A deep X-ray observation of the persistent, yet dipping ULX NGC 5408 X-1
Abstract
NGC 5408 X-1 is a well-studied ultraluminous X-ray source (ULX) that has been seen to emit in X-rays persistently above the Eddington limit of a stellar-mass black hole for years. Based on the most extensive Swift/XRT monitoring of a ULX ever, we discovered that this source experiences phases of intense dips where its X-ray count rate drops by almost two orders of magnitude compared to its long term average. The dips apparently form during certain time windows that seem to repeat in a semi-periodic manner. We propose to continue the monitoring of the source with Swift/XRT that will allow us to trigger a deep XMM-Newton observation in a period of dips. Observing NGC 5408 X-1 with XMM-Newton while in this phase will allow us to better constrain the parameters and geometry of this poorly known system.
- Publication:
-
XMM-Newton Proposal
- Pub Date:
- October 2012
- Bibcode:
- 2012xmm..prop..156G
- Keywords:
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- White Dwarf Binaries;
- Neutron Star Binaries;
- Cataclysmic Variables;
- ULXs;
- Black Holes;
- NGC 5408 X-1