M. H. Sikora - A2 Collaboration at MAMI

M. H. Sikora
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M. H. Sikora
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A2 Collaboration at MAMI
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Nuclear Experiment (22)
 
High Energy Astrophysical Phenomena (18)
 
High Energy Physics - Experiment (8)
 
Astrophysics of Galaxies (7)
 
Physics - Materials Science (5)
 
Cosmology and Nongalactic Astrophysics (3)
 
Physics - Strongly Correlated Electrons (2)
 
Physics - Mesoscopic Systems and Quantum Hall Effect (2)
 
Quantitative Biology - Biomolecules (2)
 
Instrumentation and Methods for Astrophysics (1)
 
Physics - Biological Physics (1)
 
Nuclear Theory (1)
 
Physics - Chemical Physics (1)
 
High Energy Physics - Phenomenology (1)

Publications Authored By M. H. Sikora

The double-polarization observable $E$ and the helicity-dependent cross sections $\sigma_{1/2}$ and $\sigma_{3/2}$ have been measured for the first time for single $\pi^{0}$ photoproduction from protons and neutrons bound in the deuteron at the electron accelerator facility MAMI in Mainz, Germany. The experiment used a circularly polarized photon beam and a longitudinally polarized deuterated butanol target. The reaction products, recoil nucleons and decay photons from the $\pi^0$ meson were detected with the Crystal Ball and TAPS electromagnetic calorimeters. Read More

Polysaccharides (carbohydrates) are key regulators of a large number of cell biological processes. However, precise biochemical or genetic manipulation of these often complex structures is laborious and hampers experimental structure-function studies. Molecular Dynamics (MD) simulations provide a valuable alternative tool to generate and test hypotheses on saccharide function. Read More

Precise helicity-dependent cross sections and the double-polarization observable $E$ were measured for $\eta$ photoproduction from quasi-free protons and neutrons bound in the deuteron. The $\eta\rightarrow 2\gamma$ and $\eta\rightarrow 3\pi^0\rightarrow 6\gamma$ decay modes were used to optimize the statistical quality of the data and to estimate systematic uncertainties. The measurement used the A2 detector setup at the tagged photon beam of the electron accelerator MAMI in Mainz. Read More

We study the disk-jet connection in supermassive black holes by investigating the properties of their optical and radio emissions utilizing the SDSS-DR7 and the NVSS catalogs. Our sample contains 7017 radio-loud quasars with detection both at 1.4~GHz and SDSS optical spectrum. Read More

The series of Mnx(Y0.148Zr0.852)1-xO2-{\delta} ceramics was systematically studied by means of X-ray absorption and emission spectroscopy and DC magnetic susceptibility. Read More

The double polarization observable $E$ and the helicity dependent cross sections $\sigma_{1/2}$ and $\sigma_{3/2}$ were measured for $\eta$ photoproduction from quasi-free protons and neutrons. The circularly polarized tagged photon beam of the A2 experiment at the Mainz MAMI accelerator was used in combination with a longitudinally polarized deuterated butanol target. The almost $4\pi$ detector setup of the Crystal Ball and TAPS is ideally suited to detect the recoil nucleons and the decay photons from $\eta\rightarrow 2\gamma$ and $\eta\rightarrow 3\pi^0$. Read More

Jet powers in many radio galaxies with extended radio structures appear to exceed their associated accretion luminosities. In systems with very low accretion rates, this is likely due to the very low accretion luminosities resulting from radiatively inefficient accretion flows. In systems with high accretion rates, the accretion flows are expected to be radiatively efficient, and the production of such powerful jets may require an accretion scenario which involves magnetically arrested discs (MADs). Read More

The Dalitz decay pi^0 -> e^+e^-gamma has been measured in the gamma p -> pi^0 p reaction with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The value obtained for the slope parameter of the pi^0 electromagnetic transition form factor, a_pi = 0.030+/-0. Read More

Magnetic anisotropies in a ferrofluid of core@shell MnFe2O4@CoFe2O4 nanoparticles are studied in the liquid and frozen states using a unique sample cell developed for element specific hard X-ray magnetic spectroscopies. The MnFe2O4@CoFe2O4 6.7 nm particles reveal original magnetic properties, with a gradient in coercive field inside a nanospinel. Read More

The Dalitz decays eta -> e^+e^-g and omega -> pi^0 e^+e^- have been measured in the g p -> eta p and g p -> omega p reactions, respectively, with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The value obtained for the slope parameter of the electromagnetic transition form factor of eta, Lambda^{-2}_eta=(1.97+/-0. Read More

In this work I review the observational constraints imposed on the energetics and magnetisation of quasar jets, in the context of theoretical expectations. The discussion is focused on issues regarding the jet production efficiency, matter content, and particle acceleration. I show that if the ratio of electron-positron-pairs to protons is of order $15$, as is required to achieve agreement between jet powers computed using blazar spectral fits and those computed using radio-lobe calorimetry, the magnetization of blazar jets in flat-spectrum-radio-quasars (FSRQ) must be significant. Read More

We report the first hard X-ray observations with NuSTAR of the BL Lac type blazar PKS 2155-304, augmented with soft X-ray data from XMM-Newton and gamma-ray data from the Fermi Large Area Telescope, obtained in April 2013 when the source was in a very low flux state. A joint NuSTAR and XMM spectrum, covering the energy range 0.5 - 60 keV, is best described by a model consisting of a log-parabola component with curvature beta = 0. Read More

We use published data on the power and production efficiency of jets in blazars with double radio lobes in order to compare results obtained using different methods. In order to eliminate selection effects, we use cross-matched sub-samples containing only luminous blazars. We compare the three main existing methods, namely those based on the emission of radio lobes, on spectral fitting, and on radio core shift. Read More

High statistics measurements of the photon asymmetry $\mathrm{\Sigma}$ for the $\overrightarrow{\gamma}$p$\rightarrow\pi^{0}$p reaction have been made in the center of mass energy range W=1214-1450 MeV. The data were measured with the MAMI A2 real photon beam and Crystal Ball/TAPS detector systems in Mainz, Germany. The results significantly improve the existing world data and are shown to be in good agreement with previous measurements, and with the MAID, SAID, and Bonn-Gatchina predictions. Read More

