We propose a broadband observation of the transient ULX, NGC 925 ULX-3, for 40kswith XMM-Newton quasi-simultaneous with a 100ks observation with NuSTAR. Thissource exhibits extreme levels of long-term variability of over a factor of 36,a feature also seen in several ULXs identified as neutron stars to date andlinked to different possible mechanisms that are not well understood. We plan totrigger this observation when the source exceeds a flux of 6x10^\−13ergs/s/cm2, determined from an existing Swift monitoring campaign, allowing usto constrain its high-flux broadband spectrum. Coupled with this monitoring anda complementary proposal at a low flux, we will be able to build anunderstanding of the geometry and physical processes in play in this extreme accreting system.
Instrument
EMOS1, EMOS2, EPN, OM, RGS1, RGS2
Temporal Coverage
2020-08-17T16:52:16Z/2020-08-18T04:32:16Z
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 Hannah Earnshaw, 2021, 'NGC 925 ULX-3\: a key to understanding extreme ULX variability', 18.02_20200221_1200, European Space Agency, https://doi.org/10.57780/esa-q12wxh8
