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Status pulsar studies in soft gamma-rays

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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  1. Status pulsar studiesin soft gamma-rays Lucien Kuiper, Wim Hermsen, [Hans Bloemen] Toulouse June 2005

  2. Three classes of pulsars seen in g rays 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 Toulouse June 2005

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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

  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 ↖3s IBIS ISGRI; 1 Ms GLAST Hard tails of ms pulsars can be studied in detail with 10-50x ISGRI sensitivity Toulouse June 2005

  10. 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

  11. 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 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 Toulouse June 2005

  12. AXPs continued… 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 Toulouse June 2005

  13. 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

  14. 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) ① ⑤ ⑥ ②AXP total (Chandra) ⑤AXP total [+ Kes 73 ?] (IBIS ISGRI) ② ④ ③AXP pulsed (RXTE/PCA) ③ ⑥AXP total [+ Kes 73 ?] (CGRO COMPTEL) AXP spectrum must break above ~100 keV Toulouse June 2005

  15. AXPs continued… AXP 4U0142+614 ④ ① ①DC+Pulsed (Chandra) ⑥ ④DC+Pulsed (IBIS ISGRI) ⑤ ②Pulsed (ASCA GIS) ② ⑤Pulsed (RXTE HEXTE) ③Pulsed (RXTE PCA) ③ 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

  16. 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

  17. 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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