International Journal of Modern Physics: Conference Series

I present a review of X-ray and mid-IR surveys for Compton-thick Active Galactic Nuclei (AGN). These are the most highly obscured sources having hydrogen column densities > 1.5 × 10²⁴ cm^-2. Key surveys in the local Universe are presented including the high energy SWIFT/BAT and INTEGRAL surveys, mid-IR and also optical surveys. Recently, deep X-ray surveys with Chandra and XMM-Newton have produced a number of candidate Compton-thick AGN at higher redshift primarily in the Chandra Deep Field South region. In addition, mid-IR surveys with Spitzer have helped to develop novel complementary techniques for the selection of Compton-thick AGN. The mid-IR techniques used to identify Compton-thick AGN include: a) 24 μm excess sources relative to their optical emission b) Spitzer spectroscopy for the detection of high optical depth Si 9.7μm absorption features c) low X-ray to 6μm luminosity ratio.

The results obtained with the new Laue lens prototype built in the LARIX facility in the Physics Department of University of Ferrara will be present. Thanks to the methods adopted for improving the first prototype (SPIE conference in San Diego, Ferrari et al. 2009) here we present the results of the new prototype with improved performances in terms of point spread function (PSF) and spectral response.

A recently discovered transient X-ray source, IGR J17177-3656, has received many observations, including a quasi-simultaneous multi-waveband observations. The source is modeled with the coupled accretion-jet model around a black hole. It is found that the multi-waveband spectrum can be successfully modeled with the luminous hot accretion flow (LHAF) rather than advection dominated accretion flow (ADAF). The modeled luminosity is about 5% of the Eddington luminosity, and the source may be as far as 25 kpc. Our detailed modeling result confirms the point that LHAF can explain steep radio-X-ray correlation.

Pulsars have been found more than 40 years. Observations from radio to gamma-rays present abundant information. However, the radiation mechanism is still an open question. It is found that the annular gap could be formed in the magnetosphere of pulsars (neutron stars or quark stars), which combines the advantages of the polar cap, slot gap and outer gap models. It is emphasized that observations of some radio pulsars, normal and millisecond gamma-ray pulsars (MSGPs) show that the annular gap would play a very important role. Here we show some observational and theoretical evidences about the annular gap. For example, bi-drifting sub-pulses; radio and gamma-ray millisecond pulsars and so on.

The results of analysis of approximately 3 year gamma-ray observations (August 2008–July 2011) of the core of radio galaxy Centaurus A with the Fermi Large Area Telescope (Fermi LAT) are presented. Binned likelihood analysis method applying to the data shows that below several GeV the spectrum can be described by a single power-law with photon index Γ = 2.73 ± 0.06. However, at higher energies the new data show significant excess above the extrapolation of the energy spectrum from low energies. The comparison of the corresponding Spectral Energy Distribution (SED) at GeV energies with the SED in the TeV energy band reported by the H.E.S.S. collaboration shows that we deal with two or perhaps even three components of gamma-radiation originating from different regions located within the central 10 kpc of Centaurus A.

The analysis of gamma-ray data of Centaurus A lobe accumulated from the beginning of the operation until November 14, 2011 show extension of the HE gamma-ray emission beyond the WMAP radio image in the case of the Northern lobe [9]. The possible origins of gamma-rays from giant radio lobes of Centaurus A are discussed in the context of hadronic and leptonic scenarios.

There are five X-ray astronomy satellites launched from Japan. The latest satellite, Suzaku, was launched in 2005. MAXI is an all sky survey mission in X-ray that was attached to the ISS in 2009. These two are functioning at present.

ASTRO-H is the only approved mission in X-ray that will be launched in 2014. There are four X-ray detectors on board ASTRO-H, SXS, SXI, HXI and SGD as well as X-ray telescopes made of thin foil mirrors. Most of the future missions heavily depend on them both in technology and in science. From this point of view, we have to concentrate on ASTRO-H so that we can expand our activities in future.

In Japan, the small scientific satellite project is now on-going. Two missions are already allocated while no X-ray mission is approved. DIOS, PolariS, CAST and FFAST are proposed. Here we explain FFAST in detail that will study the evolution of the universe.

We present the LAUE project devoted to develop an advanced technology for building a high focal length Laue lens for hard X and soft gamma–ray astronomy (80-600 keV). The final goal of the project, supported by the Italian Space Agency, is to build and test a focusing optics that can improve the current sensitivity in the above energy band by 2 orders of magnitude.

²⁶Al is a long-life radioactive isotope with a half lifetime of near 1 Myr. The origin of Galactic ²⁶Al is dominated by massive stars and their core-collapse supernovae. Detections of 1809 keV emission from ²⁶Al provide direct evidence that nucleosynthesis is ongoing in the Galaxy. The gamma-ray line shapes reflect the dynamics of the ejected isotopes in the interstellar medium and then probe properties of ISM and Galactic rotation effect. Gamma-ray emissions of ²⁶Al in the Galaxy are studied with the high spectral resolution INTEGRAL spectrometer (SPI). We carry out the first spectral survey of ²⁶Al gamma-ray line emission along the Galactic plane. The ²⁶Al line energy shifts reflect the large-scale Galactic rotation. The ²⁶Al intensity is brighter in the 4th than in the 1st quadrant (ratio ~ 1.3); the ²⁶Al line toward the direction of the Aquila region appears somewhat broadened; a latitudinal scale height of pc for ²⁶Al in the inner Galaxy is determined. Strong ²⁶Al emission signal is detected in the nearby star-formation regions Sco-Cen and Cygnus. The ²⁶Al line shapes in star-formation regions provide a clue to constrain the kinematic properties of ISM. In addition, we derive the flux ratio of ⁶⁰Fe/²⁶Al ~ 15% which can be directly compared with theoretical predictions. More theoretical work on nuclear reactions, massive star evolution models deserves improvements.

