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Humans spend 70-90% of their time indoors, however, there is a significant lack of knowledge regarding human exposure to microplastic particles and fibers (MPs) within the indoor environment. Fibers make up more than 90% of household settled dust worldwide and have been found in indoor air. Studies have identified MPs larger than 50 micrometers in indoor dust, but these are unlikely to be respirable and little information is available regarding smaller airborne particles. It is evident that humans are inhaling these particles as they have been found in excised diseased and healthy human lung tissues. We have developed methods to identify plastic particles in settled household dust larger than one micrometer in diameter by distinguishing plastic from cellulosic, proteinaceous, and inorganic materials using two different stains, Nile Red for plastics, and Trypan Blue for cellulosic materials. Proteinaceous and inorganic materials remain unstained. Household settled dust is collected onto silicon nitride nanomembranes where in situ analysis of particles can be characterized. The innovative use of nanomembranes allow for particle capture and multiple analyses to take place on the same substrate. Particle analysis via colorimetric staining and imaging is followed by polymer identification via Raman spectroscopy and subsequently characterized via scanning electron microscopy for size and surface morphology. Using this innovative approach, microplastic particles larger than one micrometer in diameter have been identified in all settled dust samples.

The fourth Fermi Large Area Telescope (LAT) catalog (4FGL) contains 5064 $\gamma$-ray sources detected at high significance, but 26% of them still lack associations at other wavelengths. The SPT-SZ survey, conducted between 2008 and 2011 with the South Pole Telescope (SPT), covers 2500 $\mathrm{deg^2}$ of the Southern sky in three millimeter-wavelength (mm) bands and was used to construct a catalog of nearly 5000 emissive sources. In this study, we introduce a new cross-matching scheme to search for multi-wavelength counterparts of extragalactic $\gamma$-ray sources using a mm catalog. We apply a Poissonian probability to evaluate the rate of spurious false associations and compare the multi-wavelength associations from the radio, mm, near-infrared, and X-ray with 4FGL $\gamma$-ray sources. In the SPT-SZ survey field, 85% of 4FGL sources are associated with mm counterparts. These mm sources include 94% of previously associated 4FGL sources and 56% of previously unassociated 4FGL sources. The latter group contains 40 4FGL sources for which SPT has provided the first identified counterparts. Nearly all of the SPT-associated 4FGL sources can be described as flat-spectrum radio quasars or blazars. We find that the mm band is the most efficient wavelength for detecting $\gamma$-ray blazars when considering both completeness and purity. We also demonstrate that the mm band correlates better to the $\gamma$-ray band than the radio or X-ray bands. With the next generation of CMB experiments, this technique can be extended to greater sensitivities and more sky area to further complete the identifications of the remaining unknown $\gamma$-ray blazars., Comment: 19 pages, 12 figures, 3 tables. published in ApJ

The energetic composition of radio lobes in the FR II galaxies $-$ estimated by comparing their radio luminosities with the powers required to inflate cavities in the external medium $-$ seems to exclude the possibility of their energetic domination by protons. Furthermore, if the jets were dominated by the kinetic energy of cold protons, it would be difficult to efficiently accelerate leptons in the jets' terminal shocks. Assuming that the relative energy contents of leptons, protons and magnetic fields are preserved across the shocks, the above implies that the large-scale jets should also be energetically dominated by leptons: $P_{\rm e,j} \gtrsim P_{\rm p,j}$. On the other hand, previous studies of small-scale jets in blazars and radio cores suggest a pair content (number of electrons and positrons per proton) of the order of $n_{\rm e}/n_{\rm p} \sim 20$. Assuming further that the particle composition of jets does not evolve beyond the blazar scales, we show that this implies an average random Lorentz factor of leptons in large-scale jets of $\bar\gamma_{\rm e,j} \gtrsim 70(1+\chi_{\rm p})(20n_{\rm p}/n_{\rm e})$, and that the protons should be mildly relativistic with $\chi_{\rm p} \equiv (\epsilon_{\rm p} + p_{\rm p})/\rho_{\rm p} c^2 \lesssim 2$, $p_{\rm p}$ the pressure of protons, $\epsilon_{\rm p}$ the internal energy density of protons, and $\rho_{\rm p} c^2$ the rest-mass energy density of protons. We derive the necessary conditions for loading the inner jets by electron-positron pairs and proton-electron plasma, and provide arguments that heating of leptons in jets is dominated by magnetic reconnection., Comment: 7 pages, accepted for publication in the MNRAS, updated list of references

The astrophysical journal 897(2), 177 (2020). doi:10.3847/1538-4357/ab9c1a, The uncharted territory of the high-redshift ($z≳3$) Universe holds the key to understand the evolution of quasars. In an attempt to identify the most extreme members of the quasar population, i.e., blazars, we have carried out a multi-wavelength study of a large sample of radio-loud quasars beyond $z=3$. Our sample consists of 9 $γ$-ray detected blazars and 133 candidate blazars selected based on the flatness of their soft X-ray spectra (0.3−10 keV photon index $≤1.75$), including 15 with NuSTAR observations. The application of the likelihood profile stacking technique reveals that the high-redshift blazars are faint γ-ray emitters with steep spectra. The high-redshift blazars host massive black holes $(⟨log M_{BH, M⊙⟩}>9)$ and luminous accretion disks $(⟨L_{disk}⟩>10^{46} erg s^{−1})$. Their broadband spectral energy distributions are found to be dominated by high-energy radiation indicating their jets to be among the most luminous ones. Focusing on the sources exhibiting resolved X-ray jets (as observed with the Chandra satellite), we find the bulk Lorentz factor to be larger with respect to other $z>3$ blazars, indicating faster moving jets. We conclude that the presented list of the high-redshift blazars may act as a reservoir for follow-up observations, e.g., with NuSTAR, to understand the evolution of relativistic jets at the dawn of the Universe., Published by Chicago, Ill. [u.a.]

Understanding and reducing the in-orbit instrumental backgrounds are essential to achieving high sensitivity in hard X-ray astronomical observations. The observational data of the Hard X-ray Imager (HXI) on board the Hitomi satellite provides useful information on the background components, owing to its multi-layer configuration with different atomic numbers: the HXI consists of a stack of four layers of Si (Z = 14) detectors and one layer of CdTe (Z = 48, 52) detector surrounded by well-type BGO (Bi4Ge3O12) active shields. Based on the observational data, the backgrounds of top Si layer, the three underlying Si layers, and the CdTe layer are inferred to be dominated by different components, namely, low-energy electrons, albedo neutrons, and proton-induced radioactivation, respectively. Monte Carlo simulations of the in-orbit background of the HXI reproduce the observed background spectrum of each layer well, thereby verifying the above hypothesis quantitatively. In addition, we suggest the inclusion of an electron shield to reduce the background., Comment: 12 pages, 8 figures, accepted for publication in JATIS

著者人数: 193名(所属. 宇宙航空研究開発機構宇宙科学研究所 (JAXA)(ISAS): 堂谷, 忠靖; 海老沢, 研; 林, 克洋; 飯塚, 亮; 井上, 芳幸; 石田, 学; 石川, 久美; 岩井, 将親; 国分, 紀秀; 小山, 志勇; 前田, 良知; 満田, 和久; 中川, 貴雄; 尾崎, 正伸; 佐藤, 悟郎; 佐藤, 理江; Simionescu, Aurora; 菅原, 泰晴; 高橋, 忠幸; 竹井, 洋; 田村, 隆幸; 田中, 靖郎; 冨田, 洋; 辻本, 匡弘; 上田, 周太朗; 渡辺, 伸; 山崎, 典子; 内田, 悠介), Accepted: 2018-09-30, 資料番号: SA1180351000

