Search Publications
Hitomi HXT deconvolution imaging of the Crab Nebula dazzled by the Crab pulsar
Maeda, Yoshitomo; Ishida, Manabu; Awaki, Hisamitsu +3 more
We develop a new deconvolution method to recover the precise Crab Nebula image taken by the Hitomi HXT, suppressing the artifact due to the bright Crab pulsar. We extend the Richardson-Lucy method, introducing two components corresponding to the nebula and pulsar with regularization for smoothness and flux, respectively, and performing simultaneou…
Dark matter search in the Perseus cluster with simultaneous analysis of Hitomi and Suzaku data
Kitamoto, Shunji; Sawada, Makoto; Tamura, Takayuki +1 more
The reported detection of a 3.5 keV emission line in the Perseus cluster, possibly originating from dark matter decay, is still under scrutiny. Despite extensive observations, the detection has not yet been confirmed, and its origin remains a topic of active debate. Most of the previous searches relied on spectroscopy with X-ray charge-coupled dev…
Spectral break of energetic pulsar wind nebulae detected with wideband X-ray observations
Terada, Yukikatsu; Uchida, Hiroyuki; Bamba, Aya +4 more
Pulsar wind nebulae (PWNe) are one of the most energetic galactic sources with bright emissions from radio waves to very high-energy gamma-rays. We perform wideband X-ray spectroscopy of four energetic PWNe, N 157 B, PSR J1813-1749, PSR J1400-6325, and G21.5-0.9, with the Suzaku, Chandra, NuSTAR, and Hitomi observatories. A significant spectral br…
An X-ray spectroscopic search for dark matter and unidentified line signatures in the Perseus cluster with Hitomi
Fabian, Andrew C.; Maeda, Yoshitomo; Gandhi, Poshak +14 more
The reported detection of a 3.5 keV emission signal in the Perseus cluster core by Bulbul et al. (2014, ApJ, 789, 13) was ruled out at high confidence in analysis conducted by Aharonian et al. (2017, ApJ, 837, L15) of X-ray spectra at 5 eV energy resolution obtained with the Hitomi observatory Soft X-ray Spectrometer (SXS). Using the same data, we…
Ionization age of iron ejecta in the Galactic Type Ia supernova remnant G306.3-0.9
Uchida, Hiroyuki; Bamba, Aya; Tsuru, Takeshi Go +5 more
We present a 190 ks observation of the Galactic supernova remnant (SNR) G306.3-0.9 with Suzaku. To study ejecta properties of this possible Type Ia SNR, the absolute energy-scale at the Fe-K band was calibrated to a level of uncertainty less than 10 eV by a cross-calibration with the Hitomi microcalorimeter using the Perseus cluster spectra. This …
Poisson vs. Gaussian statistics for sparse X-ray data: Application to the soft X-ray spectrometer
Eckart, Megan E.; Kelley, Richard L.; Kilbourne, Caroline A. +8 more
Reliable results when fitting X-ray data require proper consideration of the statistics involved. We probe the impact of Gaussian versus Poisson statistics at low count levels using both the standard χ2 method and maximum likelihood based on Poisson (C) statistics. The difference is studied and quantified through simulated spectra with …
Atmospheric gas dynamics in the Perseus cluster observed with Hitomi
Done, Chris; Safi-Harb, Samar; Hamaguchi, Kenji +195 more
Extending the earlier measurements reported in Hitomi collaboration (2016, Nature, 535, 117), we examine the atmospheric gas motions within the central 100 kpc of the Perseus cluster using observations obtained with the Hitomi satellite. After correcting for the point spread function of the telescope and using optically thin emission lines, we fin…
Atomic data and spectral modeling constraints from high-resolution X-ray observations of the Perseus cluster with Hitomi
Done, Chris; Safi-Harb, Samar; Hamaguchi, Kenji +192 more
The Hitomi Soft X-ray Spectrometer spectrum of the Perseus cluster, with ∼5 eV resolution in the 2-9 keV band, offers an unprecedented benchmark of the atomic modeling and database for hot collisional plasmas. It reveals both successes and challenges of the current atomic data and models. The latest versions of AtomDB/APEC (3.0.8), SPEX (3.03.00),…
Measurements of resonant scattering in the Perseus Cluster core with Hitomi SXS
Done, Chris; Safi-Harb, Samar; Hamaguchi, Kenji +192 more
Thanks to its high spectral resolution (∼5 eV at 6 keV), the Soft X-ray Spectrometer (SXS) on board Hitomi enables us to measure the detailed structure of spatially resolved emission lines from highly ionized ions in galaxy clusters for the first time. In this series of papers, using the SXS we have measured the velocities of gas motions, metallic…
Hitomi observation of radio galaxy NGC 1275: The first X-ray microcalorimeter spectroscopy of Fe-Kα line emission from an active galactic nucleus
Done, Chris; Safi-Harb, Samar; Hamaguchi, Kenji +191 more
The origin of the narrow Fe-Kα fluorescence line at 6.4 keV from active galactic nuclei has long been under debate; some of the possible sites are the outer accretion disk, the broad line region, a molecular torus, or interstellar/intracluster media. In 2016 February-March, we performed the first X-ray microcalorimeter spectroscopy with the Soft X…