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
Stellar Evolution & Predictions
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!
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
1998 the first Accreting Millisecond X-ray Pulsar & The growing family of the X-ray millisecond pulsars
Close X-ray binaries: Companion: M << M sun NS: B~10 8-9 G 14 MSP P s 180-600 Hz P orb 40 min. - few hrs. (e.g., Wijnands 2004) L ~ 10 31-10 32 erg/s L ~ 10 36-10 38 erg/s Recurence time 2-5yr 7
+ Two Intermittent Pulsars Source Name P Spin P Orbit M C,Min Discovered SAX J1808.4-3658 (ms) (min) (M ) 2.5 120 0.043 Apr. 1998 XTE J1751-306 2.3 42 0.014 Apr. 2002 XTE J0929-314 5.4 44 0.083 Apr. 2002 XTE J1807-294 XTE J1814-338 IGR J00291+5934 HETE J1900.1-2455 Swift J1756.9-2508 IGR J17511-3057 Swift J1749.4-2807 5.2 3.2 1.67 2.6 5.5 4.1 1.9 40 258 150 84 54 208 530 0.0066 0.17 0.039 0.016 0.007 0.13 0.6 Feb. 2003 Jun. 2003 Dec. 2004 Jun. 2005 Jun. 2007 Sep. 2009 Apr. 2010 IGR J18245-2452 3.9 660 0.204 Apr. 2013 8
2005 the first Accreting Millisecond X-ray Pulsar spinning-up
We measured for the first time a spin-up for an accreting X-ray millisecond Pulsar IGR J00291+5934 υ = + 8.4 10-13 Hz s -1 (Falanga et al. 2005, A&A) υ = + 3.7 10-13 (L 37 /η -1 I 45 ) (R m /R co ) 1/2 (M/1.4M sun ) (υ spin /600) -1/3 Hz s - 1 10
«Star eats companion» «Une étoile cannibale» 11
2013 the first Accreting Millisecond X-ray Pulsar Swinging between rotation and accretion power in a binary millisecond pulsar
Accreting Millisecond X-ray Pulsar in General
X-ray Flux Frequency Flux oscillations are observed in the tails of some bursts Mag. 4U 1728-34; 363 Hz ( 2.7 ms) SAX J1808.4-3658 ω Time (Strohmayer et al, 1996 ApJ) Burst oscillations reflect the NS spin frequency (D. Chakrabarty, Nature, 2003
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 J00291+5934 SAX J1808..4-3658 XTE J1814-338 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 J0929-314 XTE J1751-305 XTE J1807-294 Companion mass Mc/Msun IGR J00291+5934 SAX J1808.4-3658 XTE J1814-338 XTE J0292-314 XTE J1751-305 XTE J1807-294 H-rich donor, brown dwarf H-poor, highly evolved dwarf
θ Geometry of the emission region Thermal Comptonization in plasma of Temperature ~ 40 kev XTE J1807-294 Seed photons from the hotspot B ~ 10 8-9 G R m Thermal disk emission (Falanga et al. 2005, A&A)
X-ray bursts Bursts with Photosphere Radius Expansion Standard Candle to determine the Source Distance: L Edd 3 10 38 erg s -1 (e.g. Kuulkers 2004, ApJ) (Falanga et al, 2007, A&A) (Falanga et al, 2011, A&A)
M M Trec 0 M (t)dt T rec cont T rec M 1 F 1 <F bol,pers > -1.1
OUTBURST PROFILE Distinct knee (Falanga, Kuiper, Poutanen et al. 2005) (For a review Wijnands 2005, astro-ph/0403409) Outburst are extended as a consequence of X-ray irradiation of the disk? 21
Outburst are extended as a consequence of X-ray irradiation of the disk Theory: dwarf novae, SXT XTE J1751-305 R h < R disc (King & Ritter 1998) SAX J1808.4-3658 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)
PULSE PROFILE IGR J00291+5934 Mag. ω Porbit = 2.457 hr Ps = 1.67 ms Pdot = +8.4 x 10-13 Hz/s (Falanga, Kuiper, Poutanen et al. 2005) 23
Pulsed fraction and Time lag : IGR J00291+5934 (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
Time/Phase Lag Model (Falanga & Titarchuk 2007) t(c ill, ref, hot,n e ref,n e hot ) = upscattering lag + downscattering lag 25
The first Eclipsing and really double peaked AMXP: Swift J1749.4-2807 (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)
Thank You 27