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The Ultra-luminous X-Ray Sources Near the Center of M82

The Ultra-luminous X-Ray Sources Near the Center of M82. NTHU 10/18/2007 Yi-Jung Yang. Outline. Nature of Ultraluminous X-ray Sources (ULXs) Suggested models of ULXs X-ray sources at central region of M82 X-ray sources and star clusters correlation

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The Ultra-luminous X-Ray Sources Near the Center of M82

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  1. The Ultra-luminous X-Ray Sources Near the Center of M82 NTHU 10/18/2007 Yi-Jung Yang

  2. Outline • Nature of Ultraluminous X-ray Sources (ULXs) • Suggested models of ULXs • X-ray sources at central region of M82 • X-ray sources and star clusters correlation • Lightcurves of target transient source • Spectral analysis • Some basic of X-Ray Binaries • Summary

  3. Ultra-Luminous X-ray Sources (ULXs) • off-nuclear X-ray sources (not at the center) • with isotropic luminosities much higher than the Eddington limit for a solar mass black hole (Lx ~ 1.381038 erg/s) • Typical X-ray luminosities of ULXs are in between 1039 erg/s and 1041 erg/s (AGN > 1041 erg/s) • Many ULXs show strong variability suggesting that they are accreting compact objects!

  4. Models to explain ULXs • Thin super-Eddington, radiation pressure-dominated accretion disks orbiting the stellar-mass black hole binaries • Stellar-mass black hole binaries with anisotropic X-ray emission (mechanical beaming) • Micro-blazars observed along the direction of their relativistically beamed jet • Young supernova remnants in a high-density medium or hypernova remnants. • Background AGN or foreground stars • Intermediate mass black hole binaries (IMBHs)

  5. X-ray Image of the Central Region of the Starburst Galaxy M82 (NGC 3034, Cigar Galaxy) Transient Source (on) Transient Source (off) M82 X-1 Supernovae Remnant Possible background AGN Galactic dynamical center M82 X-1 is so far the best IMBH candidate, which is not an AGN and has a luminosity around ~1041 erg/s.

  6. Ultraluminous X-ray Sources in M82 • Chandra 0.3-7 keV images of the central 45”45” region of M82 1999-09-20 ObsID 361 2002-06-18 ObsID 2933 radius of circle ~ 1 arcsec ~17 pc

  7. Best Candidate of IMBH – M82 X-1 • has luminosity ~ 1041 erg/sec • not at the center of the galaxy => Not an AGN • has a period of 62 days • very close to a young star cluster MGG-11 • has quasi-periodic oscillation (QPO) around 55 mHz • has a mass > 500 Msolar

  8. X-ray Sources and Star Clusters Correlation

  9. Chandra Observation Log

  10. Short Term Light-curve of the Recurrent X-Ray Transient Lightcurves extracted from Chandra observations taken from 1999 to 2005. The source was first appeared in 1999 October. It turned off in 2000 January, but later reappeared and has been active since then.

  11. Long Term Light-Curve of the Transient source Long-term X-ray lightcurve of the ultraluminous X-ray transient. The luminosities are determined by spectral fits.

  12. Energy Spectrum of the Transient Source Best fitted with a Power-law model, power-law index  = 1.3 ~ 1.7 Lx = (8 ~13)1039 erg/s, NH  3 1022 cm-2 Chandra ACIS-S ObsID 5644 2005-08-17 75.1 ks exposure time

  13. Energy Spectrum of the possible Background AGN Fitted with a Power-law model, power-law index  = 0.6 ~ 2.2 Lx = (3 ~17)1039 erg/s, NH  (12~21)1022 cm-2

  14. Energy Spectrum of the possible Background AGN Fitted with an ionized absorber + power law model, power-law index  = 2, NH = 9 1023 cm-2

  15. Energy Spectrum of the Supernovae Remnant Fitted with a Power-law model, power-law index  = 2.7 ~ 4.5 Lx = (2 ~12)1039 erg/s, NH  (2~4)1022 cm-2

  16. Energy Spectrum of the Supernovae Remnant Fitted with an absorbed Raymond-Smith + Power-law model, power-law index  = 2.01 , NH = 2.9 1022 cm-2

  17. Power-Law Spectral Model Fit for J095551.0 (the Transient Source)

  18. Power-Law Spectral Model Fit for J095551.2 (possible background AGN)

  19. Power-Law Spectral Model Fit for J095550.6 (Supernovae Remnant)

  20. HMXB • Donor star is usually young • and massive • Accretor was short-lived and • massive star • Prefer star-forming region & • spiral arms • Period ~ days • Ages: Young ~ 107~108 years • LMXB • Donor star is usually white dwarf • Accretor might be lower mass • star, slowly evolved to NS/BH • Prefer galactic bulges & globular • clusters • Period ~ hours • Ages: Old > 109 years

  21. M74

  22. Antennae (NGC 4038/4039)

  23. Summary • Transient behavior & hard X-ray spectrum – rule out the supernovae remnants and background AGN • High X-ray isotropic luminosity (~1040 erg/s) – black hole accretor • No short-term variability (hours) – unlikely to be relativistically beaming jet • No disk emission & hard x-ray spectrum – unlikely to be anisotropic emission (beaming) • Within the super star clusters region and associated with a young star cluster – ideal birth place to produce Intermediate-mass black hole

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