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40 results on '"Aharonian, Felix A."'

1. Massive star clusters as the an alternative source population of galactic cosmic rays

Author: Yang, Rui-zhi, Aharonian, Felix, and de Oña Wilhelmi, Emma
Abstract: Extended γ-ray emissions in the vicinity of young star clusters are believed to be produced by the interaction of CRs accelerated therein with the ambient gas. The detailed spatial analysis reveals 1/rtype distribution of CRs, which indicates a continuous injection of CRs in these objects. The hard, ∝E-2.3type power-law energy spectra of parent protons continue up to ∼1 PeV. The efficiency of conversion of kinetic energy of powerful stellar winds to CRs can be as high as 10%. This implies that the young massive stars can operate as effective proton PeVatrons with a major or even dominant contribution to the flux of highest-energy galactic CRs.
Published: 2019
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2. The ASTRO-H (Hitomi) x-ray astronomy satellite

Author: den Herder, Jan-Willem A., Takahashi, Tadayuki, Bautz, Marshall, Takahashi, Tadayuki, Kokubun, Motohide, Mitsuda, Kazuhisa, Kelley, Richard, Ohashi, Takaya, Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steve, Anabuki, Naohisa, Angelini, Lorella, Arnaud, Keith, Asai, Makoto, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Azzarello, Philipp, Baluta, Chris, Bamba, Aya, Bando, Nobutaka, Bautz, Marshall, Bialas, Thomas, Blandford, Roger, Boyce, Kevin, Brenneman, Laura, Brown, Greg, Bulbul, Esra, Cackett, Edward, Canavan, Edgar, Chernyakova, Maria, Chiao, Meng, Coppi, Paolo, Costantini, Elisa, de Plaa, Jelle, den Herder, Jan-Willem, DiPirro, Michael, Done, Chris, Dotani, Tadayasu, Doty, John, Ebisawa, Ken, Eckart, Megan, Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew, Ferrigno, Carlo, Foster, Adam, Fujimoto, Ryuichi, Fukazawa, Yasushi, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi, Gandhi, Poshak, Gilmore, Kirk, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haas, Daniel, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harayama, Atsushi, Harrus, Ilana, Hatsukade, Isamu, Hayashi, Takayuki, Hayashi, Katsuhiro, Hayashida, Kiyoshi, Hiraga, Junko, Hirose, Kazuyuki, Hornschemeier, Ann, Hoshino, Akio, Hughes, John, Ichinohe, Yuto, Iizuka, Ryo, Inoue, Yoshiyuki, Inoue, Hajime, Ishibashi, Kazunori, Ishida, Manabu, Ishikawa, Kumi, Ishimura, Kosei, Ishisaki, Yoshitaka, Itoh, Masayuki, Iwata, Naoko, Iyomoto, Naoko, Jewell, Chris, Kaastra, Jelle, Kallman, Timothy, Kamae, Tuneyoshi, Kara, Erin, Kataoka, Jun, Katsuda, Satoru, Katsuta, Junichiro, Kawaharada, Madoka, Kawai, Nobuyuki, Kawano, Taro, Kawasaki, Shigeo, Khangulyan, Dmitry, Kilbourne, Caroline, Kimball, Mark, King, Ashley, Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kosaka, Tatsuro, Koujelev, Alex, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans, Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lebrun, François, Lee, Shiu-Huang, Leutenegger, Maurice, Limousin, Olivier, Loewenstein, Michael, Long, Knox, Lumb, David, Madejski, Grzegorz, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Masters, Candace, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McGuinness, Daniel, McNamara, Brian, Mehdipour, Missagh, Miko, Joseph, Miller, Jon, Miller, Eric, Mineshige, Shin, Minesugi, Kenji, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Koji, Mori, Hideyuki, Moroso, Franco, Moseley, Harvey, Muench, Theodore, Mukai, Koji, Murakami, Hiroshi, Murakami, Toshio, Mushotzky, Richard, Nagano, Housei, Nagino, Ryo, Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakano, Toshio, Nakashima, Shinya, Nakazawa, Kazuhiro, Namba, Yoshiharu, Natsukari, Chikara, Nishioka, Yusuke, Nobukawa, Masayoshi, Nobukawa, Kumiko, Noda, Hirofumi, Nomachi, Masaharu, O'Dell, Steve, Odaka, Hirokazu, Ogawa, Hiroyuki, Ogawa, Mina, Ogi, Keiji, Ohno, Masanori, Ohta, Masayuki, Okajima, Takashi, Okamoto, Atsushi, Okazaki, Tsuyoshi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frederik, Paltani, Stéphane, Parmar, Arvind, Petre, Robert, Pinto, Ciro, Pohl, Martin, Pontius, James, Porter, F. Scott, Pottschmidt, Katja, Ramsey, Brian, Reynolds, Christopher, Russell, Helen, Safi-Harb, Samar, Saito, Shinya, Sakai, Shin-ichiro, Sakai, Kazuhiro, Sameshima, Hiroaki, Sasaki, Toru, Sato, Goro, Sato, Yoichi, Sato, Kosuke, Sato, Rie, Sawada, Makoto, Schartel, Norbert, Serlemitsos, Peter, Seta, Hiromi, Shibano, Yasuko, Shida, Maki, Shidatsu, Megumi, Shimada, Takanobu, Shinozaki, Keisuke, Shirron, Peter, Simionescu, Aurora, Simmons, Cynthia, Smith, Randall, Sneiderman, Gary, Soong, Yang, Stawarz, Łukasz, Sugawara, Yasuharu, Sugita, Hiroyuki, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takeda, Shin'ichiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tamura, Keisuke, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki, Tashiro, Makoto, Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi, Uchida, Hiroyuki, Uchiyama, Yasunobu, Uchiyama, Hideki, Ueda, Yoshihiro, Ueda, Shutaro, Ueno, Shiro, Uno, Shin'ichiro, Urry, Meg, Ursino, Eugenio, de Vries, Cor, Wada, Atsushi, Watanabe, Shin, Watanabe, Tomomi, Werner, Norbert, Wik, Daniel, Wilkins, Dan, Williams, Brian, Yamada, Takahiro, Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko, Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Yoshida, Atsumasa, Yuasa, Takayuki, Zhuravleva, Irina, and Zoghbi, Abderahmen
Published: 2016
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3. Parametrization of gamma-ray production cross sections for pp interactions in a broad proton energy range from the kinematic threshold to PeV energies.

Author: Kafexhiu, Ervin, Aharonian, Felix, Taylor, Andrew M., and Vila, Gabriela S.
Subjects: *GAMMA rays, *IONIZING radiation, *ELECTROMAGNETIC waves, *MONTE Carlo method, *PARTICLE physics, *PARTICLES (Nuclear physics)
Abstract: Using publicly available Monte Carlo codes as well as compilation of published data on pp interactions for proton kinetic energy below 2 GeV, we parametrize the energy spectra and production rates of γ-rays by simple but quite accurate (⩽ 20%) analytical expressions in a broad range from the kinematic threshold to PeV energies. [ABSTRACT FROM AUTHOR]
Published: 2014
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4. TeV gamma rays from blazars beyond z = 1?

Author: Aharonian, Felix, Essey, Warren, Kusenko, Alexander, and Prosekin, Anton
Subjects: *GAMMA rays, *BL Lacertae objects, *NUCLEAR energy, *REDSHIFT, *ASTRONOMICAL observations, *NUCLEAR counters, UNIVERSE
Abstract: At TeV energies, the gamma-ray horizon of the Universe is limited to redshifts z« 1, and, therefore, any observation of TeV radiation from a source located beyond z = 1 would call for a revision of the standard paradigm. While robust observational evidence for TeV sources at redshifts z 1 is lacking at present, the growing number of TeV blazars with redshifts as large as z -- 0.5 suggests the possibility that the standard blazar models may have to be reconsidered. We show that TeV gamma rays can be observed even from a source at zï 1, if the observed gamma rays are secondary photons produced in interactions of high-energy protons originating from the blazar jet and propagating over cosmologica! distances almost rectilinearly. This mechanism was initially proposed as a possible explanation for the TeV gamma rays observed from blazars with redshifts z ~ 0.2, for which some other explanations were possible. For TeV gamma-ray radiation detected from a blazar with z S 1, this model would provide the only viable interpretation consistent with conventional physics. It would also have far-reaching astronomical and cosmological ramifications. In particular, this interpretation would imply that extragalactic magnetic fields along the line of sight are very weak, in the range 10~17 G < B < 10"14 G, assuming random fields with a correlation length of 1 Mpc, and that acceleration of E > 1017 eV protons in the jets of active galactic nuclei can be very effective. [ABSTRACT FROM AUTHOR]
Published: 2013
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5. Galactic sources of high energy neutrinos

Author: Aharonian, Felix
Subjects: *NEUTRINOS, *ACCELERATION (Mechanics), *PROTONS, *ABSORPTION, *GALACTIC cosmic rays, *PARTICLES (Nuclear physics)
Abstract: The undisputed galactic origin of cosmic rays at energies below the so-called knee implies an existence of a nonthemal population of galactic objects which effectively accelerate protons and nuclei to TeV-PeV energies. The distinct signatures of these cosmic PeVatrons are high energy neutrinos and γ-rays produced through hadronic interactions. While γ-rays can be produced also by directly accelerated electrons, high energy neutrinos provide the most straightforward and unambiguous information about the nucleonic component of accelerated particles. The planned km3-volume class high energy neutrino detectors are expected to be sensitive enough to provide the first astrophysically meaningful probes of potential VHE neutrino sources. This optimistic prediction is based on the recent discovery of high energy γ-ray sources with hard energy spectra extending to 10 TeV and beyond. Amongst the best-bet candidates are two young shell-type supernova remnants – RXJ 1713.7-4946 and RXJ 0852.0-4622, and perhaps also two prominent plerions – the Crab Nebula and Vela X. Because of strong absorption of TeV γ-rays, one may expect detectable neutrino fluxes also from (somewhat fainter) compact TeV γ-ray emitters like the binary systems LS 5039 and LS I+61 303, and, hopefully, also from hypothetical “hidden” or “orphan” neutrino sources. [Copyright &y& Elsevier]
Published: 2011
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6. GAMMA-RAY FLARES FROM RED GIANT/JET INTERACTIONS IN ACTIVE GALACTIC NUCLEI

