Lukasz Stawarz - Kavli Institute for Particle Astrophysics and Cosmology, Stanford University

Lukasz Stawarz
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Name
Lukasz Stawarz
Affiliation
Kavli Institute for Particle Astrophysics and Cosmology, Stanford University
City
Stanford
Country
United States

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High Energy Astrophysical Phenomena (31)
 
Cosmology and Nongalactic Astrophysics (15)
 
Astrophysics of Galaxies (8)
 
Instrumentation and Methods for Astrophysics (5)
 
Astrophysics (5)
 
Physics - Instrumentation and Detectors (1)

Publications Authored By Lukasz Stawarz

We present the results of our power spectral analysis for the BL Lac object PKS 0735+178 utilizing the Fermi-LAT survey at high-energy $\gamma$-rays, several ground-based optical telescopes, and single-dish radio telescopes operating at GHz frequencies. The novelty of our approach is that, by combining long-term and densely sampled intra-night light curves in the optical regime, we were able to construct for the first time the optical power spectrum of the blazar for a time domain extending from 23 years down to minutes. Our analysis reveals that: (i) the optical variability is consistent with a pure red noise, for which the power spectral density can well be approximated by a single power-law throughout the entire time domain probed; (ii) the slope of power spectral density at high-energy $\gamma$-rays ($\sim 1$), is significantly flatter than that found at radio and optical frequencies ($\sim 2$) within the corresponding time variability range; (iii) for the derived power spectra we did not detect any low-frequency flattening, nor do we see any evidence for cut-offs at the highest frequencies down to the noise floor levels due to measurement uncertainties. Read More

We analyze Chandra X-ray images of a sample of 11 quasars that are known to contain kiloparsec scale radio jets. The sample consists of five high-redshift (z >= 3.6) flat-spectrum radio quasars, and six intermediate redshift (2. Read More

2016Jul
Authors: Hitomi Collaboration, Felix A. Aharonian, Hiroki Akamatsu, Fumie Akimoto, Steven W. Allen, Lorella Angelini, Keith A. Arnaud, Marc Audard, Hisamitsu Awaki, Magnus Axelsson, Aya Bamba, Marshall W. Bautz, Roger D. Blandford, Laura W. Brenneman, Gregory V. Brown, Esra Bulbul, Edward M. Cackett, Maria Chernyakova, Meng P. Chiao, Paolo Coppi, Elisa Costantini, Jelle de Plaa, Jan-Willem den Herder, Chris Done, Tadayasu Dotani, Ken Ebisawa, Megan E. Eckart, Teruaki Enoto, Yuichiro Ezoe, Andrew C. Fabian, Carlo Ferrigno, Adam R. Foster, Ryuichi Fujimoto, Yasushi Fukazawa, Akihiro Furuzawa, Massimiliano Galeazzi, Luigi C. Gallo, Poshak Gandhi, Margherita Giustini, Andrea Goldwurm, Liyi Gu, Matteo Guainazzi, Yoshito Haba, Kouichi Hagino, Kenji Hamaguchi, Ilana Harrus, Isamu Hatsukade, Katsuhiro Hayashi, Takayuki Hayashi, Kiyoshi Hayashida, Junko Hiraga, Ann E. Hornschemeier, Akio Hoshino, John P. Hughes, Yuto Ichinohe, Ryo Iizuka, Hajime Inoue, Shota Inoue, Yoshiyuki Inoue, Kazunori Ishibashi, Manabu Ishida, Kumi Ishikawa, Yoshitaka Ishisaki, Masayuki Itoh, Masachika Iwai, Naoko Iyomoto, Jelle S. Kaastra, Timothy Kallman, Tuneyoshi Kamae, Erin Kara, Jun Kataoka, Satoru Katsuda, Junichiro Katsuta, Madoka Kawaharada, Nobuyuki Kawai, Richard L. Kelley, Dmitry Khangulyan, Caroline A. Kilbourne, Ashley L. King, Takao Kitaguchi, Shunji Kitamoto, Tetsu Kitayama, Takayoshi Kohmura, Motohide Kokubun, Shu Koyama, Katsuji Koyama, Peter Kretschmar, Hans A. Krimm, Aya Kubota, Hideyo Kunieda, Philippe Laurent, Francois Lebrun, Shiu-Hang Lee, Maurice Leutenegger, Olivier Limousin, Michael Loewenstein, Knox S. Long, David Lumb, Grzegorz M. Madejski, Yoshitomo Maeda, Daniel Maier, Kazuo Makishima, Maxim Markevitch, Hironori Matsumoto, Kyoko Matsushita, Dan McCammon, Brian R. McNamara, Missagh Mehdipour, Eric D. Miller, Jon M. Miller, Shin Mineshige, Kazuhisa Mitsuda, Ikuyuki Mitsuishi, Takuya Miyazawa, Tsunefumi Mizuno, Hideyuki Mori, Koji Mori, Harvey Moseley, Koji Mukai, Hiroshi Murakami, Toshio Murakami, Richard F. Mushotzky, Takao Nakagawa, Hiroshi Nakajima, Takeshi Nakamori, Toshio Nakano, Shinya Nakashima, Kazuhiro Nakazawa, Kumiko Nobukawa, Masayoshi Nobukawa, Hirofumi Noda, Masaharu Nomachi, Steve L. O'Dell, Hirokazu Odaka, Takaya Ohashi, Masanori Ohno, Takashi Okajima, Naomi Ota, Masanobu Ozaki, Frits Paerels, Stephane Paltani, Arvind Parmar, Robert Petre, Ciro Pinto, Martin Pohl, F. Scott Porter, Katja Pottschmidt, Brian D. Ramsey, Christopher S. Reynolds, Helen R. Russell, Samar Safi-Harb, Shinya Saito, Kazuhiro Sakai, Hiroaki Sameshima, Toru Sasaki, Goro Sato, Kosuke Sato, Rie Sato, Makoto Sawada, Norbert Schartel, Peter J. Serlemitsos, Hiromi Seta, Megumi Shidatsu, Aurora Simionescu, Randall K. Smith, Yang Soong, Lukasz Stawarz, Yasuharu Sugawara, Satoshi Sugita, Andrew E. Szymkowiak, Hiroyasu Tajima, Hiromitsu Takahashi, Tadayuki Takahashi, Shin'ichiro Takeda, Yoh Takei, Toru Tamagawa, Keisuke Tamura, Takayuki Tamura, Takaaki Tanaka, Yasuo Tanaka, Yasuyuki Tanaka, Makoto Tashiro, Yuzuru Tawara, Yukikatsu Terada, Yuichi Terashima, Francesco Tombesi, Hiroshi Tomida, Yohko Tsuboi, Masahiro Tsujimoto, Hiroshi Tsunemi, Takeshi Tsuru, Hiroyuki Uchida, Hideki Uchiyama, Yasunobu Uchiyama, Shutaro Ueda, Yoshihiro Ueda, Shiro Ueno, Shin'ichiro Uno, C. Meg Urry, Eugenio Ursino, Cor P. de Vries, Shin Watanabe, Norbert Werner, Daniel R. Wik, Dan R. Wilkins, Brian J. Williams, Shinya Yamada, Hiroya Yamaguchi, Kazutaka Yamaoka, Noriko Y. Yamasaki, Makoto Yamauchi, Shigeo Yamauchi, Tahir Yaqoob, Yoichi Yatsu, Daisuke Yonetoku, Atsumasa Yoshida, Irina Zhuravleva, Abderahmen Zoghbi

