Related papers: Testing microvariability in quasar differential li…
A fast and practical method is described for calculating the microlensed flux variance of an arbitrary source by uncorrelated stars. The required inputs are the mean convergence and shear due to the smoothed potential of the lensing galaxy,…
The variation of a stellar light curve owing to the rotational modulation by the magnetic features (starspots and faculae) on the star's surface can be used to investigate the magnetic properties of the host star. In this paper, we use the…
We use archival data of NASA's Chandra X-ray telescope to compile an X-ray light curve of all four images of the quadruply lensed quasar Q2237+0305 (z=1.695) from January 2006 to January 2007. We fit simulated point spread functions to the…
In this paper we discuss a simple method of testing for the presence of energy-dependent dispersion in high energy data-sets. It uses the minimisation of the Kolmogorov distance between the cumulative distribution of two probability…
The prevalence of multivariate space-time data collected from monitoring networks and satellites, or generated from numerical models, has brought much attention to multivariate spatio-temporal statistical models, where the covariance…
We consider several transitions between narrow lines that have an enhanced sensitivity to a possible variation of the fine structure constant, alpha. This enhancement may allow a search to be performed with an effective suppression of the…
The physical nature of the material responsible for the high--velocity, broad-absorption line features seen in a small fraction of quasar spectra has been the subject of debate since their discovery. This has been especially compounded by…
Our goal is to assess Gaia's performance on the period recovery of short period (p < 2 hours) and small amplitude variability. To reach this goal first we collected the properties of variable stars that fit the requirements described above.…
Many synoptic surveys are observing large parts of the sky multiple times. The resulting lightcurves provide a wonderful window to the dynamic nature of the universe. However, there are many significant challenges in analyzing these light…
Changing-look quasars exhibit dramatic variability in broad emission-line fluxes on short timescales. This behavior is challenging to many models of the quasar broad line region, due in large part to the short transition times between high…
A small fraction of all quasars are strongly lensed and multiply imaged, with usually a galaxy acting as the main lens. Some, maybe all of these quasars are also affected by microlensing, the effects of stellar mass objects in the lensing…
We present numerical studies of two photonic crystal membrane microcavities, a short line-defect cavity with relatively low quality ($Q$) factor and a longer cavity with high $Q$. We use five state-of-the-art numerical simulation techniques…
We present an analysis of 23 absorption systems along the lines of sight towards 18 quasars in the redshift range of $0.4 \leq z_{abs} \leq 2.3$ observed on the Very Large Telescope (VLT) using the Ultraviolet and Visual Echelle…
Recent advances in spectroscopic instrumentation and calibration methods dramatically improve the quality of quasar spectra. Supercomputer calculations show that, at high spectral resolution, procedures used in some previous analyses of…
We use numerical simulations of ray tracing through N-body simulations to investigate weak lensing by large-scale structure. These are needed for testing the analytic predictions of two-point correlators, to set error estimates on them and…
Measurements of the peculiar velocities of large samples of galaxies enable new tests of the standard cosmological model, including determination of the growth rate of cosmic structure that encodes gravitational physics. With the size of…
In our second paper on long-term quasar variability, we employ a much larger database of quasars than in de Vries, Becker & White. This expanded sample, containing 35165 quasars from the Sloan Digital Sky Survey Data Release 2, and 6413…
Quasars have long been known to be variable sources at all wavelengths. Their optical variability is stochastic, can be due to a variety of physical mechanisms, and is well-described statistically in terms of a damped random walk model. The…
Viewing high-redshift sources at near-opposite directions on the sky can assure, by light-travel-time arguments, acausality between their emitted photons. One utility would be true random-number generation, by sensing these via two…
Most inflationary models predict primordial perturbations to be statistically isotropic and homogeneous. Cosmic microwave background (CMB) observations, however, indicate a possible departure from statistical isotropy in the form of a…