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The current poor condition of education for Hispanic students need not exist. This book reports on high-performing schools along the Texas-Mexico border that have achieved schoolwide success by creating communities of learners. Three elementary, three middle, and two high schools in the border region were selected for study based on the following criteria: enrollment of 66.6 percent or more Mexican American students; well-above-average standardized test scores; and state or national recognition. The schools selected also had high numbers of students who were poor, limited-English-proficient, migrant, or newly arrived from Mexico. The schools were found to be communities of learners where students come first, learning is fun, and everything begins in the classroom. Most chapters are case studies that document "best practices" associated with key learning conditions in these schools: community and parent involvement; collaborative governance and leadership; culturally responsive pedagogy; and advocacy-oriented assessment. The final chapter presents a conceptual framework, based on Senge's learning organizations, for understanding the success of these schools. Chapters are: "High-Performing Hispanic Schools: An Introduction" (Alicia Paredes Scribner); "Establishing Collaborative Governance and Leadership" (Lonnie H. Wagstaff and Lance D. Fusarelli); "Building Collaborative Relationships with Parents" (Jay D. Scribner, Michelle D. Young, and Anna Pedroza); "Empowering the Surrounding Community" (Ann K. Brooks and Paul C. Kavanaugh); "Creating Student-Centered Classroom Environments: The Case of Mathematics" (Pedro Reyes and Barbara Pazey); "Creating Student-Centered Classroom Environments: The Case of Reading" (William Rutherford); "Using Student Advocacy Assessment Practices" (Alicia Paredes Scribner); and "Creating Learning Communities for High-Performing Hispanic Students: A Conceptual Framework" (Jay D. Scribner and Pedro Reyes). (Contains references in each chapter, an index, and contributor profiles.) (SV)

Representing various scholarly interests and ideologies, 7 of the 12 essays discuss ethnographers frequent misrepresentation of Chicano culture because they are unaware of the "performance" element of Chicano behavior; "agringado joking", a tactic used by Texas Chicanos to mark ethnic boundaries and to protect their cultural identity; the strengths and deficiencies of such critical approaches as formalist and culturalist; the strong political consciousness shown by contemporary Chicano poetry; Felipe Maximiliano Chacon, a prominent literary figure of the 1920's; the political favor of much Chicano poetry and their limitations; and 19th-century American responses to Mexican character and culture as determined largely by Anglo-American traditions of anti-Catholicism,"Hispanophobia", and a legacy of distorted images of the Mexican aborigines. Two essays discuss the Chicano occupation experience and their movement into American cities from 1900 to 1930. "Chicano Bilingualism" presents an overview of Chicano bilingualism, attributing the widespread retention of Spanish to the persistence of many Chicanos at the lower level of the economic structure where acculturation is minimized. "The Social Implications of Intra-Sentential Code-Switching" rejects the notion that Chicano code-switching occurs randomly and describes the particular social situations in which various forms of this activity take place. Focusing on a recently published "cancionero" by Americo Paredes, the last essay explains how various musical forms illuminate regional varieties of Chicano culture. (NQ)

We present a model to estimate the synchrotron radio emission generated in microquasar (MQ) jets due to secondary pairs created via decay of charged pions produced in proton-proton collisions between stellar wind ions and jet relativistic protons. The synchrotron radiation produced by secondary electrons/positrons is computed using consistently derived particle energy distributions. Energy losses due to synchrotron and inverse Compton (IC) processes, and adiabatic expansion, are taken into account. The space parameter for the model is explored and the corresponding spectral energy distributions (SEDs) are presented. We conclude that secondary leptonic emission represents a significant though hardly dominant contribution to the total radio emission in MQs, with observational consequences that can be used to test some still unknown processes occurring in these objects as well as the nature of the matter outflowing in their jets. [ABSTRACT FROM AUTHOR]

We report and shortly discuss here the observational work carried out in order to test the possibility that two previously detected radio sources, in the vicinity of the well known microquasar Cygnus X-3, could be hot spot tracers of interaction between its relativistic jet and the interstellar medium (ISM). The motivation behind this search is in part justified considering recent theoretical models of high energy γ-ray emission which strongly rely on the interaction sites of galactic relativistic jets with nearby ISM clouds. The results presented in this paper include an improved radio exploration of the several arc-minute field around Cygnus X-3 using the Very Large Array (VLA), as well as deep near infrared (NIR) imaging with the Calar Alto 3.5 m telescope. We anticipate here that our observations do not appear to support the initial hot spot hypothesis. Instead, the resulting images suggest that the two radio sources, originally believed to be hot spot candidates, are most likely background or foreground objects. [ABSTRACT FROM AUTHOR]

