Superwind evolution: The young starburst-driven wind galaxy NGC 2782

Abstract

We present results from a 30-ks Chandra observation of the important starburst galaxy NGC 2782, covering the 0.3–10 keV energy band. We find evidence of a superwind of small extent, which is likely in an early stage of development. We find a total of 27 X-ray point sources within a region of radius 2D25 of the galaxy centre and that are likely associated with the galaxy. Of these, 13 are ultraluminous X-ray point sources (ULXs; LX ≥ 1039 erg s−1) and a number have likely counterparts. The X-ray luminosities of the ULX candidates are 1.2–3.9 × 1039 erg s−1. NGC 2782 seems to have an unusually large number of ULXs. Central diffuse X-ray emission extending to ∼3 kpc from the nuclear region has been detected. We also find an X-ray structure to the south of the nucleus, coincident with Hα filaments and with a 5-GHz radio source. We interpret this as a blow-out region of a forming superwind. This X-ray bubble has a total luminosity (0.3–10 keV) of 5 × 1039 erg s−1 (around 15 per cent of the total luminosity of the extended emission), and an inferred wind mass of 1.5 × 106 M . We also discuss the nature of the central X-ray source in NGC 2782, and conclude that it is likely a low-luminosity active galactic nucleus, with a total X-ray luminosity of LX = 6 × 1040 erg s−1, with strong Fe line emission at 6.4 keV.