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The first interpretations (Leibowitz et al. 2006)day 196- detection of 12 significant signals- detection of 6 significant signals in reanalysed day 180- 0.75 mHz has double structure;0.729 and 0.763 mHz ... day 1960.721 and 0.777 mHz ... day 180- overtones- double frequency; 1.459,1.504 mHz- relations 2 x f, f 1+ f 2- 0.75 mHz - white dwarf rotation- other signals – WD pulsations


The first interpretations (Kang et al. 2006)days 258-265 and 1003-1011- combination of 3 frequenciesf 1= 0.041 mHz P 1= 402 min = 6.7 h (Kang et al. 2006)f 2= 0.705 mHz P 2= 24 min (Kang et al. 2006)f 3= 0.755 mHz P 3= 22 min (X-ray from Ness et al. 2003)f 3- f 1= 0.714 mHz ≈ 0.71 mHz ≈ f 2f 1– orbital frequencyf 2– beat frequency between f 1and f 3f 3– spin period of the white dwarf=> an intermediate polar candidate


Method used for period analysis- Lomb-Scargle method (Scargle 1982)- formal errors HWHM- Sine fitting- fitting of the model with n signals, 5 th order polynome and mean background- goodness criterion a likelihood- error determination from confidencecontours from likelihood difference


Method used for period analysis – tests- synthetic data sampled as day 180- added Poisson/Gaussian noise- single frequency casef = 0.72 mHz- two frequency casef 1= 0.72 mHzf 2= 0.76 mHz


Method used for period analysis – tests- synthetic data sampled as day 180- added Poisson/Gaussian noise- single frequency casef = 0.72 mHz- two frequency casef 1= 0.72 mHzf 2= 0.76 mHz


Method used for period analysis – tests- synthetic data sampled as day 180- added Poisson/Gaussian noise- single frequency casef = 0.72 mHz- two frequency casef 1= 0.72 mHzf 2= 0.76 mHz- L-S and sine fitting with n = 1 found asingle frequency at 0.744 mHz- sine fitting with n = 2 found bothsignals


Method used for period analysis – tests- synthetic data sampled as day 180- added Poisson/Gaussian noise- single frequency casef = 0.72 mHz- two frequency casef 1= 0.72 mHzf 2= 0.76 mHz- L-S and sine fitting with n = 1 found asingle frequency at 0.744 mHz- sine fitting with n = 2 found bothsignals


Analysis – Lomb-Scargle- broad peaks- blending?


Analysis – Lomb-Scargle- broad peaks – blending?


Analysis – sine fitting- detection criterion 3-σ- error measured from 3-σ contours- analysed interval 0.6 – 0.9 mHz- 3-σ closed contour => 2 signals- 3-σ open lines => 1 signal


Analysis – sine fittingday 196- detection criterion 3-σ- error measured from 3-σ contours- analysed interval 0.6 – 0.9 mHz- 3-σ closed contour => 2 signals- 3-σ open lines => 1 signal- day 180 case:n = 2 fit better than n = 1ΔL = 1978.48Leibowitzday 180


Analysis – sine fittingday 196- detection criterion 3-σ- error measured from 3-σ contours- analysed interval 0.6 – 0.9 mHz- 3-σ closed contour => 2 signals- 3-σ open lines => 1 signal- day 180 case:n = 2 fit better than n = 1ΔL = 1978.48Leibowitzday 180- other observations – single frequencyday 1286


Analysis – sine fittingday 196- detection criterion 3-σ- error measured from 3-σ contours- analysed interval 0.6 – 0.9 mHz- 3-σ closed contour => 2 signals- 3-σ open lines => 1 signal- day 180 case:n = 2 fit better than n = 1ΔL = 1978.48Leibowitzday 180- other observations – single frequency- overtones:180 ------- 2 x f 2f 1+ f 2196 2 x f 12 x f 2-------1286 2 x f 1------- -------day 1286


Analysis – frequency detectionTest – day 302, synthetic data modulated with 0.72 and 0.76 mHzDetections - L-S:0.731 mHz- 2-D, 3-σ open lines: 0.736 mHz- 2-D, global minimum: 0.678 and 0.745 mHzf = 0.72 mHzf 1= 0.72 mHz, f 2= 0.76 mHz


Analysis – frequency detection- two close frequencies f 1and f 2forms a beating with a frequency of f 1– f 2- if data longer than 1/(f 1– f 2) => long enough- 2 signals in synthetic test data shorter than beating- day 180 detection- day 302 nondetection=> amplitudes and noise!