We compile from literature the broadband SEDs of twelve TeV blazars observed simultaneously or quasi-simultaneously with Fermi/LAT and other instruments. Two SEDs are available for each of the objects and the state is identified as a low or high state according to its flux density at GeV/TeV band. The observed SEDs of BL Lac objects (BL Lacs) are fitted well with the synchrotron + synchrotron-self-Compton (syn+SSC) model, whereas the SEDs of the two flat spectrum radio quasars (FSRQs) need to include the contributions of external Compton scattering. In this scenario, it is found that the Doppler factor δ of FSRQs is smaller than that of BL Lacs, but the magnetic field strength B of FSRQs is larger than that of BL Lacs. The increase of the peak frequency of the SEDs is accompanied with the increase of the flux for the individual sources, which seems opposite to the observational phenomena of the blazar sequence. We refer this phenomenonto blazar anti-sequence of spectral variability for individual TeV blazars. However, both the blazar sequence from FSRQs to BL Lacs and blazar anti-sequence of the spectral variability from low state to high state are accompanied by an increase of the break Lorentz factor of the electron's spectrum γ_b and a decrease of B. We propose a model in which the mass accretion rate Ṁ is the driving force behind both the blazar sequence for ensembles of blazars and the blazar anti-sequence for individual blazars. Specifically we suggest that the differences in 〈Ṁ〉 of different blazars produce the observed blazar sequence, but ΔṀ in each blazar results in the observed blazar anti-sequence.

We presented a method useful for estimating parallaxes of visually close binary stars (VCBS). The method depends on atmospheric modeling of the components of the VCBS. We construct model atmospheres by using a grid of Kurucz solar metalicity blanketed models¹, which can be applied to calculate the synthetic spectral energy distribution for each component of the binary separately. In addition to study the entire system. However, the entire observational spectral energy distribution of the system was used as a reference for the comparison with the synthetic ones. We choose Hip4809 system to investigate the method, and we also study its physical and geometrical parameters. The new parallax of the system was estimated as π = 40.32 ± 5.00 mas, which disagrees with the Hipparcos parallax measurement (13.94 ± 0.90 mas). Furthermore the model atmosphere parameters of the components of the system were derived as: , , log g_a = 4.50 ± 0.13, log g_b = 4.50 ± 0.13, R_a = 0.94 ± 0.12R_⊙, R_b = 0.93 ± 0.12R_⊙, Depending on the derived parameters, the masses of the system's components were estimated as 1.03 ± 0.02M_⊙ and 1.01 ± 0.02M_⊙ for the primary and secondary components respectively, and their spectral types were concluded as G6V for both of them.

This work is mainly focused on the application of the multiple signal classification (MUSIC) algorithm for gravitational wave burst search. This algorithm extracts important gravitational wave characteristics from signals coming from detectors with arbitrary position, orientation and noise covariance.

In this paper, the MUSIC algorithm is described in detail along with the necessary adjustments required for gravitational wave burst search. The algorithm's performance is measured using simulated signals and noise. MUSIC is compared with the Q-transform for signal triggering and with Bayesian analysis for direction of arrival (DOA) estimation, using the Ω-pipeline. Experimental results show that MUSIC has a lower resolution but is faster. MUSIC is a promising tool for real-time gravitational wave search for multi-messenger astronomy.

We have finished the λ6 cm polarization survey of the Galactic plane using the Urumqi 25 m radio telescope. It covers 10° ≤ l ≤ 230° in Galactic longitude and |b| ≤ 5° in Galactic latitude. The new polarization maps not only reveal new properties of the diffuse magnetized interstellar medium, but also are very useful for studying individual objects such as HII regions, which may act as Faraday screens with strong regular magnetic fields inside, and supernova remnants for their polarization properties and spectra. The high sensitivity of the survey enables us to discover two new SNRs G178.2–4.2 and G25.3–2.1 and a number of HII regions.

We introduce a simple and useful method to interpret the 2009 data by 1.3mm VLBI, which detected the time-variable emission of Sgr A*. The flaring region can be constrained to scale comparable to black hole shadow size in East-West direction. Constraint in North-South direction is relaxed due to lack of baseline, which can be improved in future observations.

Age of a pulsar is a useful parameter, but it is difficult to get the age from observation. We can only derive the characteristic age from the observed parameters: spin period (P) and period derivative (Ṗ). In this paper, we discussed the relationship between characteristic age and magnetic field of a pulsar. Monte Carlo simulation is also used to support the idea: it is useless to study the magnetic field evolution using characteristic age. From some observation evidences we get that: the characteristic age cannot be used as true age, especially for millisecond pulsar (MSP). The difference between them is also discussed. From the studying of breaking index and MSP's initial spin period (P₀), we get the conclusion that: the problem cannot be resolved using different radiation models.

Singular-value decomposition is a powerful technique that has been used in the analysis of matrices in many fields. In this paper, we summarize how it has been applied to the analysis of gravitational-wave data analysis. These include producing basis waveforms for matched filtering, decreasing the computational cost of searching for many waveforms, improving parameter estimation, and providing a method of waveform interpolation.

Accretion disks are ubiquitous in the universe and it is generally accepted that magnetic fields play a pivotal role in accretion-disk physics. The spin history of millisecond pulsars, which are usually classified as magnetized neutron stars spun up by an accretion disk, depends sensitively on the magnetic field structure, and yet highly idealized models from the 80s are still being used for calculating the magnetic field components. We present a possible way of improving the currently used models with a semi-analytic approach. The resulting magnetic field profile of both the poloidal and the toroidal component can be very different from the one suggested previously. This might dramatically change our picture of which parts of the disk tend to spin the star up or down.

With accretion of mass from an evolving companion star, a neutron star can be spun up to an equilibrium period, which is set by the Kepler orbital period at the magnetosphere radius, expressed as a proportional relation between the spin period and magnetic field strength. The spin-up line relationship can be also expressed as a relation between period (P) and period derivative (Ṗ) for the pulsars with dipole radiation. All binary pulsars should lie below the spin-up line, if they accrete the sufficient masses from companions. So, we investigate the distribution of isolated and binary pulsars in the period (P) and magnetic field (B) diagram to see their positions relative to the spin-up line. It is found that the eight binary pulsars (of total 172) are above the spin-up line, thus we analyze their properties and present the possible process of their formations.

