1. Netherlands Institute for Space Research Toulouse June 2005 Page 1 Status pulsar studies in soft gamma-rays Lucien Kuiper, Wim Hermsen, [Hans Bloemen]

2. Netherlands Institute for Space Research Toulouse June 2005 Page 2 I:spin-down powered pulsars a) normal pulsars b) millisec pulsars (old recycled systems) II:accretion powered pulsars a) 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

3. Netherlands Institute for Space Research Toulouse June 2005 Page 3 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, …)

4. Netherlands Institute for Space Research Toulouse June 2005 Page 4 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…

5. Netherlands Institute for Space Research Toulouse June 2005 Page 5 Pulse profile vs energy PSR B0833-45 (Vela) incl. ISGRI (2 Ms) 15-150 keV (6.2  ) ComptelEGRETRXTE PCA XMM OSSE IBIS ISGRI EGRET ComptelEGRET Understanding the HE characteristics (energy-dependent single/double/triple peaked profiles) will profit from detailed light curves for more pulsars Normal pulsars continued…

6. Netherlands Institute for Space Research Toulouse June 2005 Page 6 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+0.3 Chandra PSR J1846-0258 in Kes 75 Normal pulsars continued…

7. Netherlands Institute for Space Research Toulouse June 2005 Page 7 - 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…

8. Netherlands Institute for Space Research Toulouse June 2005 Page 8 - 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 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…

9. Netherlands Institute for Space Research Toulouse June 2005 Page 9 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 ↖ 3  IBIS ISGRI; 1 Ms Hard tails of ms pulsars can be studied in detail with 10-50x ISGRI sensitivity

10. Netherlands Institute for Space Research Toulouse June 2005 Page 10 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 T e ~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

11. Netherlands Institute for Space Research Toulouse June 2005 Page 11 Status before early 2004: - Not rotation powered pulsars (L X >> L sd ) - 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 10 34-36 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 ~ 10 14-15 G powered by decay of the B-field) Young population concentrated along Galactic plane, some in SNRs Class III: Anomalous X-ray pulsars (AXPs)

12. Netherlands Institute for Space Research Toulouse June 2005 Page 12 AXP Discovery P[s] B[10 14 G] Persistent 1E2259+586 (SNR)19816.98 0.6 1E1048-59419856.45 5.0 4U 0142+61419938.69 1.3 1RXS J1708-4009199711.00 4.6 1E1841-045 (SNR)199711.77 7.1 CXOU J0100-721 (SMC)20028.02 3.9 Transients AX J1845-02619986.97 ? XTE J1810-19720035.54 2.6 AXPs continued…

13. Netherlands Institute for Space Research Toulouse June 2005 Page 13 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…

14. Netherlands Institute for Space Research Toulouse June 2005 Page 14 AXP 1E 1841-045 (+ Kes 73) (Kuiper, Hermsen & Mendez, 2004, ApJ 613, 1173) AXP + Kes 73 ① AXP + Kes 73(XMM-Newton) AXP total ② AXP total(Chandra) AXP pulsed ③ AXP pulsed(RXTE/PCA) AXP pulsed ④ AXP pulsed(RXTE/HEXTE)  = 0.94±0.16 AXP total ⑥ AXP total [+ Kes 73 ?] [+ Kes 73 ?] (CGRO COMPTEL) AXP total ⑤ AXP total [+ Kes 73 ?] (IBIS ISGRI) ① ② ③ ④ ⑤ ⑥ AXPs continued… AXP spectrum must break above ~100 keV

15. Netherlands Institute for Space Research Toulouse June 2005 Page 15 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…

16. Netherlands Institute for Space Research Toulouse June 2005 Page 16 AXP 1E2259+586 (+ CTB 109) 5.2  Screened PCU-2 exposure of747 ks 3.1  10.6  Onset hard tail AXPs continued…

17. Netherlands Institute for Space Research Toulouse June 2005 Page 17 Summary For any type of pulsar, in the soft  -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