363rd Heraeus-Seminar 1

GAMMA-RAY EMISSION OF PULSARS: STATUS AND MULTI-WAVELENGTH CONTEXT

Gottfried KanbachMax-Planck-Institut für extraterrestrische Physik

Garching, Germanygok@mpe.mpg.de

363rd Heraeus-Seminar 2

PSR B1919+21

Pulsars are not themost prominent sourcesin radio or X-ray surveys

363rd Heraeus-Seminar 3

GLAST simulated all-sky map (>1GeV) after ~55 days of exposure: EGRET Pulsars

Credit: M. Razzano

363rd Heraeus-Seminar 4

Presently known pulsars

363rd Heraeus-Seminar 5

Table of detectionsHigh-Energy Pulsars: Multiwavelength Detections

PSR P(ms)

E& /d2

rankradio opt Xlow Xhi γlow γhi

high confidence γ-ray detectionsB0531+21 (Crab) 33.4 1 P P P P P PB0833-45 (Vela) 89.3 2 P P P P P PJ0633+1746 (Geminga) 237.1 3 P? P P P ? PB1706-44 102.5 4 P ? D PB1509-58 150.7 5 P D P P PB1951+32 39.5 6 P P P PB1055-52 197.1 33 P D P P P

candidate γ-ray detectionsB0656+14 384.9 18 P P P ? ?B0355+54 156.4 36 P D ?B0631+10 287.7 53 P D ?B0144+59 196.3 120 P ?

ms -PSR γ-ray detection & candidatesJ0218+4232 2.32 43 P P PB1821-24 3.05 14 P P ?

Likely PSR - γ-ray source positional coincidenceB1046-58 123.7 8 P D D?J1105-6107 63.2 21 P D D?B1853+01 267.4 27 P D?

P = pulsed detection, P? = low significance pulsation, D = unpulsed detection

363rd Heraeus-Seminar 6

•Maximum of Emission in the hard X- and γ-ray range

•High energy spectral cut-off

• Distinct spectralcomponents

Multi-λ Spectra of γ-ray Pulsars

(pulsed emission)

363rd Heraeus-Seminar 7

Phase Averaged Pulsar Spectrum(Romani, 1996, ApJ 470, 469)τ = 104.5 y, B12=3, Ec=3GeV

log(ν) (Hz)

10 12 14 16 18 20 22 24

log(ν

Fν) (Jy

Hz)

26

28

30

32

34

SynchrotronThermalCurvature (full cascade)Curvature (primary)Compton Scatter

PSR spectral components (outer gap model)

radio

363rd Heraeus-Seminar 8

Slot gap modelSlot gap model

(Arons 1983, Muslimov & Harding 2003, 2004)

|| 0E =Γ~106-7

Γ~102

363rd Heraeus-Seminar 9

HighHigh--altitude slot gap altitude slot gap -- geometrygeometry

(Dyks & Rudak 2003, Dyks et al. 2004)

363rd Heraeus-Seminar 10

High-Energy ParticlesRelativistic e+-e- plasma

Collective processes: oscillations, bunching, beam/plasma

coherent emission

Single particles in B- & E- & photon-fields

incoherent emissionsynch, CR, ICS

radio opt, X, γ

thermal:kT ~ keV106-107 K

neutronstar

?

363rd Heraeus-Seminar 11

Gamma-Ray Details…

363rd Heraeus-Seminar 12

Each ‚Goldreich-Julian‘ particle releases ~ 15 ergs of γ-luminosity,

( e.g. in GeV photons this implies 6x103 photons/G-J particle)

If the accelerator provides particles of Lorentz factor ~ 107 (~10 erg) this implies a radiation efficiency of ~ 100%!

Luminosity

363rd Heraeus-Seminar 13

Spectral Hardness

363rd Heraeus-Seminar 14

Pulse Components Crab and Geminga

Phase

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

even

ts

-40

-20

0

20

40

60

80

100

120

140

160

Phase

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

even

ts

-20

-10

0

10

20

30

40

Phase

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

even

ts

-20

0

20

40

60

80

Phase

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

even

ts

-20

0

20

40

60

80

100

Phase

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

even

ts

-5

0

5

10

15

20

25

30

Phase

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

even

ts

0

5

Crab, PSR B0531+21

> 100 MeV

30-70 MeV

70-150 MeV

150-500 MeV

500-2000 MeV

2-10 GeV

Phase

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

even

ts

-20

0

20

40

60

80

100

Phase

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

even

ts

-15

-10

-5

0

5

10

15

20

Phase

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

even

ts-20

-10

0

10

20

30

40

Phase

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

even

ts

-10

0

10

20

30

40

Phase

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

even

ts

-5

0

5

10

15

20

25

30

Phase

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

even

ts

0

5

PSR B0633+17 Geminga

> 100 MeV

30-70 MeV

70-150 MeV

150-500 MeV

500-2000 MeV

2-10 GeV

Fits with 2 asymmetricLorentzian peaksP1, P2

363rd Heraeus-Seminar 15

Spectra of Components in Crab and Geminga

PSR B0633+17 Geminga: Relative Intensity of Pulse Components

Energy (MeV)10 100 1000 10000

% o

f tot

al In

tens

ity

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

P1

P2

PSR B0531+21 (Crab): Relative Intensity of Pulse Components

Energy (MeV)10 100 1000 10000

% o

f tot

al In

tens

ity

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

P1

P2

363rd Heraeus-Seminar 16

Pulse Components Vela

Phase

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

even

ts

-20

-10

0

10

20

30

40

50

30-70 MeV

Phase

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

even

ts

-20

0

20

40

60

80

100

120

Phase

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

even

ts

-20

0

20

40

60

80

100

120

140

160

150 - 500 MeV

Phase

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

even

ts

-10

0

10

20

30

40

50

60

70

500-2000 MeV

Phase

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

even

ts

-2

0

2

4

6

8

10

12

14

16

18

2 - 10 GeV

VELA, PSR B0833-45

Phase

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

even

ts

-50

0

50

100

150

200

250

300

> 100 MeV

70-150 MeV

Empirical Fit with 2 asymmetricLorentzian peaks and a log-normal distribution: P1, P2, IP