High-resolution X-ray spectroscopy with Hitomi was expected to resolve the origin of the faint unidentified E=3.5 keV emission line reported in several low-resolution studies of various massive systems, such as galaxies and clusters, including the Perseus cluster. We have analyzed the Hitomi first-light observation of the Perseus cluster. Read More

2016Jul
Authors: Hitomi Collaboration, Felix Aharonian, Hiroki Akamatsu, Fumie Akimoto, Steven W. Allen, Naohisa Anabuki, Lorella Angelini, Keith Arnaud, Marc Audard, Hisamitsu Awaki, Magnus Axelsson, Aya Bamba, Marshall Bautz, Roger Blandford, Laura Brenneman, Gregory V. Brown, Esra Bulbul, Edward Cackett, Maria Chernyakova, Meng Chiao, Paolo Coppi, Elisa Costantini, Jelle de Plaa, Jan-Willem den Herder, Chris Done, Tadayasu Dotani, Ken Ebisawa, Megan Eckart, Teruaki Enoto, Yuichiro Ezoe, Andrew Fabian, Carlo Ferrigno, Adam Foster, Ryuichi Fujimoto, Yasushi Fukazawa, Akihiro Furuzawa, Massimiliano Galeazzi, Luigi Gallo, Poshak Gandhi, Margherita Giustini, Andrea Goldwurm, Liyi Gu, Matteo Guainazzi, Yoshito Haba, Kouichi Hagino, Kenji Hamaguchi, Ilana Harrus, Isamu Hatsukade, Katsuhiro Hayashi, Takayuki Hayashi, Kiyoshi Hayashida, Junko Hiraga, Ann Hornschemeier, Akio Hoshino, John Hughes, Ryo Iizuka, Hajime Inoue, Yoshiyuki Inoue, Kazunori Ishibashi, Manabu Ishida, Kumi Ishikawa, Yoshitaka Ishisaki, Masayuki Itoh, Naoko Iyomoto, Jelle Kaastra, Timothy Kallman, Tuneyoshi Kamae, Erin Kara, Jun Kataoka, Satoru Katsuda, Junichiro Katsuta, Madoka Kawaharada, Nobuyuki Kawai, Richard Kelley, Dmitry Khangulyan, Caroline Kilbourne, Ashley King, Takao Kitaguchi, Shunji Kitamoto, Tetsu Kitayama, Takayoshi Kohmura, Motohide Kokubun, Shu Koyama, Katsuji Koyama, Peter Kretschmar, Hans Krimm, Aya Kubota, Hideyo Kunieda, Philippe Laurent, Francois Lebrun, Shiu-Hang Lee, Maurice Leutenegger, Olivier Limousin, Michael Loewenstein, Knox S. Long, David Lumb, Grzegorz Madejski, Yoshitomo Maeda, Daniel Maier, Kazuo Makishima, Maxim Markevitch, Hironori Matsumoto, Kyoko Matsushita, Dan McCammon, Brian McNamara, Missagh Mehdipour, Eric Miller, Jon Miller, Shin Mineshige, Kazuhisa Mitsuda, Ikuyuki Mitsuishi, Takuya Miyazawa, Tsunefumi Mizuno, Hideyuki Mori, Koji Mori, Harvey Moseley, Koji Mukai, Hiroshi Murakami, Toshio Murakami, Richard Mushotzky, Ryo Nagino, Takao Nakagawa, Hiroshi Nakajima, Takeshi Nakamori, Toshio Nakano, Shinya Nakashima, Kazuhiro Nakazawa, Masayoshi Nobukawa, Hirofumi Noda, Masaharu Nomachi, Steve O'Dell, Hirokazu Odaka, Takaya Ohashi, Masanori Ohno, Takashi Okajima, Naomi Ota, Masanobu Ozaki, Frits Paerels, Stephane Paltani, Arvind Parmar, Robert Petre, Ciro Pinto, Martin Pohl, F. Scott Porter, Katja Pottschmidt, Brian Ramsey, Christopher Reynolds, Helen Russell, Samar Safi-Harb, Shinya Saito, Kazuhiro Sakai, Hiroaki Sameshima, Goro Sato, Kosuke Sato, Rie Sato, Makoto Sawada, Norbert Schartel, Peter Serlemitsos, Hiromi Seta, Megumi Shidatsu, Aurora Simionescu, Randall Smith, Yang Soong, Lukasz Stawarz, Yasuharu Sugawara, Satoshi Sugita, Andrew Szymkowiak, Hiroyasu Tajima, Hiromitsu Takahashi, Tadayuki Takahashi, Shin'ichiro Takeda, Yoh Takei, Toru Tamagawa, Keisuke Tamura, Takayuki Tamura, Takaaki Tanaka, Yasuo Tanaka, Yasuyuki Tanaka, Makoto Tashiro, Yuzuru Tawara, Yukikatsu Terada, Yuichi Terashima, Francesco Tombesi, Hiroshi Tomida, Yohko Tsuboi, Masahiro Tsujimoto, Hiroshi Tsunemi, Takeshi Tsuru, Hiroyuki Uchida, Hideki Uchiyama, Yasunobu Uchiyama, Shutaro Ueda, Yoshihiro Ueda, Shiro Ueno, Shin'ichiro Uno, Meg Urry, Eugenio Ursino, Cor de Vries, Shin Watanabe, Norbert Werner, Daniel Wik, Dan Wilkins, Brian Williams, Shinya Yamada, Hiroya Yamaguchi, Kazutaka Yamaok, Noriko Y. Yamasaki, Makoto Yamauchi, Shigeo Yamauchi, Tahir Yaqoob, Yoichi Yatsu, Daisuke Yonetoku, Atsumasa Yoshida, Takayuki Yuasa, Irina Zhuravleva, Abderahmen Zoghbi

