Daisuke Yonetoku

Kanazawa University, Kanazawa, Ishikawa, Japan

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Publications (95)149.93 Total impact

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    ABSTRACT: We are now investigating and studying a small satellite mission HiZ-GUNDAM for future observation of gamma-ray bursts (GRBs). The mission concept is to probe "the end of dark ages and the dawn of formation of astronomical objects", i.e. the physical condition of early universe beyond the redshift z > 7. We will consider two kinds of mission payloads, (1) wide field X-ray imaging detectors for GRB discovery, and (2) a near infrared telescope with 30 cm in diameter to select the high-z GRB candidates effectively. In this paper, we explain some requirements to promote the GRB cosmology based on the past observations, and also introduce the mission concept of HiZ-GUNDAM and basic development of X-ray imaging detectors.
    06/2014;
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    ABSTRACT: Using 72 Short Gamma Ray Bursts (SGRBs) with well determined spectral data observed by BATSE, we determine their redshift and the luminosity by applying $E_p$--$L_p$ correlation for SGRBs found by Tsutsui et al. (2013). For 53 SGRBs with the observed flux brighter than $4 \times 10^{-6}~{\rm erg~cm^{-2}s^{-1}}$, the cumulative redshift distribution up to $z=1$ agrees well with that of 22 Swift SGRBs. Especially good agreement is seen for $z < 0.4$ with the KS chance probability of 5.3\%. This suggests that the redshift determination by the $E_p$--$L_p$ correlation for SGRBs works very well. The minimum event rate at $z=0$ is estimated as $R_{\rm on-axis}^{\rm min} = 2 \times 10^{-10}~{\rm events~Mpc^{-3}yr^{-1}}$ so that the minimum beaming angle is $0.57^\circ-3.6^\circ$ assuming the merging rate of $10^{-7}-4\times 10^{-6}~{\rm events~yr^{-1}galaxy^{-1}}$ suggested from the binary pulsar data. Interestingly, this angle is consistent with that for SGRB~130603B of $\sim 4^\circ-8^\circ$ (Fong et al. 2013). On the other hand, if we assume the beaming angle of $\sim 6^\circ$ suggested from four SGRBs, the minimum event rate including off-axis SGRBs is estimated as $R_{\rm all}^{\rm min}\sim 4\times 10^{-8}~{\rm events~Mpc^{-3}yr^{-1}}$. If SGRBs are induced by coalescence of binary neutron stars (NSs) and/or black holes (BHs), this event rate leads to the minimum gravitational-wave detection rate of $\rm 1.3 (50)~events~yr^{-1}$ for NS-NS (NS-BH) binary, respectively, by KAGRA, adv-LIGO, adv-Virgo and GEO network.
    The Astrophysical Journal 02/2014; 789(1). · 6.73 Impact Factor
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    ABSTRACT: We evaluate the exposure during nadir observations with JEM-EUSO, the Extreme Universe Space Observatory, on-board the Japanese Experiment Module of the International Space Station. Designed as a mission to explore the extreme energy Universe from space, JEM-EUSO will monitor the Earth's nighttime atmosphere to record the ultraviolet light from tracks generated by extensive air showers initiated by ultra-high energy cosmic rays. In the present work, we discuss the particularities of space-based observation and we compute the annual exposure in nadir observation. The results are based on studies of the expected trigger aperture and observational duty cycle, as well as, on the investigations of the effects of clouds and different types of background light. We show that the annual exposure is about one order of magnitude higher than those of the presently operating ground-based observatories.
    05/2013;
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    ABSTRACT: We report the strictest observational verification of CPT invariance in the photon sector, as a result of γ-ray polarization measurement of distant gamma-ray bursts (GRBs), which are the brightest stellar-sized explosions in the Universe. We detected γ-ray polarization of three GRBs with high significance levels, and the source distances may be constrained by a well-known luminosity indicator for GRBs. For the Lorentz- and CPT-violating dispersion relation E_{±}^{2}=p^{2}±2ξp^{3}/M_{Pl}, where ± denotes different circular polarization states of the photon, the parameter ξ is constrained as |ξ|<O(10^{-15}). Barring precise cancellation between quantum gravity effects and dark energy effects, the stringent limit on the CPT-violating effect leads to the expectation that quantum gravity presumably respects the CPT invariance.
