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Observing Orbital Motion in Strongly Curved Spacetime

Observing Orbital Motion in Strongly Curved Spacetime. Gabriel Török. Institute of Physics, Silesian University in Opava. CZ.1.07/2.3.00/20.0071 Synergy , GAČR 209/12/P740 , 202/09/0772, SGS- 1 1-201 3 , www. physics.cz. Observing Orbital Motion in Strongly Curved Spacetime.

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Observing Orbital Motion in Strongly Curved Spacetime

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  1. Observing Orbital Motion in StronglyCurvedSpacetime Gabriel Török Institute ofPhysics, Silesian University in Opava CZ.1.07/2.3.00/20.0071Synergy , GAČR 209/12/P740, 202/09/0772,SGS-11-2013, www.physics.cz

  2. Observing Orbital Motion in StronglyCurvedSpacetime Gabriel Török Institute ofPhysics, Silesian University in Opava CZ.1.07/2.3.00/20.0071Synergy , GAČR 209/12/P740, 202/09/0772,SGS-11-2013, www.physics.cz PavelBakala, Kateřina Goluchová, Martin Wildner (see Kateřina today, Martin at INAP conf.)

  3. On marginallystablecircularorbitsaround neutron stars Gabriel Török Institute ofPhysics, Silesian University in Opava CZ.1.07/2.3.00/20.0071Synergy , GAČR 209/12/P740, 202/09/0772,SGS-11-2013, www.physics.cz CO-AUTHORS: Martin Urbanec, Karel Adámek, Gabriela Urbancová

  4. 1. ISCO andNS Compactness ISCO FREQUENCY: Kluzniak et al., ApJ (1990) KERR Torok et al.(2010),ApJ OBLATENESS The influence of NS oblateness on theorbital frequencies has been extensively studied in thelast decade, e.g., Morsink, Stella, ApJ (1999); Rosinskaetal. A&A (2001); Amsterdamskietal., A&A (2002), Urbanec etal., MNRAS (2013), Kluzniak& Rosinska (2013)

  5. 1. ISCO andNS Compactness ISCO RADIUS (Hartle-Thorne Spacetime): q j The ISCO radiusdecreaseswith spin,butincreaseswithquadrupole.

  6. 1. ISCO andNS Compactness ISCO RADIUS (Hartle-Thorne Spacetime): q j Neutron star radii R evolvewithjratherslowly. The non-monotonicbehaviourof r_ISCO thusimply non-monotonicbehaviourofthequantity K= r_ISCO/ R_NS.

  7. 1. ISCO andNS Compactness Inverse compactness K=r_ISCO / R_NS (calculated for particular SKI5 EOS). ISCO above NS surface K=rISCO / RNS ISCO below NS surface SPIN [Hz] In thecase of high mass, the ISCO is above theNS surface. In thecase of low mass, theISCO is above theNS surface only for very high spins (when these are allowed).

  8. 1. ISCO andNS Compactness Inverse compactness K=r_ISCO / R_NS (calculated for particular SKI5 EOS). ISCO above NS surface K=rISCO / RNS ISCO below NS surface SPIN [Hz] In thecase of intermediate NS mass, theISCO is abovetheNS surface for low and high spins, but not for theintermediate spins. Clearly, there are implications for theISCO-NS distribution.

  9. 2. NS distribution Initial Distribution of NS [K<>1] => Distribution of ISCO-NS MASS [MSun] SPIN [Hz]

  10. 2. NS distribution InitialDistribution of NS (one concrete EoS) MASS [MSun] SPIN [Hz]

  11. 2. NS distribution InitialDistribution of NS (one concrete EoS) MASS [MSun] SPIN [Hz]

  12. 2. NS distribution ISCO-NS Distribution Mass [Msun] 0 1 1.5 2 MASS [MSun] 0 500 1000 1500 Spin [Hz] SPIN [Hz]

  13. 3. Particularapplication: Several QPO modelsrequire ISCO-NS -> the influence on QPO sources distribution ISCO-NS Distribution Mass [Msun] 0 1 1.5 2 MASS [MSun] 0 500 1000 1500 Spin [Hz] SPIN [Hz] HF QPOs due to Paczynskimodulation -> fast and slow rotators

  14. 4. Conclusions • The ISCO-NS distribution has thepeaksat the values of the spin which can be very different from the peak in the distribution of all NS. • High M -> peak at the original value of spin • Low M -> peak at the high value of spin • Inter. M -> twopeaks Number of NS [relative units] Distribution of all NS SPIN [Hz]

  15. 4. Conclusions • The ISCO-NS distribution has thepeaksat the values of the spin which can be very different from the peak in the distribution of all NS. • High M -> peak at the original value of spin • Low M -> peak at the high value of spin • Inter. M -> twopeaks Number of ISCO-NS [relative units] Distribution of all NS SPIN [Hz]

  16. 4. Conclusions • The ISCO-NS distribution has thepeaksat the values of the spin which can be very different from the peak in the distribution of all NS. • High M -> peak at the original value of spin • Low M -> peak at the high value of spin • Inter. M -> twopeaks Number of ISCO-NS [relative units] Distribution of all NS SPIN [Hz]

  17. 4. Conclusions • The ISCO-NS distribution has thepeaksat the values of the spin which can be very different from the peak in the distribution of all NS. • High M -> peak at the original value of spin • Low M -> peak at the high value of spin • Inter. M -> twopeaks Number of ISCO-NS [relative units] SPIN [Hz]

  18. 4. Conclusions • The ISCO-NS distribution has thepeaksat the values of the spin which can be very different from the peak in the distribution of all NS. • High M -> peak at the original value of spin • Low M -> peak at the high value of spin • Inter. M -> twopeaks applications Number of ISCO-NS [relative units] SPIN [Hz]

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