Open AccessXMM–Newton observations of the starburst merger galaxies NGC 3256 and NGC 3310
Author(s) -
Jenkins L. P.,
Roberts T. P.,
Ward M. J.,
Zezas A.
Publication year - 2004
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.08025.x
Subject(s) - physics , astrophysics , galaxy , supernova , astronomy , interstellar medium , plasma , active galactic nucleus , power law , thermal , epic , luminous infrared galaxy , statistics , mathematics , quantum mechanics , meteorology , art , literature
We present XMM–Newton EPIC observations of the two nearby starburst merger galaxies NGC 3256 and NGC 3310. The broad‐band (0.3–10 keV) integrated X‐ray emission from both galaxies shows evidence of multiphase thermal plasmas plus an underlying hard non‐thermal power‐law continuum. NGC 3256 is well fitted with a model comprising two mekal components ( kT = 0.6/0.9 keV) plus a hard power law (Γ= 2), while NGC 3310 has cooler mekal components ( kT = 0.3/0.6 keV) and a harder power‐law tail (Γ= 1.8). Chandra observations of both galaxies reveal the presence of numerous discrete sources embedded in the diffuse emission, which dominate the emission above ∼2 keV and are likely to be the source of the power‐law emission. The thermal components show a trend of increasing absorption with higher temperature, suggesting that the hottest plasmas arise from supernova‐heated gas within the discs of the galaxies, while the cooler components arise from outflowing galactic winds interacting with the ambient interstellar medium. We find no strong evidence for an active galactic nucleus in either galaxy.