ROSAT X-ray observations of the interacting pair of galaxies NGC 4410: evidence for a central starburst
Abstract
We present X-ray observations of the interacting pair of galaxies NGC 4410a/b with the ROSAT HRI and PSPC. The ROSAT HRI images reveal a point-like source corresponding to NGC 4410a and an X-ray halo, extending 10'' from the nucleus toward the southeast. The halo emission accounts for ~ 1/3 (LX = 1.3\tento{41} erg s(-1) in the 0.1-2.4 keV ROSAT band) of the total X-ray emission detected from NGC 4410a. The spectrum of the total X-ray emission from NGC 4410a can be fitted at best with a two-component emission model, combining a Raymond-Smith spectrum with T = 10(7) K and a power-law spectrum (Gamma = 2.2). The fraction of the thermal component to the total flux within this model is 35%, supporting the results of the HRI observation. The total unresolved X-ray luminosity detected with the PSPC amounts to 4\tento{41} erg s(-1) in the ROSAT PSPC band (for D = 97 Mpc). A preferable explanation might be the interaction between the two galaxies causing a circumnuclear starburst around the active nucleus in the peculiar late type Sab galaxy NGC 4410a. As a cumulative effect of exploding stars a superbubble forms a bipolar outflow from the galactic disk with an expansion time of ~ 8 Myr. The central source injects mechanical energy at a constant rate of a few times 10(42) erg s(-1) into the superbubble. A HST WFPC2 image decovers that NGC 4410a is seen almost face-on so that only the approaching outflow is visible. The HRI contours reveal an elongation of this outflow indicative for a faint X-ray ridge below the detection limit (LX <= 1.4\tento{39} erg s(-1) ) toward the neighbouring galaxy NGC 4410b caused by its tidal interaction. NGC 4410b houses only a faint X-ray source (LX <= 3.8\tento{39} erg s(-1) ).
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- March 1999
- DOI:
- 10.48550/arXiv.astro-ph/9812245
- arXiv:
- arXiv:astro-ph/9812245
- Bibcode:
- 1999A&A...343..373T
- Keywords:
-
- X-RAYS: GALAXIES;
- GALAXIES: STARBUST;
- GALAXIES: INTERACTIONS;
- GALAXIES: INDIVIDUAL: NGC 4410;
- GALAXIES: ACTIVE;
- Astrophysics
- E-Print:
- 13 pages, 12 ps-figures, LATEX-file