scholarly journals Exploring the tilted accretion disc of AQ Men with TESS

2021 ◽  
Vol 503 (3) ◽  
pp. 4050-4060
Author(s):  
Krystian Iłkiewicz ◽  
Simone Scaringi ◽  
James M C Court ◽  
Thomas J Maccarone ◽  
Diego Altamirano ◽  
...  
Keyword(s):  
Light Curve ◽  
Accretion Disc ◽  
Direct Test ◽  
Sinusoidal Shape

ABSTRACT AQ Men is a nova-like variable that is presumed to have a tilted, precessing accretion disc. Grazing eclipses in this system have been speculated to be useful in exploring the geometry of its accretion disc. In this work, we analysed Transiting Exoplanet Survey Satellite (TESS) observations of AQ Men, which provide the best light curve of this object thus far. We show that the depths of the eclipses are changing with the orientation of the accretion disc, which means that they can serve as a direct test of the tilted accretion disc models. The precession period of the accretion disc is increasing during the TESS observations. However, it is still shorter than the period determined in the previous studies. The amplitude of the variability related to the precession of the accretion disc varies, and so does the shape of this variability. Moreover, we have detected a positive superhump that was previously unseen in AQ Men. Interestingly, the positive superhump has a strongly non-sinusoidal shape, which is not expected for a nova-like variable.

scholarly journals Evidence for variability time-scale-dependent UV/X-ray delay in Seyfert 1 AGN NGC 7469

2020 ◽  
Vol 494 (3) ◽  
pp. 4057-4068
Author(s):  
Mayukh Pahari ◽  
I M McHardy ◽  
Federico Vincentelli ◽  
Edward Cackett ◽  
Bradley M Peterson ◽  
...  
Keyword(s):  
Light Curve ◽  
Time Lag ◽  
Accretion Disc ◽  
Light Curves ◽  
X Rays ◽  
X Ray ◽  
Cross Correlation Analysis ◽  
Optical Continuum ◽  
Delay Prediction ◽  
Ngc 7469

ABSTRACT Using a month-long X-ray light curve from RXTE/PCA and 1.5 month-long UV continuum light curves from IUE spectra in 1220–1970 Å, we performed a detailed time-lag study of the Seyfert 1 galaxy NGC 7469. Our cross-correlation analysis confirms previous results showing that the X-rays are delayed relative to the UV continuum at 1315 Å by 3.49 ± 0.22 d, which is possibly caused by either propagating fluctuation or variable Comptonization. However, if variations slower than 5 d are removed from the X-ray light curve, the UV variations then lag behind the X-ray variations by 0.37 ± 0.14 d, consistent with reprocessing of the X-rays by a surrounding accretion disc. A very similar reverberation delay is observed between Swift/XRT X-ray and Swift/UVOT UVW2, U light curves. Continuum light curves extracted from the Swift/GRISM spectra show delays with respect to X-rays consistent with reverberation. Separating the UV continuum variations faster and slower than 5 d, the slow variations at 1825 Å lag those at 1315 Å by 0.29 ± 0.06 d, while the fast variations are coincident (0.04 ± 0.12 d). The UV/optical continuum reverberation lag from IUE, Swift, and other optical telescopes at different wavelengths are consistent with the relationship: τ ∝ λ4/3, predicted for the standard accretion disc theory while the best-fitting X-ray delay from RXTE and Swift/XRT shows a negative X-ray offset of ∼0.38 d from the standard disc delay prediction.

On the Spectrum of VV Puppis

1979 ◽  
Vol 3 (5) ◽  
pp. 311-312 ◽  
Author(s):  
D. T. Wickramasinghe ◽  
N. Visvanathan
Keyword(s):  
Light Curve ◽  
Hot Spot ◽  
Accretion Disc ◽  
Dwarf Nova ◽  
Spot Model ◽  
Hot Spot Model ◽  
Linear Polarisation

Since the discovery of variable circular and linear polarisation in VV Puppis (Tapia 1977), several investigators have observed the system. The new observations particularly of polarisation (Liebert et al. 1978, Liebert and Stockman 1979 have ruled out the standard dwarf nova (accretion disc — hot spot) model previously used to interpret the light curve of VV Puppis.

