The AGILE mission: The first 2 years

We summarize here the main highlights of the AGILE astrophysics mission. The satellite, launched in April 2007, is devoted to gamma-ray observations in the 30 MeV–30 GeV energy range, with simultaneous hard X-ray imaging in the 18–60 keV band, and optimal timing capabilities for the study of transient phenomena. The very large field of view (2.5 sr) of the gamma-ray imager coupled with the hard X-ray monitoring capability makes AGILE well suited to study Galactic and extragalactic sources, as well as GRBs and other fast transients. AGILE reaches its optimal performance near 100 MeV with good imaging and sensitivity. Gamma-ray and hard X-ray sources can be monitored 14 times a day, and an extensive database has been obtained for a variety of sources. We summarize here the breakthroughs and most important results obtained for several sources including microquasars and other Galactic compact objects (most notably, the discovery of gamma-ray emission above 100 MeV from Cygnus X-3), Supernova Remnants and pulsar wind nebulae, gamma-ray pulsars, a bright class of blazars (3C 454.3, TXS 0716+714, HB 1510-089, Mrk 421), short and long GRBs (including the remarkable short burst GRB 090510), and terrestrial gamma-ray flashes (TGFs).     

Galactic sources science with AGILE: The case of the Carina Region

During its first 2 years of operation, the gamma-ray AGILE satellite accumulated an extensive dataset for the Galactic plane. The data have been monitored for transient sources and several gamma-ray sources were detected. Their variability and possible association were studied. In this talk we will focus on the results of extensive observations of the Carina Region during the time period 2007 July–2009 January, for a total livetime of 130 days. The region is extremely complex, hosting massive star formation, with the remarkable colliding wind binary Eta Carinae, massive star clusters and HII regions (e.g. NGC 3324, RCW49, Westerlund II) and a giant molecular cloud extending over 150 pc (between l=284.7 and 289). The Carina Nebula itself is the largest and IR highest surface brightness nebula of the Southern emisphere. We monitored several gamma ray sources in the Carina Region. In particular we detect a gamma ray source (1AGL J1043-5931) consistent with the position of Eta Carinae and report a remarkable 2-days gamma-ray flaring episode from this source on 2008 October 11–13. If 1AGL J1043-5931 is associated with the Eta Car system, our data provide the long sought first detection above 100 MeV of a colliding wind binary.     

Fermi gamma-ray space telescope: Science highlights for the first 8 months

The Fermi Gamma-ray Space Telescope was launched on June 11, 2008 and since August 2008 has successfully been conducting routine science observations of high energy phenomena in the gamma-ray sky. A number of exciting discoveries have been made during its first year of operation, including blazar flares, high-energy gamma-ray bursts, and numerous new gamma-ray sources of different types, among them pulsars and Active Galactic Nuclei (AGN). Fermi-LAT also performed accurate measurement of the diffuse gamma-radiation which clarifies the “GeV excess” reported by EGRET almost 10 years ago, high precision measurement of the high energy electron spectrum, and other observations. An overview of the observatory status and recent results as of April 30, 2009, are presented.     

Dark matter multi-wavelength constraints from synchrotron and inverse compton radiation

If coming from WIMP annihilation, the excess of electrons/positrons observed by the Pamela/ATIC/Fermi experiments gives rise to a noticeable amount of synchrotron and Inverse Compton Scattering (ICS) radiation around 10–100 GeV when the e⁺e⁻ interact with the Galactic Magnetic Field, and the InterStellar Radiation Field (ISRF). Further, the Pamela/ATIC/Fermi excess can be tested through the shape of the ICS signal, which is expected to show a peculiar and clean “ICS Haze” feature. We discuss the constraints coming from radio observations, as well as the implications of some preliminary Fermi results on the diffuse gamma background in the inner galactic region.     

Results from the first two years of VERITAS observations

The VERITAS observatory is an imaging atmospheric Cherenkov telescope array located in southern Arizona and covers an energy range between 100 GeV and 30 TeV. The VERITAS collaboration pursues a rigorous observing program that targets a range of key science objectives in astrophysics and particle physics; the understanding of the origin of cosmic rays, the search for supersymmetric dark matter self-annihilation, illuminating the connection between black holes and relativistic jets and constraints to the cosmological diffuse infrared background. We provide a summary of results from the first two years of observations with the full 4-telecope array reported at RICAP09.     

