Although they have large mass-to-light ratios, galaxy halos host many stars. Thestars, which are typically old and optically dim, encode information about thehalos and the process of galaxy assembly. Some stars, however, are in brightX-ray binaries (XRBs). Those XRBs in M31.s halo can be detected over vastvolumes with XMM-Newton. By using data from previous successful XMM-Newtonprograms, we need only six 20-ksec exposures to measure the gradient of XRBsbeyond the D25 isophote along both the major and minor galaxy axis. By makingcomplementary optical observations to identify counterparts, we will trace howthe stellar population diminishes across the transition region connectingrelatively bright areas to the outer halo, with its high ratio of mass to light.
Instrument
EMOS1, EMOS2, EPN, OM, RGS1, RGS2
Temporal Coverage
2011-02-01T13:03:31Z/2011-02-03T22:55:57Z
Version
17.56_20190403_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 R. Di Stefano, 2012, 'Beyond the Disk and Bulge of M31: Tracing the Transition to the Dark Halo', 17.56_20190403_1200, European Space Agency, https://doi.org/10.5270/esa-sdelvgc