LS 5039 is the only X-ray binary persistently detected at TeV energies by the Cherenkov HESS telescope. It is moreover a γ-ray emitter in the GeV and possibly MeV energy ranges. To understand important aspects of jet physics, like the magnetic field content or particle acceleration, and emission processes, such as synchrotron and inverse Compton (IC), a complete modeling of the multiwavelength data is necessary. LS 5039 has been detected along almost all the electromagnetic spectrum thanks to several radio, infrared, optical and soft X-ray detections. However, hard X-ray detections above 20 keV have been so far elusive and/or doubtful, partly due to source confusion for the poor spatial resolution of hard X-ray instruments. We report here on deep (∼300 ks) serendipitous INTEGRAL hard X-ray observations of LS 5039, coupled with simultaneous VLA radio observations. We obtain a 20-40 keV flux of 1.1±0.3 mCrab (5.9 (±1.6) ×10−12 erg cm−2 s−1), a 40-100 keV upper limit of 1.5 mCrab (9.5×10−12 erg cm−2 s−1), and typical radio flux densities of ∼25 mJy at 5 GHz. These hard X-ray fluxes are significantly lower than previous estimates obtained with BATSE in the same energy range but, in the lower interval, agree with extrapolation of previous RXTE measurements. The INTEGRAL observations also hint to a break in the spectral behavior at hard X-rays. A more sensitive characterization of the hard X-ray spectrum of LS 5039 from 20 to 100 keV could therefore constrain key aspects of the jet physics, like the relativistic particle spectrum and the magnetic field strength. Future multiwavelength observations would allow to establish whether such hard X-ray synchrotron emission is produced by the same population of relativistic electrons as those presumably producing TeV emission through IC. [ABSTRACT FROM AUTHOR]

This paper introduces a new method for normalizing cDNA microarray expression data. The proposed approach assumes that the fluctuations between replicated microarray data follow a Laplacian model and, therefore, the normalizing parameters, shifting and scaling parameters, are optimally obtained using a robust algorithm based on Least Absolute Deviation (LAD) regression. The normalization is achieved by iteratively recentering and rescaling the data sets such that the mean absolute error (MAE) between the reference set and the normalized set is minimized. The proposed approach unifies the iterative LAD based parameter estimation and the normalization procedure into a single iterative algorithm that normalizes the microarray data set, right after a rough estimation of the normalizing parameters. [ABSTRACT FROM AUTHOR]

In this paper, a novel approach for Capillary Electrophoresis data analysis based on pattern recognition techniques in the wavelet domain is presented. Low-resolution, denoised electropherograms are obtained by applying several pre-processing algorithms including discrete wavelet transform, denoising and detection of region of interest. The resultant signal is mapped into character sequences using the first derivative information and multi-level peak height quantization. Next, local alignment algorithms are applied on the coded sequence for peak pattern recognition. [ABSTRACT FROM AUTHOR]

This paper concerns to the specification of interactive mobile robot systems. A Petri net based approach is held: The definition of nLNS, a multi-level net formalism handling nets and/or symbols as tokens is proposed. nLNS supports a modular and hierarchical modelling methodology that is presented through a case study regarding a mobile robot community evolving into a structured environment. [ABSTRACT FROM AUTHOR]

The experiments discussed below are an attempt to examine two concepts of instability which stem from two different models of market adjustment used in Economics: Walrasian (W) and Marshallian (M) instability. The M model views volume as adjusting in response to the difference between demand price and supply price at that volume. The W model views price as changing in response to excess demand at that price. Do the M and the W models have a firm foundation on micro-motives, or are they just macro abstractions that we could dispense of in Microeconomics? [ABSTRACT FROM AUTHOR]

Droughts in arid and semiarid Mediterranean river basins have an increasing socioeconomic and environmental impact. The problem is especially complex in basins where droughts are very frequent and intense and where water resources are under a massive use. For that reason in the Mediterranean basins it is necessary to manage the water resources in constant alert in order to relieve the consequences of a drought. In this chapter a complete methodology for the mitigation of the droughts is defined. The methodology includes different tools: from the definition of an alert system for the different types of drought up to the simulation and optimization software for water system management. This methodology has been applied to the different hydrographic basins included in the Confederaciòn Hidrogràfica del Jùcar (CHJ, the local water agency) and it has been currently used during the extreme drought occurred in the Jùcar river basin since the hydrological years 2004/05. This chapter shows how the proposed methodology is able to forecast the occurrence of a drought and to realize a water resources management focused on the mitigation of the economic, social and environmental effects of water shortage [ABSTRACT FROM AUTHOR]