Based on Maxwell-type linearized Einstein Eqs of gravity, new ground-base torsion balance experiments are proposed to detect gravito-magnetic forces due to the rotation of the Earth. An optic system is employed to enlarge the effects so that the predicted effects are measurable by the proposed ground-based experiments.

Light is a good probe for general relativistic effects. Exploiting the asymmetry of the propagation in the vicinity of a central rotating mass it is possible to use a ring laser in order to measure the frame dragging of the reference frames by the gravitational field of the Earth (Lense-Thirring effect). I shall present the G-GranSasso experiment whose objective is precisely to measure the Lense-Thirring and the de Sitter effects in a terrestrial laboratory. The experimental apparatus will be made of a set of at least three, differently oriented, ring lasers rigidly attached to a central "monument". The signal will be in the form of the beat frequency produced in the annular cavity of each laser by the rotational anisotropy. The laboratory will be located underground in the Laboratori Nazionali del Gran Sasso facility, in Italy. The required sensitivity is just one order of magnitude below the performance of the best existing instruments and the new design will attain it.

The output of a simple Mach-Zehnder atom interferometer (with light field beam splitters) is studied in order to obtain sensitivity curves for GW signals in the paraxial approximation by using the ABCD matrices techniques and first order perturbation theory for mirroratom interaction; order of magnitude of relevant physical parameters for a realistic GW detector through atom interferometry is deduced, both for single- and coupled-interferometers configurations. Finally a synthetic overview of ongoing activities of the Florence-Urbino group in this field is presented.

We take the data of twin kilohertz quasi-periodic oscillations (kHz QPOs) in neutron stars (NSs) published before 2011 as the samples, which include 15 Atoll sources and 8 Z sources. Then we test the correlation between the twin peak kHz QPOs, and compare with the samples. We find the power law relation between the lower-frequency (ν₁) and the upper-frequency (ν₂) of kHz QPOs can fit the data much better than the other models. For the Atoll (Z) sources, the best fitting coefficient and index of power law are a = 687 (720) and b =1.50 (1.83) respectively. The Chi-square per degree of freedom (χ²/d.o.f.) are 1.93 and 1.49 respectively.

We collect the recently published data of twin kilohertz quasi-periodic oscillations (kHz QPOs) in neutron stars (NSs), and analyze two kinds of samples for five Atoll sources and five Z sources. We study the the relation between the quality factor and the peak frequency of upper frequency. We take three possible models, i.e. linear, power-law and exponential models to fit the data and find that the power-law and the exponential models can reflect the relation better than the linear model.

Recent results of pulsar observations at Nanshan are present in this paper. In total 47 glitches were detected in the young pulsars, including a giant glitch in PSR B2334+61. We also investigated the scintillation parameters with the quasi-continuous observations of PSR B0329+54 spanning twenty days. Mainly using the same dataset, consecutive mode-switching events were analyzed in pulse profiles of PSR B0329+54.

We perform a Monte Carlo simulation to investigate the distribution and evolution of 66 mass measured pulsars. We get the best fits to the distribution at 1.35 ± 0.27M_⨀ (1σ confidence level). In addition, we notice bimodal distributions in 1.34 ± 0.15M_⨀ and 1.48 ± 0.53M_⨀, this can be led to the idea that radio pulsars in binary systems have recycled. Thus we divide the data according to the characteristic spin period into two groups, millisecond pulsars (MSPs), P_Spin ≤ 20 ms and less recycled pulsars P_Spin ≥ 20 ms, respectively. We show that the distributions of MSPs at 1.42 ± 0.36M_⨀, and 1.32 ± 0.18M_⨀ for less recycled pulsars. As such, the mass of MSPs are heavier than those in less recycled pulsars by ~ 0.1M_⨀, since they accreting material from their companions. On the other hand, the formation of heavier pulsars from the accretion induced collapse of accreting white dwarfs, must be invoked.

We analyze the 3-80 keV spectrum of X-ray pulsar 4U 0115+63 taken by Rossi X-ray Timing Explorer(RXTE) on April 22nd, 2008. Two absorption features at ~13.5 keV and ~20.5 keV are detected by using cyclotron scattering feature profiles to fit the spectrum, ignoring the inadequate photons of the analyzed data. The fundamental feature is just right between ~11 and ~16 keV. It seems implausible to interprete these absorption lines as cyclotron features because of their inharmonic behavior, even when relativistic effect has been taken into account. But it is possible that the main region where first harmonic line forms is slightly different from the fundamental one.

The various types of pulsars are classified in the magnetic and spin period (B-P) diagram, by which one can recognize their properties there. We also investigate the relation of radio pulsars and X-ray neutron stars, and their distribution characteristics, implying their evolution links. B-P diagram is divided by the special lines, e.g. spin-up line and "death line", which indicate the evolution information of pulsars. Like Hertzsprung-Russell (H-R) diagram of showing the stellar evolution or "lives of stars", we try to develop B-P diagram as a function of representing the evolution track of neutron star.

We investigate the radius of the recycled pulsar in double pulsar system PSR J0737-3039. In the standard accretion spin-up model, the recycled pulsar spin up continues until arriving at a minimum spin period, or so-called "equilibrium period", which is related to the stellar magnetic field, the accretion rate and radius. The generic spin-down age may give realistic estimates for normal pulsar PSR J0737-3039B, since its present spin period is much longer than the one at birth. In this paper, we estimate the radius of millisecond pulsar (MSP) PSR J0737-3039A by assuming its true age is same as the spin-down age of its companion PSR J0737-3039B. We find that the radius of recycled pulsar PSR J0737-3039A ranges approximately from 12 to 38 km, and it should be far from the composition of strange quark matters, as shown in the mass-radius diagram.

Pulsars are one of the most polarized radio sources in the universe. Polarization measurements of pulsars provide us a lot of information, not only about the emission process itself, but also about the interstellar medium. This article describes the polarization properties of radio pulsars in general and discusses the observed rotation measure variations with time in pulsars.

