scholarly journals The detection of pulsed emission at the spin period of the white dwarf in AE Aquarii in MeerKAT and Fermi-LAT data

2021 ◽  
Author(s):  
Spencer T. Madzime ◽  
Pieter Meintjes ◽  
Hendrik van Heerden ◽  
Krishna Kumar Singh ◽  
David Buckley ◽  
...  
Keyword(s):  
White Dwarf ◽  
Spin Period

scholarly journals An improved spin-down rate for the proposed white dwarf pulsar AR scorpii

2020 ◽  
Vol 496 (4) ◽  
pp. 4849-4856
Author(s):  
Y Gaibor ◽  
P M Garnavich ◽  
C Littlefield ◽  
S B Potter ◽  
D A H Buckley
Keyword(s):  
White Dwarf ◽  
Heterogeneous Data ◽  
Colour Index ◽  
Data Sets ◽  
Emission Model ◽  
Arrival Times ◽  
Spin Period ◽  
Orbital Phase ◽  
Period Derivative ◽  
Primary Pulse

ABSTRACT We analyse rapid-cadence, multiwavelength photometry of AR Scorpii from three observatories, covering five observing seasons. We measure the arrival times of the system’s beat pulses and use them to compute an updated ephemeris. The white dwarf spin-down rate is estimated with an uncertainty of only 4 per cent. These results confirm, beyond any doubt, that the white dwarf’s spin period is increasing at the rate consistent with by that of Stiller et al. (2018). We study the evolution of the beat pulse’s colour index across the orbit. The colour of the primary pulse maxima varies significantly across the orbit, with the peaks being bluer after superior conjunction than in the first half of the orbit. Specifically, at orbital phase 0.5, the colour index of the primary pulse shows a very sharp discontinuity towards bluer indices. This supports the Potter & Buckley (2018b) synchrotron emission model where the two emitting poles differ significantly in colour. However, no corresponding jump in the colour of the secondary pulses is seen. Furthermore, our analysis reveals that the arrival times of the pulses can differ by as much as 6 s in simultaneous u and r photometry, depending on the binary orbital phase. If left uncorrected, this wavelength-dependent timing offset could lead to erroneous measurements of the spin-period derivative, particularly with heterogeneous data sets.

scholarly journals TESS observations of the asynchronous polar CD Ind: mapping the changing accretion geometry

2019 ◽  
Vol 486 (2) ◽  
pp. 2549-2556 ◽  
Author(s):  
Pasi Hakala ◽  
Gavin Ramsay ◽  
Stephen B Potter ◽  
Andrew Beardmore ◽  
David A H Buckley ◽  
...  
Keyword(s):  
Light Curve ◽  
White Dwarf ◽  
Pulse Shape ◽  
Optical Observations ◽  
Mapping Technique ◽  
Beat Period ◽  
Spin Period ◽  
Cyclotron Emission

ABSTRACT We present the results of near continuous TESS optical observations of the asynchronous polar CD Ind (RX J2115−5840). The 27.9 d long light curve, with 2 min resolution, reveals remarkable changes in the magnetic accretion geometry of the system over the 7.3 d beat period. We have modelled the changes in the optical spin period pulse shape using a cyclotron emission mapping technique. The resulting cyclotron emission maps of the magnetic white dwarf reveal how the accretion geometry changes from single- to two-pole accretion and back over the beat cycle. Finally, we present the results from particle-based numerical magnetic accretion simulations, which agree with our interpretation of the changing accretion scenario.

scholarly journals The Spin-Resolved He ɪɪ Profile of RX J0558+53

1997 ◽  
Vol 163 ◽  
pp. 715-716
Author(s):  
E.T. Harlaftis ◽  
K. Horne
Keyword(s):  
Emission Line ◽  
White Dwarf ◽  
Gas Flow ◽  
Complex Structure ◽  
Double Pulse ◽  
Spin Period

AbstractWe observed the new intermediate polar RX J0558+53 withthe 4.2m WHT in March 1995. We detect 2–3%% pulsations of the He ɪɪ emission line on the 545s spin period. The spin-resolved Hell spectrogram shows a complex structure with two roughly anti-phased components moving from red to blue (double pulse). This is most likely produced by non-axisymmetric gas flow in the rotating magnetosphere of the white dwarf.

scholarly journals Bi-Modality in the short-term photometric Properties of the Intermediate Polar V1062 Tau

2004 ◽  
Vol 190 ◽  
pp. 243-249
Author(s):  
Y. Lipkin ◽  
E. M. Leibowitz ◽  
M. Orio
Keyword(s):  
White Dwarf ◽  
Strongly Correlated ◽  
Time Resolved ◽  
Spin Period ◽  
Long Period ◽  
System A ◽  
Secular Variations ◽  
Short Time ◽  
Orbital Cycle