Author: Barkov, Maxim V., Aharonian, Felix A., and Bosch, Valenti
Abstract: Non-blazar active galactic nuclei (AGNs) have been recently established as a class of gamma-ray sources. M87, a nearby representative of this class, shows fast TeV variability on timescales of a few days. We suggest a scenario of flare gamma-ray emission in non-blazar AGNs based on a red giant (RG) interacting with the jet at the base. We solve the hydrodynamical equations that describe the evolution of the envelope of an RG blown by the impact of the jet. If the RG is at least slightly tidally disrupted by the supermassive black hole, enough stellar material will be blown by the jet, expanding quickly until a significant part of the jet is shocked. This process can render suitable conditions for energy dissipation and proton acceleration, which could explain the detected day-scale TeV flares from M87 via proton-proton collisions. Since the radiation produced would be unbeamed, such an event should be mostly detected from non-blazar AGNs. They may be frequent phenomena, detectable in the GeV-TeV range even up to distances of [?]1 Gpc for the most powerful jets. The counterparts at lower energies are expected to be not too bright. M87, and nearby non-blazar AGNs in general, can be fast variable sources of gamma-rays through RG/jet interactions.
Published: 2010

7. Modeling the Gamma-Ray Emission Produced by Runaway Cosmic Rays in the Environment of RX J1713.7$-$3946

Author: Casanova, Sabrina, Jones, David I., Aharonian, Felix A., Fukui, Yasuo, Gabici, Stefano, Kawamura, Akiko, Onishi, Toshikazu, Rowell, Gavin, Sano, Hidetoshi, Torii, Kazufumi, and Yamamoto, Hiroaki
Abstract: Diffusive shock acceleration in supernova remnants is the most widely invoked paradigm to explain the Galactic cosmic ray spectrum. Cosmic rays escaping from supernova remnants diffuse into the interstellar medium and collide with the ambient atomic and molecular gas. From such collisions gamma-rays are created, which can possibly provide the first evidence of a parent population of runaway cosmic rays. We present model predictions for the GeV to TeV gamma-ray emission produced by the collisions of runaway cosmic rays with the gas in the surroundings of the shell-type supernova remnant RX J1713.7$-$3946. The spectral and spatial distributions of the emission, which depend upon the source age, the source injection history, the diffusion regime, and the distribution of the ambient gas, as mapped by the LAB and NANTEN surveys, are studied in detail. For the surrounding region of RX J1713$-$3946 in particular, we find out that it depends on the energy band one is observing whether one may observe startlingly different spectra or may not detect any enhanced emission with respect to the diffuse emission contributed by background cosmic rays. This result has important implications for current and future gamma-ray experiments.
Published: 2010
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8. Molecular Clouds as Cosmic-Ray Barometers

Author: Casanova, Sabrina, Aharonian, Felix A., Fukui, Yasuo, Gabici, Stefano, Jones, David I., Kawamura, Akiko, Onishi, Toshikazu, Rowell, Gavin, Sano, Hidetoshi, Torii, Kazufumi, and Yamamoto, Hiroaki
Abstract: The advent of high sensitivity, high resolution $\gamma$-ray detectors, together with a knowledge of the distribution of the atomic hydrogen and especially of the molecular hydrogen in the Galaxy on a subdegree scale, creates a unique opportunity to explore the flux of cosmic rays in the Galaxy. We here present the new data on the distribution of the molecular hydrogen from a large region of the inner Galaxy obtained by the NANTEN Collaboration. We then introduce a methodology which aims to provide a test bed for current and future $\gamma$-ray observatories to explore the cosmic-ray flux at various positions in our Galaxy. In particular, for a distribution of molecular clouds, as provided by the NANTEN survey, and local cosmic-ray density as measured at the Earth, we estimate the expected GeV to TeV $\gamma$-ray signal, which can then be compared with observations, and use to test the cosmic-ray flux.
Published: 2010
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9. A Peculiar Jet and Arc of Molecular Gas toward the Rich and Young Stellar Cluster Westerlund 2 and a TeV Gamma Ray Source

Author: Fukui, Yasuo, Furukawa, Naoko, Dame, Thomas M., Dawson, Joanne R., Yamamoto, Hiroaki, Rowell, Gavin P., Aharonian, Felix, Hofmann, Werner, de Oña Wilhelmi, Emma, Minamidani, Tetsuhiro, Kawamura, Akiko, Mizuno, Norikazu, Onishi, Toshikazu, Mizuno, Akira, and Nagataki, Shigehiro
Abstract: We have discovered remarkable jet- and arc-like molecular features toward the rich and young stellar cluster Westerlund 2. The jet has a length of $\sim$100 pc and a width of $\sim$10 pc, while the arc shows a crescent shape with a radius of $\sim$30 pc. These molecular features each have masses of $\sim$10$^{4}M_{\odot}$, and show spatial correlations with the surrounding lower density H igas. The jet also shows an intriguing positional alignment with the core of the TeV gamma-ray source HESS J1023$-$575 and with the MeV/GeV gamma-ray source recently reported by the Fermi collaboration. We argue that the jet and arc are caused by an energetic event in Westerlund 2, presumably due to an anisotropic supernova explosion of one of the most massive member stars. While the origin of the TeV and GeV gamma-ray sources is uncertain, one may speculate that they are related to the same event via relativistic particle acceleration by strong shock waves produced at the explosion or by remnant objects, such as a pulsar wind nebula or a microquasar.
Published: 2009
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10. STUDY OF THE SPECTRAL AND TEMPORAL CHARACTERISTICS OF X-RAY EMISSION OF THE GAMMA-RAY BINARY LS 5039 WITH SUZAKU

Author: Takahashi, Tadayuki, Kishishita, Tetsuichi, Uchiyama, Yasunobu, Tanaka, Takaaki, Yamaoka, Kazutaka, Khangulyan, Dmitry, Aharonian, Felix A., Bosch, Valenti, and Hinton, Jim A.
Abstract: We report on the results from Suzaku broadband X-ray observations of the galactic binary source LS 5039. The Suzaku data, which have continuous coverage of more than one orbital period, show strong modulation of the X-ray emission at the orbital period of this TeV gamma-ray emitting system. The X-ray emission shows a minimum at orbital phase [?]0.1, close to the so-called superior conjunction of the compact object, and a maximum at phase [?]0.7, very close to the inferior conjunction of the compact object. The X-ray spectral data up to 70 keV are described by a hard power law with a phase-dependent photon index which varies within G [?] 1.45- 1.61. The amplitude of the flux variation is a factor of 2.5, but is significantly less than that of the factor [?]8 variation in the TeV flux. Otherwise the two light curves are similar, but not identical. Although periodic X-ray emission has been found from many galactic binary systems, the Suzaku result implies a phenomenon different from the "standard" origin of X-rays related to the emission of the hot accretion plasma formed around the compact companion object. The X-ray radiation of LS 5039 is likely to be linked to very high energy electrons which are also responsible for the TeV gamma-ray emission. While the gamma rays are the result of inverse Compton (IC) scattering by electrons on optical stellar photons, X-rays are produced via synchrotron radiation. Yet, while the modulation of the TeV gamma-ray signal can be naturally explained by the photon-photon pair production and anisotropic IC scattering, the observed modulation of synchrotron X-rays requires an additional process, the most natural one being adiabatic expansion in the radiation production region.
Published: 2009

11. Study of Nonthermal Emission from SNR RX J1713.7-3946 with Suzaku

Author: Tanaka, Takaaki, Uchiyama, Yasunobu, Aharonian, Felix A., Takahashi, Tadayuki, Bamba, Aya, Hiraga, Junko S., Kataoka, Jun, Kishishita, Tetsuichi, Kokubun, Motohide, Mori, Koji, Nakazawa, Kazuhiro, Petre, Robert, Tajima, Hiroyasu, and Watanabe, Shin
Abstract: We present results obtained from a series of observations of the supernova remnant RX J1713.7-3946 by Suzaku. Hard X-rays have been detected up to ~40 keV. The hard X-ray spectra are described by a power law with photon indices of ~3.0, which is larger than those below 10 keV. The combination of the spatially integrated XIS and HXD spectra clearly reveals a spectral cutoff which is linked to the maximum energy of accelerated electrons. The broadband coverage of Suzaku allows us to derive, for the first time, the energy spectrum of parent electrons in the cutoff region. The cutoff energy in the X-ray spectrum indicates that the electron acceleration in the remnant proceeds close to the Bohm diffusion limit. We discuss the implications of the spectral and morphological properties of the Suzaku data in the context of the origin of nonthermal emission. The Suzaku X-ray and H.E.S.S. gamma-ray data together hardly can be explained within a pure leptonic scenario. Moreover, the leptonic models require a weak magnetic field, which is inconsistent with the recently discovered X-ray filamentary structures and their short-term variability. The hadronic models with strong magnetic fields provide reasonable fits to the observed spectra, but require special arrangements of parameters to explain the lack of thermal X-ray emission. For morphology studies, we compare the X-ray and TeV gamma-ray surface brightness. We confirm the previously reported strong correlation between X-rays and TeV gamma rays. At the same time, the Suzaku data reveal a deviation from the general tendency, namely, the X-ray emission in the western rims appears brighter than expected from the average X-ray to gamma-ray ratio.
Published: 2008

12. Production of TeV Gamma Radiation in the Vicinity of the Supermassive Black Hole in the Giant Radio Galaxy M87

Author: and, Neronov and Aharonian, Felix A.
Abstract: Although the giant radio galaxy M87 harbors many distinct regions of broadband nonthermal emission, the recently reported fast variability of TeV g-rays from M87, on a timescale of days, strongly constrains the range of speculations concerning the possible sites and scenarios of particle acceleration responsible for the observed TeV emission. A natural production site of this radiation is the immediate vicinity of the central supermassive black hole (BH). Because of its low bolometric luminosity, the nucleus of M87 can be effectively transparent for g-rays up to an energy of 10 TeV, which makes this source an ideal laboratory for the study of particle acceleration processes close to the BH event horizon. We critically analyze different possible radiation mechanisms in this region and argue that the observed very high energy g-ray emission can be explained as the inverse Compton emission of ultrarelativistic electron-positron pairs produced through the development of an electromagnetic cascade in the BH magnetosphere. We demonstrate, through detailed numerical calculations of acceleration and radiation of electrons in the magnetospheric vacuum gap, that this "pulsar magnetosphere-like" scenario can satisfactorily explain the main properties of the TeV g-ray emission from M87.
Published: 2007