We compare covering factors of circumnuclear dusty obscurers in radio-loud and radio-quiet quasars. The radio-loud quasars are represented by a sample of FR II quasars obtained by cross-matching a catalog of the FR II radio sources selected by van Velzen et al. with the SDSS DR7 catalog of quasars. Read More

We have developed a quasi-analytical model for the production of radiation in strong-line blazars, assuming a spine-sheath jet structure. The model allows us to study how the spine and sheath spectral components depend on parameters describing the geometrical and physical structure of "the blazar zone". We show that typical broad-band spectra of strong-line blazars can be reproduced by assuming the magnetization parameter to be of order unity and reconnection to be the dominant dissipation mechanism. Read More

Total cross sections, angular distributions, and invariant-mass distributions have been measured for the photoproduction of $\pi^0\pi^0$ pairs off free protons and off nucleons bound in the deuteron. The experiments were performed at the MAMI accelerator facility in Mainz using the Glasgow photon tagging spectrometer and the Crystal Ball/TAPS detector. The accelerator delivered electron beams of 1508 and 1557~MeV, which produced bremsstrahlung in thin radiator foils. Read More

We present a detailed Fermi/LAT data analysis for the broad-line radio galaxy 3C 120. This source has recently entered into a state of increased gamma-ray activity which manifested itself in two major flares detected by Fermi/LAT in September 2014 and April 2015 with no significant flux changes reported in other wavelengths. We analyse available data focusing our attention on aforementioned outbursts. 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

Photoproduction of $\pi\eta$-pairs from nucleons has been investigated from threshold up to incident photon energies of $\approx$~1.4~GeV. The quasi-free reactions $\gamma p\rightarrow p\pi^0\eta$, $\gamma n\rightarrow n\pi^0\eta$, $\gamma p\rightarrow n\pi^+\eta$, and $\gamma n\rightarrow p\pi^-\eta$ were for the first time measured from nucleons bound in the deuteron. Read More

We report the results of a multi-band observing campaign on the famous blazar 3C 279 conducted during a phase of increased activity from 2013 December to 2014 April, including first observations of it with NuSTAR. The $\gamma$-ray emission of the source measured by Fermi-LAT showed multiple distinct flares reaching the highest flux level measured in this object since the beginning of the Fermi mission, with $F(E > 100\,{\rm MeV})$ of $10^{-5}$ photons cm$^{-2}$ s$^{-1}$, and with a flux doubling time scale as short as 2 hours. The $\gamma$-ray spectrum during one of the flares was very hard, with an index of $\Gamma_\gamma = 1. Read More

Luminosities of many powerful blazars are strongly dominated by $\gamma$-rays which most likely result from Comptonization of radiation produced outside a jet. This observation sets certain constraints on composition and energetics of the jet as well as the surrounding quasar environment. We study the dependence of a Compton dominance on a jet magnetization (the magnetic-to-matter energy flux) and on the location of the 'blazar zone'. Read More

We study the effect of radio-jet core shift, which is a dependence of the position of the jet radio core on the observational frequency. We derive a new method of measuring the jet magnetic field based on both the value of the shift and the observed radio flux, which complements the standard method that assumes equipartition. Using both methods, we re-analyse the blazar sample of Zamaninasab et al. Read More

Estimates of magnetic field strength in relativistic jets of active galactic nuclei (AGN), obtained by measuring the frequency-dependent radio core location, imply that the total magnetic fluxes in those jets are consistent with the predictions of the magnetically-arrested disk (MAD) scenario of jet formation. On the other hand, the magnetic field strength determines the luminosity of the synchrotron radiation, which forms the low-energy bump of the observed blazar spectral energy distribution (SED). The SEDs of the most powerful blazars are strongly dominated by the high-energy bump, which is most likely due to the external radiation Compton (ERC) mechanism. Read More

The spin polarizabilities of the nucleon describe how the spin of the nucleon responds to an incident polarized photon. The most model-independent way to measure the nucleon spin polarizabilities is through polarized Compton scattering. Double-polarized Compton scattering asymmetries on the proton were measured in the $\Delta(1232)$ region using circularly polarized incident photons and a transversely polarized proton target at the Mainz Microtron. Read More

Differential and total cross sections for the quasifree reactions $\gamma p\rightarrow\eta p$ and $\gamma n\rightarrow\eta n$ have been determined at the MAMI-C electron accelerator using a liquid deuterium target. Photons were produced via bremsstrahlung from the 1.5 GeV incident electron beam and energy-tagged with the Glasgow photon tagger. Read More

An experimental study of $\omega$ photoproduction on the proton was conducted by using the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. The $\gamma p\to\omega p$ differential cross sections are measured from threshold to the incident-photon energy $E_\gamma=1.40$ GeV ($W=1. Read More

Locating the gamma-ray emission sites in blazar jets is a long-standing and highly controversial issue. We investigate jointly several constraints on the distance scale r and Lorentz factor Gamma of the gamma-ray emitting regions in luminous blazars (primarily flat spectrum radio quasars, FSRQs). Working in the framework of one-zone external radiation Comptonization (ERC) models, we perform a parameter space study for several representative cases of actual gamma-ray flares in their multiwavelength context. Read More

Cross sections for \nuc{6}{Li}($\gamma$,$\gamma$)\nuc{6}{Li} have been measured at the High Intensity Gamma-Ray Source (\HIGS) and the sensitivity of these cross sections to the nucleon isoscalar polarizabilities was studied. Data were collected using a quasi-monoenergetic 86 MeV photon beam at photon scattering angles of 40$^{\circ}$--160$^{\circ}$. These results are an extension of a previous measurement at a lower energy. Read More