The INTEGRAL high energy sky and the MeV–GeV connection

After more than 6 years of operation, ESAs INTEGRAL Space Observatory has produced a wide number of results, ranging from the inventory of the high energy sources, depicting a gamma-ray sky populated by more than 700 high energy objects, to the discovery of the new class of Super Giant Fast X-ray Transient (SFXT) to dozens of variable galactic and extragalactic sources to the detection of the prompt emission from several tens of gamma ray bursts in the MeV range. In particular, INTEGRAL is continuing the deep observations of the Galactic Plane and, at a lower sensitivity, of the whole sky in the soft Gamma ray range reaching sensitivity better than 0.2 mCrab in the first case and better than typically 1 mCrab in the latter one. Finally, the new IBIS soft gamma-ray Survey catalogue will contain a substantially increased number of sources detected from 17 keV up to several hundreds of keV. A view of the INTEGRAL high energy sky will presented, with particular regard to sources emitting at high energy and their relation with the new AGILE, FERMI and ground based TeV results.     

The flaring blazars of the first 1.5 years of the AGILE mission

We report the AGILE γ-ray observations and the results of the multiwavelength campaigns on seven flaring blazars detected by the mission: During two multiwavelength campaigns, we observed γ-ray activity from two Flat Spectrum Radio Quasars of the Virgo region, e.g. 3C 279 and 3C 273 (the latter being the first extragalactic source simultaneously observed with the γ-ray telescope and the hard X ray imager of the mission). Due to the large FOV of the AGILE/GRID instrument, we achieved an almost continuous coverage of the FSRQ 3C 454.3. The source showed flux above 10⁻⁶ photons/cm²/s () and showed day by day variability during all the AGILE observing periods. In the EGRET era, the source was found in high γ-ray activity only once. An other blazar, PKS 1510-089 was frequently found in high γ-ray activity. S5 0716+71, an intermediate BL Lac object, exhibited a very high γ-ray activity and fast γ-ray variability during a period of intense optical activity. We observed high γ-ray activity from W Comae, a BL Lac object, and Mrk 421, a high energy peaked BL Lac object. For this source, a multiwavelength campaign from optical to TeV has been performed.     

光学综合口径望远镜设计方案讨论

本文提出新建一台4.3米光学、红外新技术望远镜。并与现有北台的几台望远镜用光纤联机提高集光能力达5.1米口径。将4.3米与2.16米望远镜用真空管道联机集像作CCD照相和光干涉测量,提高分辨率达10余米口径。     

Preliminary results on TeV sources search with AGILE

During its first 2 years of operation, the gamma-ray AGILE satellite almost completed a full study of the gamma-ray sky. This paper presents the preliminary results of the systematic study performed on the AGILE data to search for GeV counterparts and to derive flux upper limits of the TeV sources detected by various instruments (MAGIC, HESS, VERITAS, Cangaroo, MILAGRO, ARGO,….).     

The observation of gamma ray bursts and terrestrial gamma-ray flashes with AGILE

Since its early phases of operation, the AGILE mission is successfully observing Gamma Ray Bursts (GRBs) in the hard X-ray band with the SuperAGILE imager and in the MeV range with the Mini-Calorimeter. Up to now, three firm GRB detections were obtained above 25 MeV and some bursts were detected with lower statistical confidence in the same energy band. When a GRB is localized, either by SuperAGILE or Swift/BAT or INTEGRAL/IBIS or Fermi/GBM or IPN, inside the field of view of the Gamma Ray Imager of AGILE, a detection is searched for in the gamma ray band or an upper limit is provided. A promising result of AGILE is the detection of very short gamma ray transients, a few ms in duration and possibly identified with Terrestrial Gamma-ray Flashes. In this paper we show the current status of the observation of Gamma Ray Bursts and Terrestrial Gamma-ray Flashes with AGILE.     

