Deep Chandra Monitoring Observations of NGC 4278: Catalog of Source Properties

Abstract

We present the properties of the discrete X-ray sources detected in our monitoring program of the globular cluster (GC) rich elliptical galaxy, NGC 4278, observed with Chandra ACIS-S in six separate pointings, resulting in a co-added exposure of 458-ks. From this deep observation, 236 sources have been detected within the region overlapped by all observations, 180 of which lie within the D25 ellipse of the galaxy. These 236 sources range in Lx from 3.5E36 erg/s (with 3sigma upper limit <1E37 erg/s) to ~2E40 erg/s, including the central nuclear source which has been classified as a LINER. From optical data, 39 X-ray sources have been determined to be coincident with a globular cluster, these sources tend to have high X-ray luminosity, with ten of these sources exhibiting Lx>1E38 erg/s. From X-ray source photometry, it has been determined that the majority of the 236 point sources that have well constrained colors, have values that are consistent with typical LMXB spectra, with 29 of these sources expected to be background objects from the logN-logS relation. There are 103 sources in this population that exhibit long-term variability, indicating that they are accreting compact objects. 3 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.

Accepted for publication in ApJS, 143 pages, with 12 figures

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Cited by in corpus (8)

• Comparing GC and Field LMXBs in Elliptical Galaxies with deep Chandra and Hubble data
• Transient Low-Mass X-Ray Binary Populations in Elliptical Galaxies NGC 3379 and NGC 4278
• X-ray spectral variability of LINERs selected from the Palomar sample
• X-Ray Spectral Variability of Ultraluminous X-Ray Sources in Extragalactic Globular Clusters
• Chandra ACIS Survey of X-ray Point Sources in Nearby Galaxies. II. X-ray Luminosity Functions and Ultraluminous X-ray Sources
• The Hot Interstellar Medium
• Measurements of Variability of Low Mass X-ray Binary Candidates in the Early-Type Galaxy NGC 4697 from Multi-Epoch Chandra X-ray Observations
• Long term optical variability of bright X-ray point sources in elliptical galaxies