Clusters of galaxies are the most massive gravitationally-bound objects in the Universe and are still forming. They are thus important probes of cosmological parameters and a host of astrophysical processes. Knowledge of the dynamics of the pervasive hot gas, which dominates in mass over stars in a cluster, is a crucial missing ingredient. Read More

The single-mirror small-size telescope (SST-1M) is one of the three proposed designs for the small-size telescopes (SSTs) of the Cherenkov Telescope Array (CTA) project. The SST-1M will be equipped with a 4 m-diameter segmented mirror dish and an innovative fully digital camera based on silicon photo-multipliers (SiPMs). Since the SST sub-array will consist of up to 70 telescopes, the challenge is not only to build a telescope with excellent performance, but also to design it so that its components can be commissioned, assembled and tested by industry. Read More

We report on the detection of excess hard X-ray emission from the TeV BL Lac object Mrk421 during the historical low-flux state of the source in January 2013. NuSTAR observations were conducted four times between MJD56294 and MJD56312 with a total exposure of 80.9 ksec. Read More

We report the $\gamma$-ray detection of a young radio galaxy, PKS 1718$-$649, belonging to the class of Compact Symmetric Objects (CSOs), with the Large Area Telescope (LAT) on board the {\it Fermi} satellite. The third {\it Fermi} Gamma-ray LAT catalog (3FGL) includes an unassociated $\gamma$-ray source, 3FGL J1728.0$-$6446, located close to PKS 1718$-$649. Read More

We report on the 1.6 GHz (18 cm) VLBI observations of the unresolved, steady TeV source HESS J1943+213 located in the Galactic plane, performed with the European VLBI Network (EVN) in 2014. Our new observations with a nearly full EVN array provide the deepest image of HESS J1943+213 at the highest resolution ever achieved, enabling us to resolve the long-standing issues of the source identification. Read More

We present the results of the first X-ray study of a sample of 16 young radio sources classified as Compact Symmetric Objects (CSOs). We observed six of them for the first time in X-rays using {\it Chandra}, re-observed four with the previous {\it XMM-Newton} or {\it Beppo-SAX} data, and included six other with the archival data. All the sources are nearby, $z<1$ with the age of their radio structures ($<3000$~years) derived from the hotspots advance velocity. Read More

We present a detailed analysis of the best-quality multi-wavelength data gathered for the large-scale jet in the core-dominated quasar 3C 273. We analyze all the archival observations of the target with the Chandra X-ray Observatory, the far-ultraviolet observations with the Hubble Space Telescope, and a 8.4 GHz maps obtained with the Very Large Array. Read More

Most of the extragalactic objects detected so far in the very high energy (VHE) regime are blazars, but the discovered nearby radio galaxies: M87, Cen A and NGC 1275 of type FRI seem to constitute a new class of VHE emitters. The radio galaxy PKS 0625-354 was observed and detected ($\sim$6$\sigma$) with the H.E. Read More

