scholarly journals Gamma-rays from millisecond pulsar population within the central stellar cluster in the Galactic Centre

2013 ◽  
Vol 435 (1) ◽  
pp. L14-L18 ◽  
Author(s):  
W. Bednarek ◽  
T. Sobczak
Keyword(s):  
Gamma Rays ◽  
Galactic Centre ◽  
Millisecond Pulsar ◽  
Stellar Cluster

scholarly journals The ecology of the galactic centre: Nuclear stellar clusters and supermassive black holes

2019 ◽  
Vol 14 (S351) ◽  
pp. 80-83 ◽  
Author(s):  
Melvyn B. Davies ◽  
Abbas Askar ◽  
Ross P. Church
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Large Fraction ◽  
Galactic Nuclei ◽  
Supermassive Black Holes ◽  
Galactic Centre ◽  
Stellar Clusters ◽  
Stellar Cluster ◽  
Supermassive Black Hole ◽  
Multiple Clusters

AbstractSupermassive black holes are found in most galactic nuclei. A large fraction of these nuclei also contain a nuclear stellar cluster surrounding the black hole. Here we consider the idea that the nuclear stellar cluster formed first and that the supermassive black hole grew later. In particular we consider the merger of three stellar clusters to form a nuclear stellar cluster, where some of these clusters contain a single intermediate-mass black hole (IMBH). In the cases where multiple clusters contain IMBHs, we discuss whether the black holes are likely to merge and whether such mergers are likely to result in the ejection of the merged black hole from the nuclear stellar cluster. In some cases, no supermassive black hole will form as any merger product is not retained. This is a natural pathway to explain those galactic nuclei that contain a nuclear stellar cluster but apparently lack a supermassive black hole; M33 being a nearby example. Alternatively, if an IMBH merger product is retained within the nuclear stellar cluster, it may subsequently grow, e.g. via the tidal disruption of stars, to form a supermassive black hole.

scholarly journals Cosmic ray models of the ridge-like excess of gamma rays in the Galactic Centre

2015 ◽  
Vol 451 (2) ◽  
pp. 1833-1847 ◽  
Author(s):  
Oscar Macias ◽  
Chris Gordon ◽  
Roland M. Crocker ◽  
Stefano Profumo
Keyword(s):  
Gamma Rays ◽  
Cosmic Ray ◽  
Galactic Centre

scholarly journals The transitional millisecond pulsar IGR J18245-2452 during its 2013 outburst at X-rays and soft gamma-rays

2017 ◽  
Vol 603 ◽  
pp. A16 ◽  
Author(s):  
V. De Falco ◽  
L. Kuiper ◽  
E. Bozzo ◽  
C. Ferrigno ◽  
J. Poutanen ◽  
...  
Keyword(s):  
Gamma Rays ◽  
X Rays ◽  
Millisecond Pulsar

scholarly journals Radio timing in a millisecond pulsar – extreme/intermediate mass ratio binary system

2020 ◽  
Vol 644 ◽  
pp. A167
Author(s):  
T. Kimpson ◽  
K. Wu ◽  
S. Zane
Keyword(s):  
Globular Clusters ◽  
Relativistic Effects ◽  
Propagation Delay ◽  
Higher Order ◽  
Galactic Centre ◽  
Millisecond Pulsar ◽  
Fundamental Physics ◽  
Timing Model ◽  
Pulsar Timing ◽  
Timing Models

Radio timing observations of a millisecond pulsar in orbit around the Galactic centre black hole (BH) or a BH at the centre of globular clusters could answer foundational questions in astrophysics and fundamental physics. Pulsar radio astronomy typically employs the post-Keplerian approximation to determine the system parameters. However, in the strong gravitational field around the central BH, higher order relativistic effects may become important. We compare the pulsar timing delays given by the post-Keplerian approximation with those given by a relativistic timing model. We find significant discrepancies between the solutions derived for the Einstein delay and the propagation delay (i.e. Roemer and Sharpiro delay) compared to the fully relativistic solutions. Correcting for these higher order relativistic effects is essential in order to construct accurate radio timing models for pulsar systems at the Galactic centre and the centre of globular clusters and informing issues related to their detection.

scholarly journals Gamma rays from the Galactic Centre region

2015 ◽  
Vol 16 (6-7) ◽  
pp. 686-703 ◽  
Author(s):  
Meng Su ◽  
Christopher van Eldik
Keyword(s):  
Gamma Rays ◽  
Galactic Centre ◽  
Centre Region

scholarly journals Kozai resonance model for Sagittarius A* stellar orbits

2006 ◽  
Vol 2 (S238) ◽  
pp. 201-206 ◽  
Author(s):  
Ladislav Šubr ◽  
Vladimír Karas ◽  
Jaroslav Haas
Keyword(s):  
Galactic Centre ◽  
Tidal Disruption ◽  
Resonance Mechanism ◽  
Resonance Model ◽  
Stellar Orbits ◽  
Stellar Cluster ◽  
Sagittarius A ◽  
Sgr A ◽  
Different Sources ◽  
Kozai Resonance

AbstractWe study a possibility of tidal disruptions of stars orbiting a supermassive black hole due to eccentricity oscillations driven by Kozai's mechanism. We apply the model to conditions relevant for the Galactic Centre where we consider two different sources of the perturbation to the central potential, which trigger the resonance mechanism. Firstly, it is a disc of young massive stars orbiting Sgr A* atr≳ 0.08 pc, and, secondly, a molecular circumnuclear disc. Each of the two possibilities appears to be capable of exciting eccentricities to values sufficient for the tidal disruption of ∼100 stars from the nuclear stellar cluster on a time-scale of 0.1–10 Myrs. Tidally disrupted stars may cause periods of increased accretion activity of Sgr A*.

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