2014May
Affiliations: 1A2 Collaboration at MAMI, 2A2 Collaboration at MAMI, 3A2 Collaboration at MAMI, 4A2 Collaboration at MAMI, 5A2 Collaboration at MAMI, 6A2 Collaboration at MAMI, 7A2 Collaboration at MAMI, 8A2 Collaboration at MAMI, 9A2 Collaboration at MAMI, 10A2 Collaboration at MAMI, 11A2 Collaboration at MAMI, 12A2 Collaboration at MAMI, 13A2 Collaboration at MAMI, 14A2 Collaboration at MAMI, 15A2 Collaboration at MAMI, 16A2 Collaboration at MAMI, 17A2 Collaboration at MAMI, 18A2 Collaboration at MAMI, 19A2 Collaboration at MAMI, 20A2 Collaboration at MAMI, 21A2 Collaboration at MAMI, 22A2 Collaboration at MAMI, 23A2 Collaboration at MAMI, 24A2 Collaboration at MAMI, 25A2 Collaboration at MAMI, 26A2 Collaboration at MAMI, 27A2 Collaboration at MAMI, 28A2 Collaboration at MAMI, 29A2 Collaboration at MAMI, 30A2 Collaboration at MAMI, 31A2 Collaboration at MAMI, 32A2 Collaboration at MAMI, 33A2 Collaboration at MAMI, 34A2 Collaboration at MAMI, 35A2 Collaboration at MAMI, 36A2 Collaboration at MAMI, 37A2 Collaboration at MAMI, 38A2 Collaboration at MAMI, 39A2 Collaboration at MAMI, 40A2 Collaboration at MAMI, 41A2 Collaboration at MAMI, 42A2 Collaboration at MAMI, 43A2 Collaboration at MAMI, 44A2 Collaboration at MAMI, 45A2 Collaboration at MAMI, 46A2 Collaboration at MAMI, 47A2 Collaboration at MAMI, 48A2 Collaboration at MAMI, 49A2 Collaboration at MAMI, 50A2 Collaboration at MAMI, 51A2 Collaboration at MAMI, 52A2 Collaboration at MAMI, 53A2 Collaboration at MAMI, 54A2 Collaboration at MAMI, 55A2 Collaboration at MAMI, 56A2 Collaboration at MAMI, 57A2 Collaboration at MAMI, 58A2 Collaboration at MAMI, 59A2 Collaboration at MAMI, 60A2 Collaboration at MAMI, 61A2 Collaboration at MAMI, 62A2 Collaboration at MAMI, 63A2 Collaboration at MAMI, 64A2 Collaboration at MAMI, 65A2 Collaboration at MAMI, 66A2 Collaboration at MAMI, 67A2 Collaboration at MAMI, 68A2 Collaboration at MAMI, 69A2 Collaboration at MAMI, 70A2 Collaboration at MAMI, 71A2 Collaboration at MAMI, 72A2 Collaboration at MAMI, 73A2 Collaboration at MAMI, 74A2 Collaboration at MAMI, 75A2 Collaboration at MAMI, 76A2 Collaboration at MAMI, 77A2 Collaboration at MAMI, 78A2 Collaboration at MAMI, 79A2 Collaboration at MAMI

A new measurement of the rare, doubly radiative decay eta->pi^0 gamma gamma was conducted with the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. New data on the dependence of the partial decay width, Gamma(eta->pi^0 gamma gamma), on the two-photon invariant mass squared, m^2(gamma gamma), as well as a new, more precise value for the decay width, Gamma(eta->pi^0 gamma gamma) = (0.33+/-0. Read More

2014Apr
Affiliations: 1Astronomical Observatory, Jagiellonian University, 2Institute of Space and Astronautical Science, JAXA, 3Astronomical Observatory, Jagiellonian University, 4Astronomical Observatory, Jagiellonian University, 5Astronomical Observatory, Jagiellonian University, 6Space Science Division, Naval Research Laboratory, 7Nicolaus Copernicus Astronomical Center

In this paper we analyze the peculiar radio structure observed across the central region of the galaxy cluster Abell 585 (z=0.12). In the low-resolution radio maps, this structure appears uniform and diffuse on angular scales of ~3 arcmin, and is seemingly related to the distant (z=2. Read More

The electronic and magnetic properties of individual Fe atoms adsorbed on the surface of the topological insulator Bi$_2$Te$_3$(111) are investigated. Scanning tunneling microscopy and spectroscopy prove the existence of two distinct types of Fe species, while our first-principles calculations assign them to Fe adatoms in the hcp and fcc hollow sites. The combination of x-ray magnetic circular dichroism measurements and angular dependent magnetization curves reveals out-of-plane anisotropies for both species with anisotropy constants of $K_{\text{fcc}} = (10 \pm 4)$ meV/atom and $K_{\text{hcp}} = (8 \pm 4)$ meV/atom. 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

Precise angular distributions have been measured for the first time for the photoproduction of $\pi^{0}$-mesons off neutrons bound in the deuteron. The effects from nuclear Fermi motion have been eliminated by a complete kinematic reconstruction of the final state. The influence of final-state-interaction effects has been estimated by a comparison of the reaction cross section for quasi-free protons bound in the deuteron to the results for free protons and then applied as a correction to the quasi-free neutron data. Read More

Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz for the photoproduction of mixed-charge pion pairs in the reactions $\boldsymbol{\gamma}p\rightarrow n\pi^0\pi^+$ off free protons and $\boldsymbol{\gamma}d\rightarrow (p)p\pi^0\pi^-$ and $\boldsymbol{\gamma}d\rightarrow (n)n\pi^0\pi^+$ off quasi-free nucleons bound in the deuteron for incident photon energies up to 1.4 GeV. Circularly polarized photons were produced from bremsstrahlung of longitudinally polarized electrons and tagged with the Glasgow-Mainz magnetic spectrometer. Read More

We investigate Co nanostructures on Bi$_{2}$Se$_{3}$ by means of scanning tunneling microscopy and spectroscopy [STM/STS], X-ray absorption spectroscopy [XAS], X-ray magnetic dichroism [XMCD] and calculations using the density functional theory [DFT]. In the single adatom regime we find two different adsorption sites by STM. Our calculations reveal these to be the fcc and hcp hollow sites of the substrate. Read More

Gamma-ray luminosities of some quasar-associated blazars imply jet powers reaching values comparable to the accretion power even if assuming very strong Doppler boosting and very high efficiency of gamma-ray production. With much lower radiative efficiencies of protons than of electrons, and the recent reports of very strong coupling of electrons with shock-heated protons indicated by Particle-in-Cell (PIC) simulations, the leptonic models seem to be strongly favored over the hadronic ones. However, the electron-proton coupling combined with the ERC (External-Radiation-Compton) models of gamma-ray production in leptonic models predict extremely hard X-ray spectra, with energy indices about 0. Read More

