The magnification bias of large-scale structures, combined with galaxy biasing, leads to a cross-correlation of distant quasars with foreground galaxies on angular scales of the order of arc minutes and larger. The amplitude and angular shape of the cross-correlation function wQG contain information on cosmological parameters and the galaxy bias factor. While the existence of this cross-correla...

Continuous data recorded at 39 broadband stations near the Longmen Shan Fault operated by the China Earthquake Administration from 1 January 2008 to 30 September 2010 are used to study temporal variability in direct surface wave arrivals extracted from ambient noise. We use a cross-correlation technique to compute Empirical green functions (EGFs) for all available station pairs at the frequency...

We present the results of simultaneous optical multi-color observations of BL Lac object 0716+714 in November 2014 and February 2016. The intra-day variability (IDV) varies from 0.04 to 0.3 mags. Both achromatic and bluer-when-brighter (BWB) color behaviors were detected. A probable quasi-periodic oscillation overlapping on a significant flare was also observed. We used the interpolated cross-c...

Algerian eddies are the strongest and largest propagating mesoscale structures in the Western Mediterranean Sea. They have a large influence on the mean circulation, water masses and biological processes. Over 20 years of satellite altimeter data have been analyzed to characterize the propagation of these eddies using automatic detection methods and cross-correlation analysis. We found that, on...

We propose observations of the molecular gas distribution during the era of reionization. At z ∼ 6 to 8, 12CO(J = 1 − 0) line intensity results in a mean brightness temperature of about 0.5 μK with rms fluctuations of 0.1 μK at 1 to 10 Mpc spatial scales, corresponding to 30 arcminute angular scales. This intensity fluctuations can be mapped with an interferometer, similar to existing and plann...

We report the results from recent observations of Sgr A* at short-/submillimeter wavelengths made with the partially finished Sub-Millimeter Array (SMA) on Mauna Kea. A total of 25 epochs of observations were carried out over the past 15 months in 2001 March to 2002 May. Noticeable variations in flux density at 1.3 mm were observed showing three “flares”. The SMA observations suggest that Sgr A...

Models for spatial autocorrelation and cross-correlation depend on the distance and direction separating two locations, and are constrained so that for all possible sets of locations, the covariance matrices implied from the models remain nonnegative-definite. Based on spatial correlation, optimal linear predictors can be constructed that yield complete maps of spatial fields from incomplete an...

It is known that the dependence of the emission-line luminosity of a typical cloud in the AGN broad-line regions upon the incident flux of ionizing continuum can be nonlinear. We study how this nonlinearity should be taken into account in estimating the size of the BLR by means of the “reverberation” methods. We show that the BLR size estimates obtained by cross-correlation of emission-line and...

We report the results from recent observations of Sgr A* at short-/submillimeter wavelengths made with the partially finished Sub-Millimeter Array (SMA) on Mauna Kea. A total of 25 epochs of observations were carried out over the past 15 months in 2001 March to 2002 May. Noticeable variations in flux density at 1.3 mm were observed showing three “flares”. The SMA observations suggest that Sgr A...