13. Potential Neutrino Signals from Galactic ?-Ray Sources

Author: Kappes, Alexander, Hinton, Jim, Stegmann, Christian, and Aharonian, Felix A.
Abstract: The recent progress made in Galactic g-ray astronomy using the High Energy Stereoscopic System (H.E.S.S.) instrument provides for the first time a population of Galactic TeV g-rays, and hence potential neutrino sources, for which the neutrino flux can be estimated. Using the energy spectra and source morphologies measured by H.E.S.S., together with new parameterizations of pion production and decay in hadronic interactions, we estimate the signal and background rates expected for these sources in a first-generation water Cerenkov detector (ANTARES) and a next-generation neutrino telescope in the Mediterranean Sea, KM3NeT, with an instrumented volume of 1 km3. We find that the brightest g-ray sources produce neutrino rates above 1 TeV, comparable to the background from atmospheric neutrinos. The expected event rates of the brightest sources in the ANTARES detector make a detection unlikely. However, for a 1 km3 KM3NeT detector, event rates of a few neutrinos per year from these sources are expected, and the detection of individual sources seems possible. Although generally these estimates should be taken as flux upper limits, we discuss the conditions and type of g-ray sources for which the neutrino flux predictions can be considered robust.
Published: 2007

14. The X-Ray Jet in Centaurus A: Clues to the Jet Structure and Particle Acceleration

Author: Kataoka, Jun, Stawarz, Lukasz, Aharonian, Felix, Takahara, Fumio, Ostrowski, Michal, and Edwards, Philip G.
Abstract: We report detailed studies of the X-ray emission from the kiloparsec-scale jet in the nearest active galaxy, Centaurus A. By analyzing the highest quality X-ray data obtained with the Chandra ACIS-S, 41 compact sources (mostly bright jet knots) were found within the jet on angular scales less than 4'', 13 of which were newly identified. We construct the luminosity function for the detected jet knots and argue that the remaining emission is most likely to be truly diffuse, rather than resulting from the sum of many unresolved fainter knots. We subtracted the contributions of the bright knots from the total X-ray jet flux, and show that the remaining extended emission has a relatively flat-topped intensity profile in the transverse jet direction, with the intensity peaking at the jet boundaries between 50'' and 170''. We note that limb-brightened morphologies have been observed previously at radio frequencies in a few FR I and FR II jet sources, but never so clearly at higher photon energies. Our result therefore supports a stratified jet model, consisting of a relativistic outflow including a boundary layer with a velocity shear. In addition, we found that the X-ray spectrum of the diffuse component is almost uniform across and along the jet, with an X-ray energy spectral index of aX [?] 1, similar to those observed in the compact knots. We discuss this spectral behavior within a framework of shock and stochastic particle acceleration processes, connected with the turbulent, supersonic, and nonsteady nature of the relativistic outflow. We note some evidence for a possible spectral hardening at the outer sheath of the jet, and manifesting itself in observed X-ray spectra of aX < 0.5 in the most extreme cases. Due to the limited photon statistics of the present data, further deep observations of Centaurus A are required to determine the reality of this finding; however, we note that the existence of the hard X-ray features at outer jet boundaries would provide an important challenge to theories for the evolution of ultrarelativistic particles within extragalactic jets.
Published: 2006

15. Neutrinos from Accreting Neutron Stars

Author: Anchordoqui, Luis A., Torres, Diego F., McCauley, Thomas P., Romero, Gustavo E., and Aharonian, Felix A.
Abstract: The magnetospheres of accreting neutron stars develop electrostatic gaps with huge potential drops. Protons and ions, accelerated in these gaps along the dipolar magnetic field lines to energies greater than 100 TeV, can impact onto the surrounding accretion disk. A proton-induced cascade develops, and charged pion decays produce n emission. With extensive disk shower simulations using DPMJET and GEANT4, we have calculated the resulting n spectrum. We show that the spectrum produced out of the proton beam is a power law. We use this result to propose accretion-powered X-ray binaries (with highly magnetized neutron stars) as a new population of pointlike n sources for kilometer-scale detectors such as ICECUBE. As a particular example, we discuss the case of A0535+26. We show that ICECUBE should find A0535+26 to be a periodic n source, one for which the formation and loss of its accretion disk can be fully detected. Finally, we comment briefly on the possibility that smaller telescopes such as AMANDA could also detect A0535+26 by folding observations with the orbital period.
Published: 2003

16. Flat Spectrum X-Ray Emission from the Direction of a Molecular Cloud Associated with SNR RX J1713.7–3946

Author: Uchiyama, Yasunobu, Takahashi, Tadayuki, and Aharonian, Felix A.
Abstract: We report on the discovery of a diffuse X-ray source with ASCA, presumably associated with a molecular cloud in the vicinity of the supernova remnant RX J1713.7$-$3946. The energy spectrum (1–10 keV) of the hard X-ray source shows a flat continuum, which is described by a power-law with a photon index of $ \Gamma = 1.0^{+0.4}_{-0.3}$. We argue that this unusually flat spectrum can be best interpreted in terms of characteristic bremsstrahlung emission from the loss-flattened distribution of either sub-relativistic protons or mildly relativistic electrons. The strong shock of RX J1713.7$-$3946, which is likely to interact with the molecular cloud, as evidenced by CO-line observations, seems to be a natural site of acceleration of such nonthermal particles. The observed luminosity of $ L_\mathrm{X} = 1.7 \times 10^{35} \,\mathrm{erg} \,\mathrm{s}^{-1}$(for a distance of 6 kpc) seems to require a huge kinetic energy of about $ 10^{50} \,\mathrm{erg}$in the form of nonthermal particles to illuminate the cloud. The shock-acceleration at RX J1713.7$-$3946 can barely satisfy this energetic requirement, unless (i) the source is located much closer than the preferred distance of 6 kpc and/or (ii) the mechanical energy of the supernova explosion essentially exceeds $ 10^{51} \,\mathrm{erg}$. Another possibility would be that an essential part of the lost energy due to the ionization and heating of gas, is somehow converted to plasma waves, which return this energy to nonthermal particles through their turbulent reacceleration on the plasma waves.
Published: 2002
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17. LHAASO: A PeVatrons explorer

Author: Aharonian, Felix A.
Published: 2021
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18. Probing the sea of galactic cosmic rays with Fermi-LAT.

Author: Aharonian, Felix, Peron, Giada, Ruizhi Yang, Casanova, Sabrina, and Zanin, Roberta
Subjects: *GALACTIC cosmic rays, *COSMIC rays, *MOLECULAR clouds, *GALACTIC center, *SPECTRAL energy distribution, *SEA level
Abstract: High energy γ-rays from giant molecular clouds (GMCs) carry direct information about the spatial and energy distributions of galactic cosmic rays (CRs). The recently released catalogs of GMCs contain sufficiently massive clouds to be used as barometers for probing, through their γ-ray emission, the density of CRs throughout the galactic disk. Based on the data of Fermi-LAT, we report the discovery of γ-ray signals from nineteen GMCs located at distances up to 12.5 kpc. The galactocentric radial distribution of the CR density derived from the γ-ray and CO observations of these objects, as well as from some nearby clouds that belong to the Gould Belt complex, unveil a homogeneous "sea" of CRs with a constant density and spectral shape close to the flux of directly (locally) measured CRs. This concerns the galactocentric distances exceeding 8 kpc, as well as the Sagittarius B complex, in the region of the Galactic Center. On the other hand, for the galactocentric distances between 4 and 8 kpc, we found noticeable deviations from the CR sea level; in some locations, GMCs are characterized by enhanced CR density. This could be the result of a possible global increase of the level of the CR sea towards the Galactic Center and/or by the presence of recent CR accelerators close to some specific clouds. [ABSTRACT FROM AUTHOR]
Published: 2020
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19. Foreword

Author: Völk, Heinz and Aharonian, Felix
Published: 1996
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20. Interpretation of the excess of antiparticles within a modified paradigm of galactic cosmic rays.

Author: Ruizhi Yang and Aharonian, Felix
Subjects: *GALACTIC cosmic rays, *COSMIC rays, *POSITRONS, *ANTIPARTICLES, *GALACTIC nuclei, *STELLAR spectra, *INTERSTELLAR medium
Abstract: We argue that the anomalously high fluxes of positrons and antiprotons found in cosmic rays (CR) can be satisfactorily explained by introducing two additional elements to the current "standard" paradigm of Galactic CRs. First, we propose that the antiparticles are effectively produced in interactions of primary CRs with the surrounding gas not only in the interstellar medium (ISM) but also inside the accelerators. Secondly, we postulate the existence of two source populations injecting CRs into the ISM with different, (1) soft (close to FI∝E-2.3) and (2) hard (FII∝E-1.8 or harder), energy distributions. Assuming that CRs in the second population of accelerators accumulate "grammage" of the order of 1 g/cm² before their leakage into ISM, we can explain the energy distributions and absolute fluxes of both positrons and antiprotons, as well as the fluxes of secondary nuclei of the (Li, Be, B) group. The superposition of contributions of two source populations also explains the reported hardening of the spectra of CR protons and nuclei above 200 GV. The second source population accelerating CRs with a rate at the level below 10% of the power of the first source population can be responsible for the highest energy protons and nuclei of Galactic CRs up to the "knee" around 1015 eV. [ABSTRACT FROM AUTHOR]
Published: 2019
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21. Gamma-ray emission of hot astrophysical plasma.

