COMMISSION 28: GALAXIES
Proceedings of the International Astronomical Union Cambridge University Press (CUP) 4:T27A (2008) 286-294
DIVISION VIII: GALAXIES AND THE UNIVERSE
Proceedings of the International Astronomical Union Cambridge University Press (CUP) 4:T27A (2008) 283-285
Deep chandra monitoring observations of NGC 3379: Catalog of source properties
Astrophysical Journal, Supplement Series 179:1 (2008) 142-165
Abstract:
We present the properties of the discrete X-ray sources detected in our monitoring program of the 'typical' elliptical galaxy, NGC 3379, observed with Chandra ACIS-S in five separate pointings, resulting in a co-added exposure of 324 ks. From this deep observation, 132 sources have been detected within the region overlapped by all observations, 98 of which lie within the D25 ellipse of the galaxy. These 132 sources range in LX from 6 × 1035 erg s-1 (with 3 σ upper limit ≤4 × 1036 erg s-1) to ∼2 × 1039 erg s -1, including one source with LX > 1 × 10 39 erg s-1, which has been classified as a ULX. From optical data, 10 X-ray sources have been determined to be coincident with a globular cluster, these sources tend to have high X-ray luminosity, with three of these sources exhibiting LX > 1 × 1038 erg s-1. From X-ray source photometry, it has been determined that the majority of the 132 sources that have well constrained colors, have values that are consistent with typical LMXB spectra. In addition to this, a subpopulation of 10 sources has been found to exhibit very hard spectra and it is expected that most of these sources are absorbed background AGN. There are 64 sources in this population that exhibit long-term variability, indicating that they are accreting compact objects. Five of these sources have been identified as transient candidates, with a further 3 possible transients. Spectral variations have also been identified in the majority of the source population, where a diverse range of variability has been identified, indicating that there are many different source classes located within this galaxy. © 2008. The American Astronomical Society. All rights reserved.Models for low-mass X-ray binaries in the elliptical galaxies NGC 3379 and NGC 4278: Comparison with observations
Astrophysical Journal 683:1 (2008) 346-356
Abstract:
We present theoretical models for the formation and evolution of populations of low-mass X-ray binaries (LMXBs) in the two elliptical galaxies NGC 3379 and NGC 4278. The models are calculated with the recently updated StarTrack code, assuming only a primordial galactic field LMXB population. StarTrack is an advanced population synthesis code that has been tested and calibrated using detailed binary star calculations and incorporates all the important physical processes of binary evolution. The simulations are targeted to modeling and understanding the origin of the X-ray luminosity functions (XLFs) of point sources in these galaxies. For the first time we explore the population XLF in luminosities below 1037 ergs s-1, as probed by the most recent observational results. We consider models for the formation and evolution of LMXBs in galactic fields with different CE efficiencies, stellar wind prescriptions, magnetic braking laws, and IMFs. We identify models that produce XLFs consistent with the observations both in shape and absolute normalization, suggesting that a primordial galactic field LMXB population can make a significant contribution to the total population of an elliptical galaxy. We also find that the treatment of the outburst luminosity of transient systems remains a crucial factor for the determination of the XLF, since the modeled populations are dominated by transient X-ray systems. © 2008. The American Astronomical Society. All rights reserved.The SAURON project - XII. Kinematic substructures in early-type galaxies: Evidence for discs in fast rotators
Monthly Notices of the Royal Astronomical Society 390:1 (2008) 93-117