their magnetic fields Current and magnetic fields increase through the merger of currents SameOpposite

9. Saturation of Weibel Instability Kato (2005) Weibel instability saturates when currents reach the Alfvén current Weibel instability saturates when currents reach the Alfvén current Alfvén current I A =mc 2 v/e (v: bulk velocity, m: particle mass) I A =mc 2 v/e (v: bulk velocity, m: particle mass) Maximum current allowed by the self-regulated Magnetic fields Maximum current allowed by the self-regulated Magnetic fields v: shock velocity n: particle density, m: particle mass

10. Galaxy and Cluster Formation and the Weibel Instability Based on the studies on the Weibel instability I have shown you

11. New Idea We show that strong magnetic fields are instantaneously generated at the formation of galaxies (and clusters) Weibel instability at galactic-scale shocks Weibel instability at galactic-scale shocks Schlickeiser & Shukla (2003) Weibel instability by electrons at z~0 We consider shocks at z   1 and Weibel instability by protons

12. Hierarchical Clustering Typical Mass of Objects  0 =0.3,  =0.7, h=0.7,  8 =0.9  0 =0.3,  =0.7, h=0.7,  8 =0.9

13. TsTs Galactic Shocks Shocks should be created at the time of galaxy formation T vir Cosmological expansion Turn around Large-scale structure (LSS) shocks Virialization Virial shocks (e.g. Cen & Ostriker 1999, Ryu et al. 2003) Initial density fluctuation

14. Shock Mach Number LSS shocks (Furlanetto & Loeb 2004) (Furlanetto & Loeb 2004) Infall gas is cold Infall gas is cold Mach number    1 Mach number    1 Virial shocks Mach number  4 Mach number  4 Temperature of the shocked gas Virial Shock LSS Shock

15. Magnetic Fields Generated by the Weibel Instability If the shock Mach number is  2 Anisotropy of the particle velocity distribution function (PDF) is large enough v: shock velocity, n p : proton density, m p : proton mass (Kato2005) Correction factor,  P  0.5 From simulations (Kato 2005) (Silva et al. 2003) Final magnetic fields, B f ~ 0.1 B sat (Silva et al. 2003)

16. Magnetic Fields Generated by the Weibel Instability Magnetic field strength B  10 -7  10 -8 G B  10 -7  10 -8 G Strong amplification after the generation is not required Falls in a small range Falls in a small range Consistent with observations Almost no evolution In contrast with the dynamo theory In contrast with the dynamo theory Strong magnetic fields at high redshifts May affect the formation of early generation of stars and proto-galaxies May affect the formation of early generation of stars and proto-galaxies Virial Shock LSS Shock

17. Predictions High-redshift galaxies Strong magnetic fields Strong magnetic fields Nearby clusters LSS shocks may be observed through synchrotron emission and/or hard X-ray emission (SKA, NeXT) LSS shocks may be observed through synchrotron emission and/or hard X-ray emission (SKA, NeXT) Those observations will tell us the positions of the LSS shocks Through the Weibel instability, magnetic fields are generated in the plane of the shock front Through the Weibel instability, magnetic fields are generated in the plane of the shock frontPolarization Magnetic fields should be observed only on the downstream of the shock Magnetic fields should be observed only on the downstream of the shock Intergalactic magnetic fields are not required

18. `Missing Link’ Weibel instability L ~ 10 10 cm T ~ sec Cluster Magnetic Fields L ~ 10 21 cm T ~ Gyr ??

19. Japanese X-ray Missions SUZAKU (Astro-E2) Japan's fifth X-ray astronomy mission in collaboration with U.S.NeXT

20. SUZAKU (Astro-E2) Suzaku is the recovery mission for ASTRO-E ASTRO-E did not achieve orbit during launch in 2000 ASTRO-E did not achieve orbit during launch in 2000 Suzaku was launched in July 10

21. Launch (July 10)

22. The meaning of SUZAKU SUZAKU If it is written in Chinese Characters If it is written in Chinese Characters 朱雀 朱雀 すざく すざく The direct translation of the Chinese Characters is Red Sparrow The direct translation of the Chinese Characters is Red Sparrow Suzaku is also a bird in Chinese mythology Suzaku is also a bird in Chinese mythology The guardian of the southern sky

23. Instruments Aboard Suzaku

24. XRS XRS could give us ultra-high resolution spectra For example, gas motion in clusters (  100 km/s) For example, gas motion in clusters (  100 km/s) Turbulent cluster core (Fujita, Matsumoto, & Wada 2004) The simulated X-ray Spectrum observed with XRS (Fujita et al. 2005) Bold: with turbulence Thin: without turbulence

25. The Loss of XRS XRS uses liquid helium to cool the detector Unfortunately, the helium evaporated before the first light (Aug.8) The cause is under investigation The cause is under investigation Observation schedule will be changed and optimized to the remaining two detectors (XIS and HXD)

26. Other Instruments XIS and HXD are working well They will give us various information (e.g. hard X-ray from black holes, clusters of galaxies) They will give us various information (e.g. hard X-ray from black holes, clusters of galaxies) SNR (E0102-72.3) XIS first lightHXD first light Centaurus A

27. Sensitivity

28. NeXT (New X-ray Telescope ) Mission after Suzaku If the plan is approved, NeXT will be launched in 2011 Before the launches of Constellation-X and XEUS Before the launches of Constellation-X and XEUS

29. The Concept of NeXT

30. Performance Effective area Sensitivity NeXT

31. Science Example Particle acceleration and magnetic fields in clusters Particle acceleration and magnetic fields in clusters Cooperation with SKA will be useful A2256 Radio image (Giovannini, Tordi, & Feretti 1999) Simulated hard X-ray spectrum and image observed by NeXT Synchrotron Inverse Compton

32. Strong magnetite fields are generated at shocks by the Weibel instability even at high redshifts (z~10) Two instruments on Suzaku have just begun to make observations Never, never, never, never give up. - Winston Churchill - Winston Churchill Summary