The occurrence of low-amplitude flux variations in blazars on hourly timescales, commonly known as microvariability, is still a widely debated subject in high-energy astrophysics. Several competing scenarios have been proposed to explain such occurrences, including various jet plasma instabilities leading to the formation of shocks, magnetic reconnection sites, and turbulence. In this letter we present the results of our detailed investigation of a prominent, five-hour-long optical microflare detected during recent WEBT campaign in 2014, March 2-6 targeting the blazar 0716+714. Read More

Here we present a new approach for constraining luminous blazars, incorporating fully time-dependent and self-consistent modeling of bright gamma-ray flares of PKS1510-089 resolved with Fermi-LAT, in the framework of the internal shock scenario. The results of our modeling imply the location of the gamma-ray flaring zone outside of the broad-line region, namely around 0.3pc from the core for a free-expanding jet with the opening angle Gamma, \theta_\mathrm{jet} \simeq 1 (where Gamma is the jet bulk Lorentz factor), up to \simeq 3pc for a collimated outflow with Gamma, \theta_\mathrm{jet} \simeq 0. Read More

Relativistic jets in active galactic nuclei (AGN) are among the most powerful astrophysical objects discovered to date. Indeed, jetted AGN studies have been considered a prominent science case for SKA, and were included in several different chapters of the previous SKA Science Book (Carilli & Rawlings 2004). Most of the fundamental questions about the physics of relativistic jets still remain unanswered, and await high-sensitivity radio instruments such as SKA to solve them. Read More

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

The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions developed by the Institute of Space and Astronautical Science (ISAS), with a planned launch in 2015. The ASTRO-H mission is equipped with a suite of sensitive instruments with the highest energy resolution ever achieved at E > 3 keV and a wide energy range spanning four decades in energy from soft X-rays to gamma-rays. The simultaneous broad band pass, coupled with the high spectral resolution of Delta E < 7 eV of the micro-calorimeter, will enable a wide variety of important science themes to be pursued. Read More

We performed a systematic X-ray study of eight nearby gamma-ray bright radio galaxies with Suzaku for understanding the origin of their X-ray emissions. The Suzaku spectra for five of those have been presented previously, while the remaining three (M87, PKS0625-354, and 3C78) are presented here for the first time. Based on the Fe-K line strength, X-ray variability, and X-ray power-law photon indices, and using additional information on the [O III] line emission, we argue for a jet origin of the observed X-ray emission in these three sources. Read More

Blazars are the established sources of an intense and variable non-thermal radiation extending from radio wavelengths up to HE and VHE gamma-rays. Understanding the spectral evolution of blazars in selected frequency ranges, as well as multi-frequency correlations in various types of blazar sources, is of a primary importance for constraining the blazar physics. Here we present the results of a long-term optical monitoring of a sample of 30 blazars of the BL Lac type. Read More

We present our discovery of dramatic variability in SDSS J1100+4421 by the high-cadence transient survey Kiso Supernova Survey (KISS). The source brightened in the optical by at least a factor of three within about half a day. Spectroscopic observations suggest that this object is likely a narrow-line Seyfert 1 galaxy (NLS1) at z=0. Read More

We apply the jet model developed in the preceding paper of Zdziarski et al. to the hard-state emission spectra of Cyg X-1. We augment the model for the analytical treatment of the particle evolution beyond the energy dissipation region, and allow for various forms of the acceleration rate. Read More

In the framework of the unification scheme of radio-loud active galactic nuclei, BL Lac objects and quasars are the beamed end-on counterparts of low-power (FRI) and high-power (FRII) radio galaxies, respectively. Some BL Lacs have been found to possess the FRII-type large-scale radio morphology, suggesting that the parent population of BL Lacs is a mixture of low- and high-power radio galaxies. This seems to apply only to `low frequency-peaked' BL Lacs, since all the `high frequency-peaked' BL Lacs studied so far were shown to host exclusively the FRI-type radio jets. Read More

We investigate the contribution of the beamed jet component to the high energy emission in young and compact extragalactic radio sources, focusing for the first time on the gamma-ray band. We derive predictions on the gamma-ray luminosities associated with the relativistic jet assuming a leptonic radiative model. The high energy emission is produced via Compton scattering by the relativistic electrons in a spherical region at the considered scales ($\lesssim$10 kpc). Read More

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. Read More

This is part one of our study of models of jets with distributed electron acceleration. We present here our assumptions, basic equations, and their solutions for the steady-state electron distribution. We assume the shape of the rate of electron acceleration and the dependencies of its normalization and the magnetic field strength on the height along the jet. Read More

Since the discovery of kiloparsec-scale X-ray emission from quasar jets, the physical processes responsible for their high-energy emission have been poorly defined. A number of mechanisms are under active debate, including synchrotron radiation, inverse-Comptonized CMB (IC/CMB) emission, and other Comptonization processes. In a number of cases, the optical and X-ray emission of jet regions are inked by a single spectral component, and in those, high- resolution multi-band imaging and polarimetry can be combined to yield a powerful diagnostic of jet emission processes. Read More

