A5088240787- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- SAS software applications and methods
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Astronomy and Astrophysical Research
- Radio Astronomy Observations and Technology
- Astro and Planetary Science
- Neutrino Physics Research
- Stellar, planetary, and galactic studies
- Dark Matter and Cosmic Phenomena
- Calibration and Measurement Techniques
- Particle Accelerators and Free-Electron Lasers
- Atmospheric Ozone and Climate
- Galaxies: Formation, Evolution, Phenomena
- Geophysics and Gravity Measurements
- Adaptive optics and wavefront sensing
- Advanced Measurement and Detection Methods
- Organic Light-Emitting Diodes Research
- Precipitation Measurement and Analysis
- Planetary Science and Exploration
- Meteorological Phenomena and Simulations
- Particle Detector Development and Performance
- Historical Astronomy and Related Studies
Hiroshima University
2012-2020
We report the results of a multi-band observing campaign on famous blazar 3C 279 conducted during phase increased activity from 2013 December to 2014 April, including first observations it with NuSTAR. The $\gamma$-ray emission source measured by Fermi-LAT showed multiple distinct flares reaching highest flux level in this object since beginning Fermi mission, $F(E > 100\,{\rm MeV})$ $10^{-5}$ photons cm$^{-2}$ s$^{-1}$, and doubling time scale as short 2 hours. spectrum one was very hard,...
Context. Over the past few years, on several occasions, large, continuous rotations of electric vector position angle (EVPA) linearly polarized optical emission from blazars have been reported. These events are often coincident with high energy γ-ray flares and they attracted considerable attention, since could allow us to probe magnetic field structure in emitting region jet. The flat-spectrum radio quasar 3C 279 is one most prominent examples showing this behaviour.
We report the late-time evolution of Type IIb supernova (SN IIb) 2013df. SN 2013df showed a dramatic change in its spectral features at ∼1 yr after explosion. Early on it typical characteristics shared by SNe IIb/Ib/Ic dominated metal emission lines, while later was broad and flat-topped Hα He i emissions. The spectra are strikingly similar to 1993J, which is only previous example clearly showing same transition. This fully explained energy input from 56Co decay interaction between ejecta...
We have developed an optical and near-infrared instrument HONIR (Hiroshima Optical Near-InfraRed camera) with imaging, spectroscopy, polarimetry capabilities in two (one one near-infrared) bands simultaneously. Imaging capability a field of view 10 arcmin by has been available since 2011, as reported the previous SPIE conference. In addition, spectroscopic polarimetric components (grisms, Wollaston prism, half-wave plate, focal masks) were installed instrument, which enabled us to perform...
We report observations of the Type Iax supernova (SN Iax) 2012Z at optical and near-infrared (NIR) wavelengths from immediately after explosion until ∼260 days maximum luminosity using Optical Infrared Synergetic Telescopes for Education Research Target-of-Opportunity program Subaru Telescope. found that NIR light curve evolutions color are similar to those SNe 2005hk 2008ha. The absolute magnitudes ( mag mag) rate decline (m15(B) very SN mag, m15(B) 1.6 mag), yet differ significantly 2008ha...
We present optical and near-infrared observations of a low-luminosity Type IIP supernova (SN) 2016bkv from the initial rising phase to plateau phase. Our show that end is extended $\gtrsim 140$ days since explosion, indicating this SN takes one longest time finish among SNe (SNe IIP), including (LL) IIP. The line velocities various ions at middle are as low 1,000--1,500 km s$^{-1}$, which lowest even LL These measurements imply ejecta mass in larger than well-studied 2003Z. In early phase,...
We report on optical photopolarimetric results of the radio-loud narrow-line Seyfert 1 (RL-NLSy1) galaxy PMN J0948+0022 2012 December to 2013 February triggered by flux enhancements in near infrared and γ-ray bands. With one-shot polarimetry Hiroshima One-shot Wide field Polarimeter installed Kanata Telescope, we detected very rapid variability polarized-flux (PF) light curve MJD 56281 (2012 20). The rise decay times were about 140 s 180 s, respectively. polarization degree (PD) reached 36%...
We present optical and near-infrared multi-band linear polarimetry of the highly reddened Type Ia supernova (SN) 2014J that appeared in M82. SN exhibits large polarization at shorter wavelengths, e.g., 4.8% B band, which decreases rapidly longer while position angle remains approximately 40° over observed wavelength range. These polarimetric properties suggest is likely predominantly caused by interstellar dust within Further analysis shows peaks a wavelengths much than those obtained for...
Here we report on the results of WEBT photo-polarimetric campaign targeting blazar S5~0716+71, organized in March 2014 to monitor source simultaneously BVRI and near IR filters. The resulted an unprecedented dataset spanning $\sim 110$\,h nearly continuous, multi-band observations, including two sets densely sampled polarimetric data mainly R filter. During campaign, displayed pronounced variability with peak-to-peak variations about $30\%$ "bluer-when-brighter" spectral evolution,...
We report photometric and spectroscopic observations of the nearby Type Ia Supernova (SN Ia) 2012ht from $-15.8$ days to $+49.1$ after $B$-band maximum. The decline rate light curve is $Δm_{15}$($B$)$=1.39~\pm~0.05$ mag, which intermediate between normal subluminous SNe Ia, similar that `transitional' SN 2004eo. spectral line profiles also closely resemble those were able observe at very early phase, when it was still rising about three magnitudes fainter than peak. rise time maximum...
