A5091287310- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Radio Astronomy Observations and Technology
- Galaxies: Formation, Evolution, Phenomena
- Dark Matter and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Neutrino Physics Research
- Pulsars and Gravitational Waves Research
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Solar and Space Plasma Dynamics
- Calibration and Measurement Techniques
- Particle Detector Development and Performance
- Adaptive optics and wavefront sensing
- Astrophysics and Star Formation Studies
- Nuclear Physics and Applications
- Medical Imaging Techniques and Applications
- Advanced X-ray Imaging Techniques
- Noncommutative and Quantum Gravity Theories
- Particle Accelerators and Free-Electron Lasers
- Black Holes and Theoretical Physics
- Experimental and Theoretical Physics Studies
- Cosmology and Gravitation Theories
- Relativity and Gravitational Theory
General Electric (Norway)
2025
University of Virginia
2025
Clemson University
2020-2024
Universitat de Barcelona
2016-2021
University of Siena
2017-2020
Institut d'Estudis Espacials de Catalunya
2016-2019
Institute for High Energy Physics
2018
Abstract We present the multiepoch analysis of 13 variable, nearby ( z ≲ 0.1), and Compton-thin (10 22 < N H 1.5 × 10 24 cm −2 ) active galactic nuclei (AGN) selected from 105-month BAT catalog. Analyzing all available archival soft hard X-ray observations, we investigate line-of-sight hydrogen column density H,los variability on timescales ranging a few days to approximately 20 yr. Each source is analyzed by simultaneously modeling data with three physical torus models, providing tight...
Abstract Blazars, a unique class of active galactic nuclei, exhibit highly variable emission across the electromagnetic spectrum. This variability frequently manifests as intense flaring events, sparking an ongoing debate in recent literature about whether these flares periodic behavior certain sources. However, many blazars also show clear signs stochastic, uncorrelated that do not follow regular pattern. paper explores how presence one such stochastic can distort intrinsically pattern...
The merger of two or more galaxies can enhance the inflow material from galactic scales into close environments Active Galactic Nuclei (AGN), obscuring and feeding supermassive black hole (SMBH). Both recent simulations observations AGN in mergers have confirmed that are related to strong nuclear obscuration. However, it is still unclear how obscuration evolves last phases process. We study a sample 60 Luminous Ultra-luminous IR (U/LIRGs) GOALS observed by NuSTAR. find fraction Compton-thick...
Ever since the discovery of first active galactic nuclei (AGN), substantial observational and theoretical effort has been invested into understanding how massive black holes have evolved across cosmic time. Circum-nuclear obscuration is now established as a crucial component, with almost every AGN observed known to display signatures some level in their X-ray spectra. However, despite more than six decades effort, open questions remain: does accretion power impact structure circum-nuclear...
The obscuration observed in active galactic nuclei (AGNs) is mainly caused by dust and gas distributed a torus-like structure surrounding the supermassive black hole. However, properties of obscuring torus an AGN X-ray have not yet been fully investigated because lack high-quality data proper models. In this work, we perform broadband spectral analysis large, unbiased sample obscured AGNs (with line-of-sight column density 23 ≤ log( N H ) 24) nearby Universe for which archival NuSTAR are...
Abstract We present the analysis of simultaneous Nuclear Spectroscopic Telescope Array (NuSTAR) and XMM-Newton data eight Compton-thick active galactic nuclei (CT-AGN) candidates selected in Swift-BAT 100 month catalog. This work is part an ongoing effort to find characterize all CT-AGN Local ( z ≤ 0.05) Universe. used two physically motivated models, MYTorus borus02 , sources sample, finding five them be confirmed CT-AGN. These results represent increase ∼19% over previous NuSTAR-confirmed,...
ABSTRACT Blazars present highly variable gamma-ray emission. This variability, which can range from a few minutes to several years, is also observed at other wavelengths across the entire electromagnetic spectrum. We make use of first 12 yr data Fermi Large Area Telescope, complemented with multiwavelength (MWL) archival different observatories and facilities in radio, infrared, optical bands, study possible periodic emission 19 blazars previously claimed as candidates. A periodicity...