Now GRB high energy γ-emission was observed mostly by detectors onboard Fermi and Agile satellites. During most part of GRB high energy γ-emission registered some later than low energy trigger and lasts several hundreds of seconds, but its maxima are within low energy t₉₀ intervals both for short and long bursts. But GRB090323, GRB090328 and GRB090626 temporal profiles have additional maxima after low energy t₉₀ intervals finished. These bursts temporal profile analysis have shown that faint peaks in low energy bands close to the ends of low energy t₉₀ intervals preceded such maxima. Moreover, these events low energy spectral index β behavior differs from usual GRB one according to preliminary analysis. We suppose that these GRB could be separated as different GRB type. In presented article this new GRB type properties are discussed.

We introduce a new set of equations to describe the equilibrium of the core of neutron stars, composed by self-gravitating degenerate neutrons, protons and electrons in β-equilibrium. We take into account strong, weak, electromagnetic and gravitational interactions within the framework of general relativity. We extend the conditions of equilibrium based on the constancy of the Klein potentials to the strongly interactive case. The strong interactions between nucleons are modeled through the exchange of the σ, ω and ρ virtual mesons. The equations are solved numerically in the case of zero temperatures and for a non-rotating spherically symmetric neutron stars in the mean-field approximation.

We investigate the stability of general relativistic uniformly rotating white dwarfs against secular and dynamical instabilities. We determine the minimum rotation period of stable white dwarfs depending on chemical composition of the white dwarf matter taking into account the Coulomb interactions as well as the nuclear interactions and the electroweak equilibrium at high densities, within the relativistic Feynman-Metropolis-Teller equation of state.

Observations imply that long γ-ray bursts (GRBs) are originated from explosions of massive stars, therefore they may occur in the molecular clouds where their progenitors were born. We show here that the prompt optical-UV emission from GRBs may be delayed due to the dust extinction, which can well explain the observed optical delayed onset and fast rise in GRB 080319B. The density and the size of the molecular cloud around GRB 080319B are roughly constrained to be ~ 10³cm^-3 and ~ 8pc, respectively. We also investigate the other GRBs with prompt optical-UV data, and find similar values of the densities and sizes of the local molecular clouds. The future observations of prompt optical-UV emission from GRBs in subsecond timescale, e.g., by UFFO-Pathfinder and SVOM-GWAC, will provide more evidence and probes of the local GRB environments.

The identification of thermal signatures in the spectra of Gamma Ray Bursts (GRBs) has become possible now, thanks especially to the modern space missions dedicated to their observations. There are several models in literature that take into account the presence of a thermal emission, in particular in the early emission of a GRB. In this work we discuss the case of GRB 090618, where thermal signatures in the early γ and X-rays have been observed.

We present both timing and spectral analysis of the outburst of 4U 0115+63 in 2008 with INTEGRAL and RXTE observations. We have determined the spin period of the neutron star at ~ 3.61422 ± 0.00011 s, and a spin up rate during the outburst of Ṗ = (-2.66 ± 1.81) × 10^-6s d^-1, the angle of periapsis ω = 49.6° ± 0.68° in 2008 and its variation (apsidal motion) when comparing with previous measured values. During the outburst, four cyclotron absorption lines were detected (fundamental line at 10–15 keV; 2nd harmonic at 22 keV; 3rd at ~ 34 keV, 4th at ~ 42 keV), the fifth harmonic around 54 keV was also hinted in our data. The fundamental absorption line energy varies during the outburst: around 15 keV during the rising phase, and transiting to ~ 10 keV during the peak of the outburst, and further coming back to ~ 15 keV during the decreasing phase. The photon index shows the correlation with the fundamental line energy: the source becomes harder around the peak of the outburst and softer in both rising and decreasing phases. This correlation and transition processes during the outburst need further studies in both observations and theoretical work.

The nature of pulsar-like compact stars is still in controversy although the first pulsar was found more than 40 years ago. Generally speaking, conventional neutron stars and non-mainstream quark stars are two types of models to describe the inner structure of pulsars, with the former composed mainly of hadrons and the latter of a peculiar kind of matter whose state equation should be understood in the level of quarks rather than hadrons. To construct a more realistic model from both theoretical and observational points of view, we conjecture that pulsars could be "quark-cluster stars" which are composed of quark-clusters with almost equal numbers of up, down and strange quarks. Clustering quark matter could be the result of strong coupling between quarks inside realistic compact stars. The lightest quark clusters could be of H-dibaryons, while quark clusters could also be heavier with more quarks. Being essentially related to the non-perturbative quantum-chromo dynamics (QCD), the state of supra-nuclear condensed matter is really difficult to obtain strictly by only theoretical QCD-calculations, and we expect, nevertheless, that astrophysical observations could help us to have a final solution.

We discuss the implications of Fermi/LAT observations on several aspects of gamma-ray burst (GRB) physics, including the radiation process, the emission sites, the bulk Lorentz factor, and the pre-shock magnetic field: (1) MeV-range emission favors synchrotron process but the highest energy (> 10 GeV) emission may not be synchrotron origin, more likely inverse Compton origin; (2) GRB should have multi-zone emission region, with MeV emission produced at smaller radii while optical and > 100 MeV emission at larger radii; (3) the bulk Lorentz factor can be a few 100's, much lower than 10³, in multi-zone model; (4) the upstream magnetic field of afterglow shock is strongly amplified to be at least in mG scale.

