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AXPs AXPs Anomalous X-ray Pulsars Anomalous X-ray Pulsars and - PowerPoint PPT Presentation

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AXPs AXPs Anomalous X-ray Pulsars Anomalous X-ray Pulsars and SGRs SGRs and Soft Gamma Repeaters Soft Gamma Repeaters FERMI FERMI A Review in the Era A Review in the Era Launched 2008 June 11 Andreas von Kienlin Vulcano

  1. AXPs AXPs Anomalous X-ray Pulsars Anomalous X-ray Pulsars and SGRs SGRs and Soft Gamma Repeaters Soft Gamma Repeaters FERMI FERMI A Review in the Era A Review in the Era − − Launched 2008 June 11 Andreas von Kienlin Vulcano Workshop 2010 May 25, 2010 1

  2. The Fermi Observatory Observatory The Fermi Large Area Telescope (LAT) Gamma-ray Burst Monitor (GBM) Orbit: 565 km, 25.6 ° 20 % of sky whole unocculted GBM BGO detectors sky at any time ! Andreas von Kienlin Vulcano Workshop 2010 May 25, 2010 2

  3. The Fermi Observatory Observatory The Fermi LAT (high-E spectrum) NaIs (location & low-E spectrum) Orbit: 565 km, 25.6 ° 20 % of sky NaIs: 8 NaIs : 8 keV keV – – 1 MeV 1 MeV BGOs BGOs: 150 : 150 keV keV – – 40 MeV 40 MeV – – >300 LAT: 20 MeV LAT: 20 MeV >300 GeV GeV whole unocculted BGOs (mid-E spectrum) sky at any time ! Andreas von Kienlin Vulcano Workshop 2010 May 25, 2010 3

  4. GBM Triggers Weekly Triggers Weekly Triggers Aug 08 – Sept 09  GRBs >300  TGFs 17  SGRs ~170  Particles  Other Other: Cyg X-1 rises, solar- flare(1x), accidentals Andreas von Kienlin Vulcano Workshop 2010 May 25, 2010 4

  5. Main properties of SGRs & AXPs Soft Gamma Repeaters (SGRs) Venera 12 SGR 0526-66  Discovered in 1979 as transient sources of hard X-ray bursts Mazets et al., 1979 and giant flares (GF)  8 confirmed SGRs (3 emitted a GF ) .  Persistent counterparts in X-rays and coherent pulsation found  P: 2 - 8 s; P: ~ 10 -11 s/s Anomalous X-ray pulsars (AXPs) AXP 1E 2259+586  Identified in the 90’s as a peculiar class of persistent X-ray pulsar + SNR CTB 109 with no signs of binary companions  Rotational period of a few seconds (5 - 12 s)  Secular spin-down ~ 10 -11 - 5 × 10 -13 s/s  L X ~ 10 34 - 10 36 erg/ s >> Rotational Energy Loss  Soft X-ray spectrum (kT~0.5 keV) + hard tail up to 200 keV  9 confirmed AXPs (3 in SNRs, 3 transients) Einstein Observatory X-ray image AXPs  SGRs   AXPs have properties very similar to those of the “quiescent” counterparts of SGRs  Also AXPs emit bursts similar to SGRs (discovered with RXTE 2003)   same class of sources ? Andreas von Kienlin Andreas von Kienlin Vulcano Workshop 2010 Vulcano Workshop 2010 May 25, 2010 5

  6. SGRs & AXPs  Magnetars? Thomson & Duncan 1995 Both SGRs and AXPs are well explained by the Magnetar model:   (Isolated) neutron stars where the main source of energy is the magnetic field  Highly magnetized (B ~ 10 15 G), slowly rotating star (P ~ 2 - 12 s) Enough to power bursts and persistent X-ray emission   Steady dissipation of magnetic field  surface heating  persistent X-ray emission  NS crust fractures  short bursts  Magnetic field becomes unstable and undergoes a large-scale rearrangement  Giant flares But there are alternative models: accretion from a fall-back disk (e.g Trümper et al. 2010)  Most observed neutron stars have B = 10 9 - 10 12 G and are powered by rotational  energy, accretion, residual internal heat  Radio Pulsars: Powered by rotational energy (P ~ 1.5 ms - 5 s)  Accreting X-ray binaries: Powered by gravitational energy Andreas von Kienlin Andreas von Kienlin Vulcano Workshop 2010 Vulcano Workshop 2010 May 25, 2010 6