2013Sep
Affiliations: 1A2 Collaboration at MAMI, 2A2 Collaboration at MAMI, 3A2 Collaboration at MAMI, 4A2 Collaboration at MAMI, 5A2 Collaboration at MAMI, 6A2 Collaboration at MAMI, 7A2 Collaboration at MAMI, 8A2 Collaboration at MAMI, 9A2 Collaboration at MAMI, 10A2 Collaboration at MAMI, 11A2 Collaboration at MAMI, 12A2 Collaboration at MAMI, 13A2 Collaboration at MAMI, 14A2 Collaboration at MAMI, 15A2 Collaboration at MAMI, 16A2 Collaboration at MAMI, 17A2 Collaboration at MAMI, 18A2 Collaboration at MAMI, 19A2 Collaboration at MAMI, 20A2 Collaboration at MAMI, 21A2 Collaboration at MAMI, 22A2 Collaboration at MAMI, 23A2 Collaboration at MAMI, 24A2 Collaboration at MAMI, 25A2 Collaboration at MAMI, 26A2 Collaboration at MAMI, 27A2 Collaboration at MAMI, 28A2 Collaboration at MAMI, 29A2 Collaboration at MAMI, 30A2 Collaboration at MAMI, 31A2 Collaboration at MAMI, 32A2 Collaboration at MAMI, 33A2 Collaboration at MAMI, 34A2 Collaboration at MAMI, 35A2 Collaboration at MAMI, 36A2 Collaboration at MAMI, 37A2 Collaboration at MAMI, 38A2 Collaboration at MAMI, 39A2 Collaboration at MAMI, 40A2 Collaboration at MAMI, 41A2 Collaboration at MAMI, 42A2 Collaboration at MAMI, 43A2 Collaboration at MAMI, 44A2 Collaboration at MAMI, 45A2 Collaboration at MAMI, 46A2 Collaboration at MAMI, 47A2 Collaboration at MAMI, 48A2 Collaboration at MAMI, 49A2 Collaboration at MAMI, 50A2 Collaboration at MAMI, 51A2 Collaboration at MAMI, 52A2 Collaboration at MAMI, 53A2 Collaboration at MAMI, 54A2 Collaboration at MAMI, 55A2 Collaboration at MAMI, 56A2 Collaboration at MAMI, 57A2 Collaboration at MAMI, 58A2 Collaboration at MAMI, 59A2 Collaboration at MAMI, 60A2 Collaboration at MAMI, 61A2 Collaboration at MAMI, 62A2 Collaboration at MAMI, 63A2 Collaboration at MAMI, 64A2 Collaboration at MAMI, 65A2 Collaboration at MAMI, 66A2 Collaboration at MAMI, 67A2 Collaboration at MAMI, 68A2 Collaboration at MAMI, 69A2 Collaboration at MAMI, 70A2 Collaboration at MAMI, 71A2 Collaboration at MAMI, 72A2 Collaboration at MAMI, 73A2 Collaboration at MAMI, 74A2 Collaboration at MAMI, 75A2 Collaboration at MAMI, 76A2 Collaboration at MAMI

The Dalitz decay eta -> e^+ e^- gamma has been measured in the gamma p -> eta p reaction with the Crystal Ball and TAPS multiphoton spectrometers, together with the photon tagging facility at the Mainz Microtron MAMI. The experimental statistic used in this work is one order of magnitude greater than in any previous measurement of eta -> e^+ e^- gamma. The value obtained for the slope parameter 1/Lambda^2 of the eta transition form factor, 1/Lambda^2 = (1. Read More

Measurements of $\gamma p \rightarrow K^{+} \Lambda$ and $\gamma p \rightarrow K^{+} \Sigma^0$ cross-sections have been obtained with the photon tagging facility and the Crystal Ball calorimeter at MAMI-C. The measurement uses a novel $K^+$ meson identification technique in which the weak decay products are characterized using the energy and timing characteristics of the energy deposit in the calorimeter, a method that has the potential to be applied at many other facilities. The fine center-of-mass energy ($W$) resolution and statistical accuracy of the new data results in a significant impact on partial wave analyses aiming to better establish the excitation spectrum of the nucleon. Read More

The nanoscopic magneto-electronic phase separation in doped La1-xSrxCoO3 perovskites was studied with local probes. The phase separation is directly observed by M\"ossbauer spectroscopy in the studied doping range of 0.05 <= x <= 0. Read More

