Kumiko Morihana
A5000781337- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Astrophysics and Star Formation Studies
- SAS software applications and methods
- Astro and Planetary Science
- Solar and Space Plasma Dynamics
- Particle Detector Development and Performance
- Particle Accelerators and Free-Electron Lasers
- Adaptive optics and wavefront sensing
- Galaxies: Formation, Evolution, Phenomena
- Calibration and Measurement Techniques
- Magnetic confinement fusion research
- Planetary Science and Exploration
- Nuclear Physics and Applications
- Ionosphere and magnetosphere dynamics
- X-ray Spectroscopy and Fluorescence Analysis
- Methane Hydrates and Related Phenomena
- History and Developments in Astronomy
- Geophysics and Gravity Measurements
- Radio Astronomy Observations and Technology
National Astronomical Observatory of Japan
2022-2024
Subaru (Japan)
2023
Nagoya University
2017-2022
University of Hyogo
2013-2018
RIKEN
2012-2013
Astronomical Observatory
2013
The University of Tokyo
2012
The first detected gravitational wave from a neutron star merger was GW170817. In this study, we present J-GEM follow-up observations of SSS17a, an electromagnetic counterpart SSS17a shows 2.5-mag decline in the $z$-band 1.7 days to 7.7 after merger. Such rapid is not comparable with supernovae light curves at any epoch. color also evolves rapidly and becomes redder for later epochs; $z-H$ changed by approximately 2.5 mag period 0.7 days. evolution both optical brightness are consistent...
Abstract Recent detection of gravitational waves from a neutron star (NS) merger event GW170817 and identification an electromagnetic counterpart provide unique opportunity to study the physical processes in NS mergers. To derive properties ejected material merger, we perform radiative transfer simulations kilonova, optical near-infrared emissions powered by radioactive decays r-process nuclei synthesized merger. We find that observed emission lasting for >10 d is explained 0.03 M⊙...
Abstract The Japan Astrometry Satellite Mission for INfrared Exploration (JASMINE) is a planned M-class science space mission by the Institute of Space and Astronautical Science, Aerospace Agency. JASMINE has two main goals. One Galactic archaeology with Center survey, which aims to reveal Milky Way’s central core structure formation history from Gaia-level (∼25 ${\mu} $as) astrometry in near-infrared (NIR) Hw band (1.0–1.6 $m). other an exoplanet discover transiting Earth-like exoplanets...
We report the results from X-ray studies of newly discovered black hole candidate MAXI J1305-704 based on Suzaku and Swift observations in low/hard high/soft states, respectively. The long observation shows two types clear absorption dips, both which recur a dip interval 9.74 +- 0.04 hours, we identify with orbital period. There is also partially ionized non-dip (persistent) emission state and, very unusually, state. However, this (in states) has substantially lower ionization than that seen...
Abstract “Changing-look active galactic nuclei” (CLAGNs) are known to change their apparent types between 1 and 2, usually accompanied by a drastic in luminosity on timescales of years. However, it is still unclear whether materials broad-line regions (BLRs) CLAGNs appear disappear during the type-transition or remain at same location while line production simply activated deactivated. Here we present our X-ray–optical monitoring results CLAGN, NGC 3516, Suzaku, Swift, ground telescopes,...
Abstract We present optical observations of the Type Ia supernova (SN) 2019ein, starting two days after estimated explosion date. The spectra and light curves show that SN 2019ein belongs to a high-velocity (HV) broad-line group with relatively rapid decline in (Δ m 15 ( B ) = 1.36 ± 0.02 mag) short rise time (15.37 0.55 days). Si ii λ 6355 velocity, associated photospheric component but not detached feature, reached ∼20,000 km s −1 12 before -band maximum. line however, decreased very...
We present the catalog of high Galactic-latitude ($|b|>10^{\circ}$) X-ray sources detected in first 37-month data Monitor All-sky Image (MAXI) / Gas Slit Camera (GSC). To achieve best sensitivity, we develop a background model GSC that well reproduces based on detailed on-board calibration. Source detection is performed through image fit with Poisson likelihood algorithm. The contains 500 objects 4--10 keV band significance $s_{\rm D, 4-10 keV} \geq 7$. limiting sensitivity $\approx...
From 2013 April to 2014 April, we performed an X-ray and optical simultaneous monitoring of the type 1.5 Seyfert galaxy NGC 3516. It employed Suzaku, 5 Japanese ground-based telescopes, Pirka, Kiso Schmidt, Nayuta, MITSuME, Kanata telescopes. The Suzaku observations were conducted seven times with various intervals ranging from days, weeks, months, exposure $\sim50$ ksec each. $B$-band not only covered those almost simultaneously, but also followed source as frequently possible. As a result,...
Abstract γ Cas and its dozen analogs comprise a small but distinct class of X-ray sources. They are early Be-type stars with an exceptionally hard thermal emission. The production mechanism has been under intense debate. Two competing ideas (i) the magnetic activities in Be star disk, (ii) mass accretion onto unidentified white dwarf (WD). We adopt latter as working hypothesis apply physical models developed to describe spectra classical WD binaries containing late-type companion. Models...
Gamma Cassiopeiae is an enigmatic Be star with unusually strong hard X-ray emission. The Suzaku observatory detected six rapid spectral hardening events called "softness dips" in a ~100 ksec duration observation 2011. All the softness dip show symmetric ratio variations, and some of them have flat bottoms apparently due to saturation. spectra are best described by either ~40% or ~70% partial covering absorption kT ~12 keV plasma emission matter neutral hydrogen column density ~2-8e21 cm-2,...
