We derive the optical afterglow luminosity distributions at different epoches for gamma-ray bursts (GRBs) from a sample of 146 GRBs that have a well-sampled optical afterglow lightcurve, then explore the luminosity function of GRB optical afterglows using the Monte Carlo simulation. We show that an intrinsic broken power-law luminosity function can well reproduced the observed magnitude distributions.

The mass of ISM in high redshift Galaxies is a major determinant of their morphology, star formation activity and how they will evolve to low redshift. Measurement of the CO lines at z > 0.5 are time consuming, even with the sensitivity of ALMA, and the derived ISM masses are subject to uncertainty in the CO-to-H2 conversion factor. Here I describe a much faster technique— measuring the long wavelength Rayleigh-Jeans dust emission using the spectacular continuum sensitivity of ALMA. Using a metallicity-dependent gas-to-dust abundance ratio derived from studies of low-z galaxies, one then obtains the ISM mass. Initial results from our ALMA Cycle-0 observations are presented for a small sample of stellar-mass selected galaxies in COSMOS. This technique will enable measurement of 100's of galaxies at high-z with observations of typically ∼10 min per galaxy.

Using RXTE observations, we investigate the evolution of inner disk radius (Rin) of Cir X-1 during two cycles and find obvious orbital modulation. We argue that the modulation is attributed to its high orbital eccentricity. The disk luminosity is inversely with the inner disk temperature (kTin), which is ascribed to the slow increase of kTin and, however, the rapid decrease of Rin during the passage for the neutron star to depart from the companion star.

Large impacts in the outer parts of a planetary system will produce debris discs that display a strong, distinctive, asymmetry, which will last for 105 year timescales. Debris resulting from a large impact may be able to explain the asymmetries in some known debris discs that have hitherto been difficult to understand.

We demonstrate that massive simulated galaxies assemble in two phases, with the initial growth dominated by compact in situ star formation, whereas the late growth is dominated by accretion of old stars formed in subunits outside the main galaxy. We also show that 1) gravitational feedback strongly suppresses late star formation in massive galaxies contributing to the observed galaxy colour bimodality that 2) the observed galaxy downsizing can be explained naturally in the two-phased model and finally that 3) the details of the assembly histories of massive galaxies are directly connected to their observed kinematic properties.

Using the solutions of the gap equations of the magnetic-color-flavor-locked (MCFL) phase of paired quark matter in a magnetic field, and taking into consideration the separation between the longitudinal and transverse pressures due to the field-induced breaking of the spatial rotational symmetry, the equation of state (EoS) of the MCFL phase is self-consistently determined. Implications for stellar models of magnetized (self-bound) strange stars and hybrid (MCFL core) stars are discussed.

A continuous observations near an small active region (AR) NOAA 10976 by the Solar Optical Telescope (SOT) and X-Ray Telescope (XRT) on board the Hinode satellite during Dec. 02 2007 from 15:50 UT to 19:59 UT. We observed that: (a) the filament formed by merging parallel fibrils into a twist structure. (b) the filament faded by reconnecting among its own loop structures, or being stripped into pieces.These process are always preceded by the brightening. (c) for the disappearance of the filament, it has close correlation with the activity, like untwisting or expanding, of its corresponding X-ray bright rope.

To determine the spectral energy distribution of galaxies in large numerical simulations, proper treatment of the attenuation is crucial. One of the most common methods in semi–analytic models is to compute the attenuation from the gas surface density. The aim of the present study is to provide new but still simple relations between the gas surface density and the optical depth, directly calibrated on galaxies. To do so we combine multi–wavelength data and perform a pixel–by–pixel analysis on a sample of nearby galaxies. Examination of the influence of these new relations on simulated FUV and IR luminosity functions shows a clear impact compared to older oft–used relations, which in turn could affect the conclusions drawn from studies based on large scale cosmological simulations.

The first attempt at developing a fully self-consistent code coupling dynamics and collisions to study debris discs (Kral et al. 2013) is presented. So far, these two crucial mechanisms were studied separately, with N-body and statistical collisional codes respectively, because of stringent computational constraints.

We present a new model named LIDT-DD which is able to follow over long timescales the coupled evolution of dynamics (including radiation forces) and collisions in a self-consistent way.