Author: Kafexhiu, Ervin, Aharonian, Felix, and Barkov, Maxim
Subjects: *PLASMA astrophysics, *HIGH temperature plasmas, *ION temperature, *PLASMA temperature, *NUCLEAR reactions, *MESONS
Abstract: Very hot plasmas with ion temperature exceeding 1010 K can be formed in certain astrophysical environments. The distinct radiation signature of such plasmas is the γ-ray emission dominated by the prompt deexcitation nuclear lines and π0-decay γ rays. Using a large nuclear reaction network, we compute the time evolution of the chemical composition of such hot plasmas and their γ-ray line emissivity. At higher energies, we provide simple but accurate analytical presentations for the π0-meson production rate and the corresponding π0→2γ emissivity derived for the Maxwellian distribution of protons. We discuss the impact of the possible deviation of the high energy tail of the particle distribution function from the "nominal" Maxwellian distribution on the plasma γ-ray emissivity. [ABSTRACT FROM AUTHOR]
Published: 2019
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22. Detection of polarized gamma-ray emission from the Crab nebula with the Hitomi Soft Gamma-ray Detector†

Author: Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W, Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W, Blandford, Roger, Brenneman, Laura W, Brown, Gregory V, Bulbul, Esra, Cackett, Edward M, Chernyakova, Maria, Chiao, Meng P, Coppi, Paolo S, Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P, den Herder, Jan-Willem, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E, Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C, Ferrigno, Carlo, Foster, Adam R, Fujimoto, Ryuichi, Fukazawa, Yasushi, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C, Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M, Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashida, Kiyoshi, Hiraga, Junko S, Hornschemeier, Ann, Hoshino, Akio, Hughes, John P, Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L, Kilbourne, Caroline A, Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A, Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A, Limousin, Olivier, Loewenstein, Michael, Long, Knox S, Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R, Mehdipour, Missagh, Miller, Eric D, Miller, Jon M, Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F, Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Nobukawa, Kumiko K, Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Petre, Robert, Pinto, Ciro, Porter, Frederick S, Pottschmidt, Katja, Reynolds, Christopher S, Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sawada, Makoto, Schartel, Norbert, Serlemtsos, Peter J, Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K, Soong, Yang, Stawarz, Łukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shin’ichiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T, Tashiro, Makoto S, Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Uno, Shin’ichiro, Urry, C Megan, Ursino, Eugenio, Watanabe, Shin, Werner, Norbert, Wilkins, Dan R, Williams, Brian J, Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y, Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Zhuravleva, Irina, Zoghbi, Abderahmen, and Uchida, Yuusuke
Abstract: We present the results from the Hitomi Soft Gamma-ray Detector (SGD) observation of the Crab nebula. The main part of SGD is a Compton camera, which in addition to being a spectrometer, is capable of measuring polarization of gamma-ray photons. The Crab nebula is one of the brightest X-ray/gamma-ray sources on the sky, and the only source from which polarized X-ray photons have been detected. SGD observed the Crab nebula during the initial test observation phase of Hitomi. We performed data analysis of the SGD observation, SGD background estimation, and SGD Monte Carlo simulations, and successfully detected polarized gamma-ray emission from the Crab nebula with only about 5 ks exposure time. The obtained polarization fraction of the phase-integrated Crab emission (sum of pulsar and nebula emissions) is (22.1% ± 10.6%), and the polarization angle is ${110{^{\circ}_{.}}7}$+${13{^{\circ}_{.}}2}$/−${13{^{\circ}_{.}}0}$in the energy range of 60–160 keV (the errors correspond to the 1 σ deviation). The confidence level of the polarization detection was 99.3%. The polarization angle measured by SGD is about one sigma deviation with the projected spin axis of the pulsar, ${124{^{\circ}_{.}}0}$± ${0{^{\circ}_{.}}1}$.
Published: 2018
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23. Hitomi (ASTRO-H) X-ray Astronomy Satellite

Author: Takahashi, Tadayuki, Kokubun, Motohide, Mitsuda, Kazuhisa, Kelley, Richard L., Ohashi, Takaya, Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W., Anabuki, Naohisa, Angelini, Lorella, Arnaud, Keith, Asai, Makoto, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Azzarello, Philipp, Baluta, Chris, Bamba, Aya, Bando, Nobutaka, Bautz, Marshall W., Bialas, Thomas, Blandford, Roger, Boyce, Kevin, Brenneman, Laura W., Brown, Gregory V., Bulbul, Esra, Cackett, Edward M., Canavan, Edgar, Chernyakova, Maria, Chiao, Meng P., Coppi, Paolo S., Costantini, Elisa, O’ Dell, Steve, DiPirro, Michael, Done, Chris, Dotani, Tadayasu, Doty, John, Ebisawa, Ken, Eckart, Megan E., Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C., Ferrigno, Carlo, Foster, Adam R., Fujimoto, Ryuichi, Fukazawa, Yasushi, Funk, Stefan, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C., Gandhi, Poshak, Gilmore, Kirk, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haas, Daniel, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M., Hatsukade, Isamu, Hayashi, Takayuki, Hayashi, Katsuhiro, Hayashida, Kiyoshi, den Herder, Jan-Willem, Hiraga, Junko S., Hirose, Kazuyuki, Hornschemeier, Ann, Hoshino, Akio, Hughes, John P., Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Yoshiyuki, Ishibashi, Kazunori, Ishida, Manabu, Ishikawa, Kumi, Ishimura, Kosei, Ishisaki, Yoshitaka, Itoh, Masayuki, Iwai, Masachika, Iwata, Naoko, Iyomoto, Naoko, Jewell, Chris, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kara, Erin, Kataoka, Jun, Katsuda, Satoru, Katsuta, Junichiro, Kawaharada, Madoka, Kawai, Nobuyuki, Kawano, Taro, Kawasaki, Shigeo, Khangulyan, Dmitry, Kilbourne, Caroline A., Kimball, Mark, King, Ashley, Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Konami, Saori, Kosaka, Tatsuro, Koujelev, Alex, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A., Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A., Limousin, Olivier, Loewenstein, Michael, Long, Knox S., Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Masters, Candace, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, Mcguinness, Daniel, McNamara, Brian R., Mehdipour, Missagh, Miko, Joseph, Miller, Eric D., Miller, Jon M., Mineshige, Shin, Minesugi, Kenji, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Moroso, Franco, Moseley, Harvey, Muench, Theodore, Mukai, Koji, Murakami, Hiroshi, Murakami, Toshio, Mushotzky, Richard F., Nagano, Housei, Nagino, Ryo, Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakano, Toshio, Nakashima, Shinya, Nakazawa, Kazuhiro, Namba, Yoshiharu, Natsukari, Chikara, Nishioka, Yusuke, Nobukawa, Kumiko K., Nobukawa, Masayoshi, Noda, Hirofumi, Nomachi, Masaharu, Odaka, Hirokazu, Ogawa, Hiroyuki, Ogawa, Mina, Ogi, Keiji, Ohno, Masanori, Ohta, Masayuki, Okajima, Takashi, Okamoto, Atsushi, Okazaki, Tsuyoshi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Parmar, Arvind, Petre, Robert, Pinto, Ciro, de Plaa, Jelle, Pohl, Martin, Pontius, James, Porter, Frederick S., Pottschmidt, Katja, Ramsey, Brian, Reynolds, Christopher, Russell, Helen, Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sakai, Shin-ichiro, Sameshima, Hiroaki, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sato, Yoichi, Sawada, Makoto, Schartel, Norbert, Serlemitsos, Peter J., Seta, Hiromi, Shibano, Yasuko, Shida, Maki, Shidatsu, Megumi, Shimada, Takanobu, Shinozaki, Keisuke, Shirron, Peter, Simionescu, Aurora, Simmons, Cynthia, Smith, Randall K., Sneiderman, Gary, Soong, Yang, Stawarz, Łukasz, Sugawara, Yasuharu, Sugita, Satoshi, Sugita, Hiroyuki, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takeda, Shin’ichiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tamura, Keisuke, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T., Tashiro, Makoto S., Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Ueno, Shiro, Uno, Shin’ichiro, Urry, C. Megan, Ursino, Eugenio, de Vries, Cor P., Wada, Atsushi, Watanabe, Shin, Watanabe, Tomomi, Werner, Norbert, Wik, Daniel R., Wilkins, Dan R., Williams, Brian J., Yamada, Shinya, Yamada, Takahiro, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y., Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Yoshida, Atsumasa, Yuasa, Takayuki, Zhuravleva, Irina, and Zoghbi, Abderahmen
Published: 2018
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24. Hitomi X-ray observation of the pulsar wind nebula G21.5−0.9

Author: Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W, Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W, Blandford, Roger, Brenneman, Laura W, Brown, Gregory V, Bulbul, Esra, Cackett, Edward M, Chernyakova, Maria, Chiao, Meng P, Coppi, Paolo S, Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P, den Herder, Jan-Willem, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E, Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C, Ferrigno, Carlo, Foster, Adam R, Fujimoto, Ryuichi, Fukazawa, Yasushi, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C, Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M, Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashida, Kiyoshi, Hiraga, Junko S, Hornschemeier, Ann, Hoshino, Akio, Hughes, John P, Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L, Kilbourne, Caroline A, Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A, Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A, Limousin, Olivier, Loewenstein, Michael, Long, Knox S, Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R, Mehdipour, Missagh, Miller, Eric D, Miller, Jon M, Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F, Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Nobukawa, Kumiko K, Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Petre, Robert, Pinto, Ciro, Porter, Frederick S, Pottschmidt, Katja, Reynolds, Christopher S, Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sawada, Makoto, Schartel, Norbert, Serlemtsos, Peter J, Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K, Soong, Yang, Stawarz, Łukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shin’ichiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T, Tashiro, Makoto S, Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Uno, Shin’ichiro, Urry, C Megan, Ursino, Eugenio, Watanabe, Shin, Werner, Norbert, Wilkins, Dan R, Williams, Brian J, Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y, Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Zhuravleva, Irina, Zoghbi, Abderahmen, Sato, Toshiki, Nakaniwa, Nozomu, Murakami, Hiroaki, and Guest, Benson
Abstract: We present results from the Hitomi X-ray observation of a young composite-type supernova remnant (SNR) G21.5−0.9, whose emission is dominated by the pulsar wind nebula (PWN) contribution. The X-ray spectra in the 0.8–80 keV range obtained with the Soft X-ray Spectrometer (SXS), Soft X-ray Imager, and Hard X-ray Imager (HXI) show a significant break in the continuum as previously found with the NuSTAR observation. After taking into account all known emissions from the SNR other than the PWN itself, we find that the Hitomi spectra can be fitted with a broken power law with photon indices of Γ1= 1.74 ± 0.02 and Γ2= 2.14 ± 0.01 below and above the break at 7.1 ± 0.3 keV, which is significantly lower than the NuSTAR result (∼9.0 keV). The spectral break cannot be reproduced by time-dependent particle injection one-zone spectral energy distribution models, which strongly indicates that a more complex emission model is needed, as suggested by recent theoretical models. We also search for narrow emission or absorption lines with the SXS, and perform a timing analysis of PSR J1833−1034 with the HXI and the Soft Gamma-ray Detector. No significant pulsation is found from the pulsar. However, unexpectedly, narrow absorption line features are detected in the SXS data at 4.2345 keV and 9.296 keV with a significance of 3.65 σ. While the origin of these features is not understood, their mere detection opens up a new field of research and was only possible with the high resolution, sensitivity, and ability to measure extended sources provided by an X-ray microcalorimeter.
Published: 2018
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25. Atmospheric gas dynamics in the Perseus cluster observed with Hitomi*