We consider the acceleration of energetic particles by Fermi processes (i.e., diffusive shock acceleration, second order Fermi acceleration, and gradual shear acceleration) in relativistic astrophysical jets, with particular attention given to recent progress in the field of viscous shear acceleration. We analyze the associated acceleration timescales and the resulting particle distributions, and discuss the relevance of these processes for the acceleration of charged particles in the jets of AGN, GRBs and microquasars, showing that multi-component powerlaw-type particle distributions are likely to occur. [ABSTRACT FROM AUTHOR]

We report our observations on 4 AGNs viz, Mkn 421, Mkn 501, 1ES1426+428 and ON231 belonging to a sub-class called blazars. The observations were carried out using the Pachmarhi Array of Cherenkov Telescopes and span about 6 years period from 2000 to 2005. We discuss our methods of analysis adopted to extract the gamma ray signal from cosmic ray background. We present our results on the emission of TeV gamma rays from these objects. Also, we report on the status of the new high altitude experiment, a 7 telescope array at Hanle in the Himalayas at an altitude of about 4200 m above mean sea level for detecting celestial gamma-rays. [ABSTRACT FROM AUTHOR]

We have developed radiation detectors using the new synthetic diamonds. The diamond detector has an advantage for observations of "low/medium" energy gamma rays as a Compton telescope. The primary advantage of the diamond detector can reduce the photoelectric effect in the low energy range, which is background noise for tracking of the Compton recoil electron. A concept of the Diamond Compton Telescope (DCT) consists of position sensitive layers of diamond-striped detector and calorimeter layer of CdTe detector. The key part of the DCT is diamond-striped detectors with a higher positional resolution and a wider energy range from 10 keV to 10 MeV. However, the diamond-striped detector is under development. We describe the performance of prototype diamond detector and the design of a possible DCT evaluated by Monte Carlo simulations. [ABSTRACT FROM AUTHOR]

Experiment "Pi of the Sky" is designed to search for prompt optical emission from GRB sources. 32 CCD cameras covering 2 steradians will monitor the sky continuously. The data will be analysed on-line in search for optical flashes. The prototype with 2 cameras operated at Las Campanas (Chile) since 2004 has recognised several outbursts of flaring stars and has given limits for a few GRB. [ABSTRACT FROM AUTHOR]

The ARGO-YBJ experiment is almost completely installed at the YangBaJing Cosmic Ray Laboratory (4300 m a.s.l., Tibet, P.R. China). The lower energy limit of the detector (E∼1 GeV) is reached with the scaler mode, i.e., recording the single particle rate at fixed time intervals. In this technique, due to its high altitude location and large area (∼6700 m2), this experiment is the most sensitive among all present and past ground-based detectors. In the energy range under investigation, signals due to local (e.g. solar GLEs) and cosmological (e.g. GRBs) phenomena are expected as significant enhancements of the counting rate over the background. Results on the search for GRBs in coincidence with satellite detections are presented. [ABSTRACT FROM AUTHOR]

The understanding of the high energy γ-ray sky requires a coordinated multi-wavelength strategy. The Large Millimeter Telescope will be the largest and most sensitive single dish antenna operating between 0.8 mm and 3 mm in the foreseeable future. Its first light instrumentation and capabilities are well suited for studies of dust, dense molecular gas and the synchrotron emission from relativistic electrons. The Large Millimeter Telescope, due to enter commissioning and first light science phase in 2007, will be able to complement GLAST observations and help disentangling the nature of the new and old unidentified gamma-ray sources. [ABSTRACT FROM AUTHOR]

Gamma-ray astrophysics depends in many ways on multiwavelength studies. The Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) Collaboration has started multiwavelength planning well before the scheduled 2007 launch of the observatory. Some of the high-priority multiwavelength needs include: (1) availability of contemporaneous radio and X-ray timing of pulsars; (2) expansion of blazar catalogs, including redshift measurements; (3) improved observations of molecular clouds, especially at high galactic latitudes; (4) simultaneous broad-band blazar monitoring; (5) characterization of gamma-ray transients, including gamma ray bursts; (6) radio, optical, X-ray and TeV counterpart searches for reliable and effective sources identification and characterization. Several of these activities are needed to be in place before launch. [ABSTRACT FROM AUTHOR]