Well-sampled optical lightcurves of 146 gamma-ray bursts (GRBs) are complied from the literature. Multiple optical emission components are extracted with power-law function fits to these lightcurves. We present a systematical analysis for statistical properties and their relations to prompt gamma-ray emission and X-ray afterglow for each component. We show that peak luminosity in the prompt and late flares are correlated and the evolution of the peak luminosity may signal the evolution of the accretion rate. No tight correlation between the shallow decay phase/plateau and prompt gamma-ray emission is found. Assuming that they are due to a long-lasting wind injected by a compact object, we show that the injected behavior favors the scenarios of a long-lasting wind powered by a Poynting flux from a black hole via the Blandford-Znajek mechanism fed by fall-back mass or by the spin-down energy release of a magnetar after the main burst episode. The peak luminosity of the afterglow onset is tightly correlated with E_γ,iso, and it is dimmer as peaking later. Assuming that the onset bump is due to the fireball deceleration by the external medium, we examine the Γ₀ – E_γ,iso relation and find that it is confirmed with the current sample. Optical re-brightening is observed in 30 GRBs in our sample. It shares the same relation between the width and the peak time as found in the onset bump, but no clear correlation between L_R,p and E_γ,iso similar to that observed for the onset bumps is found. Although its peak luminosity also decays with time, the slope is much shallower than that of the onset peak, as is the case for the onset bumps. We get , being consistent with off-axis observations to an expanding external fireball in a wind-like circum medium. Therefore, the late re-brightening may signal another jet component. Mixing of different emission components may be the reason for the observed chromatic breaks of the shallow decay segment in different energy bands.

By taking magnetic field and detailed microphysics into account, we calculate the structure of neutrino-dominated disk in the frame of the well-known Paczyski-Witta potential, and compare the results with those without magnetic field. The results show that the temperature of the disk is lower than that without magnetic field, whereas the density is nearly the same as that without magnetic field. There also exists difference in the composition of disk matter between these two cases in the inner region of the disk.

We revisit the vertical structure of neutrino-dominated accretion flows (NDAFs) in spherical coordinates with a new boundary condition based on the mechanical equilibrium. The solutions show that the NDAF is significantly thick. The electron fraction approaches 0.5 at the surface of the disk in the outer region, which means that the matter in these regions is almost composed of α-particles and electrons in non-degenerate phase. It may be an implication for the origin of heavy nuclei in GRBs.

We summarize the recently accomplished relativistc Feynman Metropolis Teller theory of compressed atoms and its application to the description of white dwarfs and the crust of neutron stars. We briefly show also the extension of the treatment to the case of finite temperatures.

In the context of the Fireshell scenario Gamma-Ray Bursts (GRBs) find a natural explanation in the values of three main parameters: the energy of the emitting e^± plasma , the baryon load B, and the density of the Circum-Burst Medium (CBM) n_CBM. For B≲10^-5, the GRB consists of a spike-like emission without any afterglow: a genuine short burst. GRB 090227B is the first recognized genuine short GRB. Its analysis reveals that the transparency emission is not a pure thermal process, owing to a non-gradual transition between the optically thick and the optically thin phases. Within our theory we have recovered the original thermal spectrum of the e^± plasma, namely the effective Black body (BB); we indeed have determined the parameters of the Fireshell model, including the redshift. Setting a baryon load B = 10^-6, we obtain the effective temperature , the Lorentz factor at transparency Γ = 12852, and the total energy . The estimated redshift is z = 4.07±0.36.

In this work we present the results of the analysis of GRB 101023 in the fireshell scenario. We infered its redshift from the Amati Relation, obtaining z=0.9. Its light curve is very similar to the already studied GRB 090618, in the sense that it presents a double emission. We called each part Episode 1 and Episode 2. We performed a time-resolved spectral analysis with RMFIT using different spectral models, and fitted the light curve with a numerical code integrating the fireshell equations of motion. We used Fermi GBM data to build the light curve, in particular the second NaI detector, in the range (8.5-1000 keV). We considered different hypotheses about which part of the light curve could be the GRB and analyzed all of them. We noticed a great variation of the temperature with time in the first episode and almost no variation of the progenitor radius. The first emission does not match the requirements for a GRB, while the second part perfectly agrees with being a canonical GRB, with a P-GRB lasting 4s.

In this paper, we discuss that the Painlevé coordinates are not required to study tunneling effect from black holes. If the Schwarzschild coordinates are used to calculate the tunneling rate by the Parikh's method, the tunneling rate is half of the standard result.

We study perfect fluid accretion by the interior of a black hole in conformal gravity. We formulate the equation of motion for the accretion process by using energy conservation, Bernoulli equation and mass flux conservation equation. The accretion of perfect fluid (satisfying null energy condition) results the increase of black hole mass. The conditions for critical accretion are also investigated. There exist two critical points that lie in the exterior of horizons.

In this paper we give a brief review of our recent studies on the long and short gamma-ray bursts (GRBs) detected Swift, in an effort to understand the puzzle of classifying GRBs. We consider that it is still an appealing conjecture that both long and short GRBs are drawn from the same parent sample by observational biases.

This paper is devoted to investigate the Hawking radiation as a tunneling phenomenon from the Reissner-Nordström-de Sitter black hole with a global monopole. We use the semiclassical WKB approximation to the general covariant charged Dirac equation and evaluate tunneling probability as well as Hawking temperature. We also study the back reaction effects of the emitted spin particles and Bekenstein-Hawking entropy corrections of fermions tunneling through horizon.

This paper is devoted to study spherically symmetric gravitational collapse with anisotropic fluid in f(R) theory which undergoes dissipation in the form of heat flux. We develop dynamical and transport equation and finally couple them. This yields different possibilities of collapse and explosions connected with supernovae events and immense of dark energy terms arising from modifying gravity.

The ultra-relativistic precessing jet in gamma-ray bursts (GRBs) may be responsible for the complex structure in GRBs' light curves. In this work, we study the gravitational radiations of jet precession induced by neutrino-dominated accretion disks around black holes. In our model, the jet and the inner part of the disk may precess along with the black hole, which is driven by the outer part of the disk. Gravitational radiations are therefore expected to be significant from this precession system. Based our numerical results, we find that it is possible for DECIGO and BBO to detect such gravitational radiations regardless of GRBs' black hole masses, particularly for GRBs in the Local Group.

