Status pulsar studies in soft gamma rays
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Status pulsar studies in soft gamma-rays. Lucien Kuiper, Wim Hermsen, [Hans Bloemen]. Three classes of pulsars seen in g rays. I:spin-down powered pulsars a) normal pulsars b) millisec pulsars (old recycled systems)

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Status pulsar studies in soft gamma-rays

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Status pulsar studies in soft gamma rays

Status pulsar studiesin soft gamma-rays

Lucien Kuiper, Wim Hermsen, [Hans Bloemen]

Toulouse June 2005


Status pulsar studies in soft gamma rays

Three classes of pulsars seen in g rays

I:spin-down powered pulsarsa) normal pulsarsb) millisec pulsars (old recycled systems)

II:accretion powered pulsarsa) LMXB (incl. transient ms-pulsars)b) HMXB (Be-binaries, [sub-]giant binaries)III:magnetically powered pulsars (=magnetars)AXPs/SGRs

Toulouse June 2005


Class ia spin down powered normal pulsars

Class Ia: Spin-down powered [normal] pulsars

  • CGRO (20 keV-30 GeV) heritage: number of g-ray pulsars increased from 2 (Crab, Vela) to 7 (10), all young (≤ 100 ky) and energetic

  • This is the only established Galactic g-ray source population, emitting over a wide energy range (0.5 keV – 10 GeV)

  • We still do not know where the g-rays are produced in the magnetosphere (outer gap/polar cap) and which physical processes are acting (synchrotron, curvature radiation, inverse Compton, photon splitting, …)

Toulouse June 2005


Status pulsar studies in soft gamma rays

Normal pulsars continued…

At soft/medium g-ray energies (20 keV – 30 MeV) only 4 pulsars are known from CGRO/RXTE/BeppoSAX, with very different pulse profiles and spectra.

PSR B0531+21

(Crab)PSR B1509-58PSR B0540-69

↖3s IBIS ISGRI; 1 Ms

Detections near ISGRI sensitivity limit – we see just the top of the iceberg it seems

Toulouse June 2005


Status pulsar studies in soft gamma rays

Normal pulsars continued…

Pulse profile vs energy

PSR B0833-45 (Vela) incl. ISGRI (2 Ms) 15-150 keV (6.2s)

XMM

RXTE PCA

Comptel

EGRET

RXTE PCA

IBIS ISGRI

Comptel

EGRET

XMM

RXTE PCA

OSSE

EGRET

EGRET

Understanding the HE characteristics (energy-dependent single/double/triple peaked profiles) will profit from detailed light curves for more pulsars

Toulouse June 2005


Status pulsar studies in soft gamma rays

Normal pulsars continued…

Promising recent progress (Chandra/XMM/RXTE/INTEGRAL)

Deep searches at the cores of SN-remnants and in the error boxes of unidentified EGRET sources yielded detections of several radio dim/quiet energetic pulsars emitting hard X-rays (> 10 keV)

Eg.

- PSR J1930+1852 (in G54.1+0.3; radio dim)- PSR J1811-1925 (in G11.2-0.3; radio quiet)- PSR J1846-0258 (in Kes 75; radio quiet)- PSR J1617-5055 (near RCW 103)

PSR J1930+1852 in G54.1+0.3Chandra

PSR J1846-0258

in Kes 75

Toulouse June 2005


Status pulsar studies in soft gamma rays

Normal pulsars continued…

- Pulsed emission has been detected up to ~100 keV (RXTE HEXTE) from these 4 pulsars (Kuiper et al. 2005)

- HE-pulse profile: asymmetric single pulse similar to PSR B1509-58

- Pulsed spectra hard, similar to PSR B1509-58; very likely reaching maximum luminosity at MeV energies

PSR J1846-0258 (Kes 75)RXTE HEXTE 20-100 keV

↖3s IBIS ISGRI; 1 Ms

Top of the iceberg seems seen indeed… the pulsars can be studied in great detail with instruments 10-50 x ISGRI sensitivity

Toulouse June 2005


Status pulsar studies in soft gamma rays

Normal pulsars continued…

Weaker hard X-ray emitting pulsars (all with hard X-ray spectra)

  • - PSR J0537-6910 (LMC; N157B; radio quiet)- PSR J0205+64 (in 3C58)- PSR J2229+6114 in 3EG J2229+6122- PSR J1747-2958 (“Mouse”, G359.23-0.82)- PSR J2021+3651 in 3EG J2021+3716

