The fundamental INTEGRAL contributions to advance the millisecond X-ray pulsars research field

Transcription

1 The fundamental INTEGRAL contributions to advance the millisecond X-ray pulsars research field M A U R I Z I O F A L A N G A Collaborators: L. Kuipers, W. Hermsen, J. Poutanen, A. Goldwurm, L. Stella June 11, 2010

2 Stellar Evolution & Predictions

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4 Recycling model for MSPs LMXB phase preceding the MSP stage; mass transfer stops; the radio MSP switches on Young Pulsars birth Most binary MSPs have short orbital periods and mass function identifying the companions as low mass evolved dwarfs Old Neutron stars spin up by accretion from a companion Accreting NS in LMXBs are conventionally thought to be the progenitors of millisecond or recycled radio pulsars (Alpar et al. 1982) X-ray transients can be the missing link between LMXBs and MSPs!

5 1. We have to discover the first Accreting Millisecond X-ray Pulsar 2. We have to discover an AMXP spinning-up 3. We have to prove that LMXB are the progenitors of Radio MSP

6 1998 the first Accreting Millisecond X-ray Pulsar & The growing family of the X-ray millisecond pulsars

7 Close X-ray binaries: Companion: M << M sun NS: B~ G 14 MSP P s Hz P orb 40 min. - few hrs. (e.g., Wijnands 2004) L ~ erg/s L ~ erg/s Recurence time 2-5yr 7

8 + Two Intermittent Pulsars Source Name P Spin P Orbit M C,Min Discovered SAX J (ms) (min) (M ) Apr XTE J Apr XTE J Apr XTE J XTE J IGR J HETE J Swift J IGR J Swift J Feb Jun Dec Jun Jun Sep Apr IGR J Apr

9 2005 the first Accreting Millisecond X-ray Pulsar spinning-up

10 We measured for the first time a spin-up for an accreting X-ray millisecond Pulsar IGR J υ = Hz s -1 (Falanga et al. 2005, A&A) υ = (L 37 /η -1 I 45 ) (R m /R co ) 1/2 (M/1.4M sun ) (υ spin /600) -1/3 Hz s

11 «Star eats companion» «Une étoile cannibale» 11

12 2013 the first Accreting Millisecond X-ray Pulsar Swinging between rotation and accretion power in a binary millisecond pulsar

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15 Accreting Millisecond X-ray Pulsar in General

16 X-ray Flux Frequency Flux oscillations are observed in the tails of some bursts Mag. 4U ; 363 Hz ( 2.7 ms) SAX J ω Time (Strohmayer et al, 1996 ApJ) Burst oscillations reflect the NS spin frequency (D. Chakrabarty, Nature, 2003

17 Companion radius Rc/Rsun Companion Star The companion star should fill ist Roche lobe to allow sufficient accretion on the compact star M. Falanga 0.1 Gyr IGR J SAX J XTE J Brown dwarfs Brown dwarf models at different ages (Chabrier et al. 2000) Cold low-mass white dwarfs with pure-helium composition 1 Gyr 5 Gyr White dwarfs XTE J XTE J XTE J Companion mass Mc/Msun IGR J SAX J XTE J XTE J XTE J XTE J H-rich donor, brown dwarf H-poor, highly evolved dwarf

18 θ Geometry of the emission region Thermal Comptonization in plasma of Temperature ~ 40 kev XTE J Seed photons from the hotspot B ~ G R m Thermal disk emission (Falanga et al. 2005, A&A)

19 X-ray bursts Bursts with Photosphere Radius Expansion Standard Candle to determine the Source Distance: L Edd erg s -1 (e.g. Kuulkers 2004, ApJ) (Falanga et al, 2007, A&A) (Falanga et al, 2011, A&A)

20 M M Trec 0 M (t)dt T rec cont T rec M 1 F 1 <F bol,pers > -1.1

21 OUTBURST PROFILE Distinct knee (Falanga, Kuiper, Poutanen et al. 2005) (For a review Wijnands 2005, astro-ph/ ) Outburst are extended as a consequence of X-ray irradiation of the disk? 21

22 Outburst are extended as a consequence of X-ray irradiation of the disk Theory: dwarf novae, SXT XTE J R h < R disc (King & Ritter 1998) SAX J Central object prevents the disk to cool down due to Irradiation, on a viscous timescale, accounting for the exponential decay of the outburst on a timescale τ~20 40 d. (Powell, Haswell & Falanga, 2007)

23 PULSE PROFILE IGR J Mag. ω Porbit = hr Ps = 1.67 ms Pdot = +8.4 x Hz/s (Falanga, Kuiper, Poutanen et al. 2005) 23

24 Pulsed fraction and Time lag : IGR J (Falanga, Kuiper, Poutanen et al. 2005) If the spectrum has a sharp cutoff, the amplitude of the pulse at energies above the cutoff increases dramatically. F(E) E -(Γ-1) exp(-[e/e c ] β ),Componization photon index Γ(E) = Γ 0 + β(e/e c ) β

25 Time/Phase Lag Model (Falanga & Titarchuk 2007) t(c ill, ref, hot,n e ref,n e hot ) = upscattering lag + downscattering lag 25

26 The first Eclipsing and really double peaked AMXP: Swift J (Ferrigno, Bozzo, Falanga et al. 2010, A&A) Constraints on the neutron star mass-radius relation obtained by fitting the pulse profile toghether with a set of equations of state (In preparation)

27 Thank You 27