  7. INTEGRAL SPI/ACS Lightcurve Bursts/Flares/GFs SGR 1806-20 Dec27, 04 Initial Peak 6 1x10 2 x10 6 Pulsating Tail Count Rate [1/s] Giant flares: P=7.65 s Initial hard spike + pulsating tail (3x) Durations: t ~ 1 – 60 s 0.0 0.5 1.0 4 9x10 Fluence: ~ 10 44 – 10 47 erg Precursor 60 120 180 5 1x10 2005, Andreas von Kienlin (on behalf of the SPI team) -180 -120 -60 0 60 120 180 240 300 360 AXP 1547- 5408 Time [s] after 22:30:26.539 MEZ January 22, 2009 Intermediate flares: INTEGRAL SPI-ACS Sometimes pulsating light curve P=2.07s Durations: t ~ 0.5 – 40 s Fluence: ~ 10 42 – 10 44 erg SGR 1550-5418 Oct 03, 08 Short bursts: in the hard X-ray / soft gamma-ray energy range Durations: t ~ 0.01 – 0.5 s Fluence: ~ 10 38 – 10 42 erg Andreas von Kienlin Vulcano Workshop 2010 May 25, 2010 7

  8. Quiescent X-ray emission XMM & INTEGRAL  X-ray spectra:  Soft X-ray emission is predominantly of thermal origin (XMM)  Detection of persistent hard X-ray tails by INTEGRAL  Pulsation also seen Götz et al. 2008 Andreas von Kienlin Andreas von Kienlin Vulcano Workshop 2010 Vulcano Workshop 2010 May 25, 2010 8

  9. Magnetars in the in the Fermi Fermi era era Magnetars SGR Source Active Period Triggers Comments New source at Perseus 22 Aug – 03 Sep 08 J0501+4516 26 arm 1806-20 29 Nov 2008 1 Old source - reactivation Fermi/GBM Known AXP – first time 03 - 20 Oct 08 7 J1550-5418 22 Jan - 24 Feb 09 117 exhibiting burst active 22 Mar – 17 Apr 09 14 episodes discovered with GBM ! J0418+5729 05 Jun 2009 2 new source at Perseus arm discovered with Swift and 1833-0832 19 Mar 2010 RXTE – no GBM detection  GBM Magnetar Key Project (PI: Chryssa Kouveliotou)  http://gammaray.nsstc.nasa.gov/gbm/science/magnetars Andreas von Kienlin Andreas von Kienlin Vulcano Workshop 2010 Vulcano Workshop 2010 May 25, 2010 9

  10. SGR 0501+4516 SGR 0501+4516  Swift triggered on 4 bursts on 22 August 2008  First bursts was also detected by Fermi/GBM  RXTE ToO program triggered ~4 hours after the first Swift trigger for 600 s  P = 5.7620 s was reported ~ 9 hours after the first Swift trigger! .  P = 7.4980x10 -12 and B = 2.1 x 10 14 G  CXO HRC location: RA = 05h 01m 06.756s DEC = +45d 16m 33.92s (0.1” error)  IR Counterpart with UKIRT, K~18.6 (Tanvir & Varricatt 2008)  GBM triggered on 26 events from the source – total of 56 events in ~ 3.5 days Andreas von Kienlin Vulcano Workshop 2010 May 25, 2010 10

  11. SGR 0501+4516 Bursts SGR 0501+4516 Bursts Suzaku data for 080826_136: Integrated spectrum best fit by 2 BB: kT1 = 3.3 keV, kT2 = 15.1 keV Enoto et al. 2009 Andreas von Kienlin Vulcano Workshop 2010 May 25, 2010 11

