Spectral behaviour of the M7 like NS RX J0720.4-3125
Markus HohleAstrophysikalisches Institut und Universitäts-Sternwarte, Jena
&Max-Planck-Institut für extraterrestrische Physik, Garching
Summer School, Dubna, July 2008
What are the M7?
-radio quiet-isolated-young-nearby
“Magnificent Seven”
Motch et al. (2006)
RX J0720
distance : 360 pckT : 86-95 eVX ray period : P=8.3911s, =0.698
(Kaplan & Kerkwijk et al., 2005/07)
cyc p+ (?) line : 301 eV
B field : 2.4 or 5.6 G
line EW, kT, radius
long term period: p=(7.1 +/- 0.5) yr (Haberl et al. 2006, Haberl 2007)
P 1310
1310
-0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.20
5
10
15
20
25
log10
(energy [keV])
cts/
s
0078
0533
0534
0815
0986
1060
1086
1181
1265
1356
1454
spectral parameters
Observations inff & thin filter
(11 of 14 tot)
May 2000 – Nov 2007
abs. feature
EPIC-pn, 2006 EPIC-pn ff thin, 2008
spectral parameters
phase residuals
period : (7.7 +/- 0.6) yr
consistent with that derived from former spectral analyses
Haberl (2007), Kaplan & Kerkweijk (2005) 120-1200eV
timing residuals
precession
phase residualsperiod: (7.7 +/- 0.6) yr
spectral variationsperiod: (7.1 +/- 0.5) yr
precession
- two hot spots and precession
- small hot spot: ~1000 days
- period: ~2*2000 days = 2*5.5 yr
- consistent with period from phase residuals !
timing residuals
hard : 400-1000 eVsoft : 120-400 eV
using timing solution fromKaplan & Kerkwijk (2005)
two hot spots: switch of phase lag
abs(sine) Kaplan & Kerkwijk (2005) (10.694 +/- 0.058)yr
abs(sine) Kaplan & Kerkwijk (2005)+ linear (11.504 +/- 0.072)yr
abs(sine) Kerkwijk et al. (2007) + linear(10.530 +/- 0.069)yr
timing residuals
timing solution
-hardness changes-phase lag betweenhard and soft photons
requires energy dependenttiming solution
still precessing?
precession vs glitch
84 86 88 90 92 94 96 98 100-100
-80
-60
-40
-20
0
20
40
kT [eV]
EW
[eV
]
0078
0533
0534
1454
-dipolar magnetic field -> hot spots Haberl et al. (2006) & de Vries et al. (2004)
-> precession (RBS 1223) Schwope et al. (2005) -> grav. waves-no companion found Posselt et al. (2008, submitted)
-ISM
Hohle et al. (will be submitted after Dubna)
Thank you very much!
RX J1856
RX J0720 RX J1605
RX J1308RX J0420
RX J0806RX J2143