2013Jul
Authors: The CTA Consortium, :, O. Abril, B. S. Acharya, M. Actis, G. Agnetta, J. A. Aguilar, F. Aharonian, M. Ajello, A. Akhperjanian, M. Alcubierre, J. Aleksic, R. Alfaro, E. Aliu, A. J. Allafort, D. Allan, I. Allekotte, R. Aloisio, E. Amato, G. Ambrosi, M. Ambrosio, J. Anderson, E. O. Angüner, L. A. Antonelli, V. Antonuccio, M. Antonucci, P. Antoranz, A. Aravantinos, A. Argan, T. Arlen, C. Aramo, T. Armstrong, H. Arnaldi, L. Arrabito, K. Asano, T. Ashton, H. G. Asorey, T. Aune, Y. Awane, H. Baba, A. Babic, N. Baby, J. Bähr, A. Bais, C. Baixeras, S. Bajtlik, M. Balbo, D. Balis, C. Balkowski, J. Ballet, A. Bamba, R. Bandiera, A. Barber, C. Barbier, M. Barceló, A. Barnacka, J. Barnstedt, U. Barres de Almeida, J. A. Barrio, A. Basili, S. Basso, D. Bastieri, C. Bauer, A. Baushev, U. Becciani, J. Becerra, J. Becerra, Y. Becherini, K. C. Bechtol, J. Becker Tjus, V. Beckmann, W. Bednarek, B. Behera, M. Belluso, W. Benbow, J. Berdugo, D. Berge, K. Berger, F. Bernard, T. Bernardino, K. Bernlöhr, B. Bertucci, N. Bhat, S. Bhattacharyya, B. Biasuzzi, C. Bigongiari, A. Biland, S. Billotta, T. Bird, E. Birsin, E. Bissaldi, J. Biteau, M. Bitossi, S. Blake, O. Blanch Bigas, P. Blasi, A. Bobkov, V. Boccone, M. Böttcher, L. Bogacz, J. Bogart, M. Bogdan, C. Boisson, J. Boix Gargallo, J. Bolmont, G. Bonanno, A. Bonardi, T. Bonev, P. Bonifacio, G. Bonnoli, P. Bordas, A. Borgland, J. Borkowski, R. Bose, O. Botner, A. Bottani, L. Bouchet, M. Bourgeat, C. Boutonnet, A. Bouvier, S. Brau-Nogué, I. Braun, T. Bretz, M. Briggs, M. Brigida, T. Bringmann, R. Britto, P. Brook, P. Brun, L. Brunetti, P. Bruno, N. Bucciantini, T. Buanes, J. Buckley, R. Bühler, V. Bugaev, A. Bulgarelli, T. Bulik, G. Busetto, S. Buson, K. Byrum, M. Cailles, R. Cameron, J. Camprecios, R. Canestrari, S. Cantu, M. Capalbi, P. Caraveo, E. Carmona, A. Carosi, R. Carosi, J. Carr, J. Carter, P. -H. Carton, R. Caruso, S. Casanova, E. Cascone, M. Casiraghi, A. Castellina, O. Catalano, S. Cavazzani, S. Cazaux, P. Cerchiara, M. Cerruti, E. Chabanne, P. Chadwick, C. Champion, R. Chaves, P. Cheimets, A. Chen, J. Chiang, L. Chiappetti, M. Chikawa, V. R. Chitnis, F. Chollet, A. Christof, J. Chudoba, M. Cieślar, A. Cillis, M. Cilmo, A. Codino, J. Cohen-Tanugi, S. Colafrancesco, P. Colin, J. Colome, S. Colonges, M. Compin, P. Conconi, V. Conforti, V. Connaughton, J. Conrad, J. L. Contreras, P. Coppi, J. Coridian, P. Corona, D. Corti, J. Cortina, L. Cossio, A. Costa, H. Costantini, G. Cotter, B. Courty, S. Couturier, S. Covino, G. Crimi, S. J. Criswell, J. Croston, G. Cusumano, M. Dafonseca, O. Dale, M. Daniel, J. Darling, I. Davids, F. Dazzi, A. de Angelis, V. De Caprio, F. De Frondat, E. M. de Gouveia Dal Pino, I. de la Calle, G. A. De La Vega, R. de los Reyes Lopez, B. de Lotto, A. De Luca, M. de Naurois, Y. de Oliveira, E. de Oña Wilhelmi, F. de Palma, V. de Souza, G. Decerprit, G. Decock, C. Deil, E. Delagnes, G. Deleglise, C. Delgado, D. della Volpe, P. Demange, G. Depaola, A. Dettlaff, T. Di Girolamo, C. Di Giulio, A. Di Paola, F. Di Pierro, G. di Sciascio, C. Díaz, J. Dick, R. Dickherber, H. Dickinson, V. Diez-Blanco, S. Digel, D. Dimitrov, G. Disset, A. Djannati-Ataï, M. Doert, M. Dohmke, W. Domainko, D. Dominis Prester, A. Donat, D. Dorner, M. Doro, J. -L. Dournaux, G. Drake, D. Dravins, L. Drury, F. Dubois, R. Dubois, G. Dubus, C. Dufour, D. Dumas, J. Dumm, D. Durand, V. Dwarkadas, J. Dyks, M. Dyrda, J. Ebr, E. Edy, K. Egberts, P. Eger, S. Einecke, C. Eleftheriadis, S. Elles, D. Emmanoulopoulos, D. Engelhaupt, R. Enomoto, J. -P. Ernenwein, M. Errando, A. Etchegoyen, P. A. Evans, A. Falcone, A. Faltenbacher, D. Fantinel, K. Farakos, C. Farnier, E. Farrell, G. Fasola, B. W. Favill, E. Fede, S. Federici, S. Fegan, F. Feinstein, D. Ferenc, P. Ferrando, M. Fesquet, P. Fetfatzis, A. Fiasson, E. Fillin-Martino, D. Fink, C. Finley, J. P. Finley, M. Fiorini, R. Firpo Curcoll, E. Flandrini, H. Fleischhack, H. Flores, D. Florin, W. Focke, C. Föhr, E. Fokitis, L. Font, G. Fontaine, M. Fornasa, A. Förster, L. Fortson, N. Fouque, A. Franckowiak, F. J. Franco, A. Frankowski, C. Fransson, G. W. Fraser, R. Frei, L. Fresnillo, C. Fruck, D. Fugazza, Y. Fujita, Y. Fukazawa, Y. Fukui, S. Funk, W. Gäbele, S. Gabici, R. Gabriele, A. Gadola, N. Galante, D. Gall, Y. Gallant, J. Gámez-García, M. Garczarczyk, B. García, R. Garcia López, D. Gardiol, F. Gargano, D. Garrido, L. Garrido, D. Gascon, M. Gaug, J. Gaweda, L. Gebremedhin, N. Geffroy, L. Gerard, A. Ghedina, M. Ghigo, P. Ghislain, E. Giannakaki, F. Gianotti, S. Giarrusso, G. Giavitto, B. Giebels, N. Giglietto, V. Gika, M. Giomi, P. Giommi, F. Giordano, N. Girard, E. Giro, A. Giuliani, T. Glanzman, J. -F. Glicenstein, N. Godinovic, V. Golev, M. Gomez Berisso, J. Gómez-Ortega, M. M. Gonzalez, A. González, F. González, A. González Muñoz, K. S. Gothe, T. Grabarczyk, M. Gougerot, R. Graciani, P. Grandi, F. Grañena, J. Granot, G. Grasseau, R. Gredig, A. Green, T. Greenshaw, T. Grégoire, A. Grillo, O. Grimm, M. -H. Grondin, J. Grube, M. Grudzinska, V. Gruev, S. Grünewald, J. Grygorczuk, V. Guarino, S. Gunji, G. Gyuk, D. Hadasch, A. Hagedorn, R. Hagiwara, J. Hahn, N. Hakansson, A. Hallgren, N. Hamer Heras, S. Hara, M. J. Hardcastle, D. Harezlak, J. Harris, T. Hassan, K. Hatanaka, T. Haubold, A. Haupt, T. Hayakawa, M. Hayashida, R. Heller, F. Henault, G. Henri, G. Hermann, R. Hermel, A. Herrero, O. Hervet, N. Hidaka, J. A. Hinton, K. Hirotani, D. Hoffmann, W. Hofmann, P. Hofverberg, J. Holder, J. R. Hörandel, D. Horns, D. Horville, J. Houles, M. Hrabovsky, D. Hrupec, H. Huan, B. Huber, J. -M. Huet, G. Hughes, T. B. Humensky, J. Huovelin, J. -F. Huppert, A. Ibarra, D. Ikawa, J. M. Illa, D. Impiombato, S. Incorvaia, S. Inoue, Y. Inoue, F. Iocco, K. Ioka, G. L. Israel, C. Jablonski, A. Jacholkowska, J. Jacquemier, M. Jamrozy, M. Janiak, P. Jean, C. Jeanney, J. J. Jimenez, T. Jogler, C. Johnson, T. Johnson, L. Journet, C. Juffroy, I. Jung, P. Kaaret, S. Kabuki, M. Kagaya, J. Kakuwa, C. Kalkuhl, R. Kankanyan, A. Karastergiou, K. Kärcher, M. Karczewski, S. Karkar, J. Kasperek, D. Kastana, H. Katagiri, J. Kataoka, K. Katarzyński, U. Katz, N. Kawanaka, D. Kazanas, N. Kelley-Hoskins, B. Kellner-Leidel, H. Kelly, E. Kendziorra, B. Khélifi, D. B. Kieda, T. Kifune, T. Kihm, T. Kishimoto, K. Kitamoto, W. Kluźniak, C. Knapic, J. Knapp, J. Knödlseder, F. Köck, J. Kocot, K. Kodani, J. -H. Köhne, K. Kohri, K. Kokkotas, D. Kolitzus, N. Komin, I. Kominis, Y. Konno, H. Köppel, P. Korohoda, K. Kosack, G. Koss, R. Kossakowski, R. Koul, G. Kowal, S. Koyama, J. Kozioł, T. Krähenbühl, J. Krause, H. Krawzcynski, F. Krennrich, A. Krepps, A. Kretzschmann, R. Krobot, P. Krueger, H. Kubo, V. A. Kudryavtsev, J. Kushida, A. Kuznetsov, A. La Barbera, N. La Palombara, V. La Parola, G. La Rosa, K. Lacombe, G. Lamanna, J. Lande, D. Languignon, J. S. Lapington, P. Laporte, B. Laurent, C. Lavalley, T. Le Flour, A. Le Padellec, S. -H. Lee, W. H. Lee, J. -P. Lefèvre, H. Leich, M. A. Leigui