    Physical Review Letters 12/2012; 109(24):241104. · 7.73 Impact Factor
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    ABSTRACT: The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the high-energy universe via a suite of four instruments, covering a very wide energy range, from 0.3 keV to 600 keV. These instruments include a high-resolution, high-throughput spectrometer sensitive over 0.3-2 keV with high spectral resolution of Delta E < 7 eV, enabled by a micro-calorimeter array located in the focal plane of thin-foil X-ray optics; hard X-ray imaging spectrometers covering 5-80 keV, located in the focal plane of multilayer-coated, focusing hard X-ray mirrors; a wide-field imaging spectrometer sensitive over 0.4-12 keV, with an X-ray CCD camera in the focal plane of a soft X-ray telescope; and a non-focusing Compton-camera type soft gamma-ray detector, sensitive in the 40-600 keV band. The simultaneous broad bandpass, coupled with high spectral resolution, will enable the pursuit of a wide variety of important science themes.
    10/2012;
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    ABSTRACT: We report a polarization measurement in prompt γ-ray emission of GRB 100826A with the Gamma-Ray Burst Polarimeter (GAP) aboard the small solar power sail demonstrator IKAROS. We detected a firm change of polarization angle (PA) during the prompt emission with 99.9% (3.5 σ) confidence level, and an average polarization degree (Π) of 27 +/- 11% with 99.4% (2.9 σ) confidence level. Here the quoted errors are given at 1 σ confidence level for two parameters of interest. Non-axisymmetric (e.g., patchy) structures of the magnetic fields and/or brightness inside the relativistic jet are therefore required within the observable angular scale of ~ Γ-1. Our observation strongly indicates that the polarization measurement is a powerful tool to constrain the GRB production mechanism, and more theoretical works are needed to discuss the data in more details.
    Proceedings of the International Astronomical Union 09/2012;
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    ABSTRACT: We have studied the morphology of the prompt emission of 36 long gamma-ray bursts with redshifts, well determined spectra by the Band model and 64 msec resolution light curves whose peak counts are 10 times larger than background fluctuations. We parametrize the morphology by the absolute deviation from their constant luminosity (ADCL) and find a clear gap in the distribution, which divides LGRBs into two subclasses: small-ADCL events (<0.17) and large ones (>0.17). We find that two subclasses are apparently separated in the spectral peak energy (Ep) - the peak luminosity (Lp) diagram. The Ep - Lp correlations both for small and large ADCL events are much tighter than the one for the whole events.
    09/2012;
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    ABSTRACT: PolariS (Polarimetry Satellite) is a Japanese small satellite mission dedicated to polarimetry of X-ray and γ-ray sources. The primary aim of the mission is to perform wide band X-ray (4-80 keV) polarimetry of sources brighter than 10 mCrab. For this purpose, Polaris employs three hard X-ray telescopes and two types of focal plane imaging polarimeters. PolariS observations will measure the X-ray polarization for tens of sources including extragalactic ones mostly for the first time. The second purpose of the mission is γ-ray polarimetry of transient sources, such as γ-ray bursts. Wide field polarimeters based on similar concept as that used in the IKAROS/GAP but with higher sensitivity, i.e., polarization measurement of 10 bursts per year, will be employed.
    Proc SPIE 09/2012;
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    ABSTRACT: We report polarization measurements in two prompt emissions of gamma-ray bursts, GRB 110301A and GRB 110721A, observed with the Gamma-ray burst polarimeter (GAP) aboard IKAROS solar sail mission. We detected linear polarization signals from each burst with polarization degree of $\Pi = 70 \pm 22$% with statistical significance of $3.7 \sigma$ for GRB 110301A, and $\Pi = 84^{+16}_{-28}$% with $3.3 \sigma$ confidence level for GRB 110721A. We did not detect any significant change of polarization angle. These two events had shorter durations and dimmer brightness compared with GRB 100826A, which showed a significant change of polarization angle, as reported in Yonetoku et al. (2011). Synchrotron emission model can be consistent with all the data of the three GRBs, while photospheric quasi-thermal emission model is not favorable. We suggest that magnetic field structures in the emission region are globally-ordered fields advected from the central engine.