Assuming the lightest neutralino in the minimal supersymmetric extension to the Standard Model (MSSM) as the main dark matter (DM) component, we estimate the cumulative enhancement of the neutralino-induced gamma-ray signal in the Galactic halo due to the presence of subhalos. A realistic semi-analytical model for the spatial mass function of subhalos is implemented, incorporating effects that may influence the distribution and the evolution of substructures, such as the mass loss due to the tidal stripping and the orbital decay due to the dynamical friction. [ABSTRACT FROM AUTHOR]

We review the status of indirect Dark Matter searches, focusing in particular on the connection with gamma-ray Astrophysics. After a brief introduction where we review the strong motivations for indirect searches, we tackle the question of how one can "discover" Dark Matter particles with astrophysical observations. To this purpose, I will discuss some recent conflicting claims that have generated some confusion in the field, and present new strategies that may provide robust enough evidence to claim discovery, based only on astrophysical observations. [ABSTRACT FROM AUTHOR]

The study of the TeV emission from extragalactic sources is hindered by the uncertainties on the diffuse Extragalactic Background Light (EBL). The recent H.E.S.S. results on the blazars 1ES 1101-232 and H 2356-309 represent a breakthrough on this issue. Their unexpectedly hard spectra allow an upper limit to be derived on the EBL in the optical/near-infrared range, which is very close to the lower limit given by the resolved galaxy counts. This result seems to exclude a large contribution to the EBL from other sources (e.g. Population III stars) and indicates that the intergalactic space is more transparent to γ-rays than previously thought. A discussion of EBL absorption effects and further observational tests with Cherenkov telescopes are presented. [ABSTRACT FROM AUTHOR]

MAGIC is currently the world's largest single dish ground based imaging atmospheric Cherenkov telescope. During the first year of operation, more than 20 extragalactic sources have been observed and several of them detected. Here we present results of analyzed data, including discussion about spectral and temporal properties of the detected sources. In addition, we discuss implications of the measured energy spectra of distant sources for our knowledge of the extragalactic background light. [ABSTRACT FROM AUTHOR]

The observation of the universe in the VHE gamma ray domain with the new generation of Cherenkov Telescopes is producing new measurements with a direct implication for cosmology. The present results and the future prospects will be discussed. [ABSTRACT FROM AUTHOR]

It is possible that violent processes resulting in Gamma Ray Bursts produce also high energy photons and cosmic rays. The possible correlations of very short GRB with, e.g., CMB, cosmic rays is briefly discussed. We have also begun preparation of the experiment correlating in real time data from Maze cosmic ray detector and Pi of the Sky robotic telescope. [ABSTRACT FROM AUTHOR]

We discuss the possibility of observing ultra high energy cosmic ray sources in high energy gamma rays. Protons propagating away from their accelerators produce secondary electrons during interactions with cosmic microwave background photons. These electrons start an electromagnetic cascade that results in a broad band gamma ray emission. We show that in a magnetized Universe (B≳10−12 G) such emission is likely to be too extended to be detected above the diffuse background. A more promising possibility comes from the detection of synchrotron photons from the extremely energetic secondary electrons. Although this emission is produced in a rather extended region of size ∼10 Mpc, it is expected to be point-like and detectable at GeV energies if the intergalactic magnetic field is at the nanogauss level. [ABSTRACT FROM AUTHOR]

Propagation of UHE protons through CMB radiation leaves the imprint on energy spectrum in the form of Greisen-Zatsepin-Kuzmin (GZK) cutoff, bump (pile-up protons) and dip. The dip is a feature in energy range 1×1018-4×1019 eV, caused by electron-positron pair production on CMB photons. Calculated for power-law generation spectrum with index γg=2.7, the shape of the dip is confirmed with high accuracy by data of Akeno—AGASA, HiRes, Yakutsk and Fly's Eye detectors. The predicted shape of the dip is robust: it is valid for the rectilinear and diffusive propagation, for different discretenesses in the source distribution, for local source overdensity and deficit etc. This property of the dip allows us to use it for energy calibration of the detectors. The energy shift λ for each detector is determined by minimum χ2 in comparison of observed and calculated dip. After this energy calibration the absolute fluxes, measured by AGASA, HiRes and Yakutsk detectors remarkably coincide in energy region 1×1018-1×1020 eV. Below the characteristic energy Ec≈1×1018 eV the spectrum of the dip flattens for both diffusive and rectilinear propagation, and more steep galactic spectrum becomes dominant at E