Results – frequency evolution- days 50 – 526, changes- days 180 – 196, approaching- days 302 – 526, merging?- days 742 – 1286, constant?


Results – amplitudes, amplitude evolution- after day 180 – decline, connection to fast decline during day 180?- after day 526 – increase


Summary of the observational results- double frequency nature of the 0.75 mHz peak at days 180 and 196- single signal after day 526 (196 – 526, not sure, short data sets)- frequency changing up to day 526- signal constant after day 526- relative amplitudes decline after day 180- relative amplitudes increase after day 526=> different behaviour of signals before and after day 526 – decline from SSSphase -> nova was turning off!


Interpretation – white dwarf rotation- signals must be stable- if two close signals – spin and beat period (between orbital and spin)- does not agree up to day 526- agree after day 526P orb= 6.72 ± 0.01 h (Kang et al. 2006)


Interpretation – before day 526 – QPOs?- QPOs – vertical thickening in acc disc – eclipsing or reflecting the light- only 4 detections of QPOs in X-ray:- VW Hyi, 63 – 68 s (van der Woerd et al. 1987)- SS Cyg, 83 s (Mauche 1997)- U Gem, 585 s (Cordova and Mason 1984)- OY Car, 2240 s (Ramsay et al. 2001)- our periods: 1292 – 1391 s


Interpretation – before day 526 – QPOs?- QPOs – vertical thickening in acc disc – eclipsing or reflecting the light- only 4 detections of QPOs in X-ray:- VW Hyi, 63 – 68 s (van der Woerd et al. 1987)- SS Cyg, 83 s (Mauche 1997)- U Gem, 585 s (Cordova and Mason 1984)- OY Car, 2240 s (Ramsay et al. 2001)- our periods: 1292 – 1391 s- time scale of rotating vertical thickening in acc.disc, a Keplerian frequency=> SS Cyg, VW Hyi ~ 10 9 cm=> U Gem ~ 10 10 cm – too far, region not emitting X-rays=> V4743 Sgr ~ 10 10 cm – too far, region not emitting X-rays=> OY Car ~ 10 10 cm – too far, region not emitting X-rays


Interpretation – before day 526 – QPOs?- beating between white dwarf rotation in X-ray with vertical thickening rotating inthe inner disc radiating as QPOs in X-rayf beat= f QPOs– f spin=> f QPOs= f beat+ f spin≈ 680 s ( f spin= 0.75 mHz)=> distance of the QPOs source to ~ 10 10 cm – too far, not X-ray


Interpretation – before day 526 – QPOs?- eclipse of the central X-ray source (WD) by vertical thickening in theacc.disc...OY Car case- OY Car- eclipsing system, periodic dip detected in X-ray- inclination high enough, i = 83.3°


Interpretation – before day 526 – QPOs?- eclipse of the central X-ray source (WD) by vertical thickening in theacc.disc...OY Car case- OY Car- eclipsing system, periodic dip detected in X-ray- inclination high enough, i = 83.3°- V4743 Sgr- eclipse unprobable, periodic dips undetected in X-ray (P orb= 24.1 ks)- very narrow and shallow eclipse like feature in optical data- partial eclise of the acc.disc edge by the secondary=> inclination not enough to eclipse the WD by the secondary=> inclination not enough for a vertical thickening to eclipse the WD


Interpretation – before day 526 – QPOs?- eclipse of the central X-ray source (WD) by vertical thickening in theacc.disc...OY Car case- OY Car- eclipsing system, periodic dip detected in X-ray- inclination high enough, i = 83.3°- V4743 Sgr- eclipse unprobable, periodic dips undetected in X-ray (P orb= 24.1 ks)- very narrow and shallow eclipse like feature in optical data- partial eclise of the acc.disc edge by the secondary=> inclination not enough to eclipse the WD by the secondary=> inclination not enough for a vertical thickening to eclipse the WD=> QPOs unlikely!