We study the differences in X-ray properties of luminous radio galaxies and their radio-quiet counterparts. In order to avoid biases associated with the dependence of X-ray properties on the black hole mass and Eddington ratio, the radio-loud and radio-quiet objects are selected to cover similar ranges of these parameters. Our studies are based on the X-ray data from the Swift/BAT catalogue. We confirm previous results that radio galaxies are on average X-ray-louder than radio-quiet AGNs, but find that their spectral slopes are very similar. This suggests that in radio-loud and radio-quiet AGNs the hard X-rays are produced in the same region and by the same mechanism. We argue that this region can be associated with the hot, geometrically thick, central portion of the accretion flow, where production of hard X-rays is likely to be dominated by Comptonization of the optical/UV radiation of the truncated 'cold' accretion disc by hot electrons. The larger X-ray luminosities in radio-loud AGNs may result from larger radiative efficiencies of the innermost portions of the accretion flows around faster rotating black holes., 12 pages, 10 figures, 3 tables; MNRAS, in press

著者人数: 270名（所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 高橋, 忠幸; 国分, 紀秀; 満田, 和久; Baluta, Chris; 坂東, 信尚; 堂谷, 忠靖; 海老沢, 研; 林, 克洋; 廣瀬, 和之; 飯塚, 亮; 石田, 学; 石川, 久美; 石村, 康生; 岩井, 将親; 岩田, 直子; 河野, 太郎; 川崎, 繁男; 小山, 志勇; 前田, 良知; 峯杉, 賢治; 中川, 貴雄; 夏苅, 権; 小川, 博之; 小川, 美奈; 太田, 方之; 岡崎, 健; 尾崎, 正伸; 坂井, 真一郎; 鮫島, 寛明; 佐藤, 悟郎; 佐藤, 理江; 柴野, 靖子; 志田, 真樹; 嶋田, 貴信; Simionescu, Aurora; 菅原, 泰晴; 竹井, 洋; 田村, 隆幸; 田中, 靖郎; 田代, 信; 冨田, 洋; 辻本, 匡弘; 上田, 周太朗; 上野, 史郎; 和田, 篤始; 渡辺, 伸; 山田, 隆弘; 山崎, 典子）, Number of authors: 270 (Affiliation. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS): Takahashi, Tadayuki; Kokubun, Motohide; Mitsuda, Kazuhisa; Baluta, Chris; Bando, Nobutaka; Dotani, Tadayasu; Ebisawa, Ken; Hayashi, Katsuhiro; Hirose, Kazuyuki; Iizuka, Ryo; Ishida, Manabu; Ishikawa, Kumi; Ishimura, Kosei; Iwai, Masachika; Iwata, Naoko; Kawano, Taro; Kawasaki, Shigeo; Koyama, Shu; Maeda, Yoshitomo; Minesugi, Kenji; Nakagawa, Takao; Natsukari, Chikara; Ogawa, Hiroyuki; Ogawa, Mina; Ohta, Masayuki; Okazaki, Tsuyoshi; Ozaki, Masanobu; Sakai, Shinichiro; Sameshima, Hiroaki; Sato, Goro; Sato, Rie; Shibano, Yasuko; Shida, Maki; Shimada, Takanobu; Simionescu, Aurora; Sugawara, Yasuharu; Takei, Yoh; Tamura, Takayuki; Tanaka, Yasuo; Tashiro, Makoto; Tomida, Hiroshi; Tsujimoto, Masahiro; Ueda, Shutaro; Ueno, Shiro; Wada, Atsushi; Watanabe, Shin; Yamada, Takahiro; Yamasaki, Noriko Y.), Accepted: 2018-02-05, 資料番号: SA1170333000

著者人数: Hitomi Collaboration 193名（所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 堂谷, 忠靖; 海老沢, 研; 萩野, 浩一; 林, 克洋; 飯塚, 亮; 井上, 芳幸; 石田, 学; 石川, 久美; 岩井, 将親; 国分, 紀秀; 小山, 志勇; Lee, Shiu-Hang; 前田, 良知; 満田, 和久; 中川, 貴雄; 尾崎, 正伸; 佐藤, 悟郎; 佐藤, 理江; Simionescu, Aurora; 菅原, 泰晴; 高橋, 忠幸; 竹井, 洋; 田村, 隆幸; 田中, 靖郎; 冨田, 洋; 辻本, 匡弘; 上田, 周太朗; 渡辺, 伸; 山崎, 典子）, Number of authors: Hitomi Collaboration 193 (Affiliation. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS): Dotani, Tadayasu; Ebisawa, Ken; Hagino, Kouichi; Hayashi, Katsuhiro; Iizuka, Ryo; Inoue, Yoshiyuki; Ishida, Manabu; Ishikawa, Kumi; Iwai, Masachika; Kokubun, Motohide; Koyama, Shu; Lee, Shiu-Hang; Maeda, Yoshitomo; Mitsuda, Kazuhisa; Nakagawa, Takao; Ozaki, Masanobu; Sato, Goro; Sato, Rie; Simionescu, Aurora; Sugawara, Yasuharu; Takahashi, Tadayuki; Takei, Yoh; Tamura, Takayuki; Tanaka, Yasuo; Tomida, Hiroshi; Tsujimoto, Masahiro; Ueda, Shutaro; Watanabe, Shin; Yamasaki, Noriko Y.), Accepted: 2017-11-16, 資料番号: SA1170338000

著者人数: Hitomi Collaboration 194名（所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 堂谷, 忠靖; 海老沢, 研; 林, 克洋; 飯塚, 亮; 井上, 芳幸; 石田, 学; 石川, 久美; 岩井, 将親; 国分, 紀秀; 小山, 志勇; 前田, 良知; 満田, 和久; 中川, 貴雄; 尾崎, 正伸; 佐藤, 悟郎; 佐藤, 理江; Simionescu, Aurora; 菅原, 泰晴; 高橋, 忠幸; 竹井, 洋; 田村, 隆幸; 田中, 靖郎; 冨田, 洋; 辻本, 匡弘; 上田, 周太朗; 渡辺, 伸; 山崎, 典子）, Number of authors: Hitomi Collaboration 194 (Affiliation. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS): Dotani, Tadayasu; Ebisawa, Ken; Hayashi, Katsuhiro; Iizuka, Ryo; Inoue, Yoshiyuki; Ishida, Manabu; Ishikawa, Kumi; Iwai, Masachika; Kokubun, Motohide; Koyama, Shu; Maeda, Yoshitomo; Mitsuda, Kazuhisa; Nakagawa, Takao; Ozaki, Masanobu; Sato, Goro; Sato, Rie; Simionescu, Aurora; Sugawara, Yasuharu; Takahashi, Tadayuki; Takei, Yoh; Tamura, Takayuki; Tanaka, Yasuo; Tomida, Hiroshi; Tsujimoto, Masahiro; Ueda, Shutaro; Watanabe, Shin; Yamasaki, Noriko Y.), Accepted: 2017-10-08, 資料番号: SA1170335000