Author: Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W, Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W, Blandford, Roger, Brenneman, Laura W, Brown, Gregory V, Bulbul, Esra, Cackett, Edward M, Canning, Rebecca E A, Chernyakova, Maria, Chiao, Meng P, Coppi, Paolo S, Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P, den Herder, Jan-Willem, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E, Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C, Ferrigno, Carlo, Foster, Adam R, Fujimoto, Ryuichi, Fukazawa, Yasushi, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C, Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M, Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashi, Tasuku, Hayashida, Kiyoshi, Hiraga, Junko S, Hornschemeier, Ann, Hoshino, Akio, Hughes, John P, Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Shota, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L, Kilbourne, Caroline A, Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A, Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A, Limousin, Olivier, Loewenstein, Michael, Long, Knox S, Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R, Mehdipour, Missagh, Miller, Eric D, Miller, Jon M, Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F, Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Nobukawa, Kumiko K, Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Petre, Robert, Pinto, Ciro, Porter, Frederick S, Pottschmidt, Katja, Reynolds, Christopher S, Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sawada, Makoto, Schartel, Norbert, Serlemtsos, Peter J, Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K, Soong, Yang, Stawarz, Łukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shin’ichiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Keigo, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T, Tashiro, Makoto S, Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Uno, Shin’ichiro, Urry, C Megan, Ursino, Eugenio, Wang, Qian H S, Watanabe, Shin, Werner, Norbert, Wilkins, Dan R, Williams, Brian J, Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y, Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Zhuravleva, Irina, and Zoghbi, Abderahmen
Abstract: 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 find that the line-of-sight velocity dispersion of the hot gas is remarkably low and mostly uniform. The velocity dispersion reaches a maxima of approximately 200 km s−1toward the central active galactic nucleus (AGN) and toward the AGN inflated northwestern “ghost” bubble. Elsewhere within the observed region, the velocity dispersion appears constant around 100 km s−1. We also detect a velocity gradient with a 100 km s−1amplitude across the cluster core, consistent with large-scale sloshing of the core gas. If the observed gas motions are isotropic, the kinetic pressure support is less than 10% of the thermal pressure support in the cluster core. The well-resolved, optically thin emission lines have Gaussian shapes, indicating that the turbulent driving scale is likely below 100 kpc, which is consistent with the size of the AGN jet inflated bubbles. We also report the first measurement of the ion temperature in the intracluster medium, which we find to be consistent with the electron temperature. In addition, we present a new measurement of the redshift of the brightest cluster galaxy NGC 1275.
Published: 2018
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26. Measurements of resonant scattering in the Perseus Cluster core with Hitomi SXS*

Author: Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W, Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W, Blandford, Roger, Brenneman, Laura W, Brown, Gregory V, Bulbul, Esra, Cackett, Edward M, Chernyakova, Maria, Chiao, Meng P, Coppi, Paolo S, Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P, den Herder, Jan-Willem, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E, Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C, Ferrigno, Carlo, Foster, Adam R, Fujimoto, Ryuichi, Fukazawa, Yasushi, Furukawa, Maki, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C, Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M, Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashida, Kiyoshi, Hiraga, Junko S, Hornschemeier, Ann, Hoshino, Akio, Hughes, John P, Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L, Kilbourne, Caroline A, Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A, Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A, Limousin, Olivier O, Loewenstein, Michael, Long, Knox S, Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R, Mehdipour, Missagh, Miller, Eric D, Miller, Jon M, Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F, Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Nobukawa, Kumiko K, Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ogorzalek, Anna, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Petre, Robert, Pinto, Ciro, Porter, Frederick S, Pottschmidt, Katja, Reynolds, Christopher S, Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sawada, Makoto, Schartel, Norbert, Serlemtsos, Peter J, Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K, Soong, Yang, Stawarz, Łukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shiníchiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T, Tashiro, Makoto S, Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Uno, Shiníchiro, Urry, C Megan, Ursino, Eugenio, Watanabe, Shin, Werner, Norbert, Wilkins, Dan R, Williams, Brian J, Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y, Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Zhuravleva, Irina, and Zoghbi, Abderahmen
Abstract: 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, metallicities and the multi-temperature structure of the gas in the core of the Perseus Cluster. Here, we show that when inferring physical properties from line emissivities in systems like Perseus, the resonant scattering effect should be taken into account. In the Hitomi waveband, resonant scattering mostly affects the Fe xxvHeα line (w)—the strongest line in the spectrum. The flux measured by Hitomi in this line is suppressed by a factor of ∼1.3 in the inner ∼30 kpc, compared to predictions for an optically thin plasma; the suppression decreases with the distance from the center. The wline also appears slightly broader than other lines from the same ion. The observed distortions of the wline flux, shape, and distance dependence are all consistent with the expected effect of the resonant scattering in the Perseus core. By measuring the ratio of fluxes in optically thick (w) and thin (Fe xxvforbidden, Heβ, Lyα) lines, and comparing these ratios with predictions from Monte Carlo radiative transfer simulations, the velocities of gas motions have been obtained. The results are consistent with the direct measurements of gas velocities from line broadening described elsewhere in this series, although the systematic and statistical uncertainties remain significant. Further improvements in the predictions of line emissivities in plasma models, and deeper observations with future X-ray missions offering similar or better capabilities to the Hitomi SXS, will enable resonant scattering measurements to provide powerful constraints on the amplitude and anisotropy of cluster gas motions.
Published: 2018
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27. Atomic data and spectral modeling constraints from high-resolution X-ray observations of the Perseus cluster with Hitomi*

Author: Collaboration, Hitomi, Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W, Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W, Blandford, Roger, Brenneman, Laura W, Brown, Gregory V, Bulbul, Esra, Cackett, Edward M, Chernyakova, Maria, Chiao, Meng P, Coppi, Paolo S, Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P, den Herder, Jan-Willem, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E, Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C, Ferrigno, Carlo, Foster, Adam R, Fujimoto, Ryuichi, Fukazawa, Yasushi, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C, Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M, Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashida, Kiyoshi, Hell, Natalie, Hiraga, Junko S, Hornschemeier, Ann, Hoshino, Akio, Hughes, John P, Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L, Kilbourne, Caroline A, Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A, Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A, Limousin, Olivier, Loewenstein, Michael, Long, Knox S, Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R, Mehdipour, Missagh, Miller, Eric D, Miller, Jon M, Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F, Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Nobukawa, Kumiko K, Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Petre, Robert, Pinto, Ciro, Porter, Frederick S, Pottschmidt, Katja, Reynolds, Christopher S, Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sawada, Makoto, Schartel, Norbert, Serlemtsos, Peter J, Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K, Soong, Yang, Stawarz, Łukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shin’ichiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T, Tashiro, Makoto S, Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Uno, Shin’ichiro, Urry, C Megan, Ursino, Eugenio, Watanabe, Shin, Werner, Norbert, Wilkins, Dan R, Williams, Brian J, Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y, Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Zhuravleva, Irina, Zoghbi, Abderahmen, and Raassen, A J J
Abstract: 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), and CHIANTI (8.0) all provide reasonable fits to the broad-band spectrum, and are in close agreement on best-fit temperature, emission measure, and abundances of a few elements such as Ni. For the Fe abundance, the APEC and SPEX measurements differ by 16%, which is 17 times higher than the statistical uncertainty. This is mostly attributed to the differences in adopted collisional excitation and dielectronic recombination rates of the strongest emission lines. We further investigate and compare the sensitivity of the derived physical parameters to the astrophysical source modeling and instrumental effects. The Hitomi results show that accurate atomic data and models are as important as the astrophysical modeling and instrumental calibration aspects. Substantial updates of atomic databases and targeted laboratory measurements are needed to get the current data and models ready for the data from the next Hitomi-level mission.
Published: 2018
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28. Temperature structure in the Perseus cluster core observed with Hitomi*

