Speckle imaging with the SOAR and the very large telescopes

This book provides a comprehensive, self-contained introduction to one of the most exciting frontiers in astrophysics today: the quest to understand how the oldest and most distant galaxies in our universe first formed. Until now, most research on this question has been theoretical, but the next few years will bring about a new generation of large telescopes that promise to supply a flood of data about the infant universe during its first billion years after the big bang. This book bridges the gap between theory and observation. It is an invaluable reference for students and researchers on early galaxies. The book starts from basic physical principles before moving on to more advanced material. Topics include the gravitational growth of structure, the intergalactic medium, the formation and evolution of the first stars and black holes, feedback and galaxy evolution, reionization, 21-cm cosmology, and more.

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High Resolution Astrophysical Observations Using Speckle Imaging

10.21236/ada170430 ◽

1986 ◽

Author(s):

Robert W. Noyes ◽

Peter Nisenson ◽

Costas Papaliolios ◽

Robert V. Stachnik

Keyword(s):

High Resolution ◽

Speckle Imaging

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Hunting for intermediate-mass black holes in globular clusters: an astrometric study of NGC 6441

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab474 ◽

2021 ◽

Vol 503 (1) ◽

pp. 1490-1506

Author(s):

Maximilian Häberle ◽

Mattia Libralato ◽

Andrea Bellini ◽

Laura L Watkins ◽

Jörg-Uwe Pott ◽

...

Keyword(s):

Globular Clusters ◽

Velocity Dispersion ◽

Angular Resolution ◽

Hubble Space Telescope ◽

High Mass ◽

High Angular Resolution ◽

Stellar Kinematics ◽

Intermediate Mass ◽

The Core ◽

Large Telescopes

ABSTRACT We present an astrometric study of the proper motions (PMs) in the core of the globular cluster NGC 6441. The core of this cluster has a high density and observations with current instrumentation are very challenging. We combine ground-based, high-angular-resolution NACO@VLT images with Hubble Space Telescope ACS/HRC data and measure PMs with a temporal baseline of 15 yr for about 1400 stars in the centremost 15 arcsec of the cluster. We reach a PM precision of ∼30 µas yr−1 for bright, well-measured stars. Our results for the velocity dispersion are in good agreement with other studies and extend already existing analyses of the stellar kinematics of NGC 6441 to its centremost region never probed before. In the innermost arcsecond of the cluster, we measure a velocity dispersion of (19.1 ± 2.0) km s−1 for evolved stars. Because of its high mass, NGC 6441 is a promising candidate for harbouring an intermediate-mass black hole (IMBH). We combine our measurements with additional data from the literature and compute dynamical models of the cluster. We find an upper limit of $M_{\rm IMBH} \lt 1.32 \times 10^4\, \textrm{M}_\odot$ but we can neither confirm nor rule out its presence. We also refine the dynamical distance of the cluster to $12.74^{+0.16}_{-0.15}$ kpc. Although the hunt for an IMBH in NGC 6441 is not yet concluded, our results show how future observations with extremely large telescopes will benefit from the long temporal baseline offered by existing high-angular-resolution data.

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