We investigate the process of Accretion Induced Collapse (AIC) during the evolution of massive Cataclysmic Variables (CVs) type binaries, which possibly to occur in our galaxy. The relation between spin periods and orbital periods in different nature of compact objects in binaries, is investigated. We study also the implication and application of the AIC process of the MSPs population. We conclude that a significant fraction of MSPs may originate from AIC (4 - 40%). Hence, massive CVs are of key importance for the formation and evolution of binary MSPs, once they reach the Chandrasekhar limit then collapse to becomes an NS, or blow as apart in a supernova, consequently impart significant kick to the companion and creating long orbital periods. In some cases, this process disrupts the system and creates a single MSP.

Distance measurements of gamma-ray pulsars are challenging questions in present pulsar studies. The Large Area Telescope (LAT) aboard the Fermi gamma-ray observatory discovered more than 100 gamma-ray pulsars including 24 new gamma-selected pulsars which nearly have no distance information. We study the relation between gamma-ray emission efficiency (η = L_γ/Ė) and pulsar parameters for young radio-selected gamma-ray pulsars with known distance information in the first gamma-ray pulsar catalog reported by Fermi/LAT. We have introduced three generation order parameters to describe gamma-ray emission properties of pulsars, and find the strong correlation of η – ζ₃ a generation order parameter which reflects γ-ray photon generations in pair cascade processes induced by magnetic field absorption in pulsar magnetosphere. A good correlation of η – B_LC the magnetic field at the light cylinder radius is also found. These correlations would be the distance indicators in gamma-ray pulsars to evaluate distances for gamma-selected pulsars. Distances of 25 gamma-selected pulsars are estimated, which could be tested by other distance measurement methods. Physical origin of the correlations may be also interesting for pulsar studies.

By solving a set of coupled hydrodynamical and microphysical equations with some appropriate boundary conditions, we obtain three global solutions of typical neutrino-dominated accretion flows around different spinning black holes. Our results reveal that the effect of black hole spin on the flows is restricted within inner parts of neutrino-dominated regions.

Using the latest gamma-ray bursts (GRB) observed by Fermi-GBM, we perform a statistical analysis of the relation between hardness ratio (HR) and duration (ΔT) of GRBs, and find that HR and ΔT are still anti-correlated. we also find that this correlation strongly depends upon the spectral shape of GRBs and energy bands, and the bursts with the curved spectra in the typical BATSE energy bands show a tighter anti-correlation than those with the power-law spectra in the typical BAT energy bands. This might explain why the HR – ΔT correlation is not evident for Swift-BAT GRB sample as well as other GRB sample detected by instruments with a narrower/softer energy bandpass such as HETE-2.

Previous studies have found that the width of gamma-ray burst (GRB) pulse is energy dependent^1-2 and its origin keeps unknown. Here we find combining the curvature effect and the intrinsic Band spectrum could naturally result in the energy dependence of GRB pulse width. Our result suggests that the GRB decay phase is indeed related to the so-called curvature effect. A natural expectation of our study is for bursts with single power law, not Band spectrum, pulse width will not be energy dependent in our consideration.

Differential rotation is an important feature of nonlinear r-modes. We investigate the role of differential rotation in the evolution of compact stars, including its cooling and spin evolution. Both normal neutron stars and strange stars are discussed. The heating effects due to viscous dissipation of the r-mode delay the cooling and spin evolution of compact stars. Especially, slight spin-up and a long time temperature plateaus in the cooling curves of normal neutron stars are found in case of differential rotation. We suggest the spin and cooling evolution should be taken into account synthetically, for the rotation of the star is a possible huge energy source for the thermal evolution of the star.

In the field of dark matter direct detection, on the one hand, it is predicted by theoretical models that many dark matter candidates and scenarios are possible. On the other hand, a variety of detectors has been proposed, but most of them — by the fact — are still at R&D stage. Such a situation leads to some considerations on technical aspects on dark matter direct detection.

In this paper we report on the observation of the anisotropy of cosmic ray arrival direction at different angular scales with ARGO-YBJ. Evidence of new few-degree excesses throughout the sky region 195° ≤ R.A. ≤ 315° is presented for the first time.

We report also on the measurement of the light-component (p+He) spectrum of primary cosmic rays in the range 5–200 TeV.

Stochastic acceleration of charged particles due to their interactions with plasma waves may be responsible for producing superthermal particles in a variety of astrophysical systems. This process can be described as a diffusion process in the energy space with the Fokker-Planck equation. In this paper, a time-dependent numerical code is used to solve the reduced Fokker-Planck equation involving only time and energy variables with general forms of the diffusion coefficients. We also propose a self-similar model for particle acceleration in Sedov explosions and use the TeV SNR RX J1713.7-3946 as an example to demonstrate the model characteristics. Markov Chain Monte Carlo method is utilized to constrain model parameters with observations.

Scintillating bolometers, in which the simultaneous detection of light and heat allows to discriminate the nature of the interacting particle, are one of the most promising detectors for Dark Matter (DM) searches. One main advantage is the wide range of materials that can be used as target, that could provide a key for WIMP identification. The EURECA (European Underground Rare Event Calorimeter Array) project aims to install 1 ton of cryogenic detectors (Ge and solid state scintillators) to explore the spin independent (SI) scalar cross sections down to the 10^-46 cm² region. In this frame, the ROSEBUD collaboration is developing low temperature scintillating materials to be installed at the Canfranc Underground Laboratory. Work on ⁶Li and ¹⁰B based targets, that could allow to monitor the thermal and fast neutron flux within the experiments, is also presented.

The Extreme Universe Space Observatory on Japanese Experiment Module (JEM-EUSO) is a science mission planned to be launched in 2017 to the International Space Station (ISS) to investigate the nature and origin of Ultra High Energy Cosmic Rays (UHECR) beyond energy 3 × 10¹⁹ eV. JEM-EUSO is a wide-angle telescope (60 degrees full field of view) and consists of a high-transmittance Fresnel lenses 2.5 m in diameter, an advanced photo-sensitive detector at the focal surface and a suitable electronics. An infrared camera and a LIDAR system will also be used to monitor the Earth's atmosphere and provide significant information on cloud coverage. The present status of advancement of the mission is reported.

