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The Unusual Temporal and Spectral Evolution of the Type IIn Supernova 2011ht
Unusual Temporal Spectral Evolution Type IIn Supernova
2012/2/23
We present very early UV to optical photometric and spectroscopic observations of the peculiar Type IIn supernova (SN) 2011ht in UGC 5460. The UV observations of the rise to peak are only the second e...
Joint spectral-timing modelling of the hard lags in GX 339-4: constraints on reflection models
Joint spectral-timing modelling the hard lags GX 339-4 constraints reflection models
2012/2/23
The X-ray variations of hard state black hole X-ray binaries above 2 keV show 'hard lags', in that the variations at harder energies follow variations at softer energies, with a time-lag \tau dependin...
Spectral-Temporal Simulations of Internal Dissipation Models of Gamma-Ray Bursts
Spectral-Temporal Simulations Internal Dissipation Models Gamma-Ray Bursts
2011/10/19
We present calculations of the time evolution of the prompt spectra of gamma-ray burst models involving generic internal dissipation regions, including internal shocks, either by itself or in the pres...
Spectral and Timing Studies of Cyg X-1 in the Low/Hard State with Suzaku
black hole physics — accretion — stars: individual (Cygnus X-1)—X- ray:binaries
2011/10/11
From 2005 to 2009, 25 observations of Cyg X-1 were performed with Suzaku, achieving a total exposure of 446 ks. In all observations, the source was found in the low/hard state, while the 1.5--12.0 keV...
Stochastic Acceleration and the Evolution of Spectral Distributions in SSC Sources: A Self Consistent Modeling of Blazars' Flares
Stochastic Acceleration Evolution Spectral Distributions
2011/9/30
The broad-band spectral distributions of non-thermal sources, such as those of several known blazars, are well described by a log-parabolic fit. The second degree term in these fits measures the curva...
Optical Spectral Variability of the Very-High-Energy Gamma-Ray Blazar 1ES 1011+496
Optical Spectral Variability the Very-High-Energy Gamma-Ray Blazar 1ES 1011+496
2011/1/11
We present results of five years of optical (UBVRI) observations of the very-high-energy gamma-ray blazar 1ES 1011+496 at the MDM Observatory. We calibrated UBVRI magnitudes of five comparison stars i...
Detection of a Thermal Spectral Component in the Prompt Emission of GRB 100724B
Detection of a Thermal Spectral Component in the Prompt Emission of GRB 100724B
2011/1/10
Observations of GRB 100724B with the Fermi Gamma-Ray Burst Monitor (GBM) find that the spectrum is dominated by the typical Band functional form, which is usually taken to represent a non-thermal emis...
Spectral variability of quasars from multi-epoch photometric data in the Sloan Digital Sky Survey Stripe 82
Spectral variability multi-epoch photometric data
2011/1/11
We present a new approach to analysing the dependence of quasar variability on rest-frame wavelengths. We exploited the spectral archive of the Sloan Digital Sky Survey (SDSS) to create a sample of mo...
Spectral catalogue of bright gamma-ray bursts detected with the BeppoSAX/GRBM
Spectral catalogue bright gamma-ray bursts the BeppoSAX/GRBM
2011/1/11
The emission process responsible for the so-called "prompt" emission of gamma-ray bursts is still unknown. A number of empirical models fitting the typical spectrum still lack a satisfactory interpret...
Central Stars of Planetary Nebulae: New spectral classifications and catalogue
Central Stars Planetary Nebulae spectral classifications
2011/1/11
Context. There are more than 3000 true and probable known Galactic Planetary Nebulae (PNe), but only for 13% of them there is central star spectroscopic information available. Aims. To contribute to t...
An iterative method in a probabilistic approach to the spectral inverse problem: Differential emission measure from line spectra and broadband data
the spectral inverse problem Differential emission measure
2011/1/11
Inverse problems are of great importance in astrophysics for deriving information about the physical characteristics of hot optically thin plasma sources from their EUV and X-ray spectra. We describe ...
Origin of the Ultrahigh-Energy Cosmic Rays and their Spectral Break
Ultrahigh-Energy Cosmic Rays Spectral Break
2010/11/15
In this concise, albeit subjective review of structure formation, I shall introduce the cosmological standard model and its theoretical and observational underpinnings. I will focus on recent results ...
Spectral Index as a Function of Mass Accretion Rate in Black Hole Sources. Monte-Carlo Simulations and an Analytical Description
black hole physics accretion disks radiation mechanisms
2010/11/16
We present herein a theoretical study of correlations between spectral indexes of X-ray emergent spectra and mass accretion rate (m˙ ) in black hole (BH) sources,which provide a definitive signature f...
Modelling the spectral energy distribution of galaxies. V. The dust and PAH emission SEDs of disk galaxies
Radiative transfer - Scattering - (ISM): dust extinction - Galaxies spiral - Galaxies: individual
2010/11/15
We present a self-consistent model of the spectral energy distributions (SEDs) of spiral galaxies from the ultraviolet (UV) to the mid-infrared (MIR)/far-infrared (FIR)/submillimeter (submm) based on ...
X-ray spectral state is not correlated with luminosity in Holmberg II X-1
accretion accretion disks – black hole physics – X-rays binaries– X-rays
2010/11/12
The ultraluminous X-ray source (ULX) Holmberg II X-1 has been observed over 4 months in 2009/2010 by the Swift observatory. The source luminosity varied by a factor of up to 14, reaching a maximum 0.3...