    The Astrophysical Journal Letters 08/2012; 758(1). · 6.35 Impact Factor
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    ABSTRACT: We estimate the distance modulus to long gamma-ray bursts (LGRBs) using the Type I Fundamental Plane, a correlation between the spectral peak energy $E_{\rm p}$, the peak luminosity $L_{\rm p}$, and the luminosity time $T_{\rm L}$ ($\equiv E_{\rm iso}/L_{\rm p}$ where $E_{\rm iso}$ is isotropic energy) for small Absolute Deviation from Constant Luminosity(ADCL). The Type I Fundamental Plane of LGRBs is calibrated using 8 LGRBs with redshift $z<1.4$. To avoid any assumption on the cosmological model, we use the distance modulus of 557 Type Ia supernovae (SNeIa) from the Union 2 sample. This calibrated Type I Fundamental Plane is used to measure the distance moduli to 9 high-redshift LGRBs with the mean error $\bar \sigma_{\mu}=0.31$, which is comparable with that of SNe Ia $\bar \sigma_{\mu}=0.26$ where $\mu$ stands for the distance modulus. The Type I Fundamental Plane is so tight that our distance moduli have very small uncertainties. From those distance moduli, we obtained the constraint $\Omega_{\rm M}=0.22\pm0.04$ for flat $\Lambda$CDM universe. Adding 9 LGRBs distance moduli ($z>1.4$) to 557 SNeIa distance moduli ($z<1.4$) significantly improves the constraint for non-flat $\Lambda$CDM universe from ($\Omega_{\rm M}, \Omega_{\rm \Lambda}$)=($0.29\pm0.10$, $0.76\pm0.13$) for SNeIa only to ($\Omega_{\rm M}, \Omega_{\rm \Lambda}$)=($0.23\pm0.06$, $0.68\pm0.08$) for SNeIa and 9 LGRBs.
    05/2012;
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    ABSTRACT: Contributions of the JEM-EUSO Collaboration to the 32nd International Cosmic Ray Conference, Beijing, August, 2011.
    04/2012;
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    ABSTRACT: We argue a new classification scheme of long gamma-ray bursts (LGRBs) using the morphology of the cumulative light curve of the prompt emission. We parametrize the morphology by the absolute deviation from their constant luminosity ($ADCL$) and derive the value for 36 LGRBs which have spectropic redshifts, spectral parameters determined by the Band model, 1-second peak fluxes, fluences, and 64-msec resolution light curves whose peak counts are 10 times larger than background fluctuations. Then we devide the sample according to the value of ADCL into two groups ($ADCL < 0.17$ and $ADCL > 0.17$) and, for each group, derive the spectral peak energy $E_{\rm p}$ - peak luminosity $L_{\rm p}$ correlation and the Fundamental Plane of LGRBs, which is a correlation between the spectral peak energy $E_{\rm p}$, the luminosity time $T_{\rm L}$ ($\equiv E_{\rm iso}/L_{\rm p}$ where $E_{\rm iso}$ is isotropic energy) and the peak luminosity $L_{\rm p}$. We find that both of the correlations for both groups are statistically more significant compared with ones derived from all samples. The Fundamental Planes with small and large ADCL are given by $L_{\rm p}=10^{52.53\pm 0.01}(E_{\rm p}/10^{2.71}{\rm keV})^{1.84\pm 0.03} (T_{\rm L}/10^{0.86}{\rm sec})^{0.29\pm0.08}$ with $\chi^2_{\nu}=10.93/14$ and $L_{\rm p}=10^{52.98\pm0.08}(E_{\rm p}/10^{2.71}{\rm keV})^{1.82\pm 0.09} (T_{\rm L}/10^{0.86}{\rm sec})^{0.85\pm 0.27}$ with $\chi^2_{\nu}=7.58/8$, respectively. This fact implies the existence of subclasses of LGRBs characterized by the value of $ADCL$. Also there is a hint for the existence of the intermediate-$ADCL$ class which deviates from both fundamental planes. Both relations are so tight that our result provides a new accurate distance measurement scheme up to the high redshift universe.
    Publications- Astronomical Society of Japan 01/2012; · 2.44 Impact Factor
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    ABSTRACT: We collect and reanalyze about 200 GRB data of prompt-emission with known redshift observed until the end of 2009, and select 101 GRBs which were well observed to have good spectral parameters to determine the spectral peak energy ($E_p$), 1-second peak luminosity ($L_p$) and isotropic energy ($E_{\rm iso}$). Using our newly-constructed database with 101 GRBs, we first revise the $E_p$--$L_p$ and $E_p$--$E_{\rm iso}$ correlations. The correlation coefficients of the revised correlations are 0.889 for 99 degree of freedom for the $E_p$--$L_p$ correlation and 0.867 for 96 degree of freedom for the $E_p$--$E_{\rm iso}$ correlation. These values correspond to the chance probability of $2.18 \times 10^{-35}$ and $4.27 \times 10^{-31}$, respectively. It is a very important issue whether these tight correlations are intrinsic property of GRBs or caused by some selection effect of observations. In this paper, we examine how the truncation of the detector sensitivity affects the correlations, and we conclude they are surely intrinsic properties of GRBs. Next we investigate origins of the dispersion of the correlations by studying their brightness and redshift dependence. Here the brightness (flux or fluence) dependence would be regarded as an estimator of the bias due to the detector threshold. We find a weak fluence-dependence in the $E_p$--$E_{\rm iso}$ correlations and a redshift dependence in the $E_p$--$L_p$ correlation both with 2 $\sigma$ statistical level. These two effects may contribute to the dispersion of the correlations which is larger than the statistical uncertainty. We discuss a possible reason of these dependence and give a future prospect to improve the correlations.
