Authors of the article assert that they studied the ensemble X-ray variability properties of active galactic nuclei (AGN) over large ranges of timescale (20 ks ≤ T ≤ 14 yr), redshift (0 ≤ z ≲ 3), luminosity (1040 erg s−1 ≤ LX ≤ 1046 erg s−1), and black hole (BH) mass (106 ≤ M⊙ ≤ 109). The authors show that the data collected from archival observations and previous literature studies are fully consistent with a universal PSD form, which does not show any evidence for systematic evolution of shape or amplitude with redshift or luminosity, even if there may be differences between individual AGN at a given redshift or luminosity.

Authors of the article explain that they investigated the extreme X-ray variability of a z = 1.608 active galactic nucleus in the 7 Ms Chandra Deep Field-South (XID 403), which showed two significant X-ray brightening events.

Article describes how detrended fluctuation analysis (DFA) is a well-established method to evaluate scaling indices of time series, which categorize the dynamics of complex systems. The authors propose treating each reaction time as a duration time that changes the representation from operational (trial number) time n to event (temporal) time t, or X(t).

Article presents a study utilizing a carefully selected sample of 53 radio-quiet quasars that have Hβ and C iv λ1549 spectroscopy as well as Chandra coverage, to search for a robust accretion-rate indicator for quasars, particularly at the highest-accessible redshifts (z ∼ 6–7).

This article reports the Chandra discovery of the first heavily obscured QSO candidate in the early universe, hosted by a close (≈5 kpc) galaxy pair at z = 6.515.

Article studying chemical and electronic properties of ion beam synthesized Fe-Si binary structures using X-ray photoelectron spectroscopy binding energy analysis.

Article investigating ionization of atomic hydrogen by electron- and positron-impact. This article belongs to the Special Issue: Interactions of Positrons with Matter and Radiation.

Article presents a combination of first principles and quantum ballistic transport calculations to shed important insights from an atomistic viewpoint on the underlying mechanisms governing spin transport in graphene/ CrI₃ junctions.

Article presents ALMA Band 7 data of the [C ıı] 𝜆157.74 𝜇m emission line and underlying far-IR (FIR) continuum for 12 luminous quasars at 𝓏 ≃ 4.8 powered by fast-growing supermassive black holes (SMBHs).

Article studying Hydrogen-bonded pyridine–water mixtures by a time-frequency resolved coherent Raman spectroscopic technique.

This article evaluates the role that gene-environment interaction between air-pollution and Alpha-1 Antitrypsin (AAT) genes plays in the severity of COVID-19. Results find parallelism between the number of COVID deaths and the AAT*air pollution global risk in Europe.

This article presents the results of follow-up observations of the z = 6.515 radio-quiet QSO PSO167–13, which is interacting with a close companion galaxy with the goal to confirm the existence of the X-ray source and to investigate the rest-frame UV properties of the QSO. The authors observed the PSO167–13 system with Chandra/ACIS-S (177 ks) and obtained new spectroscopic observations (7.2 h) with Magellan/FIRE.

This article describes a procedure for computing the electrostatic equilibria of non-neutral plasmas in a Penning trap with a nonuniform magnetic field by solving Poisson's equation using an iterative method. Plasma equilibria in a model Penning trap with high and low field regions are computed. The plasma is assumed to follow the Boltzmann density distribution along magnetic field lines.

Article proposes the “coordination corrected enthalpies” method (CCE), based on the number of nearest neighbor cation–anion bonds, and also capable of correcting relative stability of polymorphs.

Examines the novel optical properties of a graded photonic super-crystal (GPSC) with a large size of unit cell.

This article contains visual observation data of the carbon star VY Ursae Majoris.

This article emphasizes that 1/f noise has two different origins, one compatible with Laplace determinism and one determined by unpredictable crucial events.

This article reviews comparative trace elemental concentrations of cancerous and noncancerous tissues using PIXE.

This article describes the measurement of collision-induced interaction cross sections for 1-7 MeV diatomic boron molecular ions incident on a nitrogen gas target by using a differentially pumped gas cell.

This article tests whether the modified Baldwin effect remains strong across the wides possible of ranges of redshift and luminosity.

This article presents the results of a dense and intensive X-ray and optical monitoring of the narrow-line Seyfert 1 galaxy NGC 4051 carried out in 2000.

This article contains a detailed investigation of moderate- to high-quality X-ray spectra of 10 of the most luminous active galactic nuclei known at z > 4.

This article studies the X-ray properties of a representative sample of 59 of the most optically luminous quasars in the universe spanning a redshift range of z ≈ 1.5-4.5.

This article presents Spitzer rest frame mid-infrared spectroscopy of 12z~2 millimeter-bright type 1 QSOs.