In recent work done with XMM-Newton, we have discovered that ultraluminous X-raysources have strong relativistic winds in agreement with theoretical predictionsof super-Eddington accretion. Such winds vary on timescales of days and canbecome optically thick enough to block and reprocess the disc X-ray photons,thus changing the spectral shape of the source into an ultraluminous supersoftX-ray source. We propose to test this hypothesis, by studying a transitionalobject where the wind is so strong that it is already causing significantabsorption of the harder X-ray continuum: NGC 55 ULX. A 130ks XMM observationtriggered during a high X-ray flux state will enable to performtime-/flux-resolved X-ray spectroscopy of the wind and probe the transition from supersoft to soft ULX.
Instrument
EMOS1, EMOS2, EPN, OM, RGS1, RGS2
Temporal Coverage
2020-05-24T21:26:17Z/2020-05-26T10:19:37Z
Version
18.02_20200221_1200
Mission Description
The European Space Agencys (ESA) X-ray Multi-Mirror Mission (XMM-Newton) was launched by an Ariane 504 on December 10th 1999. XMM-Newton is ESAs second cornerstone of the Horizon 2000 Science Programme. It carries 3 high throughput X-ray telescopes with an unprecedented effective area, and an optical monitor, the first flown on a X-ray observatory. The large collecting area and ability to make long uninterrupted exposures provide highly sensitive observations. Since Earths atmosphere blocks out all X-rays, only a telescope in space can detect and study celestial X-ray sources. The XMM-Newton mission is helping scientists to solve a number of cosmic mysteries, ranging from the enigmatic black holes to the origins of the Universe itself. Observing time on XMM-Newton is being made available to the scientific community, applying for observational periods on a competitive basis.
European Space Agency, Dr Ciro Pinto, 2021, 'Understanding state transitions in ULXs: diagnostics through wind spectroscopy', 18.02_20200221_1200, European Space Agency, https://doi.org/10.57780/esa-idtrrv0