scholarly journals Similar shot profile morphology of fast variability in a cataclysmic variable, X-ray binary, and blazar: The MV Lyrae case

2019 ◽  
Vol 631 ◽  
pp. A134 ◽  
Author(s):  
A. Dobrotka ◽  
H. Negoro ◽  
S. Mineshige
Keyword(s):  
Light Curve ◽  
Power Density ◽  
Accretion Disc ◽  
Noise Model ◽  
Quality Data ◽  
Power Density Spectrum ◽  
High Frequency Component ◽  
Cataclysmic Variable ◽  
Density Spectrum ◽  
Profile Method

Context. The cataclysmic variable MV Lyr has been found to be present in the Kepler field, yielding a light curve with the duration of almost 1500 days with 60 s cadence. Such high quality data of this nova-like system with obvious fast optical variability reveal multi-component power density spectra, as shown by previous works. Aims. Our goal is to study the light curve from a different point of view and perform a shot profile analysis. We search for characteristics that have not been discovered with standard methods based on power density spectrum. Methods. The shot profile method identifies individual shots in the light curve and averages these shots to reveal all substructures with typical timescales. We also tested the robustness of our analysis using a simple shot noise model. Although the principle of this method is not completely physically correct, we used it as a purely phenomenological approach. Results. We obtain mean profiles with multi-component features. The shot profile method distinguishes substructures with similar timescales which appear as a single degenerate feature in power density spectra. Furthermore, this method yields the identification of another high frequency component in the power density spectra of Kepler and XMM-Newton data that have not been detected so far. Moreover, we found side lobes accompanied with the central spike, making the profile very similar to the Kepler data of blazar W2R 1926+42 and the Ginga data of Cyg X-1. All three objects show similar timescale ratios of the rising versus declining part of the central spikes, while the two binaries also have similar rising profiles of the shots described by a power-law function. Conclusions. The similarity of both binary shot profiles suggests that the shots originate from the same origin, namely, aperiodic mass accretion in the accretion disc. Moreover, the similarity with the blazar may imply that the ejection fluctuations in the blazar jet are connected to accretion fluctuations driving the variability in binaries. This points out the connection between the jet and the accretion disc.

scholarly journals The Effect of Circumstellar Material on the Light Curves of Eclipsing Binary Systems

2011 ◽  
Vol 28 (4) ◽  
pp. 290-298
Author(s):  
S. M. R. Ghoreyshi ◽  
J. Ghanbari ◽  
F. Salehi
Keyword(s):  
Light Curve ◽  
Binary Systems ◽  
Outer Radius ◽  
Accretion Disc ◽  
Light Curves ◽  
Jet Stream ◽  
Eclipsing Binary ◽  
Circumstellar Material ◽  
Disc Model ◽  
Free Parameters

AbstractThis study inspects the influence of various effects and free parameters of the accretion disc and circumstellar material on the emerging light curve of eclipsing binary systems that have a circumstellar disc, by using the SHELLSPEC code. The results indicate that some of the parameters, namely the temperature and inclination of the disc, spot, jet, stream and shell, significantly affect on the emerging light curve, while some other parameters, namely the exponent of the power-law behavior of the density of the disc, microturbulence, inner and outer radius of the disc, do not noticeably affect on the emerging light curve. An application to the Algol-type eclipsing binary system AV Del and an accretion disc model for the system using the SHELLSPEC code is included.

scholarly journals Simultaneous Millimetre-wave and X-ray monitoring of the Seyfert galaxy NGC 7469

2019 ◽  
Vol 491 (3) ◽  
pp. 3523-3534 ◽  
Author(s):  
Ehud Behar ◽  
Shai Kaspi ◽  
Gabriel Paubert ◽  
Nicolas Billot ◽  
Uria Peretz ◽  
...  
Keyword(s):  
Light Curve ◽  
Seyfert Galaxy ◽  
Accretion Disc ◽  
X Rays ◽  
Millimetre Wave ◽  
X Ray ◽  
Daily Monitoring ◽  
Data Points ◽  
Optical Telescopes ◽  
Ngc 7469

