An Overabundance of Transient X-Ray Binaries within 1 Parsec of the Galactic Center

By M. Muno, E. Pfahl, F. Baganoff, W. N. Brandt, A. Ghez, J. Lu, M. R. M. Ucla, U. Virginia, Mit, Penn State. 2004

164 citations recorded by the source corpus.

During 5 years of Chandra observations, we have identified seven X-ray transients located within 23 pc of Sgr A*. These sources each vary in luminosity by more than a factor of 10 and have peak X-ray luminosities greater than 5 × 1033 ergs s-1, which strongly suggests that they are accreting black holes or neutron stars. The peak luminosities of the transients are intermediate between those typically considered outburst and quiescence for X-ray binaries. Remarkably, four of these transients lie within only 1 pc of Sgr A*. This implies that, compared to the numbers of similar systems located between 1 and 23 pc, transients are overabundant by a factor of ≳20 per unit stellar mass within 1 pc of Sgr A*. It is likely that the excess transient X-ray sources are low-mass X-ray binaries that were produced, as in the cores of globular clusters, by three-body interactions between binary star systems and either black holes or neutron stars that have been concentrated in the central parsec through dynamical friction. Alternatively, they could be high-mass X-ray binaries that formed among the young stars that are present in the central parsec.

Subfields: Astronomy and Astrophysics, Instrumentation

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In Astronomy and Astrophysics

1. T. Alexander
2. F. Antonini
3. R. Genzel
4. B. Kocsis
5. H. Perets
6. F. Eisenhauer
7. P. Hopkins
8. Clovis Hopman

In Instrumentation

1. T. Alexander
2. B. Kocsis
3. R. Genzel
4. F. Antonini
5. R. Schödel
6. Abraham Loeb
7. A. Eckart
8. F. Eisenhauer

Citations in the corpus

• Stellar Remnants in Galactic Nuclei: Mass Segregation (2006, methodology): “Recently, observations with the Chandra X-ray satellite have revealed seven transient sources within 23 pc of projected distance of Sgr A (Muno et al. 2005b); four of them have projected distances smaller than 1 pc, indicative of an overabundance in this central region by a factor 20 when…”
• SINFONI in the Galactic Center: Young Stars and Infrared Flares in the Central Light-Month (2005, background): “The recent indication of a high number (k 104) of neutron stars and stellar-mass black holes in the vicinity of Sgr A (Muno et al. 2005) from Chandra observations supports this scenario.”
• STRONG MASS SEGREGATION AROUND A MASSIVE BLACK HOLE (2008, background): “…in the central∼ 1 pc of the GC was interpreted as evidence of a high central concentration of neutron stars and stellar black holes (SBHs) (Muno et al. 2005); The central decrease in the surface density of the low-mass horizontal branch “red clump” giants was interpreted as evidence of…”
• SECULAR EVOLUTION OF COMPACT BINARIES NEAR MASSIVE BLACK HOLES: GRAVITATIONAL WAVE SOURCES AND OTHER EXOTICA (2012, background): “Little is known about compact binaries in the GC, though the observed overabundance of Xray sources in the central pc (Muno et al. 2005) suggests they are not rare but their properties and origin are not known.”
• Gravitational waves from scattering of stellar-mass black holes in galactic nuclei (2008, background): “In our own Galaxy, Muno et al. (2005) have found an overabundance of X-ray sources in the vicinity of Sgr A*, which seems to follow the underlying distribution of stars (Muno et al. 2006).”
• MONITORING STELLAR ORBITS AROUND THE MASSIVE BLACK HOLE IN THE GALACTIC CENTER (2008, background): “…component In addition to the population of stars not yet resolved by current instrumentation a cluster of dark objects - e.g. stellar mass black holes (SBHs) as proposed in Morris (1993); Miralda-Escudé & Gould (2000); Muno et al. (2005); Hopman & Alexander (2006) - is plausibly present in the GC.”
• The structure of the nuclear stellar cluster of the Milky Way (2006, background): “In fact, Muno et al. (2005) have found evidence that X-ray transients are overabundant by a factor of 20 per unit stellar mass in the central parsec.”
• WATCHDOG: A COMPREHENSIVE ALL-SKY DATABASE OF GALACTIC BLACK HOLE X-RAY BINARIES (2015, background): “…Altamirano et al. (2015), [493] Tachibana et al. (2014b), [494] Uemura et al. (2014), [495] Koljonen et al. (2015),[496] Yan et al. (2015), [497] Muno et al. (2005b), [498] Belanger et al. (2005),[499] Hjalmarsdotter et al. (2008), [500] Szostek & Zdziarski (2008), [501] Szostek et al. (2008),…”
• Stellar Processes Near the Massive Black Hole in the Galactic Center (2005, background): “This is interpreted asvidence for a high central concentration of NS and SBHs, of which some are accreting from a binary companion acquired in the course of a 3-body exchange encounter with a stellar binary (Muno et al2005).”
• The Two Young Star Disks in the Central Parsec of the Galaxy: Properties, Dynamics, and Formation (2006, background): “For a < 10 Myr old stellar component and a Salpeter mass function the predicted diffuse X-ray flux in the central parsec exceeds the observed value of Baganoff et al. (2003) and Muno et al. (2005) by a factor of 20 to 100.”
• BlackCAT: A catalogue of stellar-mass black holes in X-ray transients (2015, background): “However, the bulge contains ∼30% of the stellar mass of the Galaxy, which is confined in a reduced spheroid and it is expected to host a higher concentration of BHTs (Muno et al. 2005).”
• A CATALOG OF X-RAY POINT SOURCES FROM TWO MEGASECONDS OF CHANDRA OBSERVATIONS OF THE GALACTIC CENTER (2008, methodology): “Half of them have been discovered in the last nine years using Chandra, XMM-Newton, or Swift (e.g., Sakano et al. 2005; Porquet et al. 2005; Muno et al. 2005; Wijnands et al. 2006; Kennea et al. 2006).”
• The nuclear star cluster of the Milky Way: proper motions and mass (2009, background): “There are observationally supported claims for the existence of the order 104 neutron stars and stellar mass black holes in the central parsec (Muno et al. 2005).”
• Stellar Dynamics and Stellar Phenomena Near a Massive Black Hole (2017, background): “The over-abundance of transient X-ray sources in the inner 1 pc of the Galactic Center, identified as NS/BH low or high-mass X-ray binaries (Muno et al. 2005) likewise hints that binaries, or at least high-mass binaries, do exist inside rh. Long-lived low-mass binaries are gradually evaporated by…”