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The velocity dispersion profile of NGC 6388 from resolved-star spectroscopy: No evidence of a central cusp and new constraints on the black hole mass
- Publication Year :
- 2013
-
Abstract
- By combining high spatial resolution and wide-field spectroscopy performed, respectively, with SINFONI and FLAMES at the ESO/VLT we measured the radial velocities of more than 600 stars in the direction of NGC 6388, a Galactic globular cluster which is suspected to host an intermediate-mass black hole. Approximately 55% of the observed targets turned out to be cluster members. The cluster velocity dispersion has been derived from the radial velocity of individual stars: 52 measurements in the innermost 2", and 276 stars located between 18" and 600". The velocity dispersion profile shows a central value of ~13 km/s, a flat behavior out to ~60" and a decreasing trend outwards. The comparison with spherical and isotropic models shows that the observed density and velocity dispersion profiles are inconsistent with the presence of a central black hole more massive than ~2000 Msol. These findings are at odds with recent results obtained from integrated light spectra, showing a velocity dispersion profile with a steep central cusp of 23-25 km/s at r<br />Comment: Accepted for publication by ApJ; 38 pages, 3 tables, 15 figures
- Subjects :
- FOS: Physical sciences
Astrophysics
Astrophysics::Cosmology and Extragalactic Astrophysics
01 natural sciences
Spectral line
0103 physical sciences
Astrophysics::Solar and Stellar Astrophysics
010303 astronomy & astrophysics
Stellar evolution
Solar and Stellar Astrophysics (astro-ph.SR)
Astrophysics::Galaxy Astrophysics
Physics
010308 nuclear & particles physics
Velocity dispersion
Astronomy and Astrophysics
Astrophysics - Astrophysics of Galaxies
Black hole
Radial velocity
Stars
Amplitude
black hole physics
Astrophysics - Solar and Stellar Astrophysics
Space and Planetary Science
Globular cluster
Astrophysics of Galaxies (astro-ph.GA)
Astrophysics::Earth and Planetary Astrophysics
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....ec9af31ea0bb071f3e9e63d401d9dc11