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
Toulouse June 2005 Page 3Netherlands Institute for Space Research
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, …)
Toulouse June 2005 Page 4Netherlands Institute for Space Research
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…
Toulouse June 2005 Page 5Netherlands Institute for Space Research
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…
Toulouse June 2005 Page 6Netherlands Institute for Space Research
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…
Toulouse June 2005 Page 7Netherlands Institute for Space Research
- 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…
Toulouse June 2005 Page 8Netherlands Institute for Space Research
- 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…
Toulouse June 2005 Page 9Netherlands Institute for Space Research
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
Toulouse June 2005 Page 10Netherlands Institute for Space Research
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
Toulouse June 2005 Page 11Netherlands Institute for Space Research
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)
Toulouse June 2005 Page 12Netherlands Institute for Space Research
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…
Toulouse June 2005 Page 13Netherlands Institute for Space Research
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…
Toulouse June 2005 Page 14Netherlands Institute for Space Research
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
Toulouse June 2005 Page 15Netherlands Institute for Space Research
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…
Toulouse June 2005 Page 16Netherlands Institute for Space Research
AXP 1E2259+586 (+ CTB 109)
5.2
Screened PCU-2 exposure of747 ks
3.1
10.6
Onset hard tail
AXPs continued…
Toulouse June 2005 Page 17Netherlands Institute for Space Research
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