Related papers: A novel approach to identify blazar emission state…
The origin of the high-energy emission in astrophysical jets from black holes is a highly debated issue. This is particularly true for jets from supermassive black holes that are among the most powerful particle accelerators in the…
A model based clustering procedure for data of mixed type, clustMD, is developed using a latent variable model. It is proposed that a latent variable, following a mixture of Gaussian distributions, generates the observed data of mixed type.…
Blazars constitute the most interesting and enigmatic class of extragalactic gamma-ray sources dominated by non-thermal emission. In this Letter, we show how the WISE infrared data make possible to identify a distinct region of the…
Spectral clustering is a celebrated algorithm that partitions objects based on pairwise similarity information. While this approach has been successfully applied to a variety of domains, it comes with limitations. The reason is that there…
We propose a clustering-based approach for identifying coherent flow structures in continuous dynamical systems. We first treat a particle trajectory over a finite time interval as a high-dimensional data point and then cluster these data…
The Extragalactic Background Light (EBL) carries a huge astrophysical and cosmological content: its frequency spectrum and redshift evolution are determined by the integrated emission of unresolved sources, these being galaxies, active…
This work present the results of a multi-epoch observational study of the blazar S5\,1803+784, carried out from 2019 to 2023. The analysis is based on simultaneous data obtained from the Swift/UVOT/XRT, ASAS-SN, and Fermi-LAT instruments. A…
With their rapid, violent variability and broad featureless continuum emission, blazars have puzzled astronomers for over two decades. Today blazars represent the only extragalactic objects detected in high-energy gamma-rays. Their spectral…
We investigate the $\gamma$-ray and X-ray population properties of changing-look blazars (CLBs) using sources from the Fourth \textit{Fermi} LAT Source Catalog Data Release 4 (4FGL-DR4) together with X-ray information from the Living…
Clustering algorithms are often used to find subpopulations in exploratory data analysis workflows. Not only the clusters themselves, but also their shape can represent meaningful subpopulations. In this paper, we present FLASC, an…
The phenomenon of pulsar nulling -- where pulsars occasionally turn off for one or more pulses -- provides insight into pulsar-emission mechanisms and the processes by which pulsars turn off when they cross the "death line." However, while…
Blazars have been suggested as possible neutrino sources long before the recent IceCube discovery of high-energy neutrinos. We re-examine this possibility within a new framework built upon the blazar simplified view and a self-consistent…
Despite their fundamental importance in dictating the quantum mechanical properties of a system, ground states of many-body local quantum Hamiltonians form a set of measure zero in the many-body Hilbert space. Hence determining whether a…
Machine learning can provide powerful tools to detect patterns in multi-dimensional parameter space. We use K-means -a simple yet powerful unsupervised clustering algorithm which picks out structure in unlabeled data- to study a sample of…
Context. Although Blazars are a small fraction of the overall AGN population they are expected to be the dominant population of extragalactic sources in the hard X-ray and gamma-ray bands and have been shown to be the largest contaminant of…
When multiple star-forming gas structures overlap along the line-of-sight and emit optically thin emission at significantly different radial velocities, the emission can become non-Gaussian and often exhibits two distinct peaks. Traditional…
We report multi-wavelength observations of four solar flares on 2014 July 07. We firstly select these flares according to the soft X-ray (SXR) and extreme ultraviolet (EUV) emissions recorded by the Extreme Ultraviolet Variability…
Open clusters are groups of stars that form at the same time, making them an ideal laboratory to test theories of star formation, stellar evolution, and dynamics in the Milky Way disk. However, the utility of an open cluster can be limited…
Active Galaxies with a jet pointing towards us, so-called blazars, play an important role in the field of high-energy astrophysics. One of the most important features in the classification scheme of blazars is the peak frequency of the…
In search for the possible astrophysical sources behind origination of the diverse gamma-ray bursts, cluster analyses are performed to find homogeneous groups, which discover an intermediate group other than the conventional short and long…