Light neutralinos implemented in an effective Minimal Supersymmetric extension of the Standard Model at the electroweak scale without requirement of a gaugino-mass unification at a grand unification scale may have a mass around 10 GeV, i.e. in the range of interest for present data of direct search for dark matter particles in the galactic halo. In this talk we discuss the challenges and prospects of searching for them at the Large Hadron Collider.

We study a particular inflation models with a small-amplitude step-like feature in the inflaton potential as introducted by Adams et al. and we constraints it with data from the WMAP7 and ACT Cosmic Microwave Background experiments. Also we show that the possibility of a step in the inflationary potential like the one preferred by current data will soon be tested by the forthcoming temperature and polarization data from the Planck satellite mission.

The Maxwell algebra is the result of enlarging the Poincaré algebra by six additional tensorial Abelian generators that make the fourmomenta non-commutative. We present a local gauge theory based on the Maxwell algebra with vierbein, spin connection and six additional geometric Abelian gauge fields. We apply this geometric framework to the construction of Maxwell gravity, which is described by the Einstein action plus a generalized cosmological term. We mention a Friedman-Robertson-Walker cosmological approximation to the Maxwell gravity field equations, with two scalar fields obtained from the additional gauge fields. Finally, we outline further developments of the Maxwell symmetries framework.

We propose a unified model for dark matter haloes and central galactic objects as a self-gravitating system of semidegenerated fermions in thermal equilibrium. We consider spherical symmetry and then we solve the equations of gravitational equilibrium using the Fermi integrals in a dimensionless manner, obtaining the density profile and velocity curve. We also obtain scaling laws for the observables of the system and show that, for a wide range of our parameters, our model is consistent with the so called universality of the surface density of dark matter.

Recent results in Local Regge Calculus are confronted with Spin Foam Formalism. Introducing Barrett-Crane Quantization in Local Regge Calculus makes it possible to associate a unique Spin j_h with an hinge h, fulfilling one of the requirements of Spin Foam definition. It is shown that inter-twiner terms of Spin Foam can follow from the closure constraint in Local Regge Calculus.

We show how a Brownian motion on a short scale can originate a relativistic motion on scales larger than particle's Compton wavelength. Special relativity appears to be not a primitive concept, but rather it statistically emerges when a coarse graining average over distances of order, or longer than the Compton wavelength is taken. Our scheme accommodates easily also the doubly special relativistic dynamics. A previously unsuspected, common statistical origin of the two frameworks is brought to light for the first time.

Recent experimental evidences show that the universe is accelerating. There are many modified cosmological models to explain this accelerating phase including ΛCDM, quintessence model, Brans-Dicke, f(R) gravity, and others. In this talk we want to check the possibility of explaining the current accelerating phase using standard cosmological model with degenerate neutrino. We will study the evolution of distribution function of degenerate neutrinos with standard Friedmann-Lemaître-Roberston-Walker(FLRW) background.

Based on the cosmological hydrodynamic simulation, we study the properties of shock waves formed during the formation of the large scale structure (LSS) of the universe, and investigate their contribution to the cosmic ray (CR) fraction in the intergalactic medium (IGM). It is found that while strong accretion shocks prevail at high redshift, weak internal shocks become dominant in the intracluster medium (ICM) as galaxy clusters form and virialize at low redshift, z < 1. The accumulated CR proton energy is likely to be less than 10 % of the thermal energy in the ICM, since weak shocks of M ≲ 3 are most abundant. This is consistent with the upper limit constrained by radio and gamma-ray observations of galaxy clusters. In the warm-hot medium (WHIM) inside filaments, CRs and gas could be almost in energy equipartition, since relatively stronger shocks of 5 ≲ M ≲ 10 are dominant there. We suggest that the non-thermal emissions from the CR electrons and protons accelerated by cosmological shock waves could provide a new way to detect the WHIM of the universe.

The Cosmic Microwave Background anisotropies provide a unique opportunity to constrain simultaneous variations of the fine-structure constant α and Newton's gravitational constant G. Those correlated variations are possible in a wide class of theoretical models. In this brief paper we show that the current data, assuming that particle masses are constant, gives no clear indication for such variations, but already prefers that any relative variations in α should be of the same sign of those of G for variations of ≈ 1%. We also show that a cosmic complementarity is present with Big Bang Nucleosynthesis, and that a combination of current CMB and BBN data strongly constraints simultaneous variations in α and G. We finally discuss the future bounds achievable by the Planck satellite mission. We discuss present and future cosmological constraints on variations of the fine structure constant α induced by an early dark energy component having the simplest allowed (linear) coupling to electromagnetism. We find that current cosmological data show no variation of the fine structure constant at recombination respect to the present-day value, with α/α₀ = 0.975 ± 0.020 at 95% c.l., constraining the energy density in early dark energy to Ω_e < 0.060 at 95% c.l.

We briefly review the conceptual problems afflicting our understanding of the general framework which supposedly addresses the emergence of structure during inflation. We then describe an approach that attempt to deal with this problem in a manner that concepts it with problematic issues afflicting the quantum theory and gravitation interface and which in the inflationary context not acquire a sharpened importance but remarkably turn out to become susceptible to empirical studies.

Quasars at high redshift can help us to probe the nature of the early universe. Current quasar sample is incomplete in the redshift range from 2.2 to 3 because of the similar quasar colors as stars in the optical band. The main objective of the Chinese LAMOST spectroscopic quasar survey is to discover these missing quasars and provide a quasar sample consisting of 0.3million new quasars brighter than the magnitude limit i = 20.5 in the next 5 years. This will hopefully provide the largest quasar sample for the further studies of AGN physics and cosmology. The improved quasar selection criteria based on the UKIDSS near-IR and SDSS optical colors are introduced, and their advantages in uncovering the missing quasars in the quasar 'redshift desert' (z=2.2 to 3) are demonstrated. We also present some recent discoveries of new quasars from the LAMOST commissioning and other spectroscopic observations. The implications of our study to the ongoing and upcoming large optical and near-IR sky surveys are discussed.