Interpretation – before day 526 – WD pulsations?- the central accretor after nova explosion resembles PN nuclei- PN nuclei- pulsations 1000 – 5000 s (Ciardullo and Bond 1996)- frequencies changing, ex. NGC 246, 0.01 mHz/1 month- frequency change in V4743 Sgr, 0.01 mHz/2 weeks


Interpretation – before day 526 – WD pulsations?- the central accretor after nova explosion resembles PN nuclei- PN nuclei- pulsations 1000 – 5000 s (Ciardullo and Bond 1996)- frequencies changing, ex. NGC 246, 0.01 mHz/1 month- frequency change in V4743 Sgr, 0.01 mHz/2 weeks1 - instabilities in hydrogen burning shells (Sastri and Simon 1973)- typical periods much shorter than our case, ~10 s- RS Oph case with 35s X-ray oscillations (Beardmore et al. 2009)=> unlikely


Interpretation – before day 526 – WD pulsations?- the central accretor after nova explosion resembles PN nuclei- PN nuclei- pulsations 1000 – 5000 s (Ciardullo and Bond 1996)- frequencies changing, ex. NGC 246, 0.01 mHz/1 month- frequency change in V4743 Sgr, 0.01 mHz/2 weeks1 - instabilities in hydrogen burning shells (Sastri and Simon 1973)- typical periods much shorter than our case, ~10 s- RS Oph case with 35s X-ray oscillations (Beardmore et al. 2009)=> unlikely2 - instabilities in partial ionisation zone of C and O (Starrfield et al. 1984)- GW Vir isolated hot WD case- deep absorption lines of C and O in V4743 Sgr (Ness et al. 2009)- C-O WD with enough C and O?=> possible


Interpretation – before day 526 – WD pulsations?- pulsation frequency correlation with temperature (Kjeldsen and Bedding 1995)- for hydrostatic equilibrium and for stellar atmospheres- ratio of frequencies(f 1/ f 2) 2 = T 2/ T 1


Interpretation – before day 526 – WD pulsations?- pulsation frequency correlation with temperature (Kjeldsen and Bedding 1995)- for hydrostatic equilibrium and for stellar atmospheres- ratio of frequenciesT bbin 10 3 K(f 1/ f 2) 2 = T 2/ T 1- agreement for days180, 302, 371- disagreement for days196, 526, 742, 1286


Conclusion- WD pulsations- present before day 526- during SSS phase f-T relation valid, except for:- after strong decline in 180 (day 196)- decline from SSS (day 526)- none after SSS phase (after day 526)


Conclusion- WD pulsations- present before day 526- during SSS phase f-T relation valid, except for:- after strong decline in 180 (day 196)- decline from SSS (day 526)- none after SSS phase (after day 526)- WD rotation- during SSS phase– modulation buried in the overall brightness- after SSS phase –visible and dominant=> an intermediate polar candidate


Questions- what is the strong decline during day 180? (observed also in RS Oph, ...)


Questions- what is the strong decline during day 180?- why is the f-T relation valid during the SSS phase?- the same origine as stellar atmospheres in hydrostatic equilibrium?- “quasihydrostatic” equilibrium?- after strong decline in 180 (day 196) or decline from SSS (day 526)- f-T relation not valid- out of “quasihydrostatic” equilibrium?- approaching frequencies during days 180 and 196 merged into one?- why are the frequencies of pulsations and of the WD rotation so similar?


Endthank you for......attention...collaboration...opportunity...funding...lunch...

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