著者人数: Hitomi Collaboration 194名（所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 堂谷, 忠靖; 海老沢, 研; 林, 克洋; 飯塚, 亮; 井上, 芳幸; 石田, 学; 石川, 久美; 岩井, 将親; 国分, 紀秀; 小山, 志勇; 前田, 良知; 満田, 和久; 中川, 貴雄; 尾崎, 正伸; 佐藤, 悟郎; 佐藤, 理江; Simionescu, Aurora; 菅原, 泰晴; 高橋, 忠幸; 竹井, 洋; 田村, 隆幸; 田中, 靖郎; 冨田, 洋; 辻本, 匡弘; 上田, 周太朗; 渡辺, 伸; 山崎, 典子）, Number of authors: Hitomi Collaboration 194 (Affiliation. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS): Dotani, Tadayasu; Ebisawa, Ken; Hayashi, Katsuhiro; Iizuka, Ryo; Inoue, Yoshiyuki; Ishida, Manabu; Ishikawa, Kumi; Iwai, Masachika; Kokubun, Motohide; Koyama, Shu; Maeda, Yoshitomo; Mitsuda, Kazuhisa; Nakagawa, Takao; Ozaki, Masanobu; Sato, Goro; Sato, Rie; Simionescu, Aurora; Sugawara, Yasuharu; Takahashi, Tadayuki; Takei, Yoh; Tamura, Takayuki; Tanaka, Yasuo; Tomida, Hiroshi; Tsujimoto, Masahiro; Ueda, Shutaro; Watanabe, Shin; Yamasaki, Noriko Y.), Accepted: 2017-12-14, 資料番号: SA1170336000

著者人数: Hitomi Collaboration 193名（所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 堂谷, 忠靖; 海老沢, 研; 萩野, 浩一; 林, 克洋; 飯塚, 亮; 井上, 芳幸; 石田, 学; 石川, 久美; 岩井, 将親; 国分, 紀秀; 小山, 志勇; 前田, 良知; 満田, 和久; 中川, 貴雄; 尾崎, 正伸; 佐藤, 悟郎; 佐藤, 理江; Simionescu, Aurora; 菅原, 泰晴; 高橋, 忠幸; 竹井, 洋; 田村, 隆幸; 冨田, 洋; 辻本, 匡弘; 上田, 周太朗; 渡辺, 伸; 山崎, 典子; 中庭, 望）, Number of authors: Hitomi Collaboration 193 (Affiliation. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS): Dotani, Tadayasu; Ebisawa, Ken; Hagino, Kouichi; Hayashi, Katsuhiro; Iizuka, Ryo; Inoue, Yoshiyuki; Ishida, Manabu; Ishikawa, Kumi; Iwai, Masachika; Kokubun, Motohide; Koyama, Shu; Maeda, Yoshitomo; Mitsuda, Kazuhisa; Nakagawa, Takao; Ozaki, Masanobu; Sato, Goro; Sato, Rie; Simionescu, Aurora; Sugawara, Yasuharu; Takahashi, Tadayuki; Takei, Yoh; Tamura, Takayuki; Tomida, Hiroshi; Tsujimoto, Masahiro; Ueda, Shutaro; Watanabe, Shin; Yamasaki, Noriko Y.), Masahiro; Ueda, Shutaro; Watanabe, Shin; Yamasaki, Noriko Y.; Nakaniwa, Nozomi), Accepted: 2017-11-02, 資料番号: SA1170342000

著者人数: 196名(所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 堂谷, 忠靖; 海老沢, 研; 林, 克洋; 飯塚, 亮; 井上, 芳幸; 石田, 学; 石川, 久美; 岩井, 将親; 国分, 紀秀; 小山, 志勇; 前田, 良知; 満田, 和久; 中川, 貴雄; 尾崎, 正伸; 佐藤, 悟郎; 佐藤, 理江; Simionescu, Aurora; 菅原, 泰晴; 高橋, 忠幸; 竹井, 洋; 田村, 隆幸; 田中, 靖郎; 冨田, 洋; 辻本, 匡弘; 上田, 周太朗; 渡辺, 伸; 山崎, 典子; 佐藤, 寿紀; 中庭, 望), Number of authors: Hitomi Collaboration 197 (Affiliation. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS): Dotani, Tadayasu; Ebisawa, Ken; Hayashi, Katsuhiro; Hayashi, Tasuku; Iizuka, Ryo; Inoue, Yoshiyuki; Ishida, Manabu; Ishikawa, Kumi; Iwai, Masachika; Kokubun, Motohide; Koyama, Shu; Maeda, Yoshitomo; Mitsuda, Kazuhisa; Nakagawa, Takao; Ozaki, Masanobu; Sato, Goro; Sato, Rie; Simionescu, Aurora; Sugawara, Yasuharu; Takahashi, Tadayuki; Takei, Yoh; Tamura, Takayuki; Tanaka, Yasuo; Tomida, Hiroshi; Tsujimoto, Masahiro; Ueda, Shutaro; Watanabe, Shin; Yamasaki, Noriko Y.; Sato, Toshiki; Nakaniwa, Nozomu), Accepted: 2018-02-14, 資料番号: SA1180104000

著者人数: Hitomi Collaboration 193名 (所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 堂谷, 忠靖; 海老沢, 研; 林, 克洋; 飯塚, 亮; 井上, 芳幸; 石田, 学; 石川, 久美; 岩井, 將親; 国分, 紀秀; 小山, 志勇; 前田, 良知; 満田, 和久; 中川, 貴雄; 尾崎, 正伸; 佐藤, 悟郎; 佐藤, 理江; Simionescu, Aurora; 菅原, 泰晴; 高橋, 忠幸; 竹井, 洋; 田村, 隆幸; 田中, 靖郎; 冨田, 洋; 辻本, 匡弘; 上田, 周太朗; 渡辺, 伸; 山崎, 典子), Number of authors: Hitomi Collaboration 193 (Affiliation. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS): Dotani, Tadayasu; Ebisawa, Ken; Hayashi, Katsuhiro; Iizuka, Ryo; Inoue, Yoshiyuki; Ishida. Manabu; Ishikawa, Kumi; Iwai, Masachika; Kokubun, Motohide; Koyama, Shu; Maeda, Yoshitomo; Mitsuda, Kazuhisa; Nakagawa, Takao; Ozaki, Masanobu; Sato, Goro; Sato, Rie; Simionescu, Aurora; Sugawara, Yasuharu; Takahashi, Tadayuki; Takei, Yoh; Tamura, Takayuki; Tanaka, Yasuo; Tomida, Hiroshi; Tsujimoto, Masahiro; Ueda, Shutaro; Watanabe, Shin; Yamasaki, Noriko Y.), Accepted: 2017-09-21, 資料番号: SA1170128000

The most powerful sources among the blazar family are MeV blazars. Often detected at $z>2$, they usually display high X- and \gm-ray luminosities, larger-than-average jet powers and black hole masses $\gtrsim 10^9 M_{\odot}$. In the present work we perform a multiwavelength study of three high redshift blazars: 3FGL J0325.5+2223 ($z=2.06$), 3FGL J0449.0+1121 ($z= 2.15$), and 3FGL J0453.2$-$2808 ($z=2.56$), analysing quasi simultaneous data from GROND, \swift-UVOT and XRT, \nustar, and \fermi-LAT. Our main focus is on the hard X-ray band recently unveiled by \nustar~(3$-$79 keV) where these objects show a hard spectrum which enables us to constrain the inverse Compton peak and the jet power. We found that all three targets resemble the most powerful blazars, with the synchrotron peak located in the sub-millimeter range and the inverse Compton peak in the MeV range, and therefore belong to the MeV blazar class. Using a simple one zone leptonic emission model to reproduce the spectral energy distributions, we conclude that a simple combination of synchrotron and accretion disk emission reproduces the infrared-optical spectra while the X-ray to \gm-ray part is well reproduced by the inverse Compton scattering of low energy photons supplied by the broad line region. The black hole masses for each of the three sources are calculated to be $\gtrsim 4 \times 10^{8} M_{\odot}$. The three studied sources have jet power at the level of, or beyond, the accretion luminosity., 4 figures, 3 tables, accepted for publication in ApJ

