Here is a quick summary of this morning's session.
Peter Jonker presented how to observationally constrain the EoS of neutron stars and also talked about the cooling of neutron stars. He briefly mentioned the upcoming Galactic Belt Survey, a series of observation with Chandra covering a total of 6x1 arcmin in order to find more X-ray transient near the galactic plane. Overall, I found that it was an excellent presentation outlining the crucial points of LMXBs observations and quoting several well-known objects like 4U 1608-52, Cen X-4, the long duration transient KS 1731-260, or the very faint transient SAX J1808.4-3657.
This was then followed by a talk by Pawel Haensel presenting the theory behind all this. As accreting matter compresses the inner crust, material gets out of equilibrium and electron capture/neutron emission occur, releasing 1.5-2 MeV per accreted nucleon. He also talked about the timescales involved.
Finally, Nathalie Degenaar gave a very interesting talk about very faint X-ray transients with outburst luminosities as low as 10^34 erg/s. In two case, a faint burst was happening followed by a Type 1 X-ray burst suggesting right away that this small burst could be a precursor to the Type 1 burst.
Tomorrow's half day session will be fully dedicated to the methods of constraining the EoS using accreting neutron stars. I am looking forward to the presentation by R. Wijnands, N. Webb, and P. Ray.
Subscribe to:
Post Comments (Atom)
Posts
2 comments:
Hi all!
I think you meant the "Galactic Bulge Survey", although I have to admit that I am rather tempted to ask Peter whether we can change its name in "Galactic Belt Survey"!
It sounds like one of these Amsterdam theaters in the red-light district. It's way funnier! :-)
cheers,
Nanda Rea (from the cold and empty UvA)
A small remark about the comments about Nathalie Degenaar's presentation. There seems to be confusion in jargon between outbursts , bursts and type-I bursts. Outbursts should be used for huge increases in luminosity due to similar huge increases in the accretion rate onto the neutron star (or black hole), burst and type-I bursts are thermonuclear explosions on the surface of the neutrons tars.
Nathalie was talking about outbursts and she reported in one source that we saw a small, very faint outburst which lasted only less than a week and then several months later there was a much brighter outburst from the sources. Could this very weak outburst be a precursor for the stronger one? But why does the disk not go in full outburst immediately when the accretion onto the neutron star occurs?
Finally note, similar behavior has also been seen in other sources, so it is not a freak event.
Post a Comment