The precise knowledge of the atmospheric neutrino fluxes is a key ingredient in the interpretation of the results from any atmospheric neutrino experiment. In the standard atmospheric neutrino data analysis, these fluxes are theoretical inputs obtained from sophisticated numerical calculations. In this work we present an alternative approach to the determination of the atmospheric neutrino fluxes based on the direct extraction from the experimental data on neutrino event rates. [ABSTRACT FROM AUTHOR]

We propose to build a large water-Cherenkov-type muon-detector array (Tibet MD array) around the 37 000 m2 Tibet air shower array (Tibet AS array) already constructed at 4300 m above sea level in Tibet, China. Each muon detector is a waterproof concrete pool, 6 m wide × 6 m long × 1.5 m deep in size, equipped with a 20 inch-in-diameter PMT. The Tibet MD array consists of 240 muon detectors set up 2.5 m underground. Its total effective area will be 8640 m2 for muon detection. The Tibet MD array will significantly improve gamma-ray sensitivity of the Tibet AS array in the 100 TeV region (10-1000 TeV) by means of gamma/hadron separation based on counting the number of muons accompanying an air shower. The Tibet AS+MD array will have the sensitivity to gamma rays in the 100 TeV region by an order of magnitude better than any other previous existing detectors in the world. [ABSTRACT FROM AUTHOR]

The ANTARES telescope, currently in construction, is aiming to detect high energy neutrinos. Data from the first line of the detector, which became operational recently, demonstrates that the nominal time and space resolutions are achieved. Various models predict the emission of high energy neutrinos from astrophysical sources such as Supernova Remnants, Microquasars, Active Galactic Nuclei and Gamma Ray Bursts. With the custom designed data acquisition system of this detector, in combination with the existing satellite alert systems, the ANTARES telescope has an increased sensitivity for neutrinos from Gamma Ray Bursts compared to conventional time independent sources. [ABSTRACT FROM AUTHOR]

Neutrino energy spectra have been calculated based on the recently measured energy spectra of Galactic very high energy γ-ray sources. Based on these neutrino spectra the expected event rates in the ANTARES neutrino telescope and KM3NeT, a future neutrino telescope in the Mediterranean Sea with an instrumented volume of one km3, have been calculated. For the brightest γ-ray sources we find event rates of the order of one neutrino per year. Although the neutrino event rates are comparable to the background from atmospheric neutrinos the detection of individual sources seems possible. [ABSTRACT FROM AUTHOR]

The AMANDA-II telescope, operated by the IceCube collaboration, is currently the world's most sensitive telescope to fluxes of neutrinos from individual sources. A data sample of 4282 neutrino induced events collected in 1001 days of detector livetime during the years 2000-2004 have now been analyzed looking for a neutrino signal from point-like sources. A sensitivity to fluxes of $\nu_{\mu}+\bar {\nu }_{\mu}+\nu_{\tau}+\bar {\nu }_{\tau}$ of dΦ/dE=1.0×10−10(E/TeV)−2 TeV−1 cm−2 s−1 was reached in the energy range between 1.7 TeV and 2.4 PeV. So far no statistically significant localized excess of events over the background of atmospheric neutrinos has been found, which would be ascribed to a neutrino source. However, the flux upper limits derived from the non-observation of a signal are comparable to observed fluxes of high energy gamma rays from blazars and within the range of current models for neutrino emission from selected sources. Possible constraints on these models are discussed. [ABSTRACT FROM AUTHOR]

The NEMO Collaboration is conducting an R&D activity towards the construction of a Mediterranean km3 neutrino telescope. In this work, we present the results of Monte Carlo simulation studies on the capability of the proposed NEMO telescope to detect and identify point-like sources of high energy muon neutrinos. [ABSTRACT FROM AUTHOR]