PSR B0833-45: relative Intensity of Pulse Components

Energy (MeV)10 100 1000 10000

% o

f tot

al In

tens

ity

0.0

0.1

0.2

0.3

0.4

0.5

0.6

IP

P2

P1

V e la P 1 ,P 2 p h a s e d is ta n c e

E n e r g y ( M e V )

1 0 1 0 0 1 0 0 0 1 0 0 0 0

Pea

k P

hase

Sep

arat

ion

P1 -

P2

0 .4 0

0 .4 1

0 .4 2

0 .4 3

0 .4 4

0 .4 5

0 .4 6

363rd Heraeus-Seminar 17

Peak separation VelaFit (30-10000 MeV): Δφ = 0.449 – 7.19x10-3 log(EMeV)

highenergy

lowenergy

Vela P1,P 2 phase distance

Energy (MeV)

10 100 1000 10000

Pea

k P

hase

Sep

arat

ion

P1

- P

2

0.40

0.41

0.42

0.43

0.44

0.45

0.46

2000, MNRAS, 319, 477

363rd Heraeus-Seminar 18

Population Synthesis of observable γ-ray pulsars

(Sim)(Sim)

(Sim)loud: 7quiet:1

loud: 15-19quiet:7-10

loud: 37quiet:13

loud: 344quiet:276

(Gonthier et al., 2004)

363rd Heraeus-Seminar 19

Phase Averaged Pulsar Spectrum(Romani, 1996, ApJ 470, 469)τ = 104.5 y, B12=3, Ec=3GeV

log(ν) (Hz)

10 12 14 16 18 20 22 24

log(ν

Fν) (Jy

Hz)

26

28

30

32

34

SynchrotronThermalCurvature (full cascade)Curvature (primary)Compton Scatter

Pulsars in the optical range

radio

363rd Heraeus-Seminar 20

Shearer, 1999

3 4 5 6

25

30

35

log(

corre

cted

opt

ical

lum

inos

ity) e

rg/s

Log(magnetic field at l.c.) Gauss

0656+14

Geminga

Vela

0540-69

Crab

Optical Emission

363rd Heraeus-Seminar 21

Shibanov, et al.,, astro-ph/0511311

Observations with the SUBARU telescope

363rd Heraeus-Seminar 22

Shibanov, et al.,, astro-ph/0511311

363rd Heraeus-Seminar 23

OPTIMA fibers on the Crab

One fiber: 2’’

363rd Heraeus-Seminar 24

Nebula Polarization (OPTIMA)

Polarizationclose to pulsar:degree: 8-13%angle ~ 140°(Schmidt&Angel, 79)

8% ; 139°

6% ; 145°

8% ; 145°6% ; 144°

7% ; 138°

363rd Heraeus-Seminar 25

Shearer, 2002

The Crab is visible at all phases

363rd Heraeus-Seminar 26

single rotation variability studies

Crab single rotation and summed lightcurve

continuousemission

bridge

363rd Heraeus-Seminar 27

Crab Polarization (OPTIMA)

Measure lightcurves for different positionsof the rotating polarisation filterat [φ0, φ0+90°] and [φ0+45°, φ0+135°].

Calculate Stokes-Parameters:Q=I(0°)-I(90°), U=I(45°)-I(135°)

IUQ

V22 +

=

QUarctan

21⋅=Θ

P1

P2

angle of polarization:

degree of polarization:

363rd Heraeus-Seminar 28

Model: Dyks et al., 2004

~ Correspondence of Polarization Characteristics(note also striped wind model, Petri and Kirk, 2005)

MeasurementTwo Pole Caustic Model (Dyks etal, 2004)

363rd Heraeus-Seminar 29

P2/P1= 0.64

Crab: single pulse statistics (A. Slowikowska et al.)

363rd Heraeus-Seminar 30High= 568.67, P2 / P1= 0.626, σ= 0.119, χ2 / d= 1.65

3 4σ

Peak ratio statistics

363rd Heraeus-Seminar 31

all

Good conditions

bad conditions

Check for atmospheric transparencyand aperture loss due to seeing variations

363rd Heraeus-Seminar 32

Correlation of otical flux and Giant Radio Pulses(Shearer et al., Science, 301, 493, 2003)

363rd Heraeus-Seminar 33

The main peak of theOptical emission is~3-5% brighter in a Rotation that showsA GRP !

363rd Heraeus-Seminar 34

Conclusions:

High energy emission in young radio pulsars isthe dominant radiation process and some details arealready detectable in the brightest objects

(GLAST will detect `many` more radio pulsarsWhere many could be 50-100 depending onmodel)

Coupling between incoherent high-energy radiationsand coherent radio emissions in Crab (rad-opt) and Vela (talk by A. Lommen) start to become visible.

We should be on our way to a comprehensive model of pulsar emissions…