The Flat Spectrum Radio Quasar 3C 279 underwent several outbursts in the past, having flared with a peak γ-ray flux above 100 MeV (FE>100 MeV) exceeding 10−5 ph cm−2 s−1, in 2013 December, 2014 April, and 2015 June. The 2013 December outburst showed an unusually hard power-law γ-ray spectrum (index∼1.7), and an asymmetric light curve profile with few-hour time scale variability. This could be successfully explained using our second order Fermi acceleration model. The outburst in 2015 June was even more powerful, with FE>100 MeV ∼ 4×10−5 ph cm−2 s−1, the historically highest even when the EGRET era is included. For the first time, significant flux variability at sub-orbital timescales was found in blazar observations by Fermi-LAT, with flux doubling times of less than 5 minutes. In the standard external-Compton scenario with conical jet geometry, the minute-scale variability requires a very high bulk jet Lorentz factor (> 50) and extremely low magnetization even at the jet base (∼ 100RS). However, such a h...

aMax-Planck-Institut fur Physik, Germany bStanford University, USA cNASA Goddard Space Flight Center, USA dInstituto de Astrofisica de Canarias, Spain E-mail: knoda@mppmu.mpg.de The blazar Mrk 501 is among the brightest X-ray and TeV sources in the sky, and among the few sources whose (radio to Very-High-Energy (VHE; ≥ 100 GeV) gamma-rays) spectral energy distributions can be characterized by current instruments by means of relatively short observations (minutes to hours). In 2013, we organized an extensive multi-instrument campaign involving the participation of Fermi-LAT, MAGIC, VERITAS, F-GAMMA, Swift, GASP-WEBT, and other collaborations/groups and instruments which provided the most detailed temporal and energy coverage on Mrk 501 to date. This observing campaign included, for the first time, observations with the Nuclear Stereoscopic Telescope Array (NuSTAR), which is a satellite mission launched in mid-2012. NuSTAR provides unprecedented sensitivity in the hard X-ray range 3-79 keV, which, together with MAGIC and VERITAS observations, is crucial to probe the highest energy electrons in Mrk 501. The multi-instrument campaign covered a few day long flaring activity in July 2013 which could be studied with strictly simultaneous NuSTAR and MAGIC observations. A large fraction of the MAGIC data during this flaring activity was affected by hazy atmospheric conditions, due to the presence of a sand layer from the Saharan desert. These data would have been removed in any standard Cherenkov Telescope data analysis. The MAGIC collaboration has developed a technique to correct for adverse atmospheric conditions the very high energy (VHE, E > 100 GeV) observations performed by Cherenkov telescopes. The technique makes use of the atmospheric information from the LIDAR facility that is operational at the MAGIC site, and applies an event-by-event correction to recover data affected by adverse weather conditions. This is the first time that LIDAR information has been used to produce a physics result with Cherenkov Telescope data taken during adverse atmospheric conditions, and hence sets a precedent for current and future ground-based gamma-ray instruments. In this contribution we report the observational results, focusing on the LIDAR-corrected MAGIC data and the strictly simultaneous NuSTAR and MAGIC/VERITAS data, and discuss the scientific implications. The 34th International Cosmic Ray Conference, 30 July6 August, 2015 The Hague, The Netherlands

Strong and variable radiation detected over all accessible energy bands in blazar arises from a relativistic, Doppler-boosted jet pointing close to our line of sight. Flat Spectrum Radio Quasar 3C 279 was one of the brightest γ-ray blazars in the sky at the time of the discovery with EGRET. Since the successful launch of the Fermi Gamma-ray Space telescope in 2008, we have organized extensive multi-band observational campaign of 3C 279 from radio to γ-ray bands, also including optical polarimetric observations. The uninterrupted monitoring in the γ-ray band by Fermi-LAT together with the multi-band data provide us with new insights of the relativistic jet of blazar. Here, we present the results of the first-year multi-band campaign of 3C 279 including the discovery of a γ-ray flare event associated with a dramatic change of the optical polarization - as well as a discovery of an “orphan” X-ray flare, unassociated with prominent outbursts in other bands.

Many luminous blazars which are associated with quasar-type active galactic nuclei display broad-band spectra characterized by a large luminosity ratio of their high-energy (gamma-ray) and low-energy (synchrotron) spectral components. This large ratio, reaching values up to 100, challenges the standard synchrotron self-Compton models by means of substantial departures from the minimum power condition. Luminous blazars have also typically very hard X-ray spectra, and those in turn seem to challenge hadronic scenarios for the high energy blazar emission. As shown in this paper, no such problems are faced by the models which involve Comptonization of radiation provided by a broad line-region, or dusty molecular torus. The lack or weakness of bulk Compton and Klein-Nishina features indicated by the presently available data favors production of gamma-rays via up-scattering of infrared photons from hot dust. This implies that the blazar emission zone is located at parsec-scale distances from the nucleus, and as such is possibly associated with the extended, quasi-stationary reconfinement shocks formed in relativistic outflows. This scenario predicts characteristic timescales for flux changes in luminous blazars to be days/weeks, consistent with the variability patterns observed in such systems at infrared, optical and gamma-ray frequencies. We also propose that the parsec-scale blazar activity can be occasionally accompanied by dissipative events taking place at sub-parsec distances and powered by internal shocks and/or reconnection of magnetic fields. These could account for the multiwavelength intra-day flares occasionally observed in powerful blazars sources., Comment: 34 pages, accepted for publication in the Astrophysical Journal

TeV blazars are known as prominent nonthermal emitters across the entire electromagnetic spectrum with their photon power peaking in the X-ray and TeV bands. If distant, absorption of gamma-ray photons by the extragalactic background light (EBL) alters the intrinsic TeV spectral shape, thereby affecting the overall interpretation. Suzaku observations for two of the more distant TeV blazars known to date, 1ES 1101-232 and 1ES 1553+113, were carried out in 2006 May and July, respectively, including a quasi-simultaneous coverage with the state-of-the-art Cerenkov telescope facilities. We report on the resulting data sets with emphasis on the X-ray band and set in context to their historical behavior. During our campaign, we did not detect any significant X-ray or gamma-ray variability. 1ES 1101-232 was found in a quiescent state with the lowest X-ray flux ever measured. The combined XIS and HXD PIN data for 1ES 1101-232 and 1ES 1553+113 clearly indicate spectral curvature up to the highest hard X-ray data point (~30 keV), manifesting as softening with increasing energy. We describe this spectral shape by either a broken power law or a log-parabolic fit with equal statistical goodness of fits. The combined 1ES 1553+113 very high energy spectrum (90-500 GeV) did not show any significant changes with respect to earlier observations. The resulting contemporaneous broadband spectral energy distributions of both TeV blazars are discussed in view of implications for intrinsic blazar parameter values, taking into account the gamma-ray absorption in the EBL., 9 pages, 10 figures

