相关论文: Cyclostationary in the Time Variable Universe

Astronomical transients are stellar objects that become temporarily brighter on various timescales and have led to some of the most significant discoveries in cosmology and astronomy. Some of these transients are the explosive deaths of…

In biological systems, information is frequently transferred with Poisson like spike processes (shot noise) modulated in time by information-carrying signals. How then to quantify information transfer for the output for such nonstationary…

Pulsars are potentially the most remarkable physical laboratories we will ever use. Although in many senses they are extremely clean systems there are a large number of instabilities and variabilities seen in the emission and rotation of…

The X-ray emission from accreting black-holes and neutron stars features strong variability on sub-second time scales, with very complex and broad phenomenology. From high-frequency quasi-periodic oscillations to rapidly changing X-ray…

We study nonlinear dynamics of superposition of quantum wavepackets in various systems such as Kerr medium, Morse oscillator and bosonic Josephson junction. The prime reason behind this study is to find out how the superposition of states…

Long Period Transients (LPTs) are a recently identified class of sources characterized by periodic radio bursts lasting seconds to minutes, with flux densities that might reach several tens of Jy. These radio bursts repeat with periodicity…

Compact object systems exhibit Quasi-Periodic Oscillations (QPOs) as revealed by peaked features in their power density spectra. It has been known that stochastic variations in the accretion disc will propagate to the corona after a time…

In the past five years observations with the Rossi X-ray Timing Explorer have revealed fast quasi-periodic oscillations in the X-ray flux of about 20 X-ray binaries. Thought to originate close to the surface of a neutron star, these…

Millisecond pulsars in tight binaries have recently opened new challenges in our understanding of physical processes governing the evolution of binaries and the interaction between astrophysical plasma and electromagnetic fields.…

We introduce a model for pulsars in which non-radial oscillations of high spherical degree (l) aligned to the magnetic axis of a spinning neutron star reproduce the morphological features of pulsar beams. In our model, rotation of the…

We report the first results of quasi-simultaneous two passband optical monitoring of six quasi-stellar objects to search for micro-variability. We carried out photometric monitoring of these sources in an alternating sequence of R and V…

Pulsars are often lauded for their (relative) rotational and radio emission stability over long time scales. However, long-term observing programmes are identifying an increasing number of pulsars that deviate from this preconceived notion.…

While a generic open quantum system decays to its steady state, continuous time crystals (CTCs) develop spontaneous oscillation and never converge to a stationary state. Just as crystals develop correlations in space, CTCs do so in time.…

The Rossi X-Ray Timing Explorer (RXTE) has found that the neutron stars in low-mass X-ray binaries exhibit oscillations in the range 300-1200 Hz. Persistent emission may exhibit one or both of two features. In bursts a nearly coherent…

The high-frequency radio sky is bursting with synchrotron transients from massive stellar explosions and accretion events, but the low-frequency radio sky has so far been quiet beyond the Galactic pulsar population and the long-term…

Quasi-periodic oscillations (QPOs) in the X-ray lightcurves of accreting neutron star and black hole binaries have been widely interpreted as being due to standing wave modes in accretion disks. These disks are thought to be highly…

We study the time variations of the cycles of 20 active stars based on decades-long photometric or spectroscopic observations. A method of time-frequency analysis, as discussed in a companion paper, is applied to the data. Fifteen stars…

It is shown that the oscillations of brightness in classical Cepheids and other 'pulsating' variable stars are caused rather by the passing of radial solitary waves through the photosphere of a star, than by pulsations of a star. Radial…

In laboratory studies and numerical simulations, we observe clear signatures of unstable time-periodic solutions in a moderately turbulent quasi-two-dimensional flow. We validate the dynamical relevance of such solutions by demonstrating…

The spin-up of a neutron star crucially depends on the maximum orbital frequency around it, as do a host of other high energy accretion phenomena in low mass X-ray binaries, including quasi-periodic oscillations (QPOs) in the X-ray flux. We…