    Publications- Astronomical Society of Japan 01/2012; 62. · 2.44 Impact Factor
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    ABSTRACT: We report the polarization measurement in prompt γ-ray emission of GRB 100826A with the Gamma-Ray Burst Polarimeter on board the small solar-power-sail demonstrator IKAROS. We detected the firm change of polarization angle (PA) during the prompt emission with 99.9% (3.5σ) confidence level, and the average polarization degree (Π) of 27% ± 11% with 99.4% (2.9σ) confidence level. Here the quoted errors are given at 1σ confidence level for the two parameters of interest. The systematic errors have been carefully included in this analysis, unlike other previous reports. Such a high Π can be obtained in several emission models of gamma-ray bursts (GRBs), including synchrotron and photospheric models. However, it is difficult to explain the observed significant change of PA within the framework of axisymmetric jet as considered in many theoretical works. The non-axisymmetric (e.g., patchy) structures of the magnetic fields and/or brightness inside the relativistic jet are therefore required within the observable angular scale of ~Γ–1. Our observation strongly indicates that the polarization measurement is a powerful tool to constrain the GRB production mechanism, and more theoretical works are needed to discuss the data in more detail.
    The Astrophysical Journal Letters 11/2011; 743(2):L30. · 6.35 Impact Factor
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    ABSTRACT: The small solar power sail demonstrator “IKAROS” is a Japanese engineering verification spacecraft launched by H‐IIA rocket on May 21, 2010 at JAXA Tanegashima Space Center. IKAROS has a 20 m diameter sail which is made of thin polyimide membrane. This sail converts the solar radiation‐pressure into the propulsion force of IKAROS and accelerates the spacecraft. The Gamma‐Ray Burst Polarimeter (GAP) aboard IKAROS is the first polarimeter specifically designed to measure the polarization of Gamma‐Ray Bursts (GRBs) from space, and will do so in the cruising phase of the IKAROS mission. GAP is a modest detector of 3.8 kg in weight and 17 cm in size with an energy range between 50–300 keV. The GAP detector can be a member of the interplanetary network (IPN) for the determination of the GRB direction. The detection principle of gamma‐ray polarization is the anisotropy of the Compton scattering. Coincidence between the central plastic Compton scattering medium and discrete CsI detectors distributed around the sides of the plastic defines the Compton scattering angle, which is expected to show an angular dependence if polarization is present in a given GRB. We presented the GAP detector and its ground and onboard calibrations.
    AIP Conference Proceedings. 08/2011; 1358(1):408-411.
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    ABSTRACT: The accuracy and reliability of gamma-ray bursts (GRBs) as distance indicators are strongly restricted by their systematic errors which are larger than statistical errors. These systematic errors might come from either intrinsic variations of GRBs, or systematic errors in observations. In this paper, we consider the possible origins of systematic errors in the following observables, (i) the spectral peak energies (Ep) estimated by Cut-off power law (CPL) function, (ii) the peak luminosities (Lp) estimated by 1 second in observer time. Removing or correcting them, we reveal the true intrinsic variation of the Ep-TL-Lp relation of GRBs. Here TL is the third parameter of GRBs defined as TL ~ Eiso / Lp. Not only the time resolution of Lp is converted from observer time to GRB rest frame time, the time resolution with the largest likelihood is sought for. After removing obvious origin of systematic errors in observation mentioned above, there seems to be still remain some outliers. For this reason, we take account another origin of the systematic error as below, (iii) the contamination of short GRBs or other populations. To estimate the best fit parameters of the Ep-TL-Lp relations from data including outliers, we develop a new method which combine robust regression and an outlier identification technique. Using our new method for 18 GRBs with {\sigma}Ep/Ep < 0.1, we detect 6 outliers and find the Ep-TL-Lp relation become the tightest around 3 second.