X-ray Pulse profiles

↖3s IBIS ISGRI; 1 Ms

Below ISGRI limit, but good potentials with 10-50 x more sensitivity

Toulouse June 2005


Class ib spin down powered millisec pulsars

Class Ib: Spin-down powered millisec pulsars

- 6-7 systems show pulsed X-ray emission

- 2 sub-classes: I – broad pulses; soft spectra

II – narrow pulses; hard spectra up to ~20 keV seen

0.1-10 keV

↖3s IBIS ISGRI; 1 Ms

GLAST

Hard tails of ms pulsars can be studied in detail with 10-50x ISGRI sensitivity

Toulouse June 2005


Status pulsar studies in soft gamma rays

Class II: accretion powered pulsars

Currently 6 members, e.g. IGR J00291+5934, discovered in outburst during INTEGRAL GP scan:

- Single symmetric pulse [2-150 keV]; pulsed emission seen up to ~150 keV

- Total emission [5-200 keV]: thermal Comptonization on plasma with Te ~50 keV

- Pulsed spectrum shows hardening: Doppler boosting on Comptonized spectrum?

Accretion powered pulsars need high-statistics measurements above 50 keV

Toulouse June 2005


Status pulsar studies in soft gamma rays

Class III: Anomalous X-ray pulsars (AXPs)

Status before early 2004:

- Not rotation powered pulsars (LX >> Lsd)

- Not accretion powered pulsars [i.e. not X-ray pulsars in LMXBs/HMXBs](steady spin-down; no apparent optical counterpart; no periodicDoppler delay in X-ray timing)

- Characteristics:

  • Pulse periods 5 -12 s

  • “Steady” spin-down like rotation powered pulsars (incl. glitches)

  • X-ray luminosities 1034-36 erg/s (steady, but outbursts; transient AXPs)

  • [Very] soft X-ray (0.5-10 keV) spectra: BB (0.35–0.6 keV) and PL (2–4)

  • Similar to SGRs (glitches; (out)bursts), suggesting magnetars (NSs with B ~ 1014-15 G powered by decay of the B-field)

  • Young population concentrated along Galactic plane, some in SNRs

Toulouse June 2005


Status pulsar studies in soft gamma rays

AXPs continued…

AXP Discovery P[s] B[1014 G]

Persistent

1E2259+586 (SNR)19816.98 0.61E1048-59419856.45 5.04U 0142+61419938.69 1.31RXS J1708-4009199711.00 4.61E1841-045 (SNR)199711.77 7.1CXOU J0100-721 (SMC)20028.02 3.9

Transients

AX J1845-02619986.97 ?XTE J1810-19720035.54 2.6

Toulouse June 2005


Status pulsar studies in soft gamma rays

AXPs continued…

HE-picture changed dramatically with the detection of AXPs at energies >20 keV in IBIS ISGRI skymaps: 1E 1841-045

1RXS J1708-4009

4U 0142+614

- Pulsed nature of >20 keV emission

- Pulsed fraction ➙ 100%

- Emission is very hard

HEXTE

4.2s 3.1s 2.7s

Toulouse June 2005


Axp 1e 1841 045 kes 73 kuiper hermsen mendez 2004 apj 613 1173

AXPs continued…

AXP 1E 1841-045 (+ Kes 73) (Kuiper, Hermsen & Mendez, 2004, ApJ 613, 1173)

④AXP pulsed

(RXTE/HEXTE)

g = 0.94±0.16

①AXP + Kes 73

(XMM-Newton)

②AXP total

(Chandra)

⑤AXP total

[+ Kes 73 ?]

(IBIS ISGRI)

③AXP pulsed

(RXTE/PCA)

⑥AXP total

[+ Kes 73 ?]

(CGRO COMPTEL)

AXP spectrum must break above ~100 keV

Toulouse June 2005


Status pulsar studies in soft gamma rays

AXPs continued…

AXP 4U0142+614

①DC+Pulsed (Chandra)

④DC+Pulsed (IBIS ISGRI)

②Pulsed (ASCA GIS)

⑤Pulsed (RXTE HEXTE)

③Pulsed

(RXTE PCA)

⑥DC+Pulsed

(CGRO COMPTEL)

AXPs have very hard spectra in the 10-100 keV regime, followed by a drastic break… this can be studied in detail with 10-50 x ISGRI/COMPTEL sensitivity

Toulouse June 2005


Axp 1e2259 586 ctb 109

AXPs continued…

AXP 1E2259+586 (+ CTB 109)

Screened PCU-2 exposure of747 ks

5.2s

3.1s

Onset hard tail

10.6s

Toulouse June 2005


Summary

Summary

  • For any type of pulsar,in the soft g-ray band drastic spectral changes & pulse morphology changes occur

  • HE pulsar emission is

  • largely a puzzle

  • Requirements:

  • - maximum sensitivity in

  • the 50 keV – MeV regime

  • - accurate timing

  • - polarization measurement of distinct interest

Toulouse June 2005


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