Observational evidences of particle acceleration at SNRs Aya Bamba (RIKEN, Japan) and Suzaku team Suzaku Chandra

1.X-ray observation for cosmic-ray study 2.topic 1: X-ray study on acceleration efficiency of electrons 3.topic 2: X-ray study on acceleration possibility of protons 4.topic 3: X-ray study on acceleration efficiency of protons 5.Summary 0. Talk plan:

1.1. how to search accelerators? Koyama et al.(1995) Discovery of sync. X-rays from the shell of SN 1006 SN1006: type Ia d=2.18kpc 10 ´ Shocks of SNRs = cosmic ray accelerators! …. but details are unsolved TeV electron IS B (~  G) sync. emission in hard X-rays X-rays are the best indicator gyro radius of TeV e = a few pc

1.2. Remaining problems acc. efficiency of electrons acc. possibility of protons acc. efficiency of protons distribution of synch. X-rays (Chandra) -> topic 1 For all of these remaining problems, X-rays are the strong tool ! wide-band spectra (radio - TeV) (Suzaku) -> topic 2 plasma diagnostics in X-rays (Suzaku) -> topic 3

1.3. X-ray satellites spatial resolution effective area energy range spectral resolution for diffuse sources Chandra Suzaku XMM-Newton Each satellite has strong points

Topic 1: X-ray diagnostics for acc. efficiency of electrons

2.1. observational information to solve The spatial distribution their gyro radius, the turbulence of B, …. The spectrum of synchrotron emission the maximum energy, B, …. The age of the system the evolution of acceleration Spatial resolution! Chandra has excellent spatial resolution (0”.5) best for such a study

2.2. In the case of SN 1006 Mei-Getsu-Ki (The diary of Teika Fujiwara) ancient samples of guest stars Great guest star like Mars on May 1st Crab nebula 3C58 Happy Birthday!

2.3. SN 1006 image 0.3 – 2.0 keV 2.0 – 10.0 keV downstream upstream SN1006 NE shell (Bamba et al. 2003) Energy (keV) thermal (0.24 keV) extended non-thermal sharp Scale length of the filaments? u s = 2890km/s

2.4. Fitting results Mean value………………. Minimum value………… w d 0.2 pc 0.05 pc w u 0.05 pc 0.01 pc 10 ´´ = 0.1 pc 2 – 10 keV First measurement of the width of filaments

Hard No line Non-thermal! spectrum  = (fixed) (Allen et al. 2001) rolloff = 2.6 (1.9 – 3.3) x Hz Flux = 1.8 x ergs cm -2 s -1 (keV) Reynolds & Keohane (1999) rolloff = 5x10 17 Hz B 10  G E max 100TeV 2 power-law exponential cutoff SRCUT model 2.5. Spectral Fitting Sync. emission from electrons

SRCUT model E N(E) Spectrum of electrons E max  emission Synchrotron emission from a single e emission rolloff ~ E max 2 B  -1 2 Synchrotron emission from power-law electrons exp. E max B

Cas A(SN1680) Kepler(SN1604) Tycho(SN1572) SN1006 RCW 86 (SN184) 2.6. Many young historical SNRs have thin filaments with sync. X-rays (Bamba et al. 2005) thin filaments are common in young SNRs

2.7. Why are filaments so thin? ….. Small diffusion in direction to shock normal! shock updown E max of electron30-40 TeV The angle:> 85 deg. The strength:10 – 80  G ordered or turbulent B ? perpendicular B or parallel B ? perpendicular! turbulent → strongly scattered → hardly go downstream → staying long around shocks turbulent B high effic. (equipartition) Diffusion only occurs along the B First quantitative image !

B ~ 100 – 400  G very strong parallel B (Berezhko et al. 2004) shock up down Anyway, Turbulent magnetic field (Bohm limit) Very efficient acceleration (equipartition) another scenario Strong B makes the gyro radius small → diffusion becomes small First estimation of magnetic field structure

2.8. Time evolution of B w d ~ r g u s -1 ~ E max B d -1 u s -1 rolloff ~ E max 2 B d B = rolloff w d -2 ~ B d 3 u s 2 Direct estimations of the evolution of B ONLY from the observational facts! u s ~ t -0.6 (Sedov) observational facts func. of B d

t age (years) B = rolloff /w d 2 (Hz/pc 2 ) rolloff /w d 2 ~ t age B d ~t age -0.6 (Sedov) (  2 /d.o.f.=2.0/3) (B d 3 u s 2 ) (Bamba et al. 2005)

