Slide 1

Slide 2

X-ray Dim Isolated Neutron Star (INS)

As a class, they are interesting because:

	They imply the existence of a fair number of neutron stars different from standard radio pulsars and X-ray binaries
	Accreting from ISM? Unlikely: high proper motion
	Cooling NS or descendant from AXP, SGRs (old magnetars?)
	Standard radio pulsars beamed away from the Earth? (however: they are relatively numerous and all close-by)
	Genuinely radio-quiet?  (as Geminga, SGRs, AXPs)? Population synthesis models

The striking case of RX J1856.5-3754

	500 ks DDT Chandra exposure

The striking case of RX J1856.5-3754

Pulsating neutron stars:  4 so far!

Spectral variations with pulse phase

Thermal Spectra: blackbody fits

Absorption features: RBS 1223                       (Haberl et al., 2003)

Absorption features: RX J1605.3+3249                     (van Kerkwijk  et al., 2003)

Absorption features and magnetic fields:

An hotter isolated neutron star:

(the longest EPIC observation of a galactic source)

Slide 15

1E1207.4-5209: Lines vary in phase

Pulsed phase spectroscopy of proton cyclotron lines: theory