Although kilometer-scale neutrino detectors such as IceCube are discovery instruments, their conceptual design is very much anchored to the observational fact that Nature produces protons and photons with energies in excess of 1020 eV and 1013 eV, respectively. The puzzle of where and how Nature accelerates the highest energy cosmic particles is unresolved almost a century after their discovery. From energetics considerations we anticipate on the order of 10-100 neutrino events per kilometer squared per year pointing back at the source(s) of both galactic and extragalactic cosmic rays. In this context, we discuss the results of the AMANDA and IceCube neutrino telescopes which will deliver a kilometer-square-year of data over the next 3 years. [ABSTRACT FROM AUTHOR]

We investigate a possibility that non-thermal X-ray emission in a supernova remnant(SNR) is produced by jitter radiation, which is the analogue of synchrotron radiation in small-scale random magnetic fields. We can fit the multi-wavelength data of SNRs RX J1713.7-3946 (G347.3-0.5) and RX J0852.0-4622 (G266.6-1.2) by constructing pure jitter and inverse Compton (IC) emission models. We find that the physical fit parameters of random magnetic fields take values of several tens of μG strength and of the order of ∼107 cm correlation length. These properties of random magnetic fields in collisionless shock of SNRs are discussed. [ABSTRACT FROM AUTHOR]

We report hard X-ray emission of the non-thermal supernova remnant G337.2+0.1. The source presents centrally filled and diffuse X-ray emission. A spectral study confirms that the column density of the central part of the object is about NH∼5.9(±1.5)×1022 cm−2 and its X-ray spectrum is well represented by a single power-law with a photon index Γ=0.96±0.56. Detailed spectral analysis indicates that the outer region is highly absorbed and quite softer than the inner region. Characteristics already observed in other well-known X-ray plerions. Based on the gathered information, we confirm the SNR nature of G337.2+0.1, and suggest that the central region of the source is a pulsar wind nebula (PWN), originated by an energetic though yet undetected pulsar. [ABSTRACT FROM AUTHOR]

For the case of Tycho's supernova remnant (SNR) we present the relation between the blast wave and contact discontinuity radii calculated within the nonlinear kinetic theory of cosmic ray (CR) acceleration in SNRs. It is demonstrated that these radii are confirmed by recently published Chandra measurements which show that the observed contact discontinuity radius is so close to the shock radius that it can only be explained by efficient CR acceleration which in turn makes the medium more compressible. Together with the recently determined new value Esn=1.2×1051 erg of the SN explosion energy this also confirms our previous conclusion that a TeV γ-ray flux of (2-5)×10−13 erg/(cm2 s) is to be expected from Tycho's SNR. Chandra measurements and the HEGRA upper limit of the TeV γ-ray flux together limit the source distance d to 3.3≤d≤4 kpc. [ABSTRACT FROM AUTHOR]

Nonlinear kinetic theory of cosmic ray (CR) acceleration in supernova remnants (SNRs) is used to investigate the properties of Kepler's SNR and, in particular, to predict the γ-eay spectrum expected from this SNR. Observations of the nonthermal radio and X-ray emission spectra as well as theoretical constraints for the total supernova (SN) explosion energy Esn are used to constrain the astronomical and particle acceleration parameters of the system. Under the assumption that Kepler's SN is a type Ia SN we determine for any given explosion energy Esn and source distance d the mass density of the ambient interstellar medium (ISM) from a fit to the observed SNR size and expansion speed. This makes it possible to make predictions for the expected γ-eay flux. Exploring the expected distance range we find that for a typical explosion energy Esn=1051 erg the expected energy flux of TeV γ-rays varies from 2×10−11 to 10−13 erg/(cm2 s) when the distance changes from d=3.4 kpc to 7 kpc. In all cases the γ-eay emission is dominated by π0-decay γ-rays due to nuclear CRs. Therefore Kepler's SNR represents a very promising target for instruments like H.E.S.S., CANGAROO and GLAST. A non-detection of γ-rays would mean that the actual source distance is larger than 7 kpc. [ABSTRACT FROM AUTHOR]

In 2004 and 2005, the shell-type supernova remnants RX J1713.7-3946 and RX J0852.0-4622 were observed and detected with the complete H.E.S.S. array, a system of four Imaging Cherenkov Telescopes located in Namibia and dedicated to the observations of γ-rays above 100 GeV. The energy spectra of these two sources have been measured over a wide energy range and revealed an integral flux above 1 TeV similar to that of the Crab Nebula. Their morphologies were resolved with high accuracy with H.E.S.S. and exhibit a striking correlation with the X-ray images, thereby pioneering a technique of unambiguously identifying spatially extended γ-ray sources. The results of the observations will be presented. Similarities and differences between these two sources will be pointed out as well as possible implications. [ABSTRACT FROM AUTHOR]