Author: Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W, Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W, Blandford, Roger, Brenneman, Laura W, Brown, Gregory V, Bulbul, Esra, Cackett, Edward M, Chernyakova, Maria, Chiao, Meng P, Coppi, Paolo S, Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P, den Herder, Jan-Willem, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E, Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C, Ferrigno, Carlo, Foster, Adam R, Fujimoto, Ryuichi, Fukazawa, Yasushi, Furukawa, Maki, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C, Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M, Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashida, Kiyoshi, Hiraga, Junko S, Hornschemeier, Ann, Hoshino, Akio, Hughes, John P, Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Kato, Yuichi, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L, Kilbourne, Caroline A, Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A, Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A, Limousin, Olivier, Loewenstein, Michael, Long, Knox S, Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R, Mehdipour, Missagh, Miller, Eric D, Miller, Jon M, Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F, Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Nobukawa, Kumiko K, Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Petre, Robert, Pinto, Ciro, Porter, Frederick S, Pottschmidt, Katja, Reynolds, Christopher S, Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sawada, Makoto, Schartel, Norbert, Serlemtsos, Peter J, Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K, Soong, Yang, Stawarz, Łukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shiníchiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T, Tashiro, Makoto S, Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Uno, Shiníchiro, Urry, C Megan, Ursino, Eugenio, Watanabe, Shin, Werner, Norbert, Wilkins, Dan R, Williams, Brian J, Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y, Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Zhuravleva, Irina, and Zoghbi, Abderahmen
Abstract: The present paper explains the temperature structure of X-ray emitting plasma in the core of the Perseus cluster based on 1.8–20.0 keV data obtained with the Soft X-ray Spectrometer (SXS) on board the Hitomi Observatory. A series of four observations was carried out, with a total effective exposure time of 338 ks that covered a central region of ∼7΄ in diameter. SXS was operated with an energy resolution of ∼5 eV (full width at half maximum) at 5.9 keV. Not only fine structures of K-shell lines in He-like ions, but also transitions from higher principal quantum numbers were clearly resolved from Si through Fe. That enabled us to perform temperature diagnostics using the line ratios of Si, S, Ar, Ca, and Fe, and to provide the first direct measurement of the excitation temperature and ionization temperature in the Perseus cluster. The observed spectrum is roughly reproduced by a single-temperature thermal plasma model in collisional ionization equilibrium, but detailed line-ratio diagnostics reveal slight deviations from this approximation. In particular, the data exhibit an apparent trend of increasing ionization temperature with the atomic mass, as well as small differences between the ionization and excitation temperatures for Fe, the only element for which both temperatures could be measured. The best-fit two-temperature models suggest a combination of 3 and 5 keV gas, which is consistent with the idea that the observed small deviations from a single-temperature approximation are due to the effects of projecting the known radial temperature gradient in the cluster core along the line of sight. A comparison with the Chandra/ACIS and the XMM-Newton/RGS results, on the other hand, suggests that additional lower-temperature components are present in the intracluster medium (ICM), but not detectable with Hitomi/SXS giving its 1.8–20 keV energy band.
Published: 2018
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29. Search for thermal X-ray features from the Crab nebula with the Hitomi soft X-ray spectrometer*

Author: Collaboration, Hitomi, Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W, Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W, Blandford, Roger, Brenneman, Laura W, Brown, Gregory V, Bulbul, Esra, Cackett, Edward M, Chernyakova, Maria, Chiao, Meng P, Coppi, Paolo S, Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P, den Herder, Jan-Willem, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E, Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C, Ferrigno, Carlo, Foster, Adam R, Fujimoto, Ryuichi, Fukazawa, Yasushi, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C, Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M, Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashida, Kiyoshi, Hiraga, Junko S, Hornschemeier, Ann, Hoshino, Akio, Hughes, John P, Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L, Kilbourne, Caroline A, Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A, Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A, Limousin, Olivier, Loewenstein, Michael, Long, Knox S, Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R, Mehdipour, Missagh, Miller, Eric D, Miller, Jon M, Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F, Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Nobukawa, Kumiko K, Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Petre, Robert, Pinto, Ciro, Porter, Frederick S, Pottschmidt, Katja, Reynolds, Christopher S, Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sato, Toshiki, Sawada, Makoto, Schartel, Norbert, Serlemtsos, Peter J, Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K, Soong, Yang, Stawarz, Łukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shin΄ichiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T, Tashiro, Makoto S, Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Uno, Shin΄ichiro, Urry, C Megan, Ursino, Eugenio, Watanabe, Shin, Werner, Norbert, Wilkins, Dan R, Williams, Brian J, Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y, Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Zhuravleva, Irina, Zoghbi, Abderahmen, Tominaga, Nozomu, and Moriya, Takashi J
Abstract: The Crab nebula originated from a core-collapse supernova (SN) explosion observed in 1054 ad. When viewed as a supernova remnant (SNR), it has an anomalously low observed ejecta mass and kinetic energy for an Fe-core-collapse SN. Intensive searches have been made for a massive shell that solves this discrepancy, but none has been detected. An alternative idea is that SN 1054 is an electron-capture (EC) explosion with a lower explosion energy by an order of magnitude than Fe-core-collapse SNe. X-ray imaging searches were performed for the plasma emission from the shell in the Crab outskirts to set a stringent upper limit on the X-ray emitting mass. However, the extreme brightness of the source hampers access to its vicinity. We thus employed spectroscopic technique using the X-ray micro-calorimeter on board the Hitomi satellite. By exploiting its superb energy resolution, we set an upper limit for emission or absorption features from as yet undetected thermal plasma in the 2–12 keV range. We also re-evaluated the existing Chandra and XMM-Newton data. By assembling these results, a new upper limit was obtained for the X-ray plasma mass of ≲ 1 M⊙for a wide range of assumed shell radius, size, and plasma temperature values both in and out of collisional equilibrium. To compare with the observation, we further performed hydrodynamic simulations of the Crab SNR for two SN models (Fe-core versus EC) under two SN environments (uniform interstellar medium versus progenitor wind). We found that the observed mass limit can be compatible with both SN models if the SN environment has a low density of ≲ 0.03 cm−3(Fe core) or ≲ 0.1 cm−3(EC) for the uniform density, or a progenitor wind density somewhat less than that provided by a mass loss rate of 10−5M⊙yr−1at 20 km s−1for the wind environment.
Published: 2018
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30. Hitomi observation of radio galaxy NGC 1275: The first X-ray microcalorimeter spectroscopy of Fe-Kα line emission from an active galactic nucleus*

Author: Collaboration, Hitomi, Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W, Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W, Blandford, Roger, Brenneman, Laura W, Brown, Gregory V, Bulbul, Esra, Cackett, Edward M, Chernyakova, Maria, Chiao, Meng P, Coppi, Paolo S, Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P, den Herder, Jan-Willem, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E, Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C, Ferrigno, Carlo, Foster, Adam R, Fujimoto, Ryuichi, Fukazawa, Yasushi, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C, Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M, Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashida, Kiyoshi, Hiraga, Junko S, Hornschemeier, Ann, Hoshino, Akio, Hughes, John P, Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L, Kilbourne, Caroline A, Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A, Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A, Limousin, Olivier O, Loewenstein, Michael, Long, Knox S, Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R, Mehdipour, Missagh, Miller, Eric D, Miller, Jon M, Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F, Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Nobukawa, Kumiko K, Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Petre, Robert, Pinto, Ciro, Porter, Frederick S, Pottschmidt, Katja, Reynolds, Christopher S, Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sawada, Makoto, Schartel, Norbert, Serlemitsos, Peter J, Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K, Soong, Yang, Stawarz, Łukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shin’ichiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T, Tashiro, Makoto S, Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Uno, Shin’ichiro, Urry, C Megan, Ursino, Eugenio, Watanabe, Shin, Werner, Norbert, Wilkins, Dan R, Williams, Brian J, Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y, Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Zhuravleva, Irina, Zoghbi, Abderahmen, and Kawamuro, Taiki
Abstract: 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-ray Spectrometer (SXS) on board the Hitomi satellite of the Fanaroff–Riley type I radio galaxy NGC 1275 at the center of the Perseus cluster of galaxies. With the high-energy resolution of ∼5 eV at 6 keV achieved by Hitomi/SXS, we detected the Fe-Kα line with ∼5.4 σ significance. The velocity width is constrained to be 500–1600 km s−1(FWHM for Gaussian models) at 90% confidence. The SXS also constrains the continuum level from the NGC 1275 nucleus up to ∼20 keV, giving an equivalent width of ∼20 eV for the 6.4 keV line. Because the velocity width is narrower than that of the broad Hα line of ∼2750 km s−1, we can exclude a large contribution to the line flux from the accretion disk and the broad line region. Furthermore, we performed pixel map analyses on the Hitomi/SXS data and image analyses on the Chandra archival data, and revealed that the Fe-Kα line comes from a region within ∼1.6 kpc of the NGC 1275 core, where an active galactic nucleus emission dominates, rather than that from intracluster media. Therefore, we suggest that the source of the Fe-Kα line from NGC 1275 is likely a low-covering-fraction molecular torus or a rotating molecular disk which probably extends from a parsec to hundreds of parsecs scale in the active galactic nucleus system.
Published: 2018
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31. Hitomi X-ray studies of giant radio pulses from the Crab pulsar*

Author: Collaboration, Hitomi, Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W, Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W, Blandford, Roger, Brenneman, Laura W, Brown, Gregory V, Bulbul, Esra, Cackett, Edward M, Chernyakova, Maria, Chiao, Meng P, Coppi, Paolo S, Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P, den Herder, Jan-Willem, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E, Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C, Ferrigno, Carlo, Foster, Adam R, Fujimoto, Ryuichi, Fukazawa, Yasushi, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C, Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M, Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashida, Kiyoshi, Hiraga, Junko S, Hornschemeier, Ann, Hoshino, Akio, Hughes, John P, Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L, Kilbourne, Caroline A, Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A, Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A, Limousin, Olivier O, Loewenstein, Michael, Long, Knox S, Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R, Mehdipour, Missagh, Miller, Eric D, Miller, Jon M, Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F, Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Nobukawa, Kumiko K, Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Oshimizu, Kenya, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Petre, Robert, Pinto, Ciro, Porter, Frederick S, Pottschmidt, Katja, Reynolds, Christopher S, Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sawada, Makoto, Schartel, Norbert, Serlemtsos, Peter J, Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K, Soong, Yang, Stawarz, Łukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shiníchiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T, Tashiro, Makoto S, Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Uno, Shiníchiro, Urry, C Megan, Ursino, Eugenio, Watanabe, Shin, Werner, Norbert, Wilkins, Dan R, Williams, Brian J, Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y, Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Zhuravleva, Irina, Zoghbi, Abderahmen, Terasawa, Toshio, Sekido, Mamoru, Takefuji, Kazuhiro, Kawai, Eiji, Misawa, Hiroaki, Tsuchiya, Fuminori, Yamazaki, Ryo, Kobayashi, Eiji, Kisaka, Shota, and Aoki, Takahiro
Abstract: To search for giant X-ray pulses correlated with the giant radio pulses (GRPs) from the Crab pulsar, we performed a simultaneous observation of the Crab pulsar with the X-ray satellite Hitomi in the 2–300 keV band and the Kashima NICT radio telescope in the 1.4–1.7 GHz band with a net exposure of about 2 ks on 2016 March 25, just before the loss of the Hitomi mission. The timing performance of the Hitomi instruments was confirmed to meet the timing requirement and about 1000 and 100 GRPs were simultaneously observed at the main pulse and inter-pulse phases, respectively, and we found no apparent correlation between the giant radio pulses and the X-ray emission in either the main pulse or inter-pulse phase. All variations are within the 2 σ fluctuations of the X-ray fluxes at the pulse peaks, and the 3 σ upper limits of variations of main pulse or inter-pulse GRPs are 22% or 80% of the peak flux in a 0.20 phase width, respectively, in the 2–300 keV band. The values for main pulse or inter-pulse GRPs become 25% or 110%, respectively, when the phase width is restricted to the 0.03 phase. Among the upper limits from the Hitomi satellite, those in the 4.5–10 keV and 70–300 keV bands are obtained for the first time, and those in other bands are consistent with previous reports. Numerically, the upper limits of the main pulse and inter-pulse GRPs in the 0.20 phase width are about (2.4 and 9.3) × 10−11erg cm−2, respectively. No significant variability in pulse profiles implies that the GRPs originated from a local place within the magnetosphere. Although the number of photon-emitting particles should temporarily increase to account for the brightening of the radio emission, the results do not statistically rule out variations correlated with the GRPs, because the possible X-ray enhancement may appear due to a >0.02% brightening of the pulse-peak flux under such conditions.
Published: 2018
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32. Glimpse of the highly obscured HMXB IGR J16318−4848 with Hitomi*

