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 0.3-10 keV 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 2D 25 of the galaxy centre and which are likely associated with the galaxy. Of these, 13 are ULXs (L X 10 39 erg s −1 ) and a number have likely counterparts. The X-ray luminosities of the ULX candidates are 1.2 − 3.9 × 10 39 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 × 10 39 erg s −1 (around 15% of the total luminosity of the extended emission), and an inferred wind mass of 1.5 × 10 6 M . We also discuss the nature of the central X-ray source in NGC 2782, and conclude that it is likely a low-luminosity AGN (LLAGN), with a total X-ray luminosity of L X = 6 × 10 40 erg s −1 , with strong Fe line emission at 6.4 keV.

A Review of the Theory of Galactic Winds Driven by Stellar Feedback

“…X-ray satellites including Chandra and XMM-Newton observatories have been used to observe highly ionized X-ray emitting hot phase of galactic winds, and also to constrain the hard X-ray emission directly from very hot winds driven by supernova (SN) explosions [89][90][91][92][93]. Emission lines such as Hα, N II, O II, O III, and absorptions such as Na I D, K I, Mg II have been used to trace morphologies and velocities of warm, cool and cold outflows in galactic winds, including warm ionized [94][95][96][97][98][99][100][101][102], neutral atomic [19,[103][104][105][106][107][108][109][110], molecular [111][112][113][114][115][116][117][118], and dust [119][120][121][122][123][124] outflows.…”

Near-infrared to Mid-infrared Observations of Galaxy Mergers: NGC 2782 and NGC 7727

“…As described above, however, the present IR spectra do not show clear evidence of an AGN. Only recent X-ray observations indicate the presence of a low-luminosity AGN (Tzanavaris & Georgantopoulos 2007;Bravo-Guerrero & Stevens 2017). Knierman et al (2013) detected a number of star cluster candidates (SCCs) both in the western and eastern tails.…”

“…Gas motion in the central part of the galaxy is studied in detail by interferometric CO observations (Hunt et al 2008). NGC 2782 was originally classified as a Seyfert galaxy, but no direct sign of AGN had been obtained (Boer et al 1992) until recent X-ray observations found clear evidence for the presence of a low-luminosity AGN (Tzanavaris & Georgantopoulos 2007;Bravo-Guerrero & Stevens 2017). Star-formation in the tidal tails was studied extensively based on observations of CO (J=1-0), Hα, and [C II] 158 µm (Smith et al 1999;Knierman et al 2013).…”