The hard X-ray spectrum of Pulsar Wind Nebulae Data-models comparison in the Simbol-X era F. Bocchino, INAF Osservatorio Astronomico di Palermo with contributions.

The hard X-ray spectrum of Pulsar Wind Nebulae

Data-models comparison in the Simbol-X era

F. Bocchino, INAF Osservatorio Astronomico di Palermo

with contributions of

R. Bandiera (INAF-OAA), L. Del Zanna (UNIFI), D. Volpi (UNIFI), G. Cusumano (INAF-IASF Pa)

Introduction

What is a PWN...

Introduction

The mechanism which bring particles and fields to the outer edge of the nebulae is still under investigation

“It's like finding the transmission lines between the power plant and the light bulb.” (J. Hester, Arizona Univ.)

Examples of PWNe

1’

The Crab Nebula SN1054 LX=2.4 1037 erg/s Distance 2 kpc Calib. source

Examples of PWNe

1’

The Vela PWN Age 11 kyr LX=6 1033 erg s D = 0.2 kpc

Symbol-X and PWNe Doing Chandra-like imaging is hopeless Low bkg will make Symbol-X extremely

competitive w.r.t. current non-imaging hard X-ray instruments

Easy detection of PWNe above 10 keV in reasonable single-pointing exposure time

Recent advances in theoretical modeling of PWNe have pointed out the importance of the study of the shape of PWN integrated X-ray spectrum

Spectra of PWNe

Zero order approximation Synchrotron aging of a constantly

injected power-law population (Ginzburg & Syrovatskii 1965)

Spectra of PWNe Modern approaches based on

inhomogeneous models MHD simulations, calculations of

synchrotron emissivities (Del Zanna et al. 2006)

Spectra of PWNe

Alternative views Diffusive synchrotron radiation from

PWNe (Fleishman & Bietenholtz 2007)

Aimed to overcome difficulties of “classical” approaches to “non-Crab like” PWNe

X-ray spectra of PWNe

XMM-Newton 30 ks INTEGRAL/IBIS,

439 SCWs in 2003-2004, 1 Ms

fX = 0.4 mCrab Single power-law NH=2.5+/-0.1 1022

cm-2

= 1.74 +/- 0.06

Data sensitivity to spectral breaks in hard X-ray

Data sensitivity to spectral breaks in hard X-ray

VELA: Mangano et al (2006), BeppoSAX MECS+PDS

CRAB1: de Jager et al. (1996), balloon-borne experiments

CRAB2: Massaro et al. (2000) BeppoSAX NFI+HP+PDS

Data sensitivity to spectral breaks in hard X-ray

VELA: Mangano et al (2006), BeppoSAX MECS+PDS

CRAB1: de Jager et al. (1996), balloon-borne experiments

CRAB2: Massaro et al. (2000) BeppoSAX NFI+HP+PDS

Black: XMM 30 ks + ISGRI 1 Ms

VELA: Mangano et al (2006), BeppoSAX MECS+PDS

CRAB1: de Jager et al. (1996), balloon-borne experiments

CRAB2: Massaro et al. (2000) BeppoSAX NFI+HP+PDS

Data sensitivity to spectral breaks in hard X-ray

Black: XMM 30 ks + ISGRI 1 MsRED: Suzaku 300 ks std. bkg

VELA: Mangano et al (2006), BeppoSAX MECS+PDS

CRAB1: de Jager et al. (1996), balloon-borne experiments

CRAB2: Massaro et al. (2000) BeppoSAX NFI+HP+PDS

Data sensitivity to spectral breaks in hard X-ray

Black: XMM 30 ks + ISGRI 1 MsRED: Suzaku 300 ks std. BkgGreen: Simbol-X 100 ks

Data-model comparison in the Simbol-X era Simulated synchrotron emission

from PWNe (Del Zanna et al. 2006)

run A: =0.025, nearly ideal case for Crabrun B: =0.1 large equatorial unmagnetized region

equator polepole

Data-model comparison in the Simbol-X era: the Crab

Only the nebular emission is considered

VELA: Mangano et al 06 (obs)

CRAB1: de Jager et al. 1996 (obs)

CRAB2: Massaro et al 2000 (obs)

LDZ06: Del Zanna et al 2006 (models)

Data-model comparison in the Simbol-X era: the Crab

Only the nebular emission is considered

VELA: Mangano et al 06 (obs)

CRAB1: de Jager et al. 1996 (obs)

CRAB2: Massaro et al 2000 (obs)

LDZ06: Del Zanna et al 2006 (model)

Black: Simbol-X 100 ks simulated spectrum

Data-model comparison in the Simbol-X era: 3C 58 Prototype of “non-Crab like” PWNe Diffusive synchrotron radiation from

PWNe (Fleishmann & Bietenholtz 2007) seems to overcome the difficulty of low frequency and large change of slope of the break in the radio band

What about in the X-ray band?

Data-model comparison in the Simbol-X era: 3C 58

DSR 3c58: Diffusive synchrotron radiation model of Fleishmann & Bietenholz (2007) tailored to 3c58 broad band spectrum

Data-model comparison in the Simbol-X era: 3C 58

Black solid: XMM 30 ks DSR 3c58: Diffusive synchrotron radiation model of Fleishmann & Bietenholz (2007) tailored to 3c58 broad band spectrum

Data-model comparison in the Simbol-X era: 3C 58

Black solid: XMM 30 ksRed solid: Simbol-X 100 ks

DSR 3c58: Diffusive synchrotron radiation model of Fleishmann & Bietenholz (2007) tailored to 3c58 broad band spectrum

Conclusions The shape of the hard X-ray spectrum of Pulsar Wind

Nebulae is directly related to the distribution of B and e- in the source

Current measurements are just enough to provide some diagnostics for the brightest objects (Crab and Vela)

Simbol-X may provide an order of magnitude improvement in the comparison between model and observations for these bright sources

Other bright PWNe (G21.5-0.9, 3C58) are hardly detected by non-imaging hard X-ray instruments. Simbol-X will provide THE unique opportunity to study the spectrum above 5-10 keV.