著者人数: 16名, Accepted: 2006-12-28, 資料番号: SA1000323000

We present the results from a joint Suzaku/NuSTAR broad-band spectral analysis of 3C 390.3. The high quality data enables us to clearly separate the primary continuum from the reprocessed components allowing us to detect a high energy spectral cut-off ($E_\text{cut}=117_{-14}^{+18}$ keV), and to place constraints on the Comptonization parameters of the primary continuum for the first time. The hard over soft compactness is 69$_{-24}^{+124}$ and the optical depth 4.1$_{-3.6}^{+0.5}$, this leads to an electron temperature of $30_{-8}^{+32}$ keV. Expanding our study of the Comptonization spectrum to the optical/UV by studying the simultaneous Swift-UVOT data, we find indications that the compactness of the corona allows only a small fraction of the total UV/optical flux to be Comptonized. Our analysis of the reprocessed emission show that 3C 390.3 only has a small amount of reflection (R~0.3), and of that the vast majority is from distant neutral matter. However we also discover a soft X-ray excess in the source, which can be described by a weak ionized reflection component from the inner parts of the accretion disk. In addition to the backscattered emission, we also detect the highly ionized iron emission lines Fe XXV and Fe XXVI., Comment: accepted for publication in ApJ

Evidence for non-thermal activity in clusters of galaxies is well established from radio observations of synchrotron emission by relativistic electrons. New windows in the Extreme Ultraviolet and Hard X-ray ranges have provided for more powerful tools for the investigation of this phenomenon. Detection of hard X-rays in the 20 to 100 keV range have been reported from several clusters of galaxies, notably from Coma and others. Based on these earlier observations we identified the relatively high redshift cluster 1E0657-56 (also known as RX J0658-5557) as a good candidate for hard X-ray observations. This cluster, also known as the bullet cluster, has many other interesting and unusual features, most notably that it is undergoing a merger, clearly visible in the X-ray images. Here we present results from a successful RXTE observations of this cluster. We summarize past observations and their theoretical interpretation which guided us in the selection process. We describe the new observations and present the constraints we can set on the flux and spectrum of the hard X-rays. Finally we discuss the constraints one can set on the characteristics of accelerated electrons which produce the hard X-rays and the radio radiation.

The formation of relativistic astrophysical jets is presumably mediated by magnetic fields threading accretion disks and central, rapidly rotating objects. As it is accelerated by magnetic stresses, the jet's kinetic energy flux grows at the expense of its Poynting flux. However, it is unclear how efficient is the conversion from magnetic to kinetic energy and whether there are any observational signatures of this process. We address this issue in the context of jets in quasars. Using data from all spatial scales, we demonstrate that in these objects the conversion from Poynting-flux-dominated to matter-dominated jets is very likely to take place closer to the black hole than the region where most of the Doppler boosted radiation observed in blazars is produced. We briefly discuss the possibility that blazar activity can be induced by global MHD instabilities, e.g., via the production of localized velocity gradients that lead to dissipative events such as shocks or magnetic reconnection, where acceleration of relativistic particles and production of non-thermal flares is taking place., Accepted by the Astrophysical Journal

We analyze observations of the Seyfert galaxy NGC 4151 covering 90 years in the optical band and 27 years in the 2-10 keV X-ray band. We compute the Normalized Power Spectrum Density (NPSD), the Structure Function (SF) and the Autocorrelation Function (ACF) for these data. The results show that the optical and X-ray variability properties are significantly different. X-ray variations are predominantly in the timescale range of 5 - 1000 days. The optical variations have also a short timescale component which may be related to X-ray variability but the dominant effect is the long timescale variability, with timescales longer than $\sim$ 10 years. We compare our results with observations of NGC 5548 and Cyg X-1. We conclude that the long timescale variability may be caused by radiation pressure instability in the accretion disk, although the observed timescale in NGC 4151 is by a factor of few longer than expected. X-ray variability of this source is very similar to what is observed in Cyg X-1 but scaled with the mass of the black hole, which suggests that the radiation pressure instability does not affect considerably the X-ray production., 21 pages, 19 figures, 4 tables, accepted for publication in MNRAS

We analyze recent simultaneous Chandra/RXTE observations of the Seyfert 2 galaxy NGC 4945. The unprecedented spatial resolution of Chandra means we are able to separate the spectra of the nucleus, starburst, and superwind regions, while the RXTE data extend the spectrum to higher energies. The extreme absorbing column of NH ~ 4 × 1024 cm-2 means that the nucleus is only directly seen above 8-10 keV, while the lower energy spectrum from the nuclear region in Chandra is dominated by reflection. By contrast, the superwind is dominated by emission from hot plasma, but the starburst region contains both hot plasma and reflection signatures. Forming a reflected spectrum requires that the starburst region contain clumps of cool, optically thick material, perhaps star-forming cores, which are irradiated by 7-10 keV photons from the nucleus. Since photons of this energy are obscured along the line of sight, this confirms the result of Madejski et al. that the extreme absorption material is disklike rather than toroidal. However, the IR/optical limits on the lack of high-excitation emission lines show that, by contrast, the lower energy photons from the nucleus are obscured in all directions. We discuss the complex absorption structure revealed by these observations and propose an overall source geometry in which the nucleus is completely embedded in material with NH ~ 1023 cm-2.

PKS 1413+135 (z=0.24671) is one of very few radio-loud AGN with an apparent spiral host galaxy. Previous authors have attributed its nearly exponential infrared cutoff to heavy absorption but have been unable to place tight limits on the absorber or its location in the optical galaxy. In addition, doubts remain about the relationship of the AGN to the optical galaxy given the observed lack of re-emitted radiation. We present new HST, ASCA and VLBA observations which throw significant new light on these issues. The HST observations reveal an extrremely red color (V-H = 6.9 mag) for the active nucleus of PKS 1413+135, requiring both a spectral turnover at a few microns due to synchrotron aging and a GMC-sized absorber. We derive an intrinsic column N_H = 4.6^{+2.1}_{-1.6} times 10^{22}cm^{-2} and covering fraction f = 0.12^{+0.07}_{-0.05}. As the GMC is likely in the disk of the optical galaxy, our sightline is rather unlikely (P ~ 2 times 10^{-4}). The properties of the GMC typical of GMCs in our own galaxy. The HI absorber appears centered 25 milliarcseconds away from the nucleus, while the X-ray and nearly all of the molecular absorbers must cover the nucleus, implying a complicated geometry and cloud structure, with a molecular core along our line of sight to the nucleus. Interestingly, the HST/NICMOS data require the AGN to be decentered relative to the optical galaxy by 13 +/- 4 milliarcseconds. This could be interpreted as suggestive of an AGN location far in the background compared to the optical galaxy, but it can also be explained by obscuration and/or nuclear structure, which is more consistent with the observed lack of multiple images.

This paper reports X-ray spectral observations of a relatively nearby z = 0.048 BL Lacertae (BL Lac) object 1ES1959+650, which is a potential TeV emitter. The observations include 31 short pointings made by the Unconventional Stellar Aspect (USA) Experiment on board the Advanced Research and Global Observation Satellite (ARGOS), and 17 pointings by the PCA on board the Rossi X-ray Timing Explorer (RXTE). Most of these observations were spaced by less than 1 day. \es was detected by the ARGOS USA detector in the range 1-16 keV, and by the PCA in the 2-16 keV range but at different times. During the closely spaced RXTE observations beginning on 2000 July 28, an ending of one flare and a start of another are visible, associated with spectral changes, where the photon index Gamma ranges between ~ 1.4 and 1.7, and the spectrum is harder when the source is brighter. This implies that 1ES1959 is an XBL-type blazar, with the X-ray emission likely to originate via the synchrotron process. The USA observations reveal another flare that peaked on 2000 November 14 and doubled the flux within a few days, again associated with spectral changes of the same form. The spectral variability correlated with the flux and timing characteristics of this object that are similar to those of other nearby BL Lacs, and suggest relativistic beaming with a Doppler factor delta > 1.6 and magnetic fields of the order of a few mG. We also suggest that the steady component of the X-ray emission -- present in this object as well as in other XBLs -- may be due to the large-scale relativistic jet (such as measured by Chandra in many radio-loud AGN), but pointing very closely to our line of sight., To appear in ApJ June 1, 2002 issue

