Abstract
Unstable thermonuclear burning on the surface of accreting neutron stars is commonly observed as type I X-ray bursts. The flux released during some strong bursts can temporarily exceed the
Eddington limit, driving the neutron star photosphere to such large radii that heavy-element ashes of nuclear burning are ejected in the burst expansion wind. We have investigated the possibility of observing with NuSTAR some X-ray bursters selected for their high burst rate and trend to exhibit so-called superexpansion bursts. Our main ambition is to detect the photoionization edges associated with the ejected nuclear ashes, and identify the corresponding heavy elements. A positive identification of such edges would probe the nuclear burning processes, and provide a measure of the expans ion wind velocity as well as the gravitational redshift from the neutron star. Moreover, we exp ect that the high sensitivity of NuSTAR in hard X-rays will make it possible to study the behavi our of the accretion emission during the bursts, which is an important parameter to constrain the properties of the X-ray burst emission and thermonuclear burning.
Eddington limit, driving the neutron star photosphere to such large radii that heavy-element ashes of nuclear burning are ejected in the burst expansion wind. We have investigated the possibility of observing with NuSTAR some X-ray bursters selected for their high burst rate and trend to exhibit so-called superexpansion bursts. Our main ambition is to detect the photoionization edges associated with the ejected nuclear ashes, and identify the corresponding heavy elements. A positive identification of such edges would probe the nuclear burning processes, and provide a measure of the expans ion wind velocity as well as the gravitational redshift from the neutron star. Moreover, we exp ect that the high sensitivity of NuSTAR in hard X-rays will make it possible to study the behavi our of the accretion emission during the bursts, which is an important parameter to constrain the properties of the X-ray burst emission and thermonuclear burning.
| Original language | English |
|---|---|
| Journal | P o S - Proceedings of Science |
| Number of pages | 6 |
| ISSN | 1824-8039 |
| Publication status | Published - 2012 |
| Event | 9th INTEGRAL Workshop: An INTEGRAL view of the high-energy sky (the first 10 years) - Paris, France Duration: 15 Oct 2012 → 19 Oct 2012 Conference number: 9 |
Conference
| Conference | 9th INTEGRAL Workshop |
|---|---|
| Number | 9 |
| Country/Territory | France |
| City | Paris |
| Period | 15/10/2012 → 19/10/2012 |