Weak gravitational lensing is a powerful probe of the large-scale cosmic matter distribution. Wide-field galaxy surveys allow us to generate the so-called weak lensing maps, but actual observations suffer from noise due to imperfect measurement of …
Recent developments in compact object astrophysics, especially the discovery of merging neutron stars by LIGO, the imaging of the black hole in M87 by the Event Horizon Telescope, and high- precision astrometry of the Galactic Center at close to the …
We present an overview of a deep transient survey of the COSMOS field with the Subaru Hyper Suprime-Cam (HSC). The survey was performed for the 1.77 deg ultra-deep layer and 5.78 deg deep layer in the Subaru Strategic Program over 6- and 4-month …
When surrounded by a transparent emission region, black holes are expected to reveal a dark shadow caused by gravitational light bending and photon capture at the event horizon. To image and study this phenomenon, we have assembled the Event Horizon …
The Event Horizon Telescope (EHT) is a very long baseline interferometry (VLBI) array that comprises millimeter- and submillimeter-wavelength telescopes separated by distances comparable to the diameter of the Earth. At a nominal operating wavelength …
We present the calibration and reduction of Event Horizon Telescope (EHT) $1.3$ mm radio wavelength observations of the supermassive black hole candidate at the center of the radio galaxy M87 and the quasar 3C 279, taken during the 2017 April 5--11 …
We present the first Event Horizon Telescope (EHT) images of M87, using observations from April 2017 at $1.3$ mm wavelength. These images show a prominent ring with a diameter of $\sim 40$ $\mu$as, consistent with the size and shape of the lensed …
The Event Horizon Telescope (EHT) has mapped the central compact radio source of the elliptical galaxy M87 at $1.3$ mm with unprecedented angular resolution. Here we consider the physical implications of the asymmetric ring seen in the 2017 EHT data. …
We present measurements of the properties of the central radio source in M87 using Event Horizon Telescope data obtained during the 2017 campaign. We develop and fit geometric crescent models (asymmetric rings with interior brightness depressions) …
We propose an image reconstruction method for an X-ray telescope system with an angular resolution booster proposed by Maeda et al. (2018, PASJ, submitted). The system consists of double multi-grid masks in front of an X-ray mirror and an off-focused …