The Rossi X-ray Timing Explorer (RXTE) has produced many excellent observations of active galaxies, providing the best sensitivity in the 10 - 20 keV range so far. This presentation reports selected RTXE data for AGN in the context of the currently popular models. One is the recent result for two Seyfert 1 galaxies, NGC 5548 and IC4329a: both show the "canonical" Seyfert I X-ray spectra, with an underlying power law, plus Gaussian iron K line and Compton reflection. Interestingly, in both cases, the profile of the Fe K line does not extend as far to the red as seen in the famous NCG-6-30-15, and this indicates that the regions where the Fe K lines originate in AGN are diverse. Independently, in both objects we see a strong spectral variability of the primary continua, which soften as the sources brighten. The second result is for the heavily absorbed Seyfert 2 NGC 4945. The RXTE data confirm the strong absorption corresponding to the optical depth to electron scattering of about 2, but also reveal rapid variability of the hard (8-30 keV) X-ray emission on a time scale of a day or less. This suggests that for NGC 4945, the putative parsec-size molecular torus cannot be both geometrically and optically thick, and implies that the Cosmic X-ray Background is unlikely to be made up primarily of AGN with geometry as inferred for this object.

NGC 4945 is one of the brightest Seyfert galaxies on the sky at 100 keV, but is completely absorbed below 10 keV; its absorption column is probably the largest that still allows a direct view of the nucleus at hard X-ray energies. Our observations of it with the Rossi X-Ray Timing Explorer (RXTE) satellite confirm the large absorption, which for a simple phenomenological fit using an absorber with solar abundances implies a column of 4.5+0.4-0.4x1024 cm(-2). Using a more realistic scenario (requiring Monte Carlo modeling of the scattering), we infer the optical depth to Thomson scattering of approximately 2.4. If such a scattering medium were to subtend a large solid angle from the nucleus, it should smear out any intrinsic hard X-ray variability on timescales shorter than the light-travel time through it. The rapid (with a timescale of approximately 1 day) hard X-ray variability of NGC 4945 discovered by us with RXTE implies that the bulk of the extreme absorption in this object does not originate in a parsec-size, geometrically thick molecular torus. Instead, the optically thick material on parsec scales must be rather geometrically thin, subtending a half-angle less than 10 degrees, and it is likely to be the same disk of material that is responsible for the water maser emission observed in NGC 4945. Local number counts of Seyfert 1 and Seyfert 2 galaxies show a large population of heavily obscured active galactic nuclei (AGNs) which are proposed to make up the cosmic X-ray background (CXRB). However, for this to be the case, the absorption geometry in the context of axially symmetric unification schemes must have the obscuring material subtending a large scale height-contrary to our inferences about NGC 4945-implying that NGC 4945 is not a prototype of obscured AGNs postulated to make up the CXRB. The small solid angle of the absorber, together with the black hole mass (of approximately 1.4x106 M( middle dot in circle)) from megamaser measurements, allows a robust determination of the nuclear luminosity, which in turn implies that the source radiates at approximately 10% of the Eddington limit.

We report on monitoring of the BL Lac object PKS 2005-489 by the Rossi X-Ray Timing Explorer (RXTE) in 1998 October-December. During these months, the source underwent a spectacular flare; at its peak on November 10, its 2-10 keV flux was 3.33 × 10-10 ergs cm-2 s-1, over 30 times brighter than in quiescence. During the rising phase, the X-ray spectrum of PKS 2005-489 hardened considerably, reaching α = 1.32 (Fν ∝ ν-α) near maximum. During the declining phase, the X-ray spectrum steepened rapidly, reaching α = 1.82, then became somewhat harder toward the end of December (α ~ 1.6). While such behavior has been seen before, the simplicity, magnitude, and duration of this flare allowed us to study it in great detail. We argue that this flare was caused by either the injection of particles into the jet or in situ particle acceleration and that the spectral steepening which followed the flare maximum was the result of synchrotron cooling. Contrary to other recently observed blazar flares (e.g., Mrk 501, 3C 279, PKS 2155-304), our results do not imply a major shift in the location of the synchrotron peak during this flare.

Abell 754, a cluster undergoing merging, was observed in hard X-rays with the Rossi X-Ray Timing Explorer (RXTE) in order to constrain its hottest temperature component and search for evidence of nonthermal emission. Simultaneous modeling of RXTE data and those taken with previous missions yields an average intracluster temperature of ~9 keV in the 1-50 keV energy band. A multitemperature component model derived from numerical simulations of the evolution of a cluster undergoing a merger produces similar quality of fit, indicating that the emission measure from the very hot gas component is sufficiently small that it renders the two models indistinguishable. No significant nonthermal emission was detected. However, our observations set an upper limit of 7.1×10−14 ergs cm−2 s−1 keV−1 (90% confidence limit) to the nonthermal emission flux at 20 keV. Combining this result with the radio synchrotron emission flux, we find a lower limit of 0.2 μG for the intracluster magnetic field. We discuss the implications of our results for the theories of magnetic field amplifications in cluster mergers.

The Rossi X-ray Timing Explorer made a short (10 ks) observation of the radio galaxy Centaurus A on 14 August 1996. Analysis of the combined 2.5-240 keV spectrum has revealed a heavily absorbed(NH=9.42+/-0.24 e22 cm-2) primary power law (index=1.86+/-0.015) and an iron line due to fluorescence of cold matter (EW=162+/-25 eV). Flux from either a jet, primary flux scattered into the line of sight, or primary flux seen through a partial absorber was not required. The iron line width is unresolved at the 95% confidence level (sigma < 0.54 keV). No significant variability in the iron line flux is seen from measurements over the last two decades, while the overall continuum flux varied by more than a factor of four, which implies that the line emission region is distant from that of the primary emission. While radio-quiet Seyfert galaxies exhibit spectral components attributable to Compton reflection from cold matter, Cen A reveals no such component (exposed solid angle ratio < 0.09). This supports unified models of active galaxies that have little difference between Seyfert 2 and low luminosity radio galaxies

We study X-ray and soft gamma-ray spectral properties of BLRGs using data from Ginga, ASCA, OSSE and EXOSAT. The X-ray spectra are well fitted by an intrinsic power-law continuum with an energy index of alpha ~ 0.7, moderately absorbed by a cold medium. In addition, the Ginga spectra show Fe K-alpha lines with an average equivalent width of ~ 100 eV, and, in some cases, Compton reflection humps. However, the latter components are significantly weaker than both those seen in radio-quiet Seyferts and those expected if the Fe K-alpha lines were due to reflection. Some ASCA and EXOSAT spectra show soft X-ray excesses below ~ 3 keV. When that component is taken into account, the Fe K-alpha lines in the ASCA data become unresolved with equivalent widths < 200 eV. Multiple observations of 3C 390.3 and 3C 382 show the Fe K-alpha line approximately constant in flux but accompanied by strong continuum variations. This indicates the bulk of the line is formed by matter at a distance much larger than an accretion-disk scale, consistent with the ASCA line width measurements. The column density of the matter required to account for the observed line fluxes is N_H > 10^23 cm^-2. Such a medium is in the line-of-sight in 3C 445 but it has to be out of it in other objects, in which the observed N_H are substantially lower. Thus, a cold medium with that N_H and covering a large solid angle is out of the line-of-sight in most objects. The spectra of BLRGs break and become softer above ~ 100 keV, as shown by a simultaneous ASCA/OSSE observation of 3C 120 and by the OSSE spectra being on average much softer than the X-ray spectra. Finally, we find the X-ray and gamma-ray spectral properties of Cen A intrinsically very similar to BLRGs studied here., 20 pages, 13 figures, to appear in MNRAS

