Search Publications
Gravitational Wave Search through Electromagnetic Telescopes
Kohri, Kazunori; Ito, Asuka; Nakayama, Kazunori
We study the graviton-photon conversion in the magnetic fields of the Earth, the Milky Way, and intergalactic regions. Requiring that the photon flux converted from gravitons does not exceed the observed photon flux with telescopes, we derive upper limits on the stochastic gravitational waves in frequency ranges from 107-1035…
Broad-Band X-Ray Analysis of NGC 3227
Newman, Jared; Tsuruta, Sachiko; Liebmann, Andrew C. +2 more
Previously in Project A we carried out analysis of the data obtained by observations of the 1.5 Seyfert galaxy NGC 3227-the two observations performed by XMM-Newton in 2000 and 2006 and six observations by Suzaku in 2008. In the current paper, Project B, our work was extended to joint XMM-Newton and NuSTAR observations in 2016 as well as a NuSTAR …
Gravitational wave physics and astronomy in the nascent era
Fukazawa, Yasushi; Sugita, Satoshi; Sakamoto, Takanori +50 more
The detections of gravitational waves (GW) by the LIGO/Virgo collaborations provide various possibilities for both physics and astronomy. We are quite sure that GW observations will develop a lot, both in precision and in number, thanks to the continuous work on the improvement of detectors, including the expected new detector, KAGRA, and the plan…
Revisiting the oscillations in the cosmic microwave background angular power spectra at ℓ ∼ 120 in the Planck 2015 data
Ichiki, Kiyotomo; Horiguchi, Koichiro; Yokoyama, Jun'ichi
While the observed nearly scale-invariant initial power spectrum is regarded as favorable evidence of the standard inflationary cosmology, precision observations of the cosmic microwave background anisotropies also suggest possible existence of nontrivial features such as those observed around multipoles ℓ∼120 by WMAP. Here, we examine the Planck …
Distinguishing between inflationary models from cosmic microwave background
Tsujikawa, Shinji
In this paper, inflationary cosmology is reviewed, paying particular attention to its observational signatures associated with large-scale density perturbations generated from quantum fluctuations. In the most general scalar-tensor theories with second-order equations of motion, we derive the scalar spectral index n_s, the tensor-to-scalar ratio r…