  12. SGR 0501+4516 GBM data SGR 0501+4516 GBM data GBM data for 080826_136 (common with: Suzaku, Konus): Integrated spectrum can be fitted by … Watts et al. 2010 Lin Lin et al. 2010 … two BB or … one BB + PL: kT1 = 8 keV, kT2 = 18 keV kT = 11 keV, γ = -2.4 Andreas von Kienlin Vulcano Workshop 2010 May 25, 2010 12

  13. SGR 0501+4516: odd flare SGR 0501+4516: odd flare lightcurve lightcurve First magnetar candidate PRE burst ?  PRE: Photospehric Radius Expansion  Multi-peaked flare  Very rapid drop in emission PRE in thermonuclear bursts >10 keV  Luminosity reaches Eddington limit, triggering PRE 5-10 keV Counts/s  Expanding layers cool, leading to a multi-peaked light curve.  Standard candle to measure a 2-5 keV neutron star distance Andreas von Kienlin Vulcano Workshop 2010 May 25, 2010 13 Time

  14. SGR 0501+4516: odd flare SGR 0501+4516: odd flare lightcurve lightcurve First magnetar candidate PRE burst ? O t h e  PRE: Photospehric Radius r c a n d i d Expansion a t e P R E b u  Multi-peaked flare r s t s b e i n g i n  Very rapid drop in emission v e s t i g a t e d !  Distance and field strength known.  Predicted critical flux matches that recorded by GBM!  2 x 10 -4 ergs/cm 2 /s  Watts et al. 2010  Emission becomes softer during the dip in the lightcurve Watts et al. 2010 Andreas von Kienlin Vulcano Workshop 2010 May 25, 2010 14

  15. SGR 1550-5418 SGR 1550-5418 formerly known as AXP 1E1547.0-5408 formerly known as an ASCA CCO in G327.0-0.13  Three bursting episodes detected with GBM:  Oct. 2008  Jan. 2009  Mar. & Apr. 2009 .  P = 2.069s, P = 2.318 x 10 -11 s/s and B = 2.2 x 10 14 G  Near IR detection, Ks = 18.5±0.3  GBM triggered on 138 events from the source;  many more in the data Andreas von Kienlin Vulcano Workshop 2010 May 25, 2010 15

  16. SGR 1550– –5418 Bursting Activity 5418 Bursting Activity SGR 1550 von Kienlin et al. 2010 Andreas von Kienlin van der Horst et al. 2010 Vulcano Workshop 2010 May 25, 2010 16

  17. January 22, 2009 activity of AXP 1E 1547.0-5408  More than 200 bursts detected by INTEGRAL SPI/ACS (IBAS @ ISDC)  Period with strongest activity: January 22, 2009  Uninterrupted monitoring due to highly elliptical orbit  Energy release of brightest bursts ~ 10 43 erg (assumed distance: 10 kpc) Detected by: Time binning: 50 ms E > 80 keV  Fermi / GBM  Swift  Suzaku  Konus- Wind  RHESSI  INTEGRAL  SPI/ACS Andreas von Kienlin Mereghetti et al. 2009 Vulcano Workshop 2010 May 25, 2010 17

  18. January 22, 2009 activity of AXP 1E 1547.0-5408  Two bright events with pulsating tail observed at 6:48:04 UT and 8:17:29 UT  Two longest bursts  Modulated at the 2.1 s spin period  E ~10 43 erg for 10 kpc dead-time limited ! ~ 0.9 s long burst (n. 150) profile 150 not in phase with preceding pulses Dead time   Resolving loss (deadtime) in each single FEE  Blocking loss in the VCU by “OR”-ing of 92 FEE veto signals Andreas von Kienlin Mereghetti et al. 2009 Vulcano Workshop 2010 May 25, 2010 18

  19. SGR J1550-5418: Jan 08 activity period van der Horst et al. 2010 Jan 22, 2008 GBM observations  41 triggers  450 bursts on one day… van der Horst et al. 2010 Andreas von Kienlin Vulcano Workshop 2010 May 25, 2010 19

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