We present a broadband (~0.5-79 keV) spectral and temporal analysis of multiple NuSTAR observations combined with archival Suzaku and Chandra data of NGC4945, the brightest extragalactic source at 100 keV. We observe hard X-ray (> 10 keV) flux and spectral variability, with flux variations of a factor 2 on timescales of 20 ksec. A variable primary continuum dominates the high energy spectrum (>10 keV) in all the states, while the reflected/scattered flux which dominates at E< 10 keV stays approximately constant. From modelling the complex reflection/transmission spectrum we derive a Compton depth along the line of sight of tau_Thomson ~ 2.9, and a global covering factor for the circumnuclear gas of ~ 0.15. This agrees with the constraints derived from the high energy variability, which implies that most of the high energy flux is transmitted, rather that Compton-scattered. This demonstrates the effectiveness of spectral analysis in constraining the geometric properties of the circumnuclear gas, and validates similar methods used for analyzing the spectra of other bright, Compton-thick AGN. The lower limits on the e-folding energy are between 200-300 keV, consistent with previous BeppoSAX, Suzaku and Swift BAT observations. The accretion rate, estimated from the X-ray luminosity and assuming a bolometric correction typical of type 2 AGN, is in the range ~0.1-0.3 lambda_Edd depending on the flux state. The substantial observed X-ray luminosity variability of NGC4945 implies that large errors can arise from using single-epoch X-ray data to derive L/L_Edd values for obscured AGNs., Accepted for publication in ApJ

PKS 2155-304, the brightest BL Lac object in the ultraviolet sky, was monitored with the IUE satellite at ~1 hour time-resolution for ten nearly uninterrupted days in May 1994. The campaign, which was coordinated with EUVE, ROSAT, and ASCA monitoring, along with optical and radio observations from the ground, yielded the largest set of spectra and the richest short time scale variability information ever gathered for a blazar at UV wavelengths. The source flared dramatically during the first day, with an increase by a factor ~2.2 in an hour and a half. In subsequent days, the flux maintained a nearly constant level for ~5 days, then flared with ~35% amplitude for two days. The same variability was seen in both short- and long-wavelength IUE light curves, with zero formal lag (~

We use multiwavelength spectra of core-dominated flat spectrum radio-loud quasars (FSRQs) to study properties of jets in active galactic nuclei. From a comparison of the predicted bulk Compton radiation with the observed soft X-ray fluxes, we find that these jets must be optically very thin. This eliminates the importance of such processes as Coulomb interactions, pair annihilation, and bremsstrahlung and determines the minimum distance from the black hole where a powerful jet can be fully developed (accelerated, collimated, and mass loaded). In the case of pair dominated jets, this distance is 100GMBH/c2. Further constraints on the parameters of a jet can be derived from luminosities and positions of spectral peaks of low-energy (IR/optical) and high-energy (γ-ray) radiation components, provided that both are produced by the same population of electrons. Whereas there appears to be a consensus about the synchrotron origin of the low-energy component, there is still debate about the mechanism of production of γ-rays. Most likely, they result from Comptonization of a soft radiation field by the same electrons that produce synchrotron radiation. Such a soft radiation field can be provided by the synchrotron process in a jet, by the accretion disk, and by a fraction of the disk radiation that is reprocessed/rescattered by emission line clouds, dust, and intercloud medium. We show that for FSRQs, the production of the high-energy radiation can be dominated by Comptonization of synchrotron radiation only for jets with moderate bulk Lorentz factors Γj (3) or if external radiation fields are much weaker than those observed in typical quasars. Furthermore, in synchrotron self-Compton (SSC) models, the relativistic plasma producing nonthermal radiation is constrained to be very weakly magnetized (B' < 0.01 gauss) and located at very large distances (r ~ 1019 cm). These can impose problems with jet confinement and with short observed timescale of variability. In the external radiation Compton (ERC) models, the magnetic fields are predicted to be much stronger (B' ~ 100 gauss), and nonthermal radiation can be produced very closely to the black hole (r ~ 1016 cm), which alleviates the problems with plasma confinement and short timescale variability. However, because of the close proximity to the black hole, the constraints imposed by the bulk Compton radiation imply that the plasma must be free of e+e- pairs. Finally, we discuss the difficulties that existing models have in explaining the sharp spectral breaks at MeV energies and postulate a "hot electron" version of the ERC scenario for the production of MeV peaks. We show that appropriate electron "temperatures" (kT ~ 100 MeV) to produce the luminosity peak at MeV energies by Comptonization of external UV radiation are achievable at subparsec distances only for proton-electron plasmas.

We report the presence of an absorption feature in the X-ray spectrum of the BL Lacertae object H1426)428 (z \ 0.129). H1426)428 was observed at three separate epochs with BBXRT, ROSAT , and ASCA. In the BBXRT spectrum an absorption feature is clearly present at D0.66 keV, consistent with absorption by highly ionized oxygen. The phenomenological model that best describes the absorption feature is an inverted Gaussian with width km s~1. This feature is not present in the FWHM ( 43,000 ROSAT and ASCA data, both taken when the source Nux was fainter by a factor B2. Instead, these data show some evidence for absorption edge(s) at lower energies. These results are consistent with par- tially ionized, low-density gas surrounding the central engine of H1426)428. As a -rst approximation the X-ray continuum can be described with a power law with photon index !B 2. The BBXRT and ASCA data are better -tted with a convex (downward-curved) broken power law. The exact shape of the continuum depends on the assumed pro-le for the absorption feature. We show that, using a speci-c warm absorber to -t the data, there is no need for a continuum model more complex than a single power law. Subject headings: BL Lacertae objects: individual (H1426)428) E line: identi-cation E radiation mechanisms: nonthermal E X-rays: galaxies

We present the results of the -rst systematic study of correlated variability in the X-ray emission and the parsec-scale radio structure of the "" superluminal II quasar 3C 345. This quasar is one of a class of core-dominated Nat-spectrum radio sources that are believed to emit X-rays via the synchrotron self- Compton process. By studying its variability in X-rays, we can test this hypothesis for 3C 345 by model- ing the expected inverse-Compton Nux from the parsec-scale jet, using parameters derived from multifrequency VLBI imaging. Since the predicted X-ray Nux is very sensitive to the physical parameters of the compact radio-emitting regions, a study of variability, with quasi-simultaneous X-ray and VLBI data, is of particular interest because it is less sensitive to assumptions in the adopted model. The soft X-ray Nux density of 3C 345 was observed by the ROSAT PSPC instrument at seven epochs during 1990E1993, during which time its Nux density varied by a factor of 2, but with no change in spectral index. The X-ray points closely track the high-frequency radio Nux light curve. Using a series of VLBI images, we followed the time evolution of spectral shapes and angular sizes of the nucleus and the strongest jet component "" C7,II at a distance of ^0.5 mas (2 pc) from the nucleus, and derived physical parameters for the components. We -nd that component C7, not the nucleus, is the dominant generator of the observed X-rays during 1992E1993. For the nucleus, we applied the inhomogeneous-jet model of Koe nigl and found -nd that it underpredicts the X-ray Nux for any plausible combination of physical parameters derived from observation. A homogeneous sphere, with Nux density peaking at a few GHz, is adequate for modeling the evolution of C7. This sphere model requires that C7 dominated the X-ray emission, unless its Doppler factor is ?10. This contrasts with the situation at epoch 1990.55, for which comparable data (Unwin et al. 1994) showed that the nucleus and C5 (the dominant jet feature at that time) both contributed to the X-ray emission. We discuss the lack of detectable c-rays from 3C 345 in relation to other c-ray loud blazars with which it shares many observational properties. Combining the superluminal speed (from VLBI) and Doppler factor deduced from the synchrotron self-Compton calcu- lation, we solve for the jet kinematics at the position of C7, and we -nd that the jet bends away from the line of sight (from h ^ 2i to ^10i) and accelerates from c ^ 5 to over the range of (deprojected)

