A Deep Chandra Catalog of X-Ray Point Sources toward the Galactic Center

By M. Muno, F. Baganoff, M. Bautz, W. N. Brandt, Patrick S. Broos, Eric D. Feigelson, G. Garmire, Mark R. Morris, G. Ricker, L. Townsley. 2003

183 citations recorded by the source corpus.

We present a catalog of 2357 point sources detected during 590 ks of Chandra observations of the 17′ × 17′ field around Sgr A*. This field encompasses a physical area of 40 × 40 pc at a distance of 8 kpc. The completeness limit of the sample at the Galactic center is 1031 ergs s-1 (2.0-8.0 keV), while the detection limit is an order of magnitude lower. The 281 sources detected below 1.5 keV are mainly in the foreground of the Galactic center, while comparisons to the Chandra deep fields at high Galactic latitudes suggest that only about 100 of the observed sources are background AGNs. The surface density of absorbed sources (not detected below 1.5 keV) falls off as 1/θ away from Sgr A*, in agreement with the distribution of stars in infrared surveys. This demonstrates the X-ray sources trace the general stellar population at the Galactic center. Point sources brighter than our completeness limit produce 10% of the flux previously attributed to diffuse emission. The log N- log S distribution of the Galactic center sources is extremely steep (power-law slope α = 1.7). If this distribution extends down to a flux of 10-17 ergs cm-2 s-1 (1029 ergs s-1 at 8 kpc, 2.0-8.0 keV) with the same slope, then point sources would account for all of the previously reported diffuse emission. However, there are numerous diffuse, filamentary structures in the field that also contribute to the total flux, so the 2.0-8.0 keV luminosity distribution must flatten between 1029 and 1031 ergs s-1. Many types of stellar systems should be present in the field at the luminosities to which we are sensitive. However, the spectra of more than half of the Galactic center sources are very hard and can be described by a power law (E-Γ) with photon index Γ < 1. Such hard spectra have been seen previously only from magnetically accreting white dwarfs (polars and intermediate polars) and wind-accreting neutron stars (pulsars), suggesting that there are large numbers of these systems in our field.

Subfields: Astronomy and Astrophysics, Instrumentation, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/e26ddd6e54dbae9b08f665aa160f073b22805ae7

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Citations in the corpus

The UKIDSS galactic plane survey (2007, methodology): “Of the 4256 X-ray sources in the Muno et al.(2003; 2006) catalogues, 3963 X-ray sources have positional errors of less than 3′′.”
X-ray flares reveal mass and angular momentum of the Galactic Center black hole (2004, background): “The region towards the Galactic Center (GC) has been recently resolved in X-rays by Chandra measurements (Muno et al. 2003; Baganoff et al. 2003).”
An Overabundance of Transient X-Ray Binaries within 1 Parsec of the Galactic Center (2004, methodology): “We searched for periodic variability as described in Muno et al. (2003c).”
INNOVATIONS IN THE ANALYSIS OF CHANDRA-ACIS OBSERVATIONS (2010, unknown): “Point sources (Muno et al. 2003, 2006, 2009).”
10 MK Gas in M17 and the Rosette Nebula: X-Ray Flows in Galactic H II Regions (2003, background): “…in starburst superbubbles such as 30 Doradus (Chu & Mac Low 1990; Dennerl et al. 2001), the mild starburst nucleus in our Galactic Center region (Wang, Gotthelf, & Lang 2002; Muno et al. 2003), and in true nuclear starbursts such as NGC 253 (Strickland et al. 2002) and M 82 (Griffiths et al. 2000).”
GIANT GAMMA-RAY BUBBLES FROM FERMI-LAT: ACTIVE GALACTIC NUCLEUS ACTIVITY OR BIPOLAR GALACTIC WIND? (2010, background): “It has been argued that one such event happens approximately every 107 years in order to create a core of old stars in the GC, of radius 0.1 pc. Chandra has detected more than 2000 hard X-ray (2 − 10 keV) point sources within 23 pc of the GC (Muno et al. 2003).”
A Deep Chandra Survey of the Globular Cluster 47 Tucanae: Catalog of Point Sources (2005, unknown): “Our source extraction procedure generally follows the methods of Feigelson et al. (2002) and Muno et al. (2003).”
Short-period AM CVn systems as optical, X-ray and gravitational-wave sources (2003, background): “For instance the Muno et al. (2003) Chandra observations of the Galactic centre have a completeness limit of 3 × 10−15 erg cm−2 s−1, almost two orders of magnitude deeper than our assumed ROSAT limit.”
The Chandra Deep Field North Survey. XIII. 2 Ms Point-Source Catalogs (2003, unknown): “Under the simplifying assumption of ffiffiffiffi N p uncertainties, we can determine the sensitivity across the field following Muno et al. (2003) as S ¼ n 2 2 1þ 1þ 8b n2 1=2" # ; ð3Þ where S is the number of source counts for a given signalto-noise ratio (n ) and the number of background counts…”
The Consistency of Fermi-LAT Observations of the Galactic Center with a Millisecond Pulsar Population in the Central Stellar Cluster (2010, background): “The Central stellar cluster of the Milky Way has a stellar mass of approximately 4×109M [7] and harbors 2357 X-ray point sources within the central 17′ × 17′ alone [8].”
A CATALOG OF X-RAY POINT SOURCES FROM TWO MEGASECONDS OF CHANDRA OBSERVATIONS OF THE GALACTIC CENTER (2008, methodology): “Nonetheless, a comparison of the offsets between 500 foreground X-ray sources and the blue 2MASS sources that are their counterparts (as described in detail in J. Mauerhan et al., in preparation) reveals that the positions in the new catalog are ≈ 60% better than in Muno et al. (2003a, 2006a).”
HCN and HCO+ Observations of the Galactic Circumnuclear Disk (2005, background): “…a few Myr) emission-line stars (Morris & Serabyn 1996; Krabbe et al. 1995); X-ray emission, both in hundreds of point sources and in diffuse emission (Muno et al. 2003); streamers of ionized gas and dust, dubbed the “minispiral” (Ekers et al. 1983; Lo & Claussen 1983; Lacy et al. 1991; Scoville…”
Diffuse X-Ray Emission in a Deep Chandra Image of the Galactic Center (2004, methodology): “Second, we have converted the photon fluxes in Muno et al. (2003a) to energy fluxes by assuming 1 photons cm−2 s−1 = 8 × 10−9 erg cm−2 s−1 (2.0–8 keV), which is appropriate for a Γ = 0.5 powerlaw spectrum absorbed by a 6 × 1022 cm−2 column of gas and dust.”
Compact Object Modeling with the StarTrack Population Synthesis Code (2005, background): “Although, for some deep Galactic exposures Chandra has reached levels of 1030 ergs s 1 (e.g., the Galactic center image of Muno et al. 2003), and a contribution from cataclysmic variables may also become important.”
X-Ray Emissions from Accreting White Dwarfs: A Review (2017, background): “For example, Muno et al. (2003) detected 2357 sources in the 17′×17′ field around Sgr A*, and found more than half of the sources brighter than 4× 10−15 ergs cm−2s−1 (2–8 keV; 3 ∼ 1031 ergs s−1 at 8 kpc) to be hard, perhaps indicating them to be magnetic CVs. Yuasa et al. (2012) studied the…”