ALMA Measurement of 10 kpc-scale Lensing Power Spectra towards the Lensed Quasar MG J0414+0534

We report the first measurement of lensing power spectra for gravitational potential, astrometric shifts, and convergence perturbations towards the anomalous quadruply lensed quasar MG$\,$J0414+0534. To obtain the spectra, we conducted observations of MG$\,$J0414+0534 using the Atacama Large Millimeter/submillimeter Array (ALMA) with high angular resolution (0.02"-0.05"). We developed a new partially non-parametric method in which Fourier coefficients of potential perturbation are adjusted to minimise the difference between linear combinations of weighted mean de-lensed images. Using positions of radio jet components, extended dust emission on scales $>1\,$kpc, and mid-infrared flux ratios, which are microlensing free, our new multi-wavelength method provides us with a very effective tool for probing cosmological matter fluctuations on scales $< 10\,$kpc. Assuming that contributions from structures on angular scales <1.0" are negligible, on an angular scale of $\sim$1.3" (corresponding to an angular wave number of $l \sim 1.1\times 10^6$ or $\sim 8\,$kpc in the lens plane), the measured convergence, astrometric shift, and potential powers are $\varDelta_\kappa=0.021-0.028$, $\varDelta_\alpha =7-9\,$mas, and $\varDelta_\psi=1.2-1.6\,$$\textrm{mas}^2$, respectively. Our result is consistent with the predicted abundance of haloes in the line of sight and subhaloes in cold dark matter models. Our partially non-parametric lens models suggest a presence of a clump in the vicinity of object Y, a possible dusty dwarf galaxy and some small clumps in the vicinity of lensed quadruple images. Although much fainter than the previous report, we confirmed weak continuum emission from object Y with a peak flux of $\sim 100\,\mu \textrm{Jy}\, \textrm{beam} ^{-1}$ at the $\sim 4\,\sigma$ level.Comment: 29 pages, 35 figures, analyses of models with a possible dwarf galaxy, object Y and that of chi^2 fit in the visibility plane were adde

The Interpretation of Near-Infrared Star Counts at the South Galactic Pole

We present new deep $K'$ counts of stars at the South Galactic Pole (SGP) taken with the NAOJ PICNIC camera to $K'=17.25$. Star-galaxy separation to $K'=17.5$ was accomplished effectively using image profiles because the pixel size we used is 0.509 arcsec. We interpret these counts using the SKY (Cohen 1994) model of the Galactic point source sky and determine the relative normalization of halo-to-disk populations, and the location of the Sun relative to the Galactic plane, within the context of this model. The observed star counts constrain these parameters to be: halo/disk $\sim$ 1/900 and z$_\odot$=16.5$\pm$2.5 pc. These values have been used to correct our SGP galaxy counts for contamination by the point source Galactic foreground.Comment: accepted for publication in AJ, 15 pages with 2 figure

Variation of Inner Radius of Dust Torus in NGC4151

The long-term optical and near infrared monitoring observations for a type 1 act ive galactic nucleus NGC 4151 were carried out for six years from 2001 to 2006 b y using the MAGNUM telescope, and delayed response of flux variations in the $K(2.2\mu m)$ band to those in the $V(0.55\mu m)$ band was clearly detected. Based on cross correlation analysis, we precisely measured a lag time $\Delta t$ for eight separate periods, and we found that $\Delta t$ is not constant changing be tween 30 and 70 days during the monitoring period. Since $\Delta t$ is the ligh t travel time from the central energy source out to the surrounding dust torus, this is the first convincing evidence that the inner radius of dust torus did ch ange in an individual AGN. In order to relate such a change of $\Delta t$ with a change of AGN luminosity $L$, we presented a method of taking an average of th e observed $V$-band fluxes that corresponds to the measured value of $\Delta t$, and we found that the time-changing track of NGC 4151 in the $\Delta t$ versus $L$ diagram during the monitoring period deviates from the relation of $\Delta t \propto L^{0.5}$ expected from dust reverberation. This result, combined with t he elapsed time from period to period for which $\Delta t$ was measured, indicat es that the timescale of dust formation is about one year, which should be taken into account as a new constraint in future studies of dust evolution in AGNs.Comment: 5 pages, 3 figures, To appear in the ApJ Lette