2012Oct
Authors: Tadayuki Takahashi, Kazuhisa Mitsuda, Richard Kelley, Henri AartsFelix Aharonian, Hiroki Akamatsu, Fumie Akimoto, Steve Allen, Naohisa Anabuki, Lorella Angelini, Keith Arnaud, Makoto Asai, Marc Audard, Hisamitsu Awaki, Philipp Azzarello, Chris Baluta, Aya Bamba, Nobutaka Bando, Mark Bautz, Roger Blandford, Kevin Boyce, Greg Brown, Ed Cackett, Maria Chernyakova, Paolo Coppi, Elisa Costantini, Jelle de Plaa, Jan-Willem den Herder, Michael DiPirro, Chris Done, Tadayasu Dotani, John Doty, Ken Ebisawa, Megan Eckart, Teruaki Enoto, Yuichiro Ezoe, Andrew Fabian, Carlo Ferrigno, Adam Foster, Ryuichi Fujimoto, Yasushi Fukazawa, Stefan Funk, Akihiro Furuzawa, Massimiliano Galeazzi, Luigi Gallo, Poshak Gandhi, Keith Gendreau, Kirk Gilmore, Daniel Haas, Yoshito Haba, Kenji Hamaguchi, Isamu Hatsukade, Takayuki Hayashi, Kiyoshi Hayashida, Junko Hiraga, Kazuyuki Hirose, Ann Hornschemeier, Akio Hoshino, John Hughes, Una Hwang, Ryo Iizuka, Yoshiyuki Inoue, Kazunori Ishibashi, Manabu Ishida, Kosei Ishimura, Yoshitaka Ishisaki, Masayuki Ito, Naoko Iwata, Naoko Iyomoto, Jelle Kaastra, Timothy Kallman, Tuneyoshi Kamae, Jun Kataoka, Satoru Katsuda, Hajime Kawahara, Madoka Kawaharada, Nobuyuki Kawai, Shigeo Kawasaki, Dmitry Khangaluyan, Caroline Kilbourne, Masashi Kimura, Kenzo Kinugasa, Shunji Kitamoto, Tetsu Kitayama, Takayoshi Kohmura, Motohide Kokubun, Tatsuro Kosaka, Alex Koujelev, Katsuji Koyama, Hans Krimm, Aya Kubota, Hideyo Kunieda, Stephanie LaMassa, Philippe Laurent, Francois Lebrun, Maurice Leutenegger, Olivier Limousin, Michael Loewenstein, Knox Long, David Lumb, Grzegorz Madejski, Yoshitomo Maeda, Kazuo Makishima, Genevieve Marchand, Maxim Markevitch, Hironori Matsumoto, Kyoko Matsushita, Dan McCammon, Brian McNamara, Jon Miller, Eric Miller, Shin Mineshige, Kenji Minesugi, Ikuyuki Mitsuishi, Takuya Miyazawa, Tsunefumi Mizuno, Hideyuki Mori, Koji Mori, Koji Mukai, Toshio Murakami, Hiroshi Murakami, Richard Mushotzky, Housei Nagano, Ryo Nagino, Takao Nakagawa, Hiroshi Nakajima, Takeshi Nakamori, Kazuhiro Nakazawa, Yoshiharu Namba, Chikara Natsukari, Yusuke Nishioka, Masayoshi Nobukawa, Masaharu Nomachi, Steve O' Dell, Hirokazu Odaka, Hiroyuki Ogawa, Mina Ogawa, Keiji Ogi, Takaya Ohashi, Masanori Ohno, Masayuki Ohta, Takashi Okajima, Atsushi Okamoto, Tsuyoshi Okazaki, Naomi Ota, Masanobu Ozaki, Frits Paerels, Stephane Paltani, Arvind Parmar, Robert Petre, Martin Pohl, F. Scott Porter, Brian Ramsey, Rubens Reis, Christopher Reynolds, Helen Russell, Samar Safi-Harb, Shin-ichiro Sakai, Hiroaki Sameshima, Jeremy Sanders, Goro Sato, Rie Sato, Yoichi Sato, Kosuke Sato, Makoto Sawada, Peter Serlemitsos, Hiromi Seta, Yasuko Shibano, Maki Shida, Takanobu Shimada, Keisuke Shinozaki, Peter Shirron, Aurora Simionescu, Cynthia Simmons, Randall Smith, Gary Sneiderman, Yang Soong, Lukasz Stawarz, Yasuharu Sugawara, Hiroyuki Sugita, Satoshi Sugita, Andrew Szymkowiak, Hiroyasu Tajima, Hiromitsu Takahashi, Shin-ichiro Takeda, Yoh Takei, Toru Tamagawa, Takayuki Tamura, Keisuke Tamura, Takaaki Tanaka, Yasuo Tanaka, Makoto Tashiro, Yuzuru Tawara, Yukikatsu Terada, Yuichi Terashima, Francesco Tombesi, Hiroshi Tomida, Yoko Tsuboi, Masahiro Tsujimoto, Hiroshi Tsunemi, Takeshi Tsuru, Hiroyuki Uchida, Yasunobu Uchiyama, Hideki Uchiyama, Yoshihiro Ueda, Shiro Ueno, Shinichiro Uno, Meg Urry, Eugenio Ursino, Cor de Vries, Atsushi Wada, Shin Watanabe, Norbert Werner, Nicholas White, Takahiro Yamada, Shinya Yamada, Hiroya Yamaguchi, Noriko Yamasaki, Shigeo Yamauchi, Makoto Yamauchi, Yoichi Yatsu, Daisuke Yonetoku, Atsumasa Yoshida, Takayuki Yuasa

The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the high-energy universe via a suite of four instruments, covering a very wide energy range, from 0.3 keV to 600 keV. Read More