ABSTRACT We report on daily monitoring of the Seyfert galaxy ngc 7469, around 95 and 143 GHz, with the iram (Institut de Radioastronomie Millimetrique) 30- m radio telescope, and with the Swift X-ray and UV/optical telescopes, over an overlapping period of 45 d. The source was observed on 36 d with iram, and the flux density in both mm bands was on average ∼10 mJy, but varied by $\pm 50{{\ \rm per\ cent}}$, and by up to a factor of 2 between days. The present iram variability parameters are consistent with earlier monitoring, which had only 18 data points. The X-ray light curve of ngc 7469 over the same period spans a factor of 5 in flux with small uncertainties. Similar variability in the mm band and in the X-rays lends support to the notion of both sources originating in the same physical component of the active galactic nucleus (AGN), likely the accretion disc corona. Simultaneous monitoring in eight UV/optical bands shows much less variability than the mm and X-rays, implying this light originates from a different AGN component, likely the accretion disc itself. We use a tentative 14-d lag of the X-ray light curve with respect to the 95 GHz light curve to speculate on coronal implications. More precise mm-band measurements of a sample of X-ray-variable AGN are needed, preferably also on time-scales of less than a day where X-rays vary dramatically, in order to properly test the physical connection between the two bands.

scholarly journals Decomposing Interacting Binary Light Curves: The Eclipses of the Mean Light, Secular Variability and Flickering in RW Tri

1996 ◽  
Vol 158 ◽  
pp. 33-34
Author(s):  
Paul J. Bennie ◽  
R. W. Hilditch ◽  
Keith Horne
Keyword(s):  
Light Curve ◽  
Accretion Disc ◽  
Light Curves ◽  
New Method ◽  
Secular Variability ◽  
The Mean

AbstractWe describe a new method of orbital light curve decomposition which is applicable to long-term photometry of interacting binaries. This method determines the orbital dependence (including eclipses) of the mean light, secular variability and RMS flickering. We identify the true line of centres of RW Tri and find that the accretion disc is a location of secular variability and a source of flickering.

The Eclipsing Binary WX Eridani

1979 ◽  
Vol 46 ◽  
pp. 385
Author(s):  
M.B.K. Sarma ◽  
K.D. Abhankar
Keyword(s):  
Light Curve ◽  
Spectral Type ◽  
Orbital Period ◽  
Primary Component ◽  
Light Curves ◽  
Absorption Feature ◽  
Primary Star ◽  
Eclipsing Binary ◽  
The Times ◽  
Phase Angles

AbstractThe Algol-type eclipsing binary WX Eridani was observed on 21 nights on the 48-inch telescope of the Japal-Rangapur Observatory during 1973-75 in B and V colours. An improved period of P = 0.82327038 days was obtained from the analysis of the times of five primary minima. An absorption feature between phase angles 50-80, 100-130, 230-260 and 280-310 was present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with primary to be transit and secondary, an occultation. Elements derived from the solution of the light curve using Russel-Merrill method are given. From comparison of the fractional radii with Roche lobes, it is concluded that none of the components have filled their respective lobes but the primary star seems to be evolving. The spectral type of the primary component was estimated to be F3 and is found to be pulsating with two periods equal to one-fifth and one-sixth of the orbital period.

RSCVn Stars in the Southern Hemisphere

1979 ◽  
Vol 46 ◽  
pp. 371-384 ◽  
Author(s):  
J.B. Hearnshaw
Keyword(s):  
Light Curve ◽  
Southern Hemisphere ◽  
Orbital Period ◽  
Binary Stars ◽  
Small Amplitude ◽  
Light Variation ◽  
Orbital Phase

RSCVn stars are fully detached binary stars which show intrinsic small amplitude (up to 0.3 amplitude peak-to-peak) light variations, as well as, in most of the known cases, eclipses. The spectra are F to G, IV to V for the hotter component and usually KOIV for the cooler. They are also characterised by abnormally strong H and K emission from the cooler star, or, occasionally, from both components. The orbital and light curve periods are in the range 1 day to 2 weeks. An interesting feature is the migration of the light variations to earlier orbital phase, as the light variation period is shorter than the orbital period by a few parts in 10+4to a few parts in 10+3.

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