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Artistic concept of a HMXB: a collapsed star (NS or BH) Accretes mass from a massive O or B star

Artistic concept of a HMXB: a collapsed star (NS or BH) Accretes mass from a massive O or B star. Binary mass function. Radial velocity curve of HD 226868, the O9.7Iab companion star in the HMBX Cyg X-1 , folded on the 5.6-day orbital period. km/s. Phase (1 = 5.6 days).

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Artistic concept of a HMXB: a collapsed star (NS or BH) Accretes mass from a massive O or B star

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  1. Artistic concept of a HMXB: a collapsed star (NS or BH) Accretes mass from a massive O or B star

  2. Binary mass function

  3. Radial velocity curve of HD 226868, the O9.7Iab companion star in the HMBX Cyg X-1, folded on the 5.6-day orbital period km/s Phase (1 = 5.6 days)

  4. Binary mass function of Cyg X-1: F(Mx) = 0.25 M Mass of companion ~ 33 M For i = 90 deg --> Mx = 7 M It cannot be a neutron star!!

  5. NS star mass limit Chandrasekhar mass

  6. (erroneously thought to be at 15 Mpc, but actually at 30 Mpc!)

  7. How can we be sure that a SMBH resides at the center of A galaxy (and not, for instance, a compact star cluster) ? For example, if we notice that the mass-to-light ratio increases Toward the center of the galaxy, is that a proof of SMBH? No, it is not. It is difficult to get incontrovertible proof. Hints are fast variability, superluminal motion, very high Inferred mass densities, high luminosities…. Most importantly, we must resolve the sphere of influence of the putative central SMBH

  8. Sphere of influence of BH

  9. In the case of SMBHs inhabiting galactic nuclei, the “sphere of influence” is defined as the region of space within which the gravitational potential of the SMBH dominates over that of the surrounding stars. The radius of the sphere of influence is about e6 times larger Than the Schwarzschild radius of a SMBH.

  10. Beyond a few thousand Schwarzschild radii from the central SMBH, but within the sphere of influence, the motion of stars and gas is predominantly Keplerian (relativistic effects are minimal), with a component due to the combined gravitational potential of stars, dust, gas, dark matter, and anything else contributing mass to within that region. Beyond the sphere of influence, the gravitational dominance of the SMBH quickly vanishes.

  11. 600 8 For AGNs one can also use accretion disk theory

  12. The SMBH at the centre of our Galaxy Sgr A* is a compact radio source: VLBI observations at 86 GHz set a limit of 1 AU on its size. Proper motion studies with adaptive optics in K band (angular resolution of 50 mas ~ 40 AU) for ~40 stars within 1.2 arcsec of Sgr A*. Stellar orbits followed up for years, maximum approach is 45 AU, period of 15.2 yrs, velocity of 12000 km/s ! Very precise determination of SMBH mass: (4.5+-0.4) e6 M Ghez et al. 2005, ApJ, 620, 744 Ghez et al. 2008, ApJ, 689, 1044 Schoedel et al. 2002, Nature, 419, 694

  13. 1”

  14. Stellar orbits in the proximity of the Galactic Center

  15. SMBH mass determination thru stellar dynamics Stellar dynamics is more precise than gas dynamics because Gas motion may be not Keplerian, while star orbits are always Keplerian Continuity equation (Collisionless Boltzmann Equation) And Poisson equation Many assumptions are necessary

  16. Stellar kinematic is derived from the absorption lines Velocity profiles arcsec

  17. Dynamical Study of M31 (770 kpc) Surface brightness Radial profile Velocity dispersion radial profile: it rises toward the nucleus The rotation curve is Keplerian And matches perfectly the Expectation of an exponential Disk MBH =  (3.0 ± 1.5)×107 M☉

  18. M87 (= Virgo A, 20 Mpc)

  19. The SMBH in M87 MBH =  (3.2 ± 0.9)×109 M☉

  20. Microwave Amplification thru Stimulated Emission of Radiation (MASER)

  21. Water maser at 22 GHz observed with VLBI in NGC4258

  22. NGC4258 (7 Mpc) Water megamasers observed at 22 GHz with the VLBA: 1 mas = 0.035 pc H2O is in Keplerian motion MBH ~  4×107 M☉ mas

  23. MBH - σ relationship Beyond cz ~ 10000 km/s (i.e. ~150 Mpc), it becomes very difficult or impossible to measure SMBH masses of inactive Galaxies. One can rely upon the MBH -  relationship Milky Way !

  24. However, it is possible to measure SMBH masses in active Galaxies at large distances with various methods

  25. Schematic view of an AGN

  26. AGN have broad (FWHM of several thousands of km/s) and luminous emission lines

  27. Reverberation mapping Right: Light curves of Continuum and Emission lines Of Seyfert Galaxy NGC5548 Left: Correlation function of each Curve with the Optical continuum

  28. Excellent review on Supermassive Black Holes: Laura Ferrarese and Holland Ford Supermassive Black Holes in Galactic Nuclei: Past, Present and Future Research Space Science Reviews 116: 523-624 (2005) [arXiv:astro-ph/0411247]

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