The Cygnus region of the Milky Way is prolific in star formation and presents extended diffuse γ-ray emission with a few γ-ray point sources. Among them is 3EG J2020+4017, the brightest of the unidentified EGRET sources, positionally coincident with the supernova remnant G78.2+2.1. Even though the EGRET and multi-wavelength data have not provided a conclusive identification for this γ-ray loud, but otherwise faint object, the evidence favors a pulsar like source. The EGRET photon data lack the signal-to-noise ratio required for a period search, but will serve as a valuable timing baseline extension in the case that GLAST confirms the pulsar nature of the γ-Cygni source. [ABSTRACT FROM AUTHOR]

It is believed that the observed diffuse gamma-ray emission from the galactic plane is the result of interactions between cosmic rays and the interstellar gas. Such emission can be amplified if cosmic rays penetrate into dense molecular clouds. The propagation of cosmic rays inside a molecular cloud has been studied assuming an arbitrary energy and space dependent diffusion coefficient. If the diffusion coefficient inside the cloud is significantly smaller compared to the average one derived for the galactic disk, the observed gamma-ray spectrum appears harder than the cosmic ray spectrum, mainly due to the slower penetration of the low energy particles towards the core of the cloud. This may produce a great variety of gamma-ray spectra. [ABSTRACT FROM AUTHOR]

Inverse Compton (IC) scattering by relativistic electrons produces a major component of the diffuse emission from the Galaxy. The photon fields involved are the cosmic microwave background and the interstellar radiation field (ISRF) from stars and dust. Calculations of the inverse Compton distribution have usually assumed a smooth ISRF, but in fact a large part of the Galactic luminosity comes from the most luminous stars, which are rare. Therefore we expect the ISRF, and hence the inverse Compton emission, to be clumpy at some level, which could be detectable by instruments such as GLAST. Even individual nearby luminous stars could be detectable assuming just the normal cosmic-ray electron spectrum. We present the basic formalism required and give possible candidate stars to be detected and make predictions for GLAST. Then we apply the formalism to the OB associations and the Sun, showing that the IC emission produced is not negligible compared to the sensitivity of current or coming detectors. We estimate that the gamma-ray flux from the halo around the Sun contributes to the diffuse background emission at the few percent level. [ABSTRACT FROM AUTHOR]

Colliding winds of massive binaries have long been considered as potential sites of non-thermal high-energy photon production. This is motivated by the detection of non-thermal spectra in the radio band, as well as by correlation studies of yet unidentified EGRET γ-ray sources with source populations appearing in star formation regions. This work re-considers the basic radiative processes and its properties that lead to high energy photon production in long-period massive star systems. We show that Klein-Nishina effects as well as the anisotropic nature of the inverse Compton scattering, the dominating leptonic emission process, likely yield spectral and variability signatures in the γ-ray domain at or above the sensitivity of current or upcoming gamma ray instruments like GLAST-LAT. In addition to all relevant radiative losses, we include propagation (such as convection in the stellar wind) as well as photon absorption effects, which a priori can not be neglected. The calculations are applied to WR 140 and WR 147, and predictions for their detectability in the γ-ray regime are provided. Physically similar specimen of their kind like WR 146, WR 137, WR 138, WR 112 and WR 125 may be regarded as candidate sources at GeV energies for near-future γ-ray experiments. Finally, we discuss several aspects relevant for eventually identifying this source class as a γ-ray emitting population. Thereby we utilize our findings on the expected radiative behavior of typical colliding wind binaries in the γ-ray regime as well as its expected spatial distribution on the γ-ray sky. [ABSTRACT FROM AUTHOR]

We study collective wind configurations produced by a number of massive stars, and obtain densities and expansion velocities of the stellar wind gas that is to be target, in this model, of hadronic interactions. We study the expected γ-ray emission from these regions, considering in an approximate way the effect of cosmic ray modulation. We compute secondary particle production (electrons from knock-on interactions and electrons and positrons from charged pion decay), and solve the loss equation with ionization, synchrotron, bremsstrahlung, inverse Compton, and expansion losses. We provide examples where configurations can produce sources for GLAST satellite, and the MAGIC, HESS, or VERITAS telescopes in non-uniform ways, i.e., with or without the corresponding counterparts. We show that in all cases we studied no EGRET source is expected. [ABSTRACT FROM AUTHOR]