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

Abstract

We present results from a 30 ksec Chandra observation of the important starburst galaxy NGC 2782, covering the 0.3-10keV energy band. We find evidence of a superwind of small extent, that is likely in an early stage of development. We find a total of 27 X-ray point sources within a region of radius 2$D_{25}$ of the galaxy centre and which are likely associated with the galaxy. Of these, 13 are ULXs ($L_{X}\geq 10^{39}~ erg s ^{-1}$) and a number have likely counterparts. The X-ray luminosities of the ULX candidates are $1.2-3.9\times10^{39}~ erg s ^{-1}$. NGC2782 seems to have an unusually large number of ULXs. Central diffuse X-ray emission extending to ~ 3kpc from the nuclear region has been detected. We also find an X-ray structure to the south of the nucleus, coincident with H{\alpha} 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 $5\times10^{39}erg s ^{-1}$ (around $15\%$ of the total luminosity of the extended emission), and an inferred wind mass of $1.5\times10^{6}$ M$_\odot$. We also discuss the nature of the central X-ray source in NGC2782, and conclude that it is likely a low-luminosity AGN (LLAGN), with a total X-ray luminosity of $L_{X}=6\times10^{40}~erg s ^{-1}$ with strong Fe line emission at 6.4 keV.