Author: Collaboration, Hitomi, Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W, Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W, Blandford, Roger, Brenneman, Laura W, Brown, Gregory V, Bulbul, Esra, Cackett, Edward M, Chernyakova, Maria, Chiao, Meng P, Coppi, Paolo S, Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P, den Herder, Jan-Willem, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E, Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C, Ferrigno, Carlo, Foster, Adam R, Fujimoto, Ryuichi, Fukazawa, Yasushi, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C, Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M, Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashida, Kiyoshi, Hiraga, Junko S, Hornschemeier, Ann, Hoshino, Akio, Hughes, John P, Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L, Kilbourne, Caroline A, Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A, Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A, Limousin, Olivier O, Loewenstein, Michael, Long, Knox S, Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R, Mehdipour, Missagh, Miller, Eric D, Miller, Jon M, Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F, Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Nobukawa, Kumiko K, Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Petre, Robert, Pinto, Ciro, Porter, Frederick S, Pottschmidt, Katja, Reynolds, Christopher S, Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sawada, Makoto, Schartel, Norbert, Serlemtsos, Peter J, Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K, Soong, Yang, Stawarz, Łukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shiníchiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T, Tashiro, Makoto S, Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Uno, Shiníchiro, Urry, C Megan, Ursino, Eugenio, Watanabe, Shin, Werner, Norbert, Wilkins, Dan R, Williams, Brian J, Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y, Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Zhuravleva, Irina, Zoghbi, Abderahmen, and Nakaniwa, Nozomi
Abstract: We report on a Hitomi observation of IGR J16318−4848, a high-mass X-ray binary system with an extremely strong absorption of NH∼ 1024cm−2. Previous X-ray studies revealed that its spectrum is dominated by strong fluorescence lines of Fe as well as continuum emission lines. For physical and geometrical insight into the nature of the reprocessing material, we utilized the high spectroscopic resolving power of the X-ray microcalorimeter (the soft X-ray spectrometer: SXS) and the wide-band sensitivity by the soft and hard X-ray imagers (SXI and HXI) aboard Hitomi. Even though the photon counts are limited due to unintended off-axis pointing, the SXS spectrum resolves Fe Kα1and Kα2lines and puts strong constraints on the line centroid and line width. The line width corresponds to a velocity of 160$^{+300}_{-70}$km s−1. This represents the most accurate, and smallest, width measurement of this line made so far from the any X-ray binary, much less than the Doppler broadening and Doppler shift expected from speeds that are characteristic of similar systems. Combined with the K-shell edge energy measured by the SXI and HXI spectra, the ionization state of Fe is estimated to be in the range of Fe i–iv. Considering the estimated ionization parameter and the distance between the X-ray source and the absorber, the density and thickness of the materials are estimated. The extraordinarily strong absorption and the absence of a Compton shoulder component have been confirmed. These characteristics suggest reprocessing materials that are distributed in a narrow solid angle or scattering, primarily by warm free electrons or neutral hydrogen. This measurement was achieved using the SXS detection of 19 photons. It provides strong motivation for follow-up observations of this and other X-ray binaries using the X-ray Astrophysics Recovery Mission and other comparable future instruments.
Published: 2018
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33. Hitomi observations of the LMC SNR N 132 D: Highly redshifted X-ray emission from iron ejecta*

Author: Collaboration, Hitomi, Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W, Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W, Blandford, Roger, Brenneman, Laura W, Brown, Gregory V, Bulbul, Esra, Cackett, Edward M, Chernyakova, Maria, Chiao, Meng P, Coppi, Paolo S, Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P, den Herder, Jan-Willem, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E, Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C, Ferrigno, Carlo, Foster, Adam R, Fujimoto, Ryuichi, Fukazawa, Yasushi, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C, Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M, Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashida, Kiyoshi, Hiraga, Junko S, Hornschemeier, Ann, Hoshino, Akio, Hughes, John P, Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L, Kilbourne, Caroline A, Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A, Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A, Limousin, Olivier, Loewenstein, Michael, Long, Knox S, Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R, Mehdipour, Missagh, Miller, Eric D, Miller, Jon M, Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F, Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Nobukawa, Kumiko K, Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Petre, Robert, Pinto, Ciro, Porter, Frederick S, Pottschmidt, Katja, Reynolds, Christopher S, Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sato, Toshiki, Sawada, Makoto, Schartel, Norbert, Serlemtsos, Peter J, Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K, Soong, Yang, Stawarz, Łukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shin’ichiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T, Tashiro, Makoto S, Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi Go, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Shutaro, Ueda, Yoshihiro, Uno, Shin’ichiro, Urry, C Megan, Ursino, Eugenio, Watanabe, Shin, Werner, Norbert, Wilkins, Dan R, Williams, Brian J, Yamada, Shinya, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko Y, Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Zhuravleva, Irina, and Zoghbi, Abderahmen
Abstract: We present Hitomi observations of N 132 D, a young, X-ray bright, O-rich core-collapse supernova remnant in the Large Magellanic Cloud (LMC). Despite a very short observation of only 3.7 ks, the Soft X-ray Spectrometer (SXS) easily detects the line complexes of highly ionized S K and Fe K with 16–17 counts in each. The Fe feature is measured for the first time at high spectral resolution. Based on the plausible assumption that the Fe K emission is dominated by He-like ions, we find that the material responsible for this Fe emission is highly redshifted at ∼ 800 km s−1compared to the local LMC interstellar medium (ISM), with a 90% credible interval of 50–1500 km s−1if a weakly informative prior is placed on possible line broadening. This indicates (1) that the Fe emission arises from the supernova ejecta, and (2) that these ejecta are highly asymmetric, since no blueshifted component is found. The S K velocity is consistent with the local LMC ISM, and is likely from swept-up ISM material. These results are consistent with spatial mapping that shows the He-like Fe concentrated in the interior of the remnant and the S tracing the outer shell. The results also show that even with a very small number of counts, direct velocity measurements from Doppler-shifted lines detected in extended objects like supernova remnants are now possible. Thanks to the very low SXS background of ∼ 1 event per spectral resolution element per 100 ks, such results are obtainable during short pointed or slew observations with similar instruments. This highlights the power of high-spectral-resolution imaging observations, and demonstrates the new window that has been opened with Hitomi and will be greatly widened with future missions such as the X-ray Astronomy Recovery Mission (XARM) and Athena.
Published: 2018
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34. The ASTRO-H X-ray astronomy satellite