We briefly present the results of our analytical studies on CMB anisotropies and polarizations generated by scalar metric perturbations in synchronous gauge, parallel to the previous work with RGW as a generating source. The analytical the spectra are explicitly given and the influences of various cosmological processes are examined.

Both the direct sunspot observations and the indirect solar activity proxies indicate the existences of the solar grand minima during which time the solar activities are greatly reduced. They are usually coincided with periods of lower-than-average global temperatures. The existences of the grand minima pose a challenge for the solar dynamo. The main features of the grand minima and the new dynamo models to explain their existences will be reviewed in the paper.

In order to perform high resolution astrometry of the solar diameter from the ground, through the observations of eclipses, the study of the limb darkening profile is described. Knowing the profile of the solar limb is useful both to monitor the solar radius over time, and to define the oblateness, which is interesting for the classical tests of general relativity. The Limb Darkening Function (LDF) is studied in order to find the inflexion point, to which the measurements of the solar diameter are referred. The proposed method is applied to the videos of the annular eclipse in January, 15, 2010. This new method might solve the ambiguity of some eclipse obervations made with different instruments, where the measured solar diameter was clearly dependent on the aperture of the telescope and on the density of the filter used.

The action of the atmospheric seeing is blurring, image stretching and image motion. This happens even to the image of the Sun which is more than half degree wide. Low frequency seeing components affect the solar diameter values measured either through the drift-scan or the heliometer methods. We present evidences of image motion and stretching down to 0.001 Hz.

Solar astrometry deals with the accurate measumerent of the solar diameter, and in general with the measurement of the shape of the Sun. During the last decades several techniques have been developed to monitor the radius and the irradiance of the Sun: meridian transits, telescopes in drift-scan mode, solar astrolabes, balloons, and satellites dedicated to the measurements of the solar diameter, and space measurements of the total solar irradiance are now performed to know the relationship radius-luminosity for the Sun in this evolutionary stage of its life. The feedback of solar astrometry in climate studies is of paramount importance. The status of art in the various fields of research here adressed is outlined.

The role of Venus and Mercury transits is crucial to know the past history of the solar diameter. Through the W parameter, the logarithmic derivative of the radius with respect to the luminosity, the past values of the solar luminosity can be recovered. The black drop phenomenon affects the evaluation of the instants of internal and external contacts between the planetary disk and the solar limb. With these observed instants compared with the ephemerides the value of the solar diameter is recovered. The black drop and seeing effects are overcome with two fitting circles, to Venus and to the Sun, drawn in the undistorted part of the image. The corrections of ephemerides due to the atmospheric refraction will also be taken into account. The forthcoming transit of Venus will allow an accuracy on the diameter of the Sun better than 0.01 arcsec, with good images of the ingress and of the egress taken each second. Chinese solar observatories are in the optimal conditions to obtain valuable data for the measurement of the solar diameter with the Venus transit of 5/6 June 2012 with an unprecedented accuracy, and with absolute calibration given by the ephemerides.

The Clementine gnomon has been built in 1702 to measure the Earth's obliquity variation. For this reason the pinhole was located in the walls of Diocletian's times (305 a. D.) in order to remain stable along the centuries, but its original form and position have been modified. We used an astrometric method to recover the original position of the pinhole: reshaping the pinhole to a circle of 1.5 cm of diameter, the positions of the Northern and Southern limbs have been compared with the ephemerides. A sistematic shift of 4.5 mm Southward of the whole solar image shows that the original pinhole was 4.5 mm North of the actual position, as the images in the Bianchini's book (1703) suggest. The oval shape of the actual pinhole is also wrong. Using a circle the larger solar spots are clearly visible. Some reference stars of the catalogue of Philippe de la Hire (1702), used originally for measuring the ecliptic latitude of the Sun, are written next to the meridian line, but after the last restauration (2000), four of them are wrongly located. Finally the deviation from the true North, of the meridian line's azimuth confirms the value recovered in 1750. This, with the local deviations of a true line, will remain as systematic error, like for all these historical instruments.

Coronal Mass Ejection is an entire process leading to the ejection of mass and magnetic flux into interplanetary space. Its source is studied by analyzing the associated surface activity. Analysis results show that CMEs have large-scale magnetic source structures, which provide their energy, initiation, and final angular width. This paper review the studies of CME source regions with laying emphasis on their large-scale source structures.

Gerbert of Aurillac was the most prominent personality of the tenth century: astronomer, organ builder and music theoretician, mathematician, philosopher, and finally pope with the name of Silvester II (999–1003). Gerbert introduced firstly the arabic numbers in Europe, invented an abacus for speeding the calculations and found a rational approximation for the equilateral triangle area, in the letter to Adelbold here discussed. Gerbert described a semi-sphere to Constantine of Fleury with built-in sighting tubes, used for astronomical observations. The procedure to identify the star nearest to the North celestial pole is very accurate and still in use in the XII century, when Computatrix was the name of Polaris. For didactical purposes the Polaris would have been precise enough and much less time consuming, but here Gerbert was clearly aligning a precise equatorial mount for a fixed instrument for accurate daytime observations. Through the sighting tubes it was possible to detect equinoxes and solstices by observing the Sun in the corresponding days. The horalogium of Magdeburg was probably a big and fixed-mount nocturlabe, always pointing the star near the celestial pole.

The discovery of neutral atomic hydrogen (HI) in the interstellar medium was based on a prediction by H. C. van de Hulst. The story of how Jan Oort suggested that the student Van de Hulst might investigate the question, who then reported his results at a wartime colloquium in Leiden, is well known. Recent archival research has turned up letters and other documents which, while not changing the basic storyline, do throw new light on certain details. From letters to Oort, it is now possible to determine when he first heard about Reber's observations of radio emission from the Milky Way, and what his immediate reaction was. After the 1944 colloquium, Oort began his quest to detect and study the HI line, despite technical and financial limitations, and the lack of radar know-how in the Netherlands. The Dutch effort achieved success in 1951, but not before the Harvard team of Ewen and Purcell had detected the line some six weeks before.