Since the discovery of cosmic X-ray background (CXB), astronomers have strived to understand accreting supermassive black holes (SMBHs) contributing its peak in 10–40 keV band. Existing soft telescopes could study this population up only 10 keV, and, while NuSTAR (focusing on 3–24 keV) made great progress, it also left significant uncertainties characterizing hard population, crucial for calibrating current synthesis models. This paper presents an in-depth analysis simulations two...
A fundamental goal of modern-day astrophysics is to understand the connection between supermassive black hole (SMBH) growth and galaxy evolution. Merging galaxies offer one most dramatic channels for evolution known, capable driving inflows gas into galactic nuclei, potentially fueling both star formation central SMBH activity. Dual active nuclei (dual AGNs) in late-stage mergers with nuclear pair separations <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"...
We present the multi-epoch monitoring with NuSTAR and XMM-Newton of NGC 1358, a nearby Seyfert 2 galaxy whose properties made it promising candidate X-ray changing look AGN, i.e., source column density could transition from its 2017 Compton-thick (CT-, having line-of-sight Hydrogen NH,los>10^24 cm^-2) state to Compton-thin (NH,los<10^24 one. The confirmed presence significant NH,los variability over time-scales as short weeks, allowed us confirm "changing look" nature which has most recently...
Abstract The cosmic X-ray background (CXB) is dominated by the obscured and unobscured coronal light of active galactic nuclei (AGN). At energies below 10 keV, CXB can be well explained models taking into account known AGN observed distribution their obscuring, line-of-sight column densities, N H,l.o.s . However, at around Compton reflection hump (~30 keV), fall short data. This suggests existence a population as yet undetected Compton-thick (CT) ( > 1.5 × 24 cm −2 ) whose spectra are...
We present the analysis of 15 X-ray observations Mrk 477, a nearby Seyfert 2 active galactic nucleus, with objective to monitor its obscuring column density variability. The full dataset consists five archival observations, split into two XMM-Newton, NuSTAR and one Chandra observation, plus dedicated monitoring campaigns. campaigns were performed Swift-XRT NuSTAR, containing each. simultaneous using self-consistent torus models, deriving geometric properties as well obscuration along line...
Abstract We present the analysis of 15 X-ray observations Mrk 477, a nearby Seyfert 2 active galactic nucleus, with objective to monitor its obscuring column density variability. The full data set consists five archival observations, split into two XMM-Newton, NuSTAR and one Chandra observation, plus dedicated monitoring campaigns. campaigns were performed Swift-XRT NuSTAR, containing each. simultaneous using self-consistent torus models, deriving geometric properties as well obscuration...
Most of the supermassive black holes in Universe accrete material an obscured phase. While it is commonly accepted that ``dusty torus'' responsible for nuclear obscuration, its geometrical, physical, and chemical properties are far from being properly understood. In this paper, we take advantage multiple X-ray observations taken between 2007 2020, as well optical to infra-red (FIR) NGC 6300, a nearby (z=0.0037) Seyfert 2 galaxy. The goal project study emission obscuring medium, through...
Abstract Nuclear rings are excellent laboratories for studying intense star formation. We present results from a study of nuclear star-forming in five nearby normal galaxies the Star Formation Radio Survey (SFRS) and four local LIRGs Great Observatories All-sky LIRG at sub-kiloparsec resolutions using Very Large Array high-frequency radio continuum observations. find that ring formation (NRSF) contributes 49%–60% total LIRGs, compared to 7%–40% galaxies. characterize 57 individual regions...
We present the analysis of multiepoch observations a set 12 variable, Compton-thin, local ( z < 0.1) active galactic nuclei (AGN) selected from 100-month BAT catalog. analyzed all available X-ray data Chandra , XMM-Newton and NuSTAR adding up to total 53 individual observations. This corresponds between three seven per source, probing variability timescales few days ∼20 yr. All sources have at least one observation, ensuring high-energy coverage, which allowed us disentangle line-of-sight...