We observed the BL Lac object Mrk 421 with the X-ray satellite ASCA in 1994 as part of a multifrequency observation. The 24 hr observation was conducted 1 day after the onset of a TeV flare detected by the Whipple Observatory and detected an X-ray flare, with no apparent variability in the optical, UV, and EGRET GeV flux. The ASCA 2-10 keV flux peaked at 3.7 ? 10-10 ergs cm-2 s-1 and then decreased to 1.8 ? 10-10 ergs cm-2 s-1 with a doubling timescale of ~12 hr. The shape of the X-ray spectrum varied during the observation, such that the hard X-rays always led the soft X-rays, both in brightening and dimming of the source, with a lag of the 0.5-1 keV photons versus those in the 2-7.5 keV band of ~1 hr. The rapid TeV variability indicates a compact TeV-producing region, suggesting relativistic beaming with a Doppler factor ? ? 5. The correlation of the flux in the X-ray and the TeV bands indicates that a high-energy tail of a single electron population is responsible for both X-rays and TeV ?-rays, with radio, IR, UV and X-rays produced via the synchrotron process and GeV and TeV ?-rays produced via Comptonization. Under the assumption that the soft lag observed in the X-ray band is due to the synchrotron-lifetime effects, with ? = 5, we calculate the magnetic field for the X-ray-producing region to be ~0.2 G. The Lorentz factors ?el of the electrons responsible for the emission in the keV and TeV bands are ~106, consistent with the values implied by the Klein-Nishina limit.

Seyfert 2 galaxies are generally heavily absorbed in soft X-rays, plausibly because of obscuration of the Seyfert nucleus by a thick molecular torus. With a high torus column, 1023 ? NH ? 1025 cm-2, the observed flux in the classical 2-10 keV X-ray band can be strongly suppressed, while at higher energies the photoelectric absorption becomes less important and the true nuclear luminosity can be seen. The high-energy bandpass of the Ginga X-ray telescope, extending to 20 keV, allowed several such objects to be discovered, and an extrapolation of the obscured nuclear spectra out to 100 keV suggested that NGC 4945 should be among the very brightest radio-quiet Seyferts in the sky at 100 keV, second only to NGC 4151. OSSE data reported here confirm this prediction, and we analyze these, together with archival Ginga and ASCA data, in order to present a broadband spectrum from 0.6-500 keV of this object.

We study a large sample of narrow-line radio galaxies (NLRGs) with extended radio structures. Using 1.4 GHz radio luminosities, $L_{1.4}$, narrow optical emission line luminosities, $L_{\oiii}$ and $L_{H_{\alpha}}$, as well as black hole masses $M_{BH}$ derived from stellar velocity dispersions measured from the optical spectra obtained with the Sloan Digital Sky Survey, we find that: (i) NLRGs cover about 4 decades of the Eddington ratio, $\lambda \equiv L_{bol}/L_{Edd} \propto L_{line}/M_{BH}$; (ii) $L_{1.4}/M_{BH}$ strongly correlates with $\lambda$; (iii) radio-loudness, ${\cal R} \equiv L_{1.4}/L_{line}$, strongly anti-correlates with $\lambda$. A very broad range of the Eddington ratio indicates that the parent population of NLRGs includes both radio-loud quasars (RLQs) and broad-line radio galaxies (BLRGs). The correlations they obey and their high jet production efficiencies favor a jet production model which involves the so-called 'magnetically choked' accretion scenario. In this model, production of the jet is dominated by the Blandford-Znajek mechanism, and the magnetic fields in the vicinity of the central black hole are confined by the ram pressure of the accretion flow. Since large net magnetic flux accumulated in central regions of the accretion flow required by the model can take place only via geometrically thick accretion, we speculate that the massive, 'cold' accretion events associated with luminous emission-line AGN can be accompanied by an efficient jet production only if preceded by a hot, very sub-Eddington accretion phase., Comment: 24 pages, 6 figures, published in ApJ, moderate revisions to match the published version

The Kavli Institute of Particle Astrophysics and Cosmology, or KIPAC, at Stanford University, and the LeCosPA Institute at the Taiwan National University were sibling institutions even before their respective official births. The existence of both institutes was to a great extent facilitated by the foresight of Prof. Pisin Chen, current director of LeCosPA, and we fully envision the vibrant on-going collaboration between the two institutes for the years to come. This presentation highlights the current research direction of KIPAC, including the wide range of programs in particle astrophysics and cosmology. Of the on-going projects, the main current effort at KIPAC is the operation of, and the analysis of data from the Large Area Telescope on-board the space-borne Fermi Gamma-ray Space Telescope, which is described in more detail in the article by Prof. Kamae in these proceedings. That article focuses on the instrument, and the results gleaned from observations of our own Galaxy. Here, the second part of this article also includes the highlights for astrophysics of jets emanating from the vicinity of black holes, which are prominent gamma-ray sources detected by Fermi: this is the area of research of the article’s author.

We report the discovery of gamma-ray emission from the Circinus galaxy using the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope. Circinus is a nearby (~4 Mpc) starburst with a heavily obscured Seyfert-type active nucleus, bipolar radio lobes perpendicular to the spiral disk, and kpc-scale jet-like structures. Our analysis of 0.1-100 GeV events collected during 4 years of LAT observations reveals a significant (~ 7.3 sigma) excess above the background. We find no indications of variability or spatial extension beyond the LAT point-spread function. A power-law model used to describe the 0.1-100 GeV gamma-ray spectrum yields a flux of (18.8+/-5.8)x10^{-9} ph cm^{-2} s^{-1} and photon index 2.19+/-0.12, corresponding to an isotropic gamma-ray luminosity of 3 x 10^{40} erg s^{-1}. This observed gamma-ray luminosity exceeds the luminosity expected from cosmic-ray interactions in the interstellar medium and inverse Compton radiation from the radio lobes. Thus the origin of the GeV excess requires further investigation.

Blazars are strongly variable sources that occasionally show spectacular flares visible in various energy bands. These flares are often, but not always, correlated. In a number of cases the peaks of optical flares are found to be somewhat delayed with respect to the gamma-ray peaks. One notable example of such a delay was found in 3C 279 by Hayashida et al. and interpreted as a result of steeper drop with distance of the energy density of external radiation field than of the magnetic energy density. In this paper we demonstrate that in general, depending on the respective energy density profile along the jet, such lags can have both signs and that they can take place for any ratio of these energy densities. We study the dependence of such lags on the ratio of these energy densities at a distance of a maximal energy dissipation in a jet, on their gradients, as well as on the time profile of the relativistic electron injection within the moving source. We show how prominent such lags can be, and what are their expected time scales. We suggest that studies of such lags can provide a powerful tool to resolve the structure of relativistic jets and their radiative environment. As an example we model the lag observed in 3C 279, showing that in this object the flare is produced at a distance of a few parsecs from the central black hole, consistent with our previous inferences based on the spectra and optical polarization properties.