de Oliveira, D. Lelas, J. -P. Lenain, R. Leoni, D. J. Leopold, T. Lerch, L. Lessio, G. Leto, B. Lieunard, S. Lieunard, R. Lindemann, E. Lindfors, A. Liolios, A. Lipniacka, H. Lockart, T. Lohse, S. Lombardi, F. Longo, A. Lopatin, M. Lopez, R. López-Coto, A. López-Oramas, A. Lorca, E. Lorenz, F. Louis, P. Lubinski, F. Lucarelli, H. Lüdecke, J. Ludwin, P. L. Luque-Escamilla, W. Lustermann, O. Luz, E. Lyard, M. C. Maccarone, T. J. Maccarone, G. M. Madejski, A. Madhavan, M. Mahabir, G. Maier, P. Majumdar, G. Malaguti, G. Malaspina, S. Maltezos, A. Manalaysay, A. Mancilla, D. Mandat, G. Maneva, A. Mangano, P. Manigot, K. Mannheim, I. Manthos, N. Maragos, A. Marcowith, M. Mariotti, M. Marisaldi, S. Markoff, A. Marszałek, C. Martens, J. Martí, J. -M. Martin, P. Martin, G. Martínez, F. Martínez, M. Martínez, F. Massaro, A. Masserot, A. Mastichiadis, A. Mathieu, H. Matsumoto, F. Mattana, S. Mattiazzo, A. Maurer, G. Maurin, S. Maxfield, J. Maya, D. Mazin, L. Mc Comb, A. McCann, N. McCubbin, I. McHardy, R. McKay, K. Meagher, C. Medina, C. Melioli, D. Melkumyan, D. Melo, S. Mereghetti, P. Mertsch, M. Meucci, M. Meyer, J. Michałowski, P. Micolon, A. Mihailidis, T. Mineo, M. Minuti, N. Mirabal, F. Mirabel, J. M. Miranda, R. Mirzoyan, A. Mistò, T. Mizuno, B. Moal, R. Moderski, I. Mognet, E. Molinari, M. Molinaro, T. Montaruli, C. Monte, I. Monteiro, P. Moore, A. Moralejo Olaizola, M. Mordalska, C. Morello, K. Mori, G. Morlino, A. Morselli, F. Mottez, Y. Moudden, E. Moulin, I. Mrusek, R. Mukherjee, P. Munar-Adrover, H. Muraishi, K. Murase, A. StJ. Murphy, S. Nagataki, T. Naito, D. Nakajima, T. Nakamori, K. Nakayama, C. Naumann, D. Naumann, M. Naumann-Godo, P. Nayman, D. Nedbal, D. Neise, L. Nellen, A. Neronov, V. Neustroev, N. Neyroud, L. Nicastro, J. Nicolau-Kukliński, A. Niedźwiecki, J. Niemiec, D. Nieto, A. Nikolaidis, K. Nishijima, K. -I. Nishikawa, K. Noda, S. Nolan, R. Northrop, D. Nosek, N. Nowak, A. Nozato, L. Oakes, P. T. O'Brien, Y. Ohira, M. Ohishi, S. Ohm, H. Ohoka, T. Okuda, A. Okumura, J. -F. Olive, R. A. Ong, R. Orito, M. Orr, J. P. Osborne, M. Ostrowski, L. A. Otero, N. Otte, E. Ovcharov, I. Oya, A. Ozieblo, L. Padilla, I. Pagano, S. Paiano, D. Paillot, A. Paizis, S. Palanque, M. Palatka, J. Pallota, M. Palatiello, K. Panagiotidis, J. -L. Panazol, D. Paneque, M. Panter, M. R. Panzera, R. Paoletti, A. Papayannis, G. Papyan, J. M. Paredes, G. Pareschi, J. -M. Parraud, D. Parsons, G. Pauletta, M. Paz Arribas, M. Pech, G. Pedaletti, V. Pelassa, D. Pelat, M. d. C. Perez, M. Persic, P. -O. Petrucci, B. Peyaud, A. Pichel, D. Pieloth, E. Pierre, S. Pita, G. Pivato, F. Pizzolato, M. Platino, Ł. Platos, R. Platzer, S. Podkladkin, L. Pogosyan, M. Pohl, G. Pojmanski, J. D. Ponz, W. Potter, J. Poutanen, E. Prandini, J. Prast, R. Preece, F. Profeti, H. Prokoph, M. Prouza, M. Proyetti, I. Puerto-Giménez, G. Pühlhofer, I. Puljak, M. Punch, R. Pyzioł, E. J. Quel, J. Quesada, J. Quinn, A. Quirrenbach, E. Racero, S. Rainò, P. J. Rajda, M. Rameez, P. Ramon, R. Rando, R. C. Rannot, M. Rataj, M. Raue, D. Ravignani, P. Reardon, O. Reimann, A. Reimer, O. Reimer, K. Reitberger, M. Renaud, S. Renner, B. Reville, W. Rhode, M. Ribó, M. Ribordy, G. Richards, M. G. Richer, J. Rico, J. Ridky, F. Rieger, P. Ringegni, J. Ripken, P. R. Ristori, A. Rivière, S. Rivoire, L. Rob, G. Rodeghiero, U. Roeser, R. Rohlfs, G. Rojas, P. Romano, W. Romaszkan, G. E. Romero, S. R. Rosen, S. Rosier Lees, D. Ross, G. Rouaix, J. Rousselle, S. Rousselle, A. C. Rovero, F. Roy, S. Royer, B. Rudak, C. Rulten, M. Rupiński, F. Russo, F. Ryde, O. Saavedra, B. Sacco, E. O. Saemann, A. Saggion, V. Sahakian, K. Saito, T. Saito, Y. Saito, N. Sakaki, R. Sakonaka, A. Salini, F. Sanchez, M. Sanchez-Conde, A. Sandoval, H. Sandaker, E. Sant'Ambrogio, A. Santangelo, E. M. Santos, A. Sanuy, L. Sapozhnikov, S. Sarkar, N. Sartore, H. Sasaki, K. Satalecka, M. Sawada, V. Scalzotto, V. Scapin, M. Scarcioffolo, J. Schafer, T. Schanz, S. Schlenstedt, R. Schlickeiser, T. Schmidt, J. Schmoll, P. Schovanek, M. Schroedter, A. Schubert, C. Schultz, J. Schultze, A. Schulz, K. Schure, F. Schussler, T. Schwab, U. Schwanke, J. Schwarz, S. Schwarzburg, T. Schweizer, S. Schwemmer, U. Schwendicke, C. Schwerdt, A. Segreto, J. -H. Seiradakis, G. H. Sembroski, M. Servillat, K. Seweryn, M. Sharma, M. Shayduk, R. C. Shellard, J. Shi, T. Shibata, A. Shibuya, S. Shore, E. Shum, E. Sideras-Haddad, L. Sidoli, M. Sidz, J. Sieiro, M. Sikora, J. Silk, A. Sillanpää, B. B. Singh, G. Sironi, J. Sitarek, C. Skole, R. Smareglia, A. Smith, D. Smith, J. Smith, N. Smith, D. Sobczyńska, H. Sol, G. Sottile, M. Sowiński, F. Spanier, D. Spiga, S. Spyrou, V. Stamatescu, A. Stamerra, R. L. C. Starling, Ł. Stawarz, R. Steenkamp, C. Stegmann, S. Steiner, C. Stella, N. Stergioulas, R. Sternberger, M. Sterzel, F. Stinzing, M. Stodulski, Th. Stolarczyk, U. Straumann, E. Strazzeri, L. Stringhetti, A. Suarez, M. Suchenek, R. Sugawara, K. -H. Sulanke, S. Sun, A. D. Supanitsky, T. Suric, P. Sutcliffe, J. M. Sykes, M. Szanecki, T. Szepieniec, A. Szostek, G. Tagliaferri, H. Tajima, H. Takahashi, K. Takahashi, L. Takalo, H. Takami, G. Talbot, J. Tammi, M. Tanaka, S. Tanaka, J. Tasan, M. Tavani, J. -P. Tavernet, L. A. Tejedor, I. Telezhinsky, P. Temnikov, C. Tenzer, Y. Terada, R. Terrier, M. Teshima, V. Testa, D. Tezier, J. Thayer, D. Thuermann, L. Tibaldo, L. Tibaldo, O. Tibolla, A. Tiengo, M. C. Timpanaro, M. Tluczykont, C. J. Todero Peixoto, F. Tokanai, M. Tokarz, K. Toma, A. Tonachini, K. Torii, M. Tornikoski, D. F. Torres, M. Torres, S. Toscano, G. Toso, G. Tosti, T. Totani, F. Toussenel, G. Tovmassian, P. Travnicek, A. Treves, M. Trifoglio, I. Troyano, K. Tsinganos, H. Ueno, G. Umana, K. Umehara, S. S. Upadhya, T. Usher, M. Uslenghi, F. Vagnetti, J. F. Valdes-Galicia, P. Vallania, G. Vallejo, W. van Driel, C. van Eldik, J. Vandenbrouke, J. Vanderwalt, H. Vankov, G. Vasileiadis, V. Vassiliev, D. Veberic, I. Vegas, S. Vercellone, S. Vergani, V. Verzi, G. P. Vettolani, C. Veyssière, J. P. Vialle, A. Viana, M. Videla, C. Vigorito, P. Vincent, S. Vincent, J. Vink, N. Vlahakis, L. Vlahos, P. Vogler, V. Voisin, A. Vollhardt, H. -P. von Gunten, S. Vorobiov, C. Vuerli, V. Waegebaert, R. Wagner, R. G. Wagner, S. Wagner, S. P. Wakely, R. Walter, T. Walther, K. Warda, R. S. Warwick, P. Wawer, R. Wawrzaszek, N. Webb, P. Wegner, A. Weinstein, Q. Weitzel, R. Welsing, M. Werner, H. Wetteskind, R. J. White, A. Wierzcholska, S. Wiesand, A. Wilhelm, M. I. Wilkinson, D. A. Williams, R. Willingale, M. Winde, K. Winiarski, R. Wischnewski, Ł. Wiśniewski, P. Wojcik, M. Wood, A. Wörnlein, Q. Xiong, K. K. Yadav, H. Yamamoto, T. Yamamoto, R. Yamazaki, S. Yanagita, J. M. Yebras, D. Yelos, A. Yoshida, T. Yoshida, T. Yoshikoshi, P. Yu, V. Zabalza, M. Zacharias, A. Zajczyk, L. Zampieri, R. Zanin, A. Zdziarski, A. Zech, A. Zhao, X. Zhou, K. Zietara, J. Ziolkowski, P. Ziółkowski, V. Zitelli, C. Zurbach, P. Zychowski