AbstractWe conducted coordinated time-resolved observations of the long-period Intermediate Polar V1062 Tauri at the WIYN Observatory in Kitt Peak, Arizona and at Wise Observatory, Israel, and follow-up observations at the second site. We confirm the presence of two previously reported periodicities of the system: a long period (P≈10 h) which was interpreted as the orbital period of the underlying binary system, and a shorter one (P≈ 1 h), which was interpreted as the spin of the white dwarf. Our data also revealed a third photometric periodicity, corresponding to the orbital sideband of the spin period (OSB). The amplitude of the OSB was found to be strongly correlated with the varying brightness of the system at the orbital cycle.Our observations suggest bi-modality in the photometric characteristics of the star. In one mode, the light of V1062 Tau varies with the spin period of the white dwarf, whereas the OSB is undetected. In the other mode, the OSB is the main modulation at short time-scales, and the spin period is absent from the light curve. Switching between the two modes occurred three times during the 10 weeks that spanned our observations. Also, we detected an outburst of 1.1 mag, which lasted between ~1 and ~5 days. In addition to the outburst, secular variations in the brightness of the star (0.3 mag on time scale of a few of tens of days) suggest that the system was in a brief low state during 2002 January.

scholarly journals The Spin-Up Rate of the White Dwarf in GK Per

2004 ◽  
Vol 190 ◽  
pp. 120-123
Author(s):  
Christopher W. Mauche
Keyword(s):  
White Dwarf ◽  
Light Curves ◽  
Optical Measurements ◽  
Pulse Period ◽  
X Ray ◽  
Spin Period

AbstractWe use hard X-ray light curves measured by the Chandra HETG and RXTE PCA during the late rise and plateau phases of the 2002 March–April outburst of the intermediate polar GK Per to determine that its X-ray pulse period P = 351.332 ± 0.002 s. Combined with previous X-ray and optical measurements of the spin period of the white dwarf, we find that its spin-up rate Ṗ = 0.00027 ± 0.00005 s yr−1.

scholarly journals X-ray and optical observations of BY Cam

1996 ◽  
Vol 158 ◽  
pp. 213-214 ◽  
Author(s):  
Gavin Ramsay ◽  
Paul A. Mason
Keyword(s):  
Power Spectrum ◽  
Orbital Period ◽  
White Dwarf ◽  
Optical Observations ◽  
Optical Data ◽  
Spin Orbit ◽  
Side Band ◽  
X Ray ◽  
Beat Period ◽  
Spin Period

We present preliminary results of an analysis of X-ray and optical data of the asynchronous AM Her star BY Cam [1]. We use X-ray data from EXOSAT (0.1… 50 keV), Ginga (1.5… 50 keV) and ROSAT (0.1…2.0 keV) and optical data obtained during a 45-day campaign in 1994.There are 4 known periods: the orbital period (201.30 m), the spin period of the white dwarf (199.3303 m), a spin-orbit beat period (14.15 d) and a side-band period (197.4 m). The detection of this side-band period lends credence to the theory of [2], who suggest that for a stream accreting, diskless, magnetic CV a frequency, f = 2ωspin − Ωorb (=197.399 m), will appear as a strong spike in the power spectrum for certain systems. Wu & Mason (this volume) discuss a competing model where Pspin = 197.4 m.

scholarly journals Remarkable spectral variability on the spin period of the accreting white dwarf in V455 And

2013 ◽  
Vol 429 (4) ◽  
pp. 3433-3438 ◽  
Author(s):  
S. Bloemen ◽  
D. Steeghs ◽  
K. De Smedt ◽  
J. Vos ◽  
B. T. Gänsicke ◽  
...  
Keyword(s):  
White Dwarf ◽  
Spectral Variability ◽  
Spin Period

scholarly journals The submillimeter properties of AE Aqr

2012 ◽  
Vol 8 (S290) ◽  
pp. 145-148
Author(s):  
Ulf Torkelsson
Keyword(s):  
White Dwarf ◽  
Cataclysmic Variable ◽  
X Rays ◽  
Spin Period

AbstractAE Aqr is a cataclysmic variable consisting of a magnetised white dwarf with a spin period of 33 s, and a K-dwarf companion. Because of the rapid spin the magnetosphere of the white dwarf the matter that is flowing over from the secondary cannot accrete onto the white dwarf, and rather it is ejected from the system. AE Aqr is subject to extended flaring activity at all wavelengths from radio via optical to X-rays. I present observations of AE Aqr at 345 and 850 GHz using the LABOCA and SABOCA bolometers on APEX. These observations are good enough to distinguish individual flares at both 345 and 850 GHz, and the SABOCA observation is the first measurement of the system at 850 GHz.

scholarly journals Recycling Pulsars: spins, masses and ages

2012 ◽  
Vol 8 (S291) ◽  
pp. 137-140 ◽  
Author(s):  
T. M. Tauris ◽  
M. Kramer ◽  
N. Langer
Keyword(s):  
White Dwarf ◽  
Formation Process ◽  
Intermediate Mass ◽  
Millisecond Pulsars ◽  
X Ray ◽  
Spin Period ◽  
X Ray Binaries

AbstractAlthough the first millisecond pulsars (MSPs) were discovered 30 years ago we still do not understand all details of their formation process. Here, we present new results from Tauris, Langer & Kramer (2012) on the recycling scenario leading to radio MSPs with helium or carbon-oxygen white dwarf companions via evolution of low- and intermediate mass X-ray binaries (LMXBs, IMXBs). We discuss the location of the spin-up line in the PṖ–diagram and estimate the amount of accreted mass needed to obtain a given spin period and compare with observations. Finally, we constrain the true ages of observed recycled pulsars via calculated isochrones in the PṖ–diagram.

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