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Towards an Understanding of the Isolated Neutron Star RX J1856.5-3754 Wynn Ho Kavli Institute for Particle Astrophysics and Cosmology Stanford University.

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Presentation on theme: "Towards an Understanding of the Isolated Neutron Star RX J1856.5-3754 Wynn Ho Kavli Institute for Particle Astrophysics and Cosmology Stanford University."— Presentation transcript:

1 Towards an Understanding of the Isolated Neutron Star RX J1856.5-3754 Wynn Ho Kavli Institute for Particle Astrophysics and Cosmology Stanford University 2005 Hubble Fellows Symposium – 7-8 April 2005

2 Physics from Neutron Star Surface Emission (Yakovlev & Pethick 2004) Equation of state Thermal evolution Surface composition Magnetic field

3 Lattimer & Prakash 2004, Courtesy of Page () Neutron Star Surface Emission Atmosphere scale height H  1 cm << R Emission is anisotropic and polarized in magnetic field Vacuum polarization important at B > B Q = m e 2 c 3 /e ℏ = 4.4  10 13 G Atoms bound by magnetic field

4 RX J1856.5-3754 (Burwitz et al. 2003) Thermal emission No spectral features BB underpredicts optical by 7 Atmosphere overpredicts by >> 1 Two blackbodies kT=63 eV, R=4.4 km kT=26 eV, R=18.2 km No X-ray pulsations (1.3% limit)

5 RX J1856.5-3754 Model Spectra/ Observations

6 RX J1856.5-3754 (Burwitz et al. 2003) Thermal emission No spectral features BB underpredicts optical by 7 Atmosphere overpredicts by >> 1 Two blackbodies kT=63 eV, R=4.4 km kT=26 eV, R=18.2 km No X-ray pulsations (1.3% limit)

7 RX J1856.5-3754 Model Spectra/ Observations

8 Thin Atmospheres

9

10 Condensed Iron Surface Emission 10 5

11 Condensed Iron Surface Emission 10 5

12 RX J1856.5-3754 Model Spectra/ Observations

13 Collaborators David L. Kaplan (Massachusetts Institute of Technology) Philip Chang (University of California, Santa Barbara) Matthew van Adelsberg and Dong Lai (Cornell University) Alexander Y. Potekhin (Ioffe Physico-Technical Institute) Gilles Chabrier (Ecole Normale Superieure de Lyon, CRAL)

14 RX J1856.5-3754 Effect of Redshift

15 Dim Isolated Neutron Stars Radio-quiet F X-ray / F optical > 10 3 Optical excess Blackbody fit to X-ray spectra kT BB  85 eV, R BB  6 km DINSPeriod (s)PFT (eV)E line (keV)EW (keV) RX J1308.6+212710.315 %860.30.15 RX J1605.3+3249?< 3-5 %950.450.08 RX J0806.4-412311.46 %960.41-0.460.06-0.03 RX J0420.0-50223.45 or 22.713 %450.330.045 RX J0720.4-31258.411 %85*0.270.04 RX J2143.0+06549.44 %1010.7 (XMM-van Kerkwijk 2003)

16 RX J2143.0+0654 T (eV)χ 2 / dofE (eV)σ (eV)τ blackbody1011.36 blackbody+line1021.20754274.8 blackbody+edge1041.176940.25 H atm (B=0 G)29.81.94 H atm (B=10 12 G)47.31.99 H atm (B=10 13 G)50.02.19 (XMM-Zane et al. 2005) line or edge?


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