We present simultaneous optical and near-infrared (NIR) polarimetric results for the black hole binary V404 Cygni spanning duration of its 7-day long optically-brightest phase 2015 June outburst. The R Ks-band light curves showed almost same temporal variation except isolated (~30 min duration) orphan flare observed at MJD 57193.54. did not find any significant polarization degree (PD) position angle (PA) in both Ks bands throughout our observations, including NIR flare. show that PD PA are...
We present the early-phase spectra and light curves of broad-lined supernova (SN) 2016coi from $t=7$ to $67$ days after estimated explosion date. This SN was initially reported as a Type Ic (SN Ic-BL). However, we found that up $t=12$ exhibited He~{\sc i} $\lambda$5876, $\lambda$6678, $\lambda$7065 absorption lines. show smoothed blueshifted normal SNe Ib are remarkably similar observed spectrum 2016coi. The line velocities were those Ic-BL significantly faster than Ib. Analyses velocity...
Abstract We report X-ray, optical, and near-infrared monitoring of the new X-ray transient MAXI J1820+070 discovered with on 2018 March 11. Its intensity reached ∼2 crab at 2–20 keV end March, then gradually decreased until middle June. In this period, spectrum was described by Comptonization disk emission, a photon index ∼1.5 an electron temperature ∼50 keV, which is consistent black hole binary in low/hard state. The slightly decreased, increased, increasing flux. source showed significant...
We report a new observation of the Jupiter-family comet 209P/LINEAR during its 2014 return. The is recognized as dust source meteor shower, May Camelopardalids. was apparently inactive at heliocentric distance rh = 1.6 au and showed weak activity < 1.4 au. found an active region <0.001% entire nuclear surface comet's dormant phase. An edge-on image suggests that particles up to 1 cm in size (with uncertainty factor 3-5) were ejected following differential power-law distribution with index...
We present comprehensive spectroscopic and photometric analyses of the intermediate luminosity Type Iax supernova (SN Iax) 2019muj based on multi-band datasets observed through framework OISTER target-of-opportunity program. SN exhibits almost identical characteristics with subluminous SNe 2008ha 2010ae in terms spectral features light curve evolution at early phase, except for peak luminosity. The long-term observations unveil flattening curves late time as seen a luminous 2014dt. This can...
Apparently diffuse X-ray emission has been known to exist along the central quarter of Galactic Plane since beginning astronomy, which is referred as Ridge (GRXE). Recent deep observations have shown that numerous point sources account for a large fraction GRXE in hard band (2-8 keV). However, nature these poorly understood. Using deepest made Chandra Bulge Field (Revnivtsev et al., 2009,2011), we present result coherent photometric and spectroscopic analysis individual purpose constraining...
We conducted an optical and near-infrared polarimetric observation of the highly dormant Jupiter-Family Comet, 209P/LINEAR. Because its low activity, we were able to determine linear polarization degrees coma dust particles nucleus independently, that is Pn = % at α 922 995 for nucleus, Pc coma. detected no significant variation in P phase angle coverage 922–995, which may imply obtained are nearly maximum phase-polarization curves. By fitting with empirical function, values Pmax 30.8% 29.6%...
Abstract The Laser Interferometer Gravitational-wave Observatory Scientific Collaboration and Virgo (LVC) sent out 56 gravitational-wave (GW) notices during the third observing run (O3). Japanese for Gravitational wave ElectroMagnetic follow-up (J-GEM) performed optical near-infrared observations to identify observe an electromagnetic (EM) counterpart. We constructed a web-based system that enabled us obtain share information on candidate host galaxies counterpart, status of our...
ABSTRACT We present high-resolution long-slit spectroscopy of a Balmer-dominated shock in the northeastern limb Cygnus Loop with Subaru high dispersion spectrograph. By setting slit angle along normal, we investigate variations flux and profile H α line from preshock to postshock regions spatial resolution ∼4 × 10 15 cm. The can be represented by narrow (28.9 ± 0.7 km s −1 ) Gaussian diffuse region ahead shock, i.e., photoionization precursor, (33.1 0.2 plus broad (130–230 Gaussians at...
We present the first results on a new black-hole candidate, MAXI J1305–704, observed by MAXI/GSC. The X-ray transient, named as MAXIJ1305–704, was detected MAXI-GSC all-sky survey 2012 April 9 in direction to outer Galactic bulge at $(l,b)=(304_\cdot^\circ 2,-7_\cdot^\circ 6)$. A Swift/XRT follow-up observation confirmed uncatalogued point source, and localized it position $(13^\textrm h06^\textrm m56_\cdot^\textrm s44,-70^\circ27^\prime4.^{\prime\prime}91)$. source continued its activity...
Gamma Cas analog sources are a subset of Be stars that emit intense and hard X-ray emission. Two competing ideas for their production mechanism (a) the magnetic activities star its disk (b) accretion from to an unidentified compact object. Among such sources, Pi Aqr plays pivotal role as it is one only two spectroscopic binaries observed many orbital cycles three with brightness sufficient detailed spectroscopy. Bjorkman et al. (2002) estimated secondary mass > 2.0 Mo optical spectroscopy,...
Abstract We present the results of spectroscopic monitoring FU Orionis type star V960 Mon. Spectroscopic variations an will provide valuable information its physical nature and mechanism outburst. conducted medium-resolution ( R ∼ 10000) observations Mon with 2 m Nayuta telescope at Nishi-Harima Astronomical Observatory, from 2015 January to 2017 January, for 53 nights in total. focused on H α line nearby atomic lines, we detected strength both absorption emission lines. The observed...