2012May
Authors: The Fermi-LAT collaboration, :, M. Ackermann, M. Ajello, W. B. Atwood, L. Baldini, G. Barbiellini, D. Bastieri, K. Bechtol, R. Bellazzini, R. D. Blandford, E. D. Bloom, E. Bonamente, A. W. Borgland, E. Bottacini, T. J. Brandt, J. Bregeon, M. Brigida, P. Bruel, R. Buehler, S. Buson, G. A. Caliandro, R. A. Cameron, P. A. Caraveo, J. M. Casandjian, C. Cecchi, E. Charles, A. Chekhtman, J. Chiang, S. Ciprini, R. Claus, J. Cohen-Tanugi, J. Conrad, A. Cuoco, S. Cutini, F. D'Ammando, A. de Angelis, F. de Palma, C. D. Dermer, E. do Couto e Silva, P. S. Drell, A. Drlica-Wagner, L. Falletti, C. Favuzzi, S. J. Fegan, W. B. Focke, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, D. Gasparrini, S. Germani, N. Giglietto, F. Giordano, M. Giroletti, T. Glanzman, G. Godfrey, I. A. Grenier, S. Guiriec, M. Gustafsson, D. Hadasch, M. Hayashida, D. Horan, R. E. Hughes, M. S. Jackson, T. Jogler, G. Jóhannesson, A. S. Johnson, T. Kamae, J. Knödlseder, M. Kuss, J. Lande, L. Latronico, A. M. Lionetto, M. Llena Garde, F. Longo, F. Loparco, B. Lott, M. N. Lovellette, P. Lubrano, M. N. Mazziotta, J. E. McEnery, J. Mehault, P. F. Michelson, W. Mitthumsiri, T. Mizuno, A. A. Moiseev, C. Monte, M. E. Monzani, A. Morselli, I. V. Moskalenko, S. Murgia, M. Naumann-Godo, J. P. Norris, E. Nuss, T. Ohsugi, M. Orienti, E. Orlando, J. F. Ormes, D. Paneque, J. H. Panetta, M. Pesce-Rollins, M. Pierbattista, F. Piron, G. Pivato, H. Poon, S. Rainò, R. Rando, M. Razzano, S. Razzaque, A. Reimer, O. Reimer, C. Romoli, C. Sbarra, J. D. Scargle, C. Sgrò, E. J. Siskind, G. Spandre, P. Spinelli, Łukasz Stawarz, A. W. Strong, D. J. Suson, H. Tajima, H. Takahashi, T. Tanaka, J. G. Thayer, J. B. Thayer, L. Tibaldo, M. Tinivella, G. Tosti, E. Troja, T. L. Usher, J. Vandenbroucke, V. Vasileiou, G. Vianello, V. Vitale, A. P. Waite, E. Wallace, K. S. Wood, M. Wood, Z. Yang, G. Zaharijas, S. Zimmer

We have performed an analysis of the diffuse gamma-ray emission with the Fermi Large Area Telescope in the Milky Way Halo region searching for a signal from dark matter annihilation or decay. In the absence of a robust dark matter signal, constraints are presented. We consider both gamma rays produced directly in the dark matter annihilation/decay and produced by inverse Compton scattering of the e+e- produced in the annihilation/decay. Read More

We discuss how future X-ray instruments which are under development can contribute to our understanding of the non-thermal Universe. Much progress has been made in the field of X-ray Astronomy recently, thanks to the operation of modern X-ray telescopes such as Chandra, XMM-Newton, Suzaku, and Swift, but more in-depth investigation awaits future missions. These future missions include ASTROSAT, NuStar, e-ROSITA, ASTRO-H and GEMS, which will be realized in the next decade, and also much larger projects such as Athena and LOFT, which have been proposed for the 2020's. Read More

We combine data from two all-sky surveys in order to study the connection between the infrared and hard X-ray (>10keV) properties for local active galactic nuclei (AGN). The Swift/Burst Alert Telescope all-sky survey provides an unbiased, flux-limited selection of hard X-ray detected AGN. Cross-correlating the 22-month hard X-ray survey with the AKARI all-sky survey, we studied 158 AGN detected by the AKARI instruments. Read More

The large majority of extragalactic very high energy (VHE; E>100 GeV) sources belongs to the class of active galactic nuclei (AGN), in particular the BL Lac sub-class. AGNs are characterized by an extremely bright and compact emission region, powered by a super-massive black hole (SMBH) and an accretion disk, and relativistic outflows (jets) detected all across the electro-magnetic spectrum. In BL Lac sources the jet axis is oriented close to the line of sight, giving rise to a relativistic boosting of the emission. Read More

2012Mar
Affiliations: 1Harvard Smithsonian Center for Astrophysics, USA, 2ISAS/JAXA, Japan, 3NRCR/NSF/NRL Washington, DC, USA, 4Harvard Smithsonian Center for Astrophysics, USA, 5Steward Observatory, USA, 6Harvard Smithsonian Center for Astrophysics, USA, 7Harvard Smithsonian Center for Astrophysics, USA, 8Leiden Observatory, The Netherlands, 9Astronomical Observatory, Jagiellonian University, Poland, 10Harvard Smithsonian Center for Astrophysics, USA

We report results from our deep Chandra X-ray observations of a nearby radio galaxy, 4C+29.30 (z=0.0647). Read More

