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  10 38 erg/s)  Typical X-ray luminosities of ULXs are in between 10 39 erg/s and 10 41 erg/s (AGN > 10 41 erg/s)  Many ULXs show strong variability suggesting that they are accreting compact objects!

4.  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) Models to explain ULXs

5. X-ray Image of the Central Region of the Starburst Galaxy M82 (NGC 3034, Cigar Galaxy) Galactic dynamical center M82 X-1 Transient Source (on)Transient Source (off) M82 X-1 is so far the best IMBH candidate, which is not an AGN and has a luminosity around ~10 41 erg/s. Possible background AGN Supernovae Remnant

6. Ultraluminous X-ray Sources in M82 1999-09-20 ObsID 3612002-06-18 ObsID 2933  Chandra 0.3-7 keV images of the central 45”  45” region of M82 radius of circle ~ 1 arcsec ~17 pc

7.  has luminosity ~ 10 41 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 M solar Best Candidate of IMBH – M82 X-1

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 L x = (8 ~13)  10 39 erg/s, N H  3  10 22 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 L x = (3 ~17)  10 39 erg/s, N H  (12~21)  10 22 cm -2

14. Energy Spectrum of the possible Background AGN Fitted with an ionized absorber + power law model, power-law index  = 2, N H = 9  10 23 cm -2

15. Energy Spectrum of the Supernovae Remnant Fitted with a Power-law model, power-law index  = 2.7 ~ 4.5 L x = (2 ~12)  10 39 erg/s, N H  (2~4)  10 22 cm -2

16. Energy Spectrum of the Supernovae Remnant Fitted with an absorbed Raymond-Smith + Power-law model, power-law index  = 2.01, N H = 2.9  10 22 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)

21. 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 ~ 10 7 ~10 8 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 > 10 9 years

22. M74

24. Antennae (NGC 4038/4039)

25.  Transient behavior & hard X-ray spectrum – rule out the supernovae remnants and background AGN  High X-ray isotropic luminosity (~10 40 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 Summary