    Publications- Astronomical Society of Japan 06/2011; 63. · 2.44 Impact Factor
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    ABSTRACT: We reconsider correlations among the spectral peak energy ($E_p$), 1-second peak luminosity ($L_p$) and isotropic energy (\Eiso), using the database constructed by \citet{yonetoku10} which consists of 109 Gamma-Ray Bursts (GRBs) whose redshifts are known and $E_p$, $L_p$ and \Eiso are well determined. We divide the events into two groups by their data quality. One (gold data set) consists of GRBs with peak energies determined by the Band model with four free parameters. On the other hand, GRBs in the other group (bronze data set) have relatively poor energy spectra so that their peak energies were determined by the Band model with fixed spectral index (i.e. three free parameters) or by the Cut-off power law (CPL) model with three free parameters. Using only the gold data set we found the intrinsic dispersion in $\log L_p$ ($=\sigma_{\rm int}$) is 0.13 and 0.22 for \tsutsui correlation ($T_L \equiv E_{\rm iso}/L_p$) and \yonetoku correlation, respectively. We also find that GRBs in the bronze data set have systematically larger $E_p$ than expected by the correlations constructed with the gold data set. This means that the intrinsic dispersion of correlations among $E_p$, $L_p$, and \Eiso of GRBs depends on the quality of data set. At present, using \tsutsui correlation with gold data set, we would be able to determine the luminosity distance with $\sim 16%$ error, which might be useful to determine the nature of the dark energy at high redshift $z > 3$. Comment: 11 pages, 1 figure, submitted to ApJ Letter
    12/2010;
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    ABSTRACT: The small solar power sail demonstrator "IKAROS" is a Japanese engineering verification spacecraft launched by H-IIA rocket on May 21, 2010 at JAXA Tanegashima Space Center. IKAROS has a huge sail with 20 m in diameter which is made of thin polyimide membrane. This sail converts the solar radiation-pressure into the propulsion force of IKAROS and accelerates the spacecraft. The Gamma-Ray Burst Polarimeter (GAP) aboard IKAROS is the first polarimeter to observe the gamma-ray polarization of Gamma-Ray Bursts (GRBs) during the IKAROS cruising phase. GAP is a tinny detector of 3.8 kg in weight and 17 cm in size with an energy range between 50-300 keV. The GAP detector also plays a role of the interplanetary network (IPN) to determine the GRB direction. The detection principle of gamma-ray polarization is the anisotropy of the Compton scattering. GAP works as the GRB polarimeter with the full coincidence mode between the central plastic and the surrounding CsI detectors. GAP is the first instrument, devoted for the observation of gamma-ray polarization in the astronomical history. In this paper, we present the GAP detector and its ground and onboard calibrations. Comment: Submitted to Publications of the Astronomical Society of Japan (PASJ), 23 pages, 14 figures
    Publications- Astronomical Society of Japan 10/2010; · 2.44 Impact Factor
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    ABSTRACT: The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the high-energy universe by performing high-resolution, high-throughput spectroscopy with moderate angular resolution. ASTRO-H covers very wide energy range from 0.3 keV to 600 keV. ASTRO-H allows a combination of wide band X-ray spectroscopy (5-80 keV) provided by multilayer coating, focusing hard X-ray mirrors and hard X-ray imaging detectors, and high energy-resolution soft X-ray spectroscopy (0.3-12 keV) provided by thin-foil X-ray optics and a micro-calorimeter array. The mission will also carry an X-ray CCD camera as a focal plane detector for a soft X-ray telescope (0.4-12 keV) and a non-focusing soft gamma-ray detector (40-600 keV) . The micro-calorimeter system is developed by an international collaboration led by ISAS/JAXA and NASA. The simultaneous broad bandpass, coupled with high spectral resolution of Delta E ~7 eV provided by the micro-calorimeter will enable a wide variety of important science themes to be pursued. Comment: 18 pages, 12 figures, Proceedings of the SPIE Astronomical Instrumentation "Space Telescopes and Instrumentation 2010: Ultraviolet to Gamma Ray"
    10/2010;

Publication Stats

587 Citations
149.93 Total Impact Points

Institutions

  • 2002–2014
    • Kanazawa University
      • • School of Mathematics and Physics
      • • Department of Physics
      Kanazawa, Ishikawa, Japan
  • 2006
    • Aoyama Gakuin University
      • Department of Physics and Mathematics
      Tokyo, Tokyo-to, Japan
  • 2003
    • The University of Tokyo
      • Department of Physics
      Tokyo, Tokyo-to, Japan
  • 2001–2002
    • Saitama University
      • Department of Physics
      Saitama, Saitama, Japan
  • 2000
    • Nihon Fukushi University
      Kioto, Kyōto, Japan