Compilation of CTA contributions to the proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), which took place in 2-9 July, 2013, in Rio de Janeiro, Brazil 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

2013Jun
Affiliations: 1A2 Collaboration at MAMI, 2A2 Collaboration at MAMI, 3A2 Collaboration at MAMI, 4A2 Collaboration at MAMI, 5A2 Collaboration at MAMI, 6A2 Collaboration at MAMI, 7A2 Collaboration at MAMI, 8A2 Collaboration at MAMI, 9A2 Collaboration at MAMI, 10A2 Collaboration at MAMI, 11A2 Collaboration at MAMI, 12A2 Collaboration at MAMI, 13A2 Collaboration at MAMI, 14A2 Collaboration at MAMI, 15A2 Collaboration at MAMI, 16A2 Collaboration at MAMI, 17A2 Collaboration at MAMI, 18A2 Collaboration at MAMI, 19A2 Collaboration at MAMI, 20A2 Collaboration at MAMI, 21A2 Collaboration at MAMI, 22A2 Collaboration at MAMI, 23A2 Collaboration at MAMI, 24A2 Collaboration at MAMI, 25A2 Collaboration at MAMI, 26A2 Collaboration at MAMI, 27A2 Collaboration at MAMI, 28A2 Collaboration at MAMI, 29A2 Collaboration at MAMI, 30A2 Collaboration at MAMI, 31A2 Collaboration at MAMI, 32A2 Collaboration at MAMI, 33A2 Collaboration at MAMI, 34A2 Collaboration at MAMI, 35A2 Collaboration at MAMI, 36A2 Collaboration at MAMI, 37A2 Collaboration at MAMI, 38A2 Collaboration at MAMI, 39A2 Collaboration at MAMI, 40A2 Collaboration at MAMI, 41A2 Collaboration at MAMI, 42A2 Collaboration at MAMI, 43A2 Collaboration at MAMI, 44A2 Collaboration at MAMI, 45A2 Collaboration at MAMI, 46A2 Collaboration at MAMI, 47A2 Collaboration at MAMI, 48A2 Collaboration at MAMI, 49A2 Collaboration at MAMI, 50A2 Collaboration at MAMI, 51A2 Collaboration at MAMI, 52A2 Collaboration at MAMI, 53A2 Collaboration at MAMI, 54A2 Collaboration at MAMI, 55A2 Collaboration at MAMI, 56A2 Collaboration at MAMI, 57A2 Collaboration at MAMI, 58A2 Collaboration at MAMI, 59A2 Collaboration at MAMI, 60A2 Collaboration at MAMI, 61A2 Collaboration at MAMI, 62A2 Collaboration at MAMI, 63A2 Collaboration at MAMI, 64A2 Collaboration at MAMI, 65A2 Collaboration at MAMI, 66A2 Collaboration at MAMI, 67A2 Collaboration at MAMI, 68A2 Collaboration at MAMI, 69A2 Collaboration at MAMI, 70A2 Collaboration at MAMI, 71A2 Collaboration at MAMI, 72A2 Collaboration at MAMI, 73A2 Collaboration at MAMI, 74A2 Collaboration at MAMI, 75A2 Collaboration at MAMI, 76A2 Collaboration at MAMI, 77A2 Collaboration at MAMI, 78A2 Collaboration at MAMI