According to a popular scenario supported by numerical models, the mass assembly and growth of massive galaxies, in particular the Early-Type Galaxies (ETGs), is, below a redshift of 1, mainly due to the accretion of multiple gas–poor satellites. In order to get observational evidence of the role played by minor dry mergers, we are obtaining extremely deep optical images of a complete volume limited sample of nearby ETGs. These observations, done with the CFHT as part of the ATLAS3D, NGVS and MATLAS projects, reach a stunning 28.5 – 29 mag.arcsec−2 surface brightness limit in the g' band. They allow us to detect the relics of past collisions such as faint stellar tidal tails as well as the very extended stellar halos which keep the memory of the last episodes of galactic accretion. Images and preliminary results from this on-going survey are presented, in particular a possible correlation between the fine structure index (which parametrizes the amount of tidal perturbation) of the ETGs, their stellar mass, effective radius and gas content.

The Herschel Reference Survey is a guaranteed time key project aimed at studying the physical properties of the interstellar medium (ISM) of 323 nearby galaxies, covered by multi-wavelength data. This volume limited, K-band selected sample is composed of galaxies spanning the whole range of morphological types and environments. We conduct a statistical study on the ISM properties of nearby galaxies based on the analysis of their SED. To achieve this goal, we fit the data with the models of Draine & Li (2007) to obtain the intensity of interstellar radiation field, the PAH abundance, the contribution of photodissociation regions, and the dust mass.

We summarise the results of observing faint cataclysmic variables from the Catalina Real-Time Transient Survey, resulting in confirming the theoretically predicted maximum in the orbital period histogram near a period of 80 minutes.

The long-term variability of the sunspot cycle, as recorded by the Wolf numbers, are imprinted in different kinds of statistical relations which relate the cycle amplitudes, duration and shapes. This subject always gets a special attention because it is important for the solar activity forecast. We discuss statistical properties of the mean-field dynamo model with the fluctuating α-effect. Also, we estimate dynamical properties of the model for the long and short time-scale and compare it with the dynamics of the sunspot numbers data sets.

Ultra-compact X-ray binaries (UCXBs) are accreting systems with periods less than 1 hour, which qualifies them to contain a degenerate donor-companion. One would expect such systems to have the easiest theoretical explanation, compared to other kinds of X-ray binaries. Nonetheless, current theory fails to explain high mass transfer (MT) rates in three recently well observed long-period UCXBs. We find that this range of MT rates can be maintained if the donor is a remnant of an out-of-thermal-equilibrium naked core of a giant which was revealed in a very recent episode of a common envelope (CE) event.

I summarize a recent study scrutinizing the various sources of uncertainties in estimating the dust mass of a galaxy. These effects are demonstrated on the Herschel observations of the Large Magellanic Cloud.

The formation of the brightest cluster galaxies (BCG) is a challenge for galaxy formation theory. We performed high resolution cosmological hydrodynamical simulations with the AMR code RAMSES to study the properties of the BCG which forms at the center of a Virgo–like cluster. We compare the results of 2 galaxy formation scenarios, one in which only supernovae feedback is included, and one in which also AGN feedback is considered. Properties of the simulated BCG which are comparable with those of observed massive elliptical galaxies and BCGs cannot be obtained if AGN feedback is not considered. The stellar-to-halo mass ratio in simulations without AGN feedback appears too large when compared to observations, while it is compatible the observationally determined values when AGN feedback is included. The kinematical and structural properties of the BCG are extremely different in the two models. When we do not include AGN feedback, the BCG is quickly rotating, with high Sérsic index, a clear mass excess in the center and a very large stellar mass fraction. When AGN feedback is considered, the BCG is slowly rotating, with a significantly cored surface density profile and low stellar mass fraction.

The HR 8799 four-planet host is known to host a multi-component disk from Spitzer observations. We have obtained Herschel† observations of the disk which provide increased sensitivity and resolution of its outer components: the planetesimal belt and halo. We find that the two components cannot be discerned from the spectral energy distribution alone, but require resolved images to independently identify them. In the resolved images, the halo stands out for its steep radial profile and large radial extent to 2000 AU, a factor of two larger than was estimated from Spitzer data.

We explore the origin of the radio emission from the low-luminosity active galactic nuclei (LLAGNs), by investigating the ADAF model with a hybrid of thermal and nonthermal electrons. We find that the radio emission of LLAGNs is severely underpredicted by pure ADAF model, and can be naturally explained by the ADAF model with a hybrid electron population. Our model can roughly reproduce the anti-correlation between the mass-corrected radio loudness and the Eddington ratio for the LLAGNs. We further model the SEDs of each source, and find that roughly all sources can be well fitted if a small fraction of the steady state electron energy is ejected into the nonthermal electrons.

A new model of the pulsar force-free magnetosphere is suggested, which includes the presence of the polar, outer and slot gaps. It is based on a new exact solution of the pulsar equation in the form of an offset monopole and the resultant split-offset monopole scheme.