We report on our second-year campaign of X-ray follow-up observations of unidentified Fermi-LAT \gamma-ray sources at high Galactic latitudes (|b|>10 degree) using the X-ray Imaging Spectrometer onboard the Suzaku X-ray Observatory. In this second year of the project, seven new targets were selected from the First Fermi-LAT Catalog, and studied with 20-40 ks effective Suzaku exposures. We detected an X-ray point source coincident with the position of the recently discovered millisecond pulsar PSR J2302+4442 within the 95% confidence error circle of 1FGL J2302. Read More

During the last decade, M87's jet has been the site of an extraordinary variability event, with one knot (HST-1) increasing by over a factor 100 in brightness. Variability was also seen on timescales of months in the nuclear flux. Here we discuss the optical-UV polarization and spectral variability of these components, which show vastly different behavior. Read More

We report on the results of deep X-ray follow-up observations of four unidentified Fermi/LAT gamma-ray sources at high Galactic latitudes using Suzaku. The studied objects were detected with high significance during the first 3 months of Fermi/LAT operation, and subsequently better localized in the Fermi/LAT 1 year catalog (1FGL). Possible associations with pulsars and active galaxies have subsequently been discussed, and our observations provide an important contribution to this debate. Read More

2010Oct
Authors: Tadayuki Takahashi, Kazuhisa Mitsuda, Richard Kelley, Felix Aharonian, Fumie Akimoto, Steve Allen, Naohisa Anabuki, Lorella Angelini, Keith Arnaud, Hisamitsu Awaki, Aya Bamba, Nobutaka Bando, Mark Bautz, Roger Blandford, Kevin Boyce, Greg Brown, Maria Chernyakova, Paolo Coppi, Elisa Costantini, Jean Cottam, John Crow, Jelle de Plaa, Cor de Vries, Jan-Willem den Herder, Michael DiPirro, Chris Done, Tadayasu Dotani, Ken Ebisawa, Teruaki Enoto, Yuichiro Ezoe, Andrew Fabian, Ryuichi Fujimoto, Yasushi Fukazawa, Stefan Funk, Akihiro Furuzawa, Massimiliano Galeazzi, Poshak Gandhi, Keith Gendreau, Kirk Gilmore, Yoshito Haba, Kenji Hamaguchi, Isamu Hatsukade, Kiyoshi Hayashida, Junko Hiraga, Kazuyuki Hirose, Ann Hornschemeier, John Hughes, Una Hwang, Ryo Iizuka, Kazunori Ishibashi, Manabu Ishida, Kosei Ishimura, Yoshitaka Ishisaki, Naoki Isobe, Masayuki Ito, Naoko Iwata, Jelle Kaastra, Timothy Kallman, Tuneyoshi Kamae, Hideaki Katagiri, Jun Kataoka, Satoru Katsuda, Madoka Kawaharada, Nobuyuki Kawai, Shigeo Kawasaki, Dmitry Khangaluyan, Caroline Kilbourne, Kenzo Kinugasa, Shunji Kitamoto, Tetsu Kitayama, Takayoshi Kohmura, Motohide Kokubun, Tatsuro Kosaka, Taro Kotani, Katsuji Koyama, Aya Kubota, Hideyo Kunieda, Philippe Laurent, Francois Lebrun, Olivier Limousin, Michael Loewenstein, Knox Long, Grzegorz Madejski, Yoshitomo Maeda, Kazuo Makishima, Maxim Markevitch, Hironori Matsumoto, Kyoko Matsushita, Dan McCammon, Jon Miller, Shin Mineshige, Kenji Minesugi, Takuya Miyazawa, Tsunefumi Mizuno, Koji Mori, Hideyuki Mori, Koji Mukai, Hiroshi Murakami, Toshio Murakami, Richard Mushotzky, Yujin Nakagawa, Takao Nakagawa, Hiroshi Nakajima, Takeshi Nakamori, Kazuhiro Nakazawa, Yoshiharu Namba, Masaharu Nomachi, Steve O' Dell, Hiroyuki Ogawa, Mina Ogawa, Keiji Ogi, Takaya Ohashi, Masanori Ohno, Masayuki Ohta, Takashi Okajima, Naomi Ota, Masanobu Ozaki, Frits Paerels, Stéphane Paltani, Arvind Parmer, Robert Petre, Martin Pohl, Scott Porter, Brian Ramsey, Christopher Reynolds, Shin-ichiro Sakai, Rita Sambruna, Goro Sato, Yoichi Sato, Peter Serlemitsos, Maki Shida, Takanobu Shimada, Keisuke Shinozaki, Peter Shirron, Randall Smith, Gary Sneiderman, Yang Soong, Lukasz Stawarz, Hiroyuki Sugita, Andrew Szymkowiak, Hiroyasu Tajima, Hiromitsu Takahashi, Yoh Takei, Toru Tamagawa, Takayuki Tamura, Keisuke Tamura, Takaaki Tanaka, Yasuo Tanaka, Yasuyuki Tanaka, Makoto Tashiro, Yuzuru Tawara, Yukikatsu Terada, Yuichi Terashima, Francesco Tombesi, Hiroshi Tomida, Miyako Tozuka, Yoko Tsuboi, Masahiro Tsujimoto, Hiroshi Tsunemi, Takeshi Tsuru, Hiroyuki Uchida, Yasunobu Uchiyama, Hideki Uchiyama, Yoshihiro Ueda, Shinichiro Uno, Meg Urry, Shin Watanabe, Nicholas White, Takahiro Yamada, Hiroya Yamaguchi, Kazutaka Yamaoka, Noriko Yamasaki, Makoto Yamauchi, Shigeo Yamauchi, Yoichi Yatsu, Daisuke Yonetoku, Atsumasa Yoshida