2.9. Time evolution of energy densities thermal u th : ~ T ~ t age -1.2 kinetic u kin : ~ u s 2 ~ t age -1.2 Magnetic energy density u B : ~ B d 2 ~ t age -1.2 CR energy density u CR : u A = B 4  (Lucek & Bell 2000) u B = u CR uAusuAus u CR ~ B d u s ~ t age -1.2 All energy densities have same time dependence! acc. efficiency for electron is very high! Sedov Our result (B d ~ t age -0.6 ) assumption:

Shock energy density thermal kinetic mag. energy density CR energy density Non-linear Effect shock evolution In mag. field interaction of mag. Field and CR strong interaction for each other In each filament: equipartition evolution keeping equipartition? Images We must consider these three energy density simultaneously!

Topic 2: X-ray diagnostics for acc. possibility of protons

3.1. How to search proton accelerators ? The efficiency of electron acceleration is so high. however … How about protons ? electrons -> synch. X-rays + IC  -rays protons ->  -rays via  0 decay searching for X-ray dim &  -ray bright sources TeV & X-ray observations are strong tool! To find out proton accelerators … Energy E 2 dF/DE X-rays  -rays sync. IC 00

HESS: TeV  -ray Namibia Imaging Atmospheric Cherenkov Telescopes since 2004 They have done Galactic Plane survey for the first time TeV gamma-ray observations

Sgr A * RX J1713 HESS J HESS J HESS J HESS J HESS J HESS J HESS J HESS J Aharonian et al They have no counterpart. New accelerator candidates?

3.3. A candidate of p accelerators ? … HESS unIDs along Galactic plane diffuse sources -> Galactic ? -> X-ray follow-up is needed ! Their nature is unknown <- lack of counterparts With deep absorption on Galactic plane, follow-up obs. are very difficult.

3.4. Introduction of Suzaku The 5th Japanese X-ray satellite. It was launched on July 10th Suzaku is “Red Phoenix”, the protector God of the South. The wall painting of Suzaku in “Kitora” tomb 朱雀 (Suzaku)

3.5. Instruments XRT (X-Ray Telescope) Large effective area 450cm XIS (X-ray Imaging Spectrometer) Improved X-ray CCD with high efficiency and good energy resolution Low Background Energy band : keV HXD (Hard X-ray Detector) Wide energy band Si-PIN (10-70keV) & Scintillator (30-600keV) Non-imaging detector, but low background XRT XIS HXD Suzaku is best for follow-up of TeV unIDs !

young SNRs old SNRs large shock speed both e and p are accelerated strong synchrotron X-rays small shock speed electrons are deccelerated no emission SNRs colliding with MCs amount of targets strong  0 decay 3.7. One possible scenario for TeV unID sources: Emission from SNRs in various phases (Yamazaki et al. astro-ph/ ) TeV unIDs are old SNRs colliding with MCs? Their nature is still unknown, but Suzaku will solve it !

Topic 3: X-ray diagnostics for acc. efficiency of protons

kinetic E of shocks thermal E of downstream plasma kinetic E of shocks thermal E of downstream plasma E of accelerated particles kinetic E of shocks Thin thermal plasma (~keV) emits lines in the X-ray band. X-ray plasma diagnostics can determine precise plasma parameters. Suzaku XIS has good spectral resolution -> best for the study ! 4.1. how to measure acc. efficiency of protons ? from Rankine-Hugoniot relation kT d = mv s 2 2(  -1) (  +1) 2 ~ 0.19 E shock (no acc.) < 0.19 E shock (efficient acc.)

5. Summary 1.We detected sync. X-rays from filaments in young SNRs. 2.The filaments are very thin ! 3.Thin filaments reveal us that the acc. efficiency of electrons is very high. 4.Suzaku deep observations reveal us that HESS unID sources might be proton accelerators. 5.They might be old SNRs ? 6.Suzaku will enable us to estimate the acc. efficiency of protons.

Notice ! Suzaku is providing a lot of fruitful data, and many results of Suzaku observation are reported ! We will hold the conference “The Extreme Universe in the Suzaku Era” at Kyoto on December 4-8, 2006 ! Topics are not only SNRs but all high E topics. We are looking forward to your participating !!