Determining the system parameters of low mass X-ray binaries

Objective

Low mass X-ray binaries are two gravitationally bound stars where the secondary is a normal solar type like star and the primary a compact object, i.e. a black hole or neutron star. Matter is transferred from the secondary, thereby forming an accretion disk around the compact object that gives rise to the X-rays. These systems are excellent laboratories to test several theories, including stellar evolution, theory of accretion and the theory of relativity. However, accurate measurements of the masses of the two components in these binaries are necessary to test these theories, and that has been complicated since the secondary is many magnitudes fainter than the accretion disk around the compact object.
We propose a new technique to measure the masses more accurately than has been possible thus far. Recent observations have shown that a signature of the secondary is present in certain fluorescence lines, in particular the Bowen fluorescence lines around 4640 Angstroms. Furthermore, the observed optical emission is mainly due to reprocessing of the X-rays, and any variability observed in the X-rays should also be present in the optical, but delayed with a few seconds depending on the reprocessing time and distance of the optical site compared to that of the X-rays. Simultaneous high temporal X-ray and optical observations, either narrow band photometry or spectroscopy, should be able to measure the delay in the fluorescence lines coming from the donor, and thereby constrain the system parameters of low mass X-ray binaries. For the optical observations however, large 10 m class telescopes with high timing capabilities will be necessary, and these will become available early 2009 in the form of GranteCan. Here we ask for the grant to have minor adjustments to the instrumentation on this telescope that will be necessary to perform the science proposed.

Fields of science (EuroSciVoc)

CORDIS classifies projects with EuroSciVoc, a multilingual taxonomy of fields of science, through a semi-automatic process based on NLP techniques. See: https://op.europa.eu/en/web/eu-vocabularies/euroscivoc.

• natural sciences physical sciences astronomy stellar astronomy neutron stars
• natural sciences physical sciences astronomy astrophysics black holes
• natural sciences physical sciences optics spectroscopy

Keywords

Project’s keywords as indicated by the project coordinator. Not to be confused with the EuroSciVoc taxonomy (Fields of science)

• Astronomy
• Astrophysics
• Physical sciences

Programme(s)

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• FP7-PEOPLE - Specific programme "People" implementing the Seventh Framework Programme of the European Community for research, technological development and demonstration activities (2007 to 2013)

Topic(s)

Calls for proposals are divided into topics. A topic defines a specific subject or area for which applicants can submit proposals. The description of a topic comprises its specific scope and the expected impact of the funded project.

• PEOPLE-2007-2-2.ERG - Marie Curie Action: "European Reintegration Grants"

Call for proposal

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FP7-PEOPLE-ERG-2008
See other projects for this call

Funding Scheme

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MC-ERG - European Re-integration Grants (ERG)

Coordinator