The Long-term Variability of the X-ray Sources in M82

Abstract

We investigate the long-term variability exhibited by the X-ray point sources in the starburst galaxy M82. By combining 9 Chandra observations taken between 1999 and 2007, we detect 58 X-ray point sources within the D25 isophote of M82 down to a luminosity of ~ 10^37 ergs/s. Of these 58 sources, we identify 3 supernova remnant candidates and one supersoft source. Twenty-six sources in M82 exhibit long-term (i.e., days to years) flux variability and 3 show long-term spectral variability. Furthermore, we classify 26 sources as variables and 10 as persistent sources. Among the total 26 variables, 17 varied by a flux ratio of > 3 and 6 are transient candidates. By comparing with other nearby galaxies, M82 shows extremely strong long-term X-ray variability that 47% of the X-ray sources are variables with a flux ratio of > 3. The strong X-ray variability of M82 suggests that the population is dominated by X-ray binaries.

Accepted for publication in MNRAS

References in corpus (7)

• Deep MERLIN 5GHz Radio Imaging of Supernova Remnants in the M82 Starburst
• The Long-Term Variability of the X-Ray Sources in NGC 6946 and NGC 4485/4490
• CO(1-0), CO(2-1) and Neutral Gas in NGC 6946: Molecular Gas in a Late-Type, Gas Rich, Spiral Galaxy
• The Ultraluminous X-ray Sources near the Center of M82
• A Comparison of Ultraluminous X-ray Sources in NGC 1399 and the Antennae Galaxies (NGC 4038/4039)
• The Remarkable Stability of Probable Black Hole Low-Mass X-ray Binaries in Nearby Galaxies
• Measurements of Variability of Low Mass X-ray Binary Candidates in the Early-Type Galaxy NGC 4697 from Multi-Epoch Chandra X-ray Observations

Cited by in corpus (14)

• A 400 solar mass black hole in the Ultraluminous X-ray source M82 X-1 accreting close to its Eddington limit
• Lambda = 3 mm line survey of nearby active galaxies
• The accretion regimes of a highly magnetised NS: the unique case of NuSTAR J095551+6940.8
• The hyperluminous X-ray source candidate in IC 4320: another HLX bites the dust
• Ultraluminous X-ray sources with flat-topped noise and QPO
• Diffraction-limited Subaru imaging of M82: sharp mid-infrared view of the starburst core
• Black Holes and Neutron Stars in Nearby Galaxies: Insights from NuSTAR
• A Possible 55-day X-ray Period of the Ultraluminous Accreting Pulsar M82 X-2
• On the Nature of the mHz X-Ray Quasi-periodic Oscillations from Ultraluminous X-Ray Source M82 X-1: Search for Timing-Spectral Correlations
• Resolving the Ultra-Luminous X-ray Sources in the Ly$\alpha$ Emitting Galaxy Haro 11
• Does the 62-day X-ray periodicity come from ULX M82 X-1?
• X-ray supernova remnants in the starburst region of M82
• Monitoring Variable X-ray Sources in Nearby Galaxies
• The kilo-second variability of X-ray sources in nearby galaxies