Related papers: Reconstructing AGN X-ray spectral parameter distri…

Gaussian time-series models are often specified through their spectral density. Such models present several computational challenges, in particular because of the non-sparse nature of the covariance matrix. We derive a fast approximation of…

We present a novel approach using neural networks to recover X-ray spectral model parameters and quantify uncertainties, balancing accuracy and computational efficiency against traditional frequentist and Bayesian methods. Frequentist…

(ABRIDGED) We investigate here the XLF of absorbed (Nh between 4E21 and E24 cm-2) and unabsorbed (Nh < 4E21 cm-2) AGN, the fraction of absorbed AGN as a function of Lx (and z), the intrinsic Nh distribution of the AGN population, and the…

We examine the equations to obtain atomic pair distribution functions (PDFs) from x-ray, neutron and electron powder diffraction data with a view to obtaining reliable and accurate PDFs from the raw data using a largely \emph{ad hoc}…

Context. The soft excess, a surplus of X-ray photons above 2 keV with respect to a power law, is a feature of debated physical origin found in the X-ray spectra of many type-1 active galactic nuclei (AGN). The eROSITA instrument aboard the…

The maximum entropy method (MEM) and the Gaussian process (GP) regression, which are both well-suited for the treatment of inverse problems, are used to reconstruct net-baryon number distributions based on a finite number of cumulants of…

In this paper we focus on a type of inverse problem in which the data is expressed as an unknown function of the sought and unknown model function (or its discretised representation as a model parameter vector). In particular, we deal with…

AIMS. This work addresses the AGN IR-selection dependency on intrinsic source luminosity and obscuration, in order to identify and charaterise biases which could affect conclusions in studies. METHODS. We study IR-selected AGN in the…

Using a suite of X-ray, mid-IR and optical active galactic nuclei (AGN) luminosity indicators, we search for Compton-thick (CT) AGNs with intrinsic L_X>10^42erg/s at z~0.03-0.2, a region of parameter space which is currently poorly…

We present a Bayesian reconstruction algorithm to generate unbiased samples of the underlying dark matter field from halo catalogues. Our new contribution consists of implementing a non-Poisson likelihood including a deterministic…

We propose a genetic algorithm (GA) for hyperparameter optimization of artificial neural networks which includes chromosomal crossover as well as a decoupling of parameters (i.e., weights and biases) from hyperparameters (e.g., learning…

Strong gravitational lensing of active galactic nuclei (AGN) enables measurements of cosmological parameters through time-delay cosmography (TDC). With data from the upcoming LSST survey, we anticipate using a sample of O(1000) lensed AGN…

We investigate the physical nature of active galactic nuclei (AGNs) using machine learning (ML) tools. We show that the redshift, $z$, bolometric luminosity, $L_{\rm Bol}$, central mass of the supermassive black hole (SMBH), $M_{\rm BH}$,…

We discuss the Bayesian approach to the solution of inverse problems and apply the formalism to analyse the closure tests performed by the NNPDF collaboration. Starting from a comparison with the approach that is currently used for the…

We compute the effect of the galactic absorption on AGN emission in a cosmological context by including a physical model for AGN feeding and feedback in a semi-analytic model of galaxy formation. This is based on galaxy interactions as…

AIMS: We present the optical classification and redshift of 348 X-ray selected sources from the XMM-Newton Bright Serendipitous Survey (XBS) which contains a total of 400 objects (identification level = 87%). About 240 are new…

Bayesian inference for inverse problems hinges critically on the choice of priors. In the absence of specific prior information, population-level distributions can serve as effective priors for parameters of interest. With the advent of…

We present a new method of transient point source deconvolution for coded-aperture X-Ray detectors. Our method is based upon the calculation of the likelihood function and its interpretation as a probability density for the transient source…

A large population of heavily obscured, Compton Thick AGNs is predicted by models of galaxy formation, models of Cosmic X-ray Background and by the ``relic'' super-massive black-hole mass function measured from local bulges. However, so far…

A complete demographic of active galactic nuclei (AGN) is essential to understand the evolution of the Universe. Optical surveys estimate the population of AGN in the local Universe to be of $\sim$ 4%. However, these results could be biased…