Observational appearance of strong gravity in X-rays

Transcription

1 Observational appearance of strong gravity in X-rays

2 Compact object Companion star (5000 K)

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4 Schwarzschild radius Schwarzschild metric R s 2GM Schwarzschild radius (= 2.95 km for 1М ) c 2

5 Accretion Black holes can be seen via their influence on nearby objects Accretion gradual motion of matter towards gravitating object Where the matter comes from? interstellar from companion star Mass accretion rate and the luminosity

6 Accretion luminosity 1 GMcM 2R c 2 2 L ~ ~ Mc Mc R c R s 2GM Rs - Schwarzschildradius(= 3 km for 1M 2 c 2R Rs c 1 - accretionefficiency sun ) M ~ 10 L x ~ Msun/yr erg/s ~ 0.1, R c ~ 5R s (~ 15km for 1M sun )

7 Why X-rays? R ~ 5 R S = 4 R L x ~ T 2 4 s ~ 15 - emitting area S T ~ (Stefan - Boltzman law) M M M M Sun Sun 1/2 km K ~ 1-2 M M Sun 1/2 kev ~ 1 2 kev for NS ~ kev for BH

8 Black body emission Rayleigh-Jeans law

9 Stefan-Boltzman law

10 Black body normalization => size of the emitter

11 Scheme of BH with accreton disk

12 Non rotating BH Rotating BH Inner disk radius -> BH parameters

13 Radius of innermost stable orbit around rotating BH

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15 ~kt ~Rin Inner disk radius?

16 Problem 1: Brightness distribution The simplest case T~ R -3/4

17 RJ law The simplest case

18 Shakura, Sunyaev 1973

19 Norman, Krolik, Schnittman et al.

20 Disk surface brightness in simulations Beckwith et al. 2008

21 Problem 2: Disk atmosphere (opacity and Comptonization)

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23 Opacity dependence on energy/wavelength

24 Comptonization Одно рассеяние: ~ E e m e c 2 ~ 4kT e m e c 2 если гладкий спектр / 1 Степенной закон между ~kt seed and ~3kT e Тепловой завал e ~ + 4kT e m e c 2 h m e c 2

25 Suleimanov et al. In order to have the outgoing flux one need to have gradient of energy density, gradient of temperature Atmosphere

26 Suleimanov et al. Spectral kt c ~1.7kT distortion

27 Lum-Tdisk dependence and color correction Davis et al. 2006

28 Problem 3 (small) Light bending

29 Black hole parameters from properties of fluorescent emission lines?

30 Reflection from rapidly rotating accretion disk

31 Relativistic line in AGN MCG ? ASCA (1995) Tanaka et al. 1995

32 MCG XMM (2002)

33 Interpretation problem: line of sight absorption?

34 Problems 4. Characteristics of instruments

35 Energy response of instruments X-rays are measured in counts(c) at energy channels (h) h- energy channel (from pulse height ) M model of true emission of the source A(E) effective area of the instrument as a function of energy R(E,h) redistribution matrix of photons into channels

36 Finite energy resolution

37 Even worse in early experiments:

38 Processes in detectors

39 Counts Photopeak Ka photons Compton effect

40 Non-diagonal elements redistribution matrix of Si CCD

41 1995 Proportional Counters response 1979 Limited by electron counts Escape peaks

42 CCD camera SIS/ASCA ( )

43 CHANDRA/ACIS-I (1999- )

44 Effective area of instruments

45 Calibration issues Schellenberger et al XMM-CHANDRA cross-calibration

46 XMM-CHANDRA-SUZAKU cross-calibration with blazar Ishida et al. 2011

47 XMM-CHANDRA-SUZAKU-SWIFT-RXTE-INTEGRAL cross-calibration with supernova remnant Tsujimoto et al. 2010

48 Ice absorption on SSS detector of EINSTEIN

49 Accuracy of effective areas of detectors CHANDRA ACIS-S Effective area Drops at energies below 2 kev due to CCD surface contamination

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52 Spatial distribution of abs.contamination (SUZAKU)

53 CHANDRA/ACIS

54 Charge transfer inefficiency

55 Catechism of X-ray astronomer 1. Before making strong claims one should pay attention to calibration issues!

56 E E Problem pile-up dt(pile-up) 2E 2 photons with some energies might look as one photon with larger energy

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58 Or might even be rejected after post processing due to energy higher than high threshold

59 Even in gas counters pile up effect is present PCA spectrometer (dt~10-5 sec) For CCD dt~0.1-1 sec!

60 Pile-up problems of XMM

61 MOS PN comparison EPIC-PN CCD camera less affected by pile up

62 Fluorescent lines in emission of NS binaries Ng et al. 2011

63 With wrong Cackett et al. correction With correction Dias-Trigo et al.

64 Example of file with events

65 EXAMPLE of real event file of X-ray detector

66 Next step- microcalorimeter Astro-H(Japan) 2015?

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69 Maximum likelihood

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