The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the high-energy universe by performing high-resolution, high-throughput spectroscopy with moderate angular resolution. ASTRO-H covers very wide energy range from 0. Read More

2010Feb
Affiliations: 1Harvard-Smithsonian Center for Astrophysics, 2Copernicus Astronomical Center, Warsaw, Poland, 3Copernicus Astronomical Center, Warsaw, Poland, 4KAVLI/Stanford University, USA, 5European Space Astronomy Center of ESA, Madrid, Spain, 6SISSA/ISAS, Trieste, Italy, 7SISSA/ISAS, Trieste, Italy, 8European Space Astronomy Center of ESA, Madrid, Spain

Large scale X-ray jets that extend to >100 kpc distances from the host galaxy indicate the importance of jets interactions with the environment on many different physical scales. Morphology of X-ray clusters indicate that the radio-jet activity of a cD galaxy is intermittent. This intermittency might be a result of a feedback and/or interactions between galaxies within the cluster. Read More

Recent observations of cosmic ray electrons from several instruments have revealed various degrees of deviation in the measured electron energy distribution from a simple power-law, in a form of an excess around TeV energies. An even more prominent deviation has been observed in the fraction of cosmic ray positrons around 100 GeV energies. In this paper we show that the observed excesses in the electron spectrum may be easily re-produced without invoking any unusual sources other than the general diffuse Galactic components of cosmic rays. Read More

We investigate the variability timescales in the jet of M87 with two goals. The first is to use the rise times and decay times in the radio, ultraviolet and X-ray lightcurves of HST-1 to constrain the source size and the energy loss mechanisms affecting the relativistic electron distributions. HST-1 is the first jet knot clearly resolved from the nuclear emission by Chandra and is the site of the huge flare of 2005. Read More

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. Read More

2009Mar
Affiliations: 1Copernicus Astronomical Center, Warsaw, 2Harvard-Smithsonian Center for Astrophysics, Cambridge, 3Copernicus Astronomical Center, Warsaw, 4Copernicus Astronomical Center, Warsaw, 5Kavli Institute for Particle Astrophysics and Cosmology, Stanford University

We associate the existence of short-lived compact radio sources with the intermittent activity of the central engine caused by a radiation pressure instability within an accretion disk. Such objects may constitute a numerous sub-class of Giga-Hertz Peaked Spectrum sources, in accordance with the population studies of radio-loud active galaxies, as well as detailed investigations of their radio morphologies. We perform the model computations assuming the viscosity parametrization as proportional to a geometrical mean of the total and gas pressure. Read More

(Abridged) Data collected by the Pierre Auger Observatory (Auger) provide evidence for anisotropy in the arrival directions of cosmic rays (CRs) with energies >57 EeV that suggests a correlation with the positions of AGN located within ~75 Mpc. A detailed study of the sample of AGN whose positions are located within 3.2 degrees of the CR events (and extending our analysis out to ~150 Mpc) shows that most of them are classified as Seyfert 2 and low-ionization nuclear emission-line region (LINER) galaxies whose properties do not differ substantially from other local AGN of the same types. Read More

2007Aug
Affiliations: 1Harvard-Smithonian Center for Astrophysics, Cambridge, MA, 2Harvard-Smithonian Center for Astrophysics, Cambridge, MA, 3Harvard-Smithonian Center for Astrophysics, Cambridge, MA, 4Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, CA, 5Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, CA, 6Copernicus Astronomical Center, Warsaw, Poland, 7Steward Observatory, University of Arizona, Tucson, AZ
Category: Astrophysics

The complex X-ray morphology of the 300 kpc long X-ray jet in PKS1127-145 (z=1.18 quasar) is clearly discerned in a ~100 ksec Chandra observation. The jet X-ray surface brightness gradually decreases by an order of magnitude going out from the core. Read More

2006Nov
Affiliations: 1Harvard-Smithsonian Center for Astrophysics, Cambridge, 2Landessternwarte Heidelberg, Konigstuhl, and Max-Planck-Institut fur Kernphysik, Heidelberg, Germany, 3Jansky Postdoctoral Fellow, National Radio Astronomy Observatory, 4Harvard-Smithsonian Center for Astrophysics, Cambridge, 5Copernicus Astronomical Center, Warsaw, Poland, 6Harvard-Smithsonian Center for Astrophysics, Cambridge, 7Steward Observatory, University of Arizona, Tucson
Category: Astrophysics

We present a ~100 ksec Chandra X-ray observation and new VLA radio data of the large scale, 300 kpc long X-ray jet in PKS1127-145, a radio loud quasar at redshift z=1.18. With this deep X-ray observation we now clearly discern the complex X-ray jet morphology and see substructure within the knots. Read More

We report detailed studies of the X-ray emission from the kpc scale jet in the nearest active galaxy, Cen A. 41 compact sources were found within the jet, 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 pile-up of unresolved faint knots. Read More

We examine a systematic comparison of jet-knots, hotspots and radio lobes recently observed with Chandra and ASCA. This report will discuss the origin of their X-ray emissions and investigate the dynamics of the jets. The data was compiled at well sampled radio (5GHz) and X-ray frequencies (1keV) for more than 40 radio galaxies. Read More