The Magnetic Field of an Isolated Neutron Star from X-ray Cyclotron Absorption Lines

G.F.Bignami (1,2)

P.A.Caraveo (3)

A.De Luca (3,4)

S.Mereghetti (3)

(1) CESR, Toulouse, France

(2) Università di Pavia, Pavia, Italy

(3) CNR-IASF, Milano, Italy

(4) Università di Milano Bicocca, Milano, Italy

INS results from Chandra

PSR B0656+14

PSR B1055-52

Vela pulsarRX J0720.4-3125

INS results from XMM-Newton

Puppis A PSR J0030+0451

PSR B1055-52 RX J0720.4-3125

Then came 1E1207.4-5209

•Discovered by Einstein

•Close to the center of SNR G296.5+10.0

•“High” galactic latitude: b≈10°

•SNR age: 7 kyears

•SNR distance: 2 kpc

A radio-quiet INS candidate

•Lack of optical counterpart

•No radio source

•BB-like X-ray spectrum

Radio-quiet INS?

NS nature confirmed by Chandra

P~424 ms (Zavlin et al.2000)

Estimate of Pdot (0.7-3.1)x10-14 s s-1 (Pavlov et al.2002)

Age Problem: τPSR >> τSNR

This INS was the first to show features in its spectrum

ChandraSanwal et al, 2002

Same dataHailey & Mori 2002

XMM-Newton Mereghetti et al, 2002

The latest EPIC view: 260 ksec

The deepest XMM-Newton galactic field

Phase-averaged spectroscopy

pn data

208,000 photons

MOS (1+2) data

151,300 photons

0.7 keV1.4 keV

2.1 keV 2.8 keV

Check for possible miscalibrations

Red: 3C273 Black: 1E1207.4-5209

0.7 1.4

2.1(2.8)

AuSi

Timing Analysis

Pulsed fraction ~ 7%

Phase-resolved spectroscopy

Conclusions

IF electron cyclotron: <B> 8 1010

IF proton <B> 1.6 1014

Problem with B as derived from timing parameters:

Current pdot:(1.4 0.3) 10-14 s/s implies B= 2-3 1012

but also implies an age of 5 105 years in contrast with the SNR age ( about 104 ys)

0.7 keV

1.4 keV 2.1 keV 2.8 keV