Toulouse June 2005 Page 1Netherlands Institute for Space Research

Status pulsar studiesin soft gamma-rays

Lucien Kuiper, Wim Hermsen, [Hans Bloemen]

Toulouse June 2005 Page 2Netherlands Institute for Space Research

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

Three classes of pulsars seen in rays

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Class Ia: Spin-down powered [normal] pulsars

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

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

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

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At soft/medium -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 B1509-58

PSR B0540-69

↖3 IBIS ISGRI; 1 Ms

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

Normal pulsars continued…

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Pulse profile vs energyPSR B0833-45 (Vela) incl. ISGRI (2 Ms) 15-150 keV (6.2)

Comptel EGRETRXTE PCA

RXTE PCA

RXTE PCAXMM

XMM

OSSE

IBIS ISGRI

EGRET

Comptel EGRET

EGRET

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

Normal pulsars continued…

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

PSR J1930+1852 in G54.1+0.3Chandra

PSR J1846-0258in Kes 75

Normal pulsars continued…

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- 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

↖3 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

Normal pulsars continued…

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

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

X-ray Pulse profiles

↖3 IBIS ISGRI; 1 Ms

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

Normal pulsars continued…

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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

GLAST

↖3IBIS ISGRI; 1 Ms

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

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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?

Class II: accretion powered pulsars

Accretion powered pulsars need high-statistics measurements above 50 keV

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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 periodic

Doppler 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

Class III: Anomalous X-ray pulsars (AXPs)

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AXP Discovery P[s] B[1014 G]

Persistent

1E2259+586 (SNR) 1981 6.98 0.61E1048-594 1985 6.45 5.04U 0142+614 1993 8.69 1.31RXS J1708-4009 1997 11.00 4.61E1841-045 (SNR) 1997 11.77 7.1CXOU J0100-721 (SMC) 2002 8.02 3.9

Transients

AX J1845-026 1998 6.97 ?XTE J1810-197 2003 5.54 2.6

AXPs continued…

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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

4.2 3.1 2.7

HEXTE

AXPs continued…

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

① AXP + Kes 73AXP + Kes 73(XMM-Newton)(XMM-Newton)

② AXP total AXP total (Chandra)(Chandra)

③ AXP pulsed AXP pulsed (RXTE/PCA)(RXTE/PCA)

④ AXP pulsed AXP pulsed (RXTE/HEXTE)(RXTE/HEXTE)

= 0.94±0.16= 0.94±0.16

⑥ AXP totalAXP total [+ Kes 73 ?][+ Kes 73 ?] (CGRO COMPTEL)(CGRO COMPTEL)

⑤ AXP totalAXP total[+ Kes 73 ?] [+ Kes 73 ?] (IBIS ISGRI)(IBIS ISGRI)

①

②

③

④

⑤ ⑥

AXPs continued…

AXP spectrum must break above ~100 keV

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① DC+Pulsed (Chandra)

①

② Pulsed (ASCA GIS)

②

③ Pulsed(RXTE PCA)

③

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

④ DC+Pulsed (IBIS ISGRI)

④

⑤ Pulsed (RXTE HEXTE)

⑤

⑥ DC+Pulsed(CGRO COMPTEL)

⑥

AXP 4U0142+614

AXPs continued…

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AXP 1E2259+586 (+ CTB 109)

5.2

Screened PCU-2 exposure of747 ks

3.1

10.6

Onset hard tail

AXPs continued…

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Summary

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

• HE pulsar emission islargely a puzzle

• Requirements:

- maximum sensitivity in the 50 keV – MeV

regime- accurate timing- polarization measurement of distinct interest