Abstract The Kiso Supernova Survey (KISS) is a high-cadence optical wide-field supernova (SN) survey. primary goal of the survey to catch very early light SN, during shock breakout phase. Detection SN breakouts combined with multi-band photometry obtained other facilities would provide detailed physical information on progenitor stars SNe. performed using 2 $_{.}^{\circ}$2 × field-of-view instrument 1.05-m Schmidt telescope, Wide Field Camera (KWFC). We take 3-min exposure in g-band once...
We present a set of photometric and spectroscopic observations bright Type Ib supernova SN 2012au from -6d until ~+150d after maximum. The shape its early R-band light curve is similar to that an average Ib/c supernova. peak absolute magnitude M_R=-18.7+-0.2 mag, which suggests this belongs very luminous group among supernovae. line velocity He I {\lambda}5876 about 15,000 km/s around maximum, much faster than in typical From the quasi-bolometric luminosity (6.7+-1.3)x10^(42) erg/s, we...
Blazars are highly variable active galactic nuclei which emit radiation at all wavelengths from radio to gamma-rays. Polarized blazars is one key piece of evidence for synchrotron low energies and it also varies dramatically. The polarization interest understanding the origin, confinement, propagation jets. However, even though numerous measurements have been performed, mechanisms behind jet creation, composition variability still debated. We performed simultaneous gamma-ray optical...
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,...
The occurrence of low-amplitude flux variations in blazars on hourly timescales, commonly known as microvariability, is still a widely debated subject high-energy astrophysics. Several competing scenarios have been proposed to explain such occurrences, including various jet plasma instabilities leading the formation shocks, magnetic reconnection sites, and turbulence. In this Letter, we present results our detailed investigation prominent, five-hour-long optical microflare detected during...
We present results of optical polarimetric and multi-band photometric observations for gamma-ray loud narrow-line Seyfert 1 galaxy 1H 0323+342. This object has been monitored by 1.5 m Kanata telescope since 2012 September but following a flux enhancement detected Fermi-LAT on MJD 56483 (2013 July 10) dense follow-up was performed ten 0.5-2.0 telescopes in Japan over one week. The 2-year R_C-band light curve showed clear brightening corresponding to the increase then decayed gradually. high...
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 report on monitoring observations of the TeV gamma-ray binary HESS J0632+057, which were carried out to constrain interaction between Be circumstellar disk and compact object unknown nature, provide for first time high-dispersion (R > 50000) optical spectra in second half orbital cycle, from apastron through periastron. The Halpha, Hbeta, Hgamma line profiles are found exhibit remarkable short-term variability ~1 month after (phase 0.6--0.7), whereas they show little variation near These...
Abstract We performed monitoring observations of a gamma-ray-emitting radio galaxy, NGC 1275, in the X-ray and optical bands with Suzaku/XIS, Kanata telescope, Okayama telescope. The flux nucleus was estimated by imaging spectroscopy hard band. In band, continuum flux, broad H$ \alpha$ line polarization degree were measured. could not find any time variability (2006–2011) (2010–2011) within 30%, regardless recent gamma-ray factor 3. observed very small at $ \sim$ 0.4% showed little...
CTA 102, classified as a flat spectrum radio quasar at z = 1.037, produced an exceptionally bright optical flare in 2012 September. Following the Fermi Large Area Telescope detection of enhanced γ-ray activity, we closely monitored this source and near-infrared bands for 10 subsequent nights using 12 telescopes Japan South Africa. On MJD 56197 (2012 September 27, four to five days after peak flare), polarized flux showed transient increase, while total polarization angle (PA) remained almost...
We present optical and near-infrared observations of the nearby Type Iax supernova (SN) 2014dt from 14 to 410 days after maximum light. The velocities iron absorption lines in early phase indicated that SN showed slower expansion than well-observed SNe 2002cx, 2005hk 2012Z. In late phase, evolution light curve spectra were considerably slower. spectral energy distribution kept roughly same shape ~100 days, bolometric flattened during period. These suggest existence an optically thick...
We present our discovery of dramatic variability in SDSS J1100+4421 by the high-cadence transient survey Kiso Supernova Survey (KISS). The source brightened optical at least a factor three within about half day. Spectroscopic observations suggest that this object is likely narrow-line Seyfert 1 galaxy (NLS1) z=0.840, however with unusually strong narrow emission lines. estimated black hole mass ~ 10^7 Msun implies bolometric nuclear luminosity close to Eddington limit. also extremely...
Abstract We present extensively dense observations of the super-Chandrasekhar supernova (SC SN) candidate SN 2012dn from −11 to +140 d after date its B-band maximum in optical and near-infrared (NIR) wavelengths conducted through OISTER ToO (Optical Infrared Synergetic Telescopes for Education Research Target Opportunity) program. The NIR light curves color evolutions up 35 days provided an excellent match with those another SC 2009dc, providing further support nature as SN. found that...
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%...
We have developed an optical-infrared instrument HONIR (Hiroshima Optical and Near-InfraRed camera) to be attached the 1.5-m Kanata telescope at Higashi-Hiroshima Observatory, Hiroshima University. is a three color (one optical two near-infrared bands among 0.5–2.4 µm) simultaneous imager spectrograph with polarimetry function. The field of view imaging mode 10 arcmin square spatial sampling 0".29. Among planned multipurpose functions, (0.5–1.0 µm 1.15–2.40 function has been installed...