Author: Takahashi, Tadayuki, den Herder, Jan-Willem A., Bautz, Mark, Takahashi, Tadayuki, Mitsuda, Kazuhisa, Kelley, Richard, Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steve, Anabuki, Naohisa, Angelini, Lorella, Arnaud, Keith, Asai, Makoto, Audard, Marc, Awaki, Hisamitsu, Azzarello, Philipp, Baluta, Chris, Bamba, Aya, Bando, Nobutaka, Bautz, Marshall, Bialas, Thomas, Blandford, Roger D., Boyce, Kevin, Brenneman, Laura, Brown, Gregory, Cackett, Ed, Canavan, Edgar, Chernyakova, Maria, Chiao, Meng, Coppi, Paolo, Costantini, Elisa, de Plaa, Jelle, den Herder, Jan-Willem, DiPirro, Michael, Done, Chris, Dotani, Tadayasu, Doty, John, Ebisawa, Ken, Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew, Ferrigno, Carlo, Foster, Adam, Fujimoto, Ryuichi, Fukazawa, Yasushi, Funk, Stefan, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi, Gandhi, Poshak, Gilmore, Kirk, Guainazzi, Matteo, Haas, Daniel, Haba, Yoshito, Hamaguchi, Kenji, Harayama, Atsushi, Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashida, Kiyoshi, Hiraga, Junko, Hirose, Kazuyuki, Hornschemeier, Ann, Hoshino, Akio, Hughes, John, Hwang, Una, Iizuka, Ryo, Inoue, Yoshiyuki, Ishibashi, Kazunori, Ishida, Manabu, Ishikawa, Kumi, Ishimura, Kosei, Ishisaki, Yoshitaka, Itoh, Masayuki, Iwata, Naoko, Iyomoto, Naoko, Jewell, Chris, Kaastra, Jelle, Kallman, Timothy, Kamae, Tuneyoshi, Kataoka, Jun, Katsuda, Satoru, Katsuta, Junichiro, Kawaharada, Madoka, Kawai, Nobuyuki, Kawano, Taro, Kawasaki, Shigeo, Khangaluyan, Dmitry, Kilbourne, Caroline, Kimball, Mark, Kimura, Masashi, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Konami, Saori, Kosaka, Tatsuro, Koujelev, Alexander, Koyama, Katsuji, Krimm, Hans, Kubota, Aya, Kunieda, Hideyo, LaMassa, Stephanie, Laurent, Philippe, Lebrun, François, Leutenegger, Maurice, Limousin, Olivier, Loewenstein, Michael, Long, Knox, Lumb, David, Madejski, Grzegorz, Maeda, Yoshitomo, Makishima, Kazuo, Markevitch, Maxim, Masters, Candace, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McGuinness, Daniel, McNamara, Brian, Miko, Joseph, Miller, Jon, Miller, Eric, Mineshige, Shin, Minesugi, Kenji, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Koji, Mori, Hideyuki, Moroso, Franco, Muench, Theodore, Mukai, Koji, Murakami, Hiroshi, Murakami, Toshio, Mushotzky, Richard, Nagano, Housei, Nagino, Ryo, Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Namba, Yoshiharu, Natsukari, Chikara, Nishioka, Yusuke, Nobukawa, Masayoshi, Noda, Hirofumi, Nomachi, Masaharu, O'Dell, Steve, Odaka, Hirokazu, Ogawa, Hiroyuki, Ogawa, Mina, Ogi, Keiji, Ohashi, Takaya, Ohno, Masanori, Ohta, Masayuki, Okajima, Takashi, Okazaki, Tsuyoshi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stéphane, Parmar, Arvind, Petre, Robert, Pinto, Ciro, Pohl, Martin, Pontius, James, Porter, F. S., Pottschmidt, Katja, Ramsey, Brian, Reis, Rubens, Reynolds, Christopher, Ricci, Claudio, Russell, Helena, Safi-Harb, Samar, Saito, Shinya, Sakai, Shin-ichiro, Sameshima, Hiroaki, Sato, Kosuke, Sato, Rie, Sato, Goro, Sawada, Makoto, Serlemitsos, Peter, Seta, Hiromi, Shibano, Yasuko, Shida, Maki, Shimada, Takanobu, Shirron, Peter, Simionescu, Aurora, Simmons, Cynthia, Smith, Randall, Sneiderman, Gary, Soong, Yang, Stawarz, Lukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiroaki, Takahashi, Hiromitsu, Takeda, Shin-ichiro, Takei, Yoh, Tamagawa, Toru, Tamura, Keisuke, Tamura, Takayuki, Tanaka, Takaaki, Tanaka, Yasuyuki, Tanaka, Yasuo, Tashiro, Makoto, Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yoko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Takeshi, Uchida, Hiroyuki, Uchiyama, Hideki, Uchiyama, Yasunobu, Ueda, Yoshihiro, Ueda, Shutaro, Ueno, Shiro, Uno, Shinichiro, Urry, Meg, Ursino, Eugenio, de Vries, Cor, Wada, Atsushi, Watanabe, Shin, Watanabe, Tomomi, Werner, Norbert, White, Nicholas, Wilkins, Dan, Yamada, Shinya, Yamada, Takahiro, Yamaguchi, Hiroya, Yamaoka, Kazutaka, Yamasaki, Noriko, Yamauchi, Makoto, Yamauchi, Shigeo, Yaqoob, Tahir, Yatsu, Yoichi, Yonetoku, Daisuke, Yoshida, Atsumasa, Yuasa, Takayuki, Zhuravleva, Irina, Zoghbi, Abderahmen, and ZuHone, John
Published: 2014
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35. Erratum: "Potential Neutrino Signals from Galactic ?-Ray Sources" (ApJ, 656, 870 [2007])

Author: Kappes, Alexander, Hinton, Jim, Stegmann, Christian, and Aharonian, Felix A.
Published: 2007

36. Galactic halo origin of the neutrinos detected by IceCube.

Author: Taylor, Andrew M., Gabici, Stefano, and Aharonian, Felix
Subjects: *NEUTRINOS, *FERMI energy, *COSMIC rays, *SPIRAL galaxies, *MAGNETIC energy storage, *STANDARD deviations
Abstract: Recent IceCube results suggest that the first detection of very high energy astrophysical neutrinos have been accomplished. We consider these results at face value in a Galactic origin context. Emission scenarios from both the Fermi bubble and broader halo region are considered. We motivate that such an intensity of diffuse neutrino emission could be Galactic in origin if it is produced from an outflow into the halo region. This scenario requires cosmic ray transport within the outflow environment to be different to that inferred locally within the disk and that activity in the central part of the Galaxy accelerates cosmic rays to trans-"knee" energies before they escape into an outflow. The presence of a large reservoir of gas in a very extended halo around the Galaxy, recently inferred from x-ray observations, implies that the relatively modest acceleration power of 1039 erg s-1 in PeV energy cosmic rays may be sufficient to explain the observed neutrino flux. Such a luminosity is compatible with that required to explain the observed intensity of cosmic rays around the knee. [ABSTRACT FROM AUTHOR]
Published: 2014
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37. Need for a local source of ultrahigh-energy cosmic-ray nuclei.

Author: Taylor, Andrew M., Ahlers, Markus, and Aharonian, Felix A.
Subjects: *FLUORESCENCE, *DETECTORS, *COSMIC rays, *NUCLEAR physics, *MAGNETIC fields
Abstract: Recent results of the Pierre Auger (Auger) fluorescence detectors indicate an increasingly heavy composition of ultra-high energy (UHE) cosmic rays (CRs). Assuming that this trend continues up to the highest energies observed by the Auger surface detectors, we derive the constraints this places on the local source distribution of UHE CR nuclei. Utilizing an analytic description of UHE CR propagation, we derive the expected spectra and composition for a wide range of source emission spectra. We find that sources of intermediate-to-heavy nuclei are consistent with the observed spectra and composition data above the ankle. This consistency requires the presence of nearby sources within 60 Mpc and 80 Mpc for silicon and iron-only sources, respectively. The necessity of these local sources becomes even more compelling in the presence nano-Gauss local extragalactic magnetic fields. [ABSTRACT FROM AUTHOR]
Published: 2011
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38. Analytical treatment for the development of electromagnetic cascades in intense magnetic fields.

Author: Jie-Shuang Wang, Ruo-Yu Liu, Aharonian, Felix, and Zi-Gao Dai
Subjects: *PHYSICS periodicals, *MAGNETIC fields, *POSITRONIUM, *SPECTRAL energy distribution
Abstract: In a strong magnetic field, a high-energy photon can be absorbed and then produce an electron-positron pair. The produced electron/positron will in turn radiate a high-energy photon via synchrotron radiation, which then initiates a cascade. We built a one-dimensional Monte Carlo code to study the development of the cascade especially after it reaches the saturated status, when almost all the energy of the primary particles transfers to the photons. The photon spectrum in this status has a cutoff due to the absorption by magnetic fields, which is much sharper than the exponential one. Below the cutoff, the spectral energy distribution (SED) manifest itself as a broken power-law with a spectral index of 0.5 and 0.125, respectively, below and above the broken energy. The SED can be fitted by a simple analytical function, which is solely determined by the product of the cascade scale R and the magnetic field perpendicular to the motion of the particle B1, with an accuracy better than 96%. The similarity of the spectrum to that from the cascade in an isotropic black-body photon field is also studied. [ABSTRACT FROM AUTHOR]
Published: 2018
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39. Diffuse PeV neutrinos from EeV cosmic ray sources: Semirelativistic hypernova remnants in star-forming galaxies.

Author: Ruo-Yu Liu, Xiang-Yu Wang, Inoue, Susumu, Crocker, Roland, and Aharonian, Felix
Subjects: *COSMIC rays, *RELATIVISTIC astrophysics, *PROTON-proton interactions, *FERMI Gamma-ray Space Telescope (Spacecraft), *NEUTRINOS, *GALAXIES
Abstract: We argue that the excess of sub-PeV/PeV neutrinos recently reported by IceCube could plausibly originate through pion-production processes in the same sources responsible for cosmic rays (CRs) with energy above the second knee around 1018 eV. The pion-production efficiency for escaping CRs that produce PeV neutrinos is required to be >≳.1 in such sources. On the basis of current data, we identify semirelativistic hypernova remnants as possible sources that satisfy the requirements. By virtue of their fast ejecta, such objects can accelerate protons to EeV energies, which, in turn, can interact with the dense surrounding medium during propagation in their host galaxies to produce sufficient high-energy neutrinos via proton-proton (pp) collisions. Their accompanying gamma-ray flux can remain below the diffuse isotropic gamma-ray background observed by the Fermi Large Area Telescope. In order to test this scenario and discriminate from alternatives, the density of target protons/nuclei and the residence time of CRs in the interacting region are crucial uncertainties that need to be clarified. As long as the neutrinos and EeV CRs originate from the same source class, detection of ≳10 PeV neutrinos may be expected within 5-10 years' operation of IceCube. Together with further observations in the PeV range, the neutrinos can help in revealing the currently unknown sources of EeV CRs. [ABSTRACT FROM AUTHOR]
Published: 2014
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40. Indication of a local fog of subankle ultrahigh energy cosmic rays.

Author: Ruo-Yu Liu, Taylor, Andrew M., Xiang-Yu Wang, and Aharonian, Felix A.
Subjects: *COSMIC rays, *BACKGROUND radiation, *ELECTRON pairs
Abstract: During their propagation through intergalactic space, ultrahigh energy cosmic rays (UHECRs) interact with the background radiation fields. These interactions give rise to energetic electron/positron pairs and photons which in turn feed electromagnetic cascades, contributing to the isotropic gamma-ray background (IGRB). The gamma-ray flux level generated in this way highly depends upon the UHECR propagation distance, as well as the evolution of their sources with redshift. Recently, the Fermi-LAT Collaboration reported that the majority of the total extragalactic gamma-ray flux originates from extragalactic point sources. This posits a stringent upper limit on the IGRB generated via UHECR propagation, and subsequently constrains their abundance in the distant Universe. Focusing on the contribution of UHECR at energies below the ankle within a narrow energy band ((1-4)1018 eV), we calculate the diffuse gamma-ray flux generated through UHECR propagation, normalizing the total cosmic ray energy budget in this band to that measured. We find that in order to not over-produce the new IGRB limit, a local "fog" of UHECR produced by nearby sources may exist, with a possible non-negligible contribution from our Galaxy. Following the assumption that a given fraction of the observed IGRB at 820 GeV originates from UHECR, we obtain a constraint on the maximum distance for the majority of their sources. With other unresolved source populations still contaminating the new IGRB limit, and UHECR above the ankle invariably contributing also to this background, the results presented here are rather conservative. [ABSTRACT FROM AUTHOR]
Published: 2016
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