The effect of energy resolution on the extraction of information content from gamma-ray spectra

Rapid unambiguous identification of illicit radioactive materials is a matter of international concern that has yet to be fully attained. This is particularly true for shielded fissile materials in the presence of background radiation and routinely encountered benign radionuclides. We present a systematic treatment of the effect of detector resolution on the identification of nuclides in simple and complex shielded γ-ray spectra. Case studies of some problematic spectra with 1000 counts suggest that, at moderate count rates, near-unambiguous identification (<1% probability of misidentification) of potential fissile sources requires a detector with an energy resolution of at least 1-2% at 662 keV. While somewhat limited in scope, the study establishes a quantitative basis for the comparative evaluation of detectors of comparable efficiency.     

Development of an atmospheric Cherenkov imaging camera for the CANGAROO-III experiment

A Cherenkov imaging camera for the CANGAROO-III experiment has been developed for observations of gamma-ray-induced air showers at energies from 10¹¹ to 10¹⁴ eV. The camera consists of 427 pixels, arranged in a hexagonal shape at 0.17° intervals, each of which is a -in. diameter photomultiplier module with a Winston-cone-shaped light guide. The camera was designed to have a large dynamic range of signal linearity, a wider field of view, and an improvement in photon-collection efficiency compared with the CANGAROO-II camera. The camera, and a number of the calibration experiments made to test its performance, are described in detail in this paper.     

Preparation and characterization of some substituted bioglasses and their ceramic derivatives from the system SiO2–Na2O–CaO–P2O5 and effect of gamma irradiation

Glasses having chemical composition based on Hench's bioglass^® and with some substituted oxides were prepared and crystallized through thermal treatments. These glasses and corresponding glass–ceramics were characterized by Fourier transform infrared spectroscopy (FTIR) either through absorption or reflection studies. Chemical corrosion of the prepared glassy and crystalline samples as grains was examined by the action of 0.1 M HCl or NaOH solutions or by distilled water. Also, UV–vis absorption measurements were carried out before and after successive gamma rays to reveal their response to ionizing radiation.

The formation of hydroxyapatite layer was checked by FTIR studies and X-ray diffraction experiments which show that the crystalline soda lime silicate phase (1Na₂O·2CaO·3SiO₂) is separated as the main phase in all tested glasses beside some secondary phases depending on the introduced substituted oxide. The corrosion behavior was found to vary depending on the type of the introduced oxides and their ability to freely ion exchange and dissolve in the leaching solution.     

2011年上半年转子压缩机市场概述

描述2011年上半年转子压缩机市场总体运行情况,并从变频技术、热泵热水器压缩机、工质替代及行业关注的价格等几个主要方面进行分析,最后对下半年市场情况进行预测。     

Effect of high-flux astronomical sources on the constellation-X microcalorimeter spectrometer

We study the effects of high flux on transition-edge sensors by using a non-linear microcalorimeter model with parameters suitable for the Constellation-X mission. A photon event list was created that simulated the flux and spectrum of the Crab nebula incident on the detector when folded through the Constellation-X optics and filters. Simulations show that even at Crab levels of flux, the Con-X microcalorimeter does not “latch” into the normal state.     

Overview on dislocation-point defect interaction: the brownian picture of dislocation motion

The interactions between dislocations (D) and point defects (PD) are one of the most important causes of mechanical damping in metals. In the past 40 years, many experimental results have been obtained and published, from which it appears that two fundamental behaviors can be observed when dislocations interact with motionless point defects: thermally activated behaviors and athermal behaviors. In this paper, it is shown that these two observed behaviors can be consistently explained by a “brownian picture” of the motion of dislocations interacting with PD distributed at different distances from the dislocation glide plane.     

Determination of the number of pulsed laser-Compton scattering photons

We measured pulse-height spectra of 16.7 MeV laser-Compton scattering photons with a 6 in.×5 in. NaI(Tl) detector for blank and three lead materials of 75.8, 50.9, and 25.9% transmissions at the NewSUBARU facility to investigate how the original Poisson distribution of the pulsed photons is modified after passing through thick-target materials. We present a well-prescribed method of determining the number of incident photons within 3.5% accuracy based on the response of the NaI(Tl) detector to the pulsed photon beams.