1. X-ray pulsars through the eyes of INTEGRAL A.Lutovinov, S.Tsygankov (IKI) & the discussion with J.Poutanen, M.Revnivtsev and V.Suleimanov Funasdalen 2008

2. OUTLINE (What is a new in hard X-rays) I. Hard X-ray spectra of X-ray pulsars II. Cyclotron line energy dependence on the X-ray pulsars luminosity III. Pulse profiles dependence on the luminosity and energy band IV. Pulse fraction dependence on the luminosity and energy band

3. Name Type P Porb Companion INTEGRAL totally observed more than 70 X-ray pulsars during 5 years of the operation, discovered several new pulsars. 38 of them were detected at the high significance level, that gave a possibility to reconstruct their spectra

4. B=5.3x10 12 Гс Filippova, Tsygankov, Lutovinov, Sunyaev (2005) B=3x10 12 G B=3.1x10 12 G B=2.6x10 12 G B=1.4x10 12 G

5. Range of luminosities ~2х10 37 – ~5х10 38 erg/s (d ~7 kpc), P spin ~ 4.375 s, P orb ~ 34.25 d High state α = -0.09+/-0.01 E cut = 9.15+/-0.03 кэВ E cyc1 = 26.21+/-0.15 кэВ E cyc2 = 50.66+/-0.3 кэВ E cyc3 = 73.8+/-1.8 кэВ E cyc1 /E cyc2 /E cyc3 = 1/1.93/2.82 Tsygankov, Lutovinov, Churazov, Sunyaev (2006) V0332+53

6. The cyclotron line energy dependence on the source luminosity E cyc ≈-0.1L 37 +29.0 keV B=((1+z)/11.6)xE cyc x10 12 G=3x10 12 G

7. Accretion column structure Accretion stream structure (Basko, Sunyaev, 1976) Shock height above the neutron star surface: 1) L<L* - no shock 2) L>L* - shock L*~10 37 erg/s In an approaching of the dipole magnetic field ΔE cycl ~ 25% corresponds to a ΔR~ 7.5%, thus “effective” height of the cyclotron feature formation is l~750 m. - accretion rate (10 39 erg/s) H ~ few km (Lyubarskyi, Sunyaev, 1982)

8. X-ray outbursts of 4U 0115+63 Maximal luminosity range ~1х10 37 – ~2х10 38 erg/s (d~7 kpc) Tsygankov, Lutovinov, Churazov, Sunyaev (2007) Spectral parameters α = 0.09+/-0.01 E cut = 8.9+/-0.1 keV E cyc1 = 11.16+/-0.03 keV E cyc2 = 21.2+/-0.1 keV E cyc3 = 34.6+/-0.2 keV E cyc4 = 44.9+/-0.3 keV E cyc1 /E cyc2 /E cyc3 /E cyc4 = 1/1.9/3.1/4.0 E cyc1 E cyc2 E cyc3 E cyc4

9. L x ~5x10 37 erg/s Sharp shift of the cyclotron energy occurs at the same luminosity – the fundamental property of pulsar (?) The cyclotron line energy dependence on the source luminosity

10. Disk accretion (Ghosh,Lamb 1978) : A0535+26KS1947+300 Tsygankov, Lutovinov (2005)Tsygankov, Lutovinov (2008)

11. Luminosity and energy dependence of pulse profiles (V0332+53 example) 2.6х10 38 erg/s 1.8х10 38 erg/s 8.2х10 37 erg/s 6х10 37 erg/s

12. Evolution of pulse profiles near the main cyclotron line harmonic E cycl 2.6х10 38 erg/s 6х10 37 erg/s

13. 3D- and 2D-pulse profile variations 2.6х10 38 erg/s 6х10 37 erg/s Tsygankov, Lutovinov, Churazov, Sunyaev (2006)

14. Her X-1Vela X-1 There is catalog of hard pulse profiles of 10 bright X-ray pulsars, their dependences on the energy, luminosity, orbital phases, etc. Soon on the web!

15. Toy model Rotation axis is inclined in a such way that the accretion column at one of the poles is seen over its entire height, but only the upper part emitting softer photons is seen in the second column. Should be taking into account also a light bending, possible reflection from the neutron star surface and plasma on the Alfven surface, beam function dependence from the energy, etc. See e.g. poster Annala & Poutanen

16. Pulse fraction dependence on the luminosity and energy band Timing analysis of the INTEGRAL/IBIS data of X-ray pulsars in narrow energy bands. Only bright sources (flux in the 20-50 keV range >100 mCrab): NameE cyc 4U 0115+63~11, 21, 34, 45 keV V 0332+53~28, 55 keV A 0535+262~45, 100 keV Hercules X-1~38 keV Vela X-1~22, 56 keV GX 301-2~50 keV GX 1+4- Cen X-3~31 keV OAO 1657-415~78 keV ( not detected with INTEGRAL) EXO 2030+375-

17. Pulse fraction dependence on the energy Also for millisecond pulsars (Falanga 2007)

18. for Crab-like spectrum Crab - spectrum of the Nebula (non-pulsed) - spectrum of the pulsar (pulsed) Segreto et al. (2005) The increasing of the pulse fraction is a steeper than we expect from our simple suggestion.

19. Presence of cyclotron lines; PF dependence on the luminosity Different mechanisms of the emission; X-ray pulsars The situation is more complicated: Typical X-ray pulsars spectrum ; corresponds to

20. A(E) - non-universal and different for different X-ray pulsars PF vs I(E) -1

21. The rise of the amplitude in the exponential tail: Temperature grows towards deeper layers At higher inclinations - cooler outer layers At lower inclinations – hotter deeper layers are visible The intensity in the Wien tail will be strongly modulated The rise of the amplitude in the cyclotron line: A strong dependence of the opacity on the angle with the magnetic field can give a large modulation. Preliminary ideas

22. Summary   Mostly accurate results of the spectral and timing analysis of several dozens X-ray pulsars in hard X-rays at the moment   The evolution of the cyclotron energy with the source luminosity was studied in detail for the first time. It was shown that for V0332+53 and A535+26 this dependence is linear, but for 4U0115+63 is more complicated   Strong dependence of the pulse fraction on the energy and source luminosity is revealed and study in detail   The prominent feature in the dependence of the pulse fraction on energy band was revealed near the cyclotron frequency for several bright sources   There are preliminary ideas how to explain above, but may be something else?...