A Luminous X-ray Flare From The Nucleus of The Dormant Bulgeless Spiral Galaxy NGC 247
arXiv:1506.00790 · doi:10.1088/0004-637X/807/2/185
Abstract
NGC 247 is a nearby late-type bulgeless spiral galaxy that contains an inactive nucleus. We report a serendipitous discovery of an X-ray flare from the galaxy center with a luminosity up to 2*10^39 erg/s in the 0.3-10 keV band with XMM-Newton. A Chandra observation confirms that the new X-ray source is spatially coincident with the galaxy nucleus. The XMM-Newton data revealed a hard power-law spectrum with a spectral break near 3-4 keV, no pulsations on timescales longer than 150 ms, and a flat power spectrum consistent with Poisson noise from 1 mHz to nearly 10 Hz. Follow-up observations with Swift detected a second flux peak followed by a luminosity drop by factor of almost 20. The spectral and temporal behaviors of the nuclear source are well consistent with the scenario that the flare was due to an outburst of a low-mass X-ray binary that contains a stellar-mass black hole emitting near its Eddington limit at the peak. However, it cannot be ruled out that the sudden brightening in the nucleus was due to accretion onto a possible low-mass nuclear black hole, fed by a tidally disrupted star or a gas cloud; the MAXI observations limit the peak luminosity of the flare to less than ~10^43 erg/s, suggesting that it is either a low mass black hole or an inefficient tidal disruption event (TDE).
accepted for publication in ApJ
References in corpus (17)
- X-ray Properties of Black-Hole Binaries
- An Ultraluminous X-ray Source Powered by An Accreting Neutron Star
- A New Sample of Low-mass Black Holes in Active Galaxies
- XMM-Newton observations of the brightest Ultraluminous X-ray sources
- An actively accreting massive black hole in the dwarf starburst galaxy Henize 2-10
- A mass of less than 15 solar masses for the black hole in an ultraluminous X-ray source
- Evolution of tidal disruption candidates discovered by XMM-Newton
- Candidate tidal disruption events from the XMM-Newton Slew Survey
- The Galactic Center cloud G2 and its gas streamer
- An X-ray Selected Sample of Candidate Black Holes in Dwarf Galaxies
- Low-Mass Seyfert 2 Galaxies in the Sloan Digital Sky Survey
- Tidal disruption of a super-Jupiter by a massive black hole
- RBS 1032: A Tidal Disruption Event in Another Dwarf Galaxy?
- The Araucaria Project. The Distance to the Sculptor Galaxy NGC 247 from Near-Infrared Photometry of Cepheid Variables
- Evidence of a pure starburst nature of the nuclear region of NGC 253
- Deep Spectroscopy of the Host Galaxy of a Tidal Disruption Flare in A1795
- Deep-Survey Constraints on X-ray Outbursts from Galactic Nuclei