The g p -> K^0 Sigma^+ reaction has been measured from threshold to Eg=1.45 GeV (W_cm=1.9 GeV) using the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. Read More

Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz for the photoproduction of neutral pion pairs in the reactions $\vec{\gamma}p\rightarrow p\pi^0\pi^0$ and $\vec{\gamma}d\rightarrow (n)p\pi^0\pi^0$, $\vec{\gamma}d\rightarrow (p)n\pi^0\pi^0$ off free protons and off quasi-free nucleons bound in the deuteron for incident photon energies up to 1.4 GeV. Circularly polarized photons were produced from bremsstrahlung of longitudinally polarized electrons and tagged with the Glasgow magnetic spectrometer. Read More

We consider mechanical stability of dimeric and monomeric proteins with the cystine knot motif. A structure based dynamical model is used to demonstrate that all dimeric and some monomeric proteins of this kind should have considerable resistance to stretching that is significantly larger than that of titin. The mechanisms of the large mechanostability are elucidated. Read More

We argue that the magnetic flux threading the black hole, rather than black hole spin or Eddington ratio, is the dominant factor in launching powerful jets and thus determining the radio loudness of active galactic nuclei (AGN). Most AGN are radio quiet because the thin accretion disks that feed them are inefficient in depositing magnetic flux close to the black hole. Flux accumulation is more likely to occur during a hot accretion (or thick disk) phase, and we argue that radio-loud quasars and strong emission-line radio galaxies occur only when a massive, cold accretion event follows an episode of hot accretion. Read More