THE CONNECTION BETWEEN X-RAY BINARIES AND STAR CLUSTERS IN NGC 4449

Journal Article · Thu Nov 10 04:00:00 EST 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/741/2/86; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21612693

Rangelov, Blagoy; Chandar, Rupali ^[1]

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1. Department of Physics and Astronomy, University of Toledo, 2801 West Bancroft Street, Toledo, OH 43606 (United States)

We present 23 candidate X-ray binaries with luminosities down to 1.8 Multiplication-Sign 10{sup 36} erg s{sup -1}, in the nearby starburst galaxy NGC 4449, from observations totaling 105 ks taken with the ACIS-S instrument on the Chandra Space Telescope. We determine count rates, luminosities, and colors for each source, and perform spectral fits for sources with sufficient counts. We also compile a new catalog of 129 compact star clusters in NGC 4449 from high-resolution, multi-band optical images taken with the Hubble Space Telescope, doubling the number of clusters known in this galaxy. The UBVI, H{alpha} luminosities of each cluster are compared with predictions from stellar evolution models to estimate their ages and masses. We find strong evidence for a population of very young massive, black hole binaries, which comprise nearly 50% of the detected X-ray binaries in NGC 4449. Approximately a third of these remain within their parent star clusters, which formed {tau} {approx}< 6-8 Myr ago, while others have likely been ejected from their parent clusters. We also find evidence for a population of somewhat older X-ray binaries, including both supergiant and Be-binaries, which appear to be associated with somewhat older {tau} Almost-Equal-To 100-400 Myr star clusters, and one X-ray binary in an ancient ({tau} Almost-Equal-To 10 Gyr) globular cluster. Our results suggest that detailed information on star clusters can significantly improve constraints on X-ray binary populations in star-forming galaxies.

• OSTI ID: 21612693
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 741; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BLACK HOLES
CATALOGS
DOCUMENT TYPES
EVOLUTION
GALAXIES
LUMINOSITY
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
STAR CLUSTERS
STAR EVOLUTION
STARS
TELESCOPES