TY - JOUR
T1 - The Spectral and Temporal Properties of Transient Sources in Early-type Galaxies
AU - Brassington, Nicola
AU - Fabbiano, G.
AU - Zezas, A.
AU - Kim, D.-W.
AU - Fragos, T.
AU - Kundu, A.
AU - King, A.R.
AU - Pellegrini, S.
AU - Trinchieri, G.
AU - Zepf, S.
AU - Wright, N.J.
N1 - Copyright 2012 Elsevier B.V., All rights reserved.
PY - 2012/8/20
Y1 - 2012/8/20
N2 - We report the spectral and temporal variability properties of 18 candidate transient (TC) and potential transient (PTC) sources detected in deep multi-epoch Chandra observation of the nearby elliptical galaxies, NGC3379, NGC4278, and NGC4697. Only one source can be identified with a background counterpart, leaving 17 TCs + PTCs in the galaxies. Of these, 14 are in the galaxy field, supporting the theoretical picture that the majority of field X-ray binaries (XRBs) will exhibit transient accretion for >75% of their lifetime. Three sources are coincident with globular clusters, including two high-luminosity candidate black hole (BH) XRBs, with Lx= 5.4 × 10 erg/s and Lx= 2.8 × 10 erg/s, respectively. The spectra, luminosities, and temporal behavior of these 17 sources suggest that the transient population is heterogeneous, including neutron star (NS) and BH XRBs in both normal and high-rate accretion modes, and super soft sources containing white dwarf binaries. Our TC and PTC detections are noticeably fewer than the number expected from the population synthesis (PS) models of Fragos et al., tailored to our new Chandra pointings of NGC4278. We attribute this discrepancy to the PS assumption that the transient population is composed of NS XRBs, as well as differences between the statistical analysis and error estimates used in the model and our observations
AB - We report the spectral and temporal variability properties of 18 candidate transient (TC) and potential transient (PTC) sources detected in deep multi-epoch Chandra observation of the nearby elliptical galaxies, NGC3379, NGC4278, and NGC4697. Only one source can be identified with a background counterpart, leaving 17 TCs + PTCs in the galaxies. Of these, 14 are in the galaxy field, supporting the theoretical picture that the majority of field X-ray binaries (XRBs) will exhibit transient accretion for >75% of their lifetime. Three sources are coincident with globular clusters, including two high-luminosity candidate black hole (BH) XRBs, with Lx= 5.4 × 10 erg/s and Lx= 2.8 × 10 erg/s, respectively. The spectra, luminosities, and temporal behavior of these 17 sources suggest that the transient population is heterogeneous, including neutron star (NS) and BH XRBs in both normal and high-rate accretion modes, and super soft sources containing white dwarf binaries. Our TC and PTC detections are noticeably fewer than the number expected from the population synthesis (PS) models of Fragos et al., tailored to our new Chandra pointings of NGC4278. We attribute this discrepancy to the PS assumption that the transient population is composed of NS XRBs, as well as differences between the statistical analysis and error estimates used in the model and our observations
U2 - 10.1088/0004-637X/755/2/162
DO - 10.1088/0004-637X/755/2/162
M3 - Article
AN - SCOPUS:84864694972
SN - 0004-637X
VL - 755
JO - The Astrophysical Journal
JF - The Astrophysical Journal
IS - 2
M1 - 162
ER -