Average hard X-ray emission from NS LMXBs: observational evidence of different spectral states in NS LMXBs

Resolving the Mystery of X-ray–faint Elliptical Galaxies: Chandra X-ray Observations of Ngc 4697

Chandra observations of the X-ray–faint elliptical galaxy NGC 4697 resolve much of the X-ray emission (61% within one effective radius) into ∼80 point sources, of which most are low-mass X-ray binaries (LMXBs). These LMXBs provide the bulk of the hard emission and much of the soft emission as well. Of the remaining unresolved emission, it is likely that about half is from fainter LMXBs, while t...

The broad band X-ray/hard X-ray spectra of accreting neutron stars

I review the energy spectra of low mass X-ray binaries (LMXBs) containing weakly magnetized accreting neutron stars (NS), emphasizing the most recent broad band (0.1-200 keV) spectral and timing observations performed by Beppo-SAX and RXTE. Drawing on the similarities between black hole candidate (BHC) and NS accretion, I discuss the accretion geometry and emission processes of NS LMXBs. INTROD...

Radiation of RR states from NS Fivebranes

We show that the recent observation that near extremal NS fivebranes decay due to Hawking radiation, can be understood in terms of their coupling to RR states which does not vanish even as the string coupling goes to zero. e-mail: [email protected], [email protected] On leave from Department of Physics, Box 390, University of Colorado, Boulder, CO 80309. In a recent paper [1] it has...

Hard X-ray Emission From Low Mass X-ray Binaries

We report on Rossi X-ray Timing Explorer observations of four type I X-ray bursters; namely 1E1724– 3045, GS1826–238, SLX1735–269 and KS1731-260. The first three were in a low state, with 1-200 keV Xray luminosities in the range ∼ 0.05−0.1 LEdd (LEdd: Eddington luminosity for a neutron star = 2.5×10 38 ergs s), whereas KS1731-260 was in a high state with a luminosity ∼ 0.35 LEdd. The low state ...

ns-states of hydrogenic systems