Observing Orbital Motion in Strongly Curved Spacetime Institute of Physics, Silesian University in Opava Gabriel Török CZ.1.07/2.3.00/20.0071 Synergy , GAČR 209/12/P740, 202/09/0772, SGS- 11-2013, www.physics.cz
Feb 23, 2016
Observing Orbital Motion in Strongly Curved Spacetime
Institute of Physics, Silesian University in OpavaGabriel Török
CZ.1.07/2.3.00/20.0071 Synergy , GAČR 209/12/P740, 202/09/0772, SGS-11-2013, www.physics.cz
Observing Orbital Motion in Strongly Curved Spacetime
Institute of Physics, Silesian University in OpavaGabriel Török
CZ.1.07/2.3.00/20.0071 Synergy , GAČR 209/12/P740, 202/09/0772, SGS-11-2013, www.physics.cz
Pavel Bakala, Kateřina Goluchová, Martin Wildner(see Kateřina today, Martin at INAP conf.)
Institute of Physics, Silesian University in OpavaGabriel Török
CZ.1.07/2.3.00/20.0071 Synergy , GAČR 209/12/P740, 202/09/0772, SGS-11-2013, www.physics.cz
On marginally stable circular orbits around neutron stars
CO-AUTHORS:Martin Urbanec, Karel Adámek, Gabriela Urbancová
KERR
1. ISCO and NS Compactness
OBLATENESS
The influence of NS oblateness on the orbital frequencies has been extensively studied in the last decade, e.g.,Morsink, Stella, ApJ (1999); Rosinska et al. A&A (2001); Amsterdamski et al., A&A (2002), Urbanec et al., MNRAS (2013), Kluzniak & Rosinska (2013)
Kluzniak et al., ApJ (1990)
Toro
k et
al.
(201
0),A
pJ
ISCO FREQUENCY:
1. ISCO and NS Compactness
ISCO RADIUS (Hartle-Thorne Spacetime):
The ISCO radius decreases with spin, but increases with quadrupole.
j
q
1. ISCO and NS Compactness
Neutron star radii R evolve with j rather slowly. The non-monotonic behaviour of r_ISCO thus imply non-monotonic behaviour of the quantity
K= r_ISCO/ R_NS.
j
q
ISCO RADIUS (Hartle-Thorne Spacetime):
1. ISCO and NS Compactness
SPIN [Hz]
In the case of high mass, the ISCO is above the NS surface. In the case of low mass, the ISCO is above the NS surface only for very high spins (when these are allowed).
ISCO below NS surface
ISCO above NS surface
Inverse compactness K= r_ISCO / R_NS (calculated for particular SKI5 EOS).K=
rISC
O /
RN
S
1. ISCO and NS Compactness
In the case of intermediate NS mass, the ISCO is above the NS surface for low and high spins, but not for the intermediate spins. Clearly, there are implications for the ISCO-NS distribution.
SPIN [Hz]
ISCO below NS surface
ISCO above NS surface
Inverse compactness K= r_ISCO / R_NS (calculated for particular SKI5 EOS).K=
rISC
O /
RN
S
2. NS distribution
M
ASS
[MSu
n]
SPIN [Hz]
Initial Distribution of NS[K<>1] =>
Distribution of ISCO-NS
2. NS distribution
SPIN [Hz]
MAS
S [M
Sun]
Initial Distribution of NS (one concrete EoS)
SPIN [Hz]
MAS
S [M
Sun]
2. NS distribution
Initial Distribution of NS (one concrete EoS)
0 500 1000 1500 Spin [Hz]
Mass [M
sun]
0 1 1.5 2
MAS
S [M
Sun]
SPIN [Hz]
2. NS distribution
ISCO-NS Distribution
0 500 1000 1500 Spin [Hz]
Mass [M
sun]
0 1 1.5 2
MAS
S [M
Sun]
SPIN [Hz]
3. Particular application:
ISCO-NS Distribution
Several QPO models require ISCO-NS -> the influence on QPO sources distribution
HF QPOs due to Paczynski modulation -> fast and slow rotators
4. Conclusions
SPIN [Hz]
Num
ber o
f NS
[rel
ative
uni
ts]
Distribution ofall NS
The ISCO-NS distribution has the peaks at 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 -> two peaks
4. Conclusions
SPIN [Hz]
Num
ber o
f ISC
O-N
S [r
elati
ve u
nits
]
Distribution ofall NS
The ISCO-NS distribution has the peaks at 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 -> two peaks
4. Conclusions
SPIN [Hz]
Num
ber o
f ISC
O-N
S [r
elati
ve u
nits
]
Distribution ofall NS
The ISCO-NS distribution has the peaks at 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 -> two peaks
4. Conclusions
SPIN [Hz]
Num
ber o
f ISC
O-N
S [r
elati
ve u
nits
]
The ISCO-NS distribution has the peaks at 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 -> two peaks
4. Conclusions
SPIN [Hz]
Num
ber o
f ISC
O-N
S [r
elati
ve u
nits
]
The ISCO-NS distribution has the peaks at 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 -> two peaks
applications