Constraining the primary growth channel of supermassive black holes (SMBH) remains one most actively debated questions in context cosmological structure formation. Owing to expected connection between SMBH spin parameter evolution and accretion merger history individual holes, population measurements offer a rare observational window into cosmic growth. As today, common method for estimating relies on modeling relativistically broaden atomic profiles reflection spectrum observed X-rays. In...
We use the CN/CO intensity ratio to obtain dense gas fraction, $f_{\text{dense}}$, for a sample of 16 Ultra-luminous and Luminous Infrared Galaxies compare $f_{\text{dense}}$ with suite global galaxy properties. find significant correlation between star formation rate calculated using both infrared luminosities radio continuum, although there is scatter in each relation. no trend or peak merger stage. X-ray luminosity; however, becomes when we measure at location emission. Our interpretation...
Abstract We use the CN/CO intensity ratio to obtain dense gas fraction, f , for a sample of 16 ultraluminous and luminous infrared (IR) galaxies compare with suite global galaxy properties. find significant correlation between star formation rate calculated using both IR luminosities radio continuum, although there is scatter in each relation. no trend or peak merger stage. X-ray luminosity; however, becomes when we measure at location emission. Our interpretation that co-localized strong...
X-ray polarimetric observations from the Imaging Polarimeter Explorer ( IXPE ) is an excellent tool for probing geometry and dynamics of emitting corona in active galactic nuclei (AGNs). This work aims to investigate Seyfert 2 AGN, NGC 2110, using its first observation with conducted over a net exposure 554 ks beginning on October 16, 2024. We performed model-independent analysis 2–8 keV estimate polarization properties 2110. Furthermore, we spectral spectro-polarimetric analyses combining...
Context. We present the broad-band X-ray spectral analysis (0.6–50 keV) of seven Compton-thick active galactic nuclei (CT-AGN; line-of-sight (LOS) column density > 10 24 cm −2 ) candidates selected from Swift -BAT 100 month catalogue using archival NuSTAR data. Aims. aim to obtain a complete census heavily obscured AGN in local Universe ( z < 0.05). Methods. This work is continuation ongoing research Clemson-INAF group classify CT-AGN at redshift 0.05 physically motivated torus models....
Blazars in elliptical hosts have a population of red giants surrounding their jet. These stars can carry large wind-blown bubbles into the jets, leading to gamma-ray emission through bubble-jet interactions. We study interaction dynamics and produced when formed by giant winds penetrate jet blazar an galaxy. First, we characterized masses penetration rates wind that enter Then, dynamical evolution these under impact was analysed analytically numerically, radiation losses particles...
ABSTRACT Blazars display variable emission across the entire electromagnetic spectrum, with time-scales that can range from a few minutes to several years. Our recent work has shown sample of five blazars exhibit hints periodicity global significance ${\gtrsim}2\, \sigma$ at γ-ray energies, in 0.1 GeV &lt; E 800 GeV. In this work, we study their multiwavelength emission, covering X-ray, ultraviolet, optical, and radio bands. We show three these present similar periodic patterns optical...
Abstract Active galactic nuclei are powered by accreting supermassive black holes, surrounded a torus of obscuring material. Recent studies have shown how the structure, formerly thought to be homogeneous, appears “patchy”: detection variability in line-of-sight hydrogen column density, fact, matches description an obscurer with complex structure made clouds different density. In this work, we perform multiepoch analysis X-ray spectra Seyfert 2 galaxy NGC 7479 order estimate its properties,...
The central regions of galaxies are complex environments, rich in evolved and/or massive stars. For hosting an active galactic nucleus (AGN) with jets, the interaction jets winds stars within can lead to particle acceleration, and extended high-energy emitting regions. We compute non-thermal emission produced by jet flow shocked stellar on scale, far from jet-star direct region. First, prescriptions for relevant populations different types obtained. scenarios adopted include their dominated...