Stefano Marchesi✉
Stefano Marchesi is an Adjunct Professor at Clemson University and also holds a Researcher in Astrophysics at the University of Bologna, Italy. His research focuses on accreting supermassive black holes in the center of galaxies, and particularly on the most obscured among these sources.
He obtained his PhD in Astronomy in 2015 at the University of Bologna, Italy. During his PhD years, he was a visiting graduate student at Dartmouth College (Hanover, NH, USA), the Yale Center for Astronomy and Astrophyisics (New Haven, CT, USA) and at the Center for Astrophysics | Harvard & Smithsonian (Cambridge, MA, USA). After graduating, he was a PostDoctoral Fellow at Clemson University (SC, USA), from 2016 to 2019.
Núria Torres-Albà✉
Núria Torres-Albà is a GECO Fellow at the University of Virginia, in Charlottesville, USA. Her research is focused on active galactic nuclei (AGN) and their surroundings across the electromagnetic spectrum. In particular, she has worked on X-ray analysis of luminous infrared galaxies (LIRGs) and Compton-thick AGN in the local Universe, as well as the modeling of gamma-ray emission produced in the interactions between AGN jets and obstacles. Currently, her main focus is on studied of AGN obscuration variability.
She obtained her PhD in 2019 at the University of Barcelona, in Spain, and then moved to Clemson University for her first postdoc.
Marco Ajello
Marco Ajello is a professor at Clemson University, (Clemson, USA). He is an Astrophysicist with strong interests in astro-particle physics and cosmology. His interests lie in the evolution of super-massive black holes and galaxies, the generation of truly diffuse backgrounds (from infrared to gamma rays), high-energy transients and high-energy sources in general. Recently, he turned his attention to the evolution of the extragalactic background light and the role of the first stars during the epoch of re-ionization. He works with a number of instruments and telescopes both from the ground and in space, but his all-time favorites are the NASA missions Fermi, Swift, and NuSTAR.
Isaiah Cox
Isaiah Cox is a sixth year graduate student at Clemson University. His research involves the spectral modeling of X-ray data. In particular, he is interested in obscuration variability in AGN spectra and how this can probe the geometry and dynamics of the obscuring material. This has implications for the coevolution of the supermassive black hole and the host galaxy.
He obtained his bachelor’s degrees in Physics and Mathematics at East Tennessee State University in 2020. He joined Dr. Ajello’s group in 2021.
Vittoria Elvezia Gianolli
Vittoria Elvezia Gianolli is a postdoctoral fellow at Clemson University, where she joined the high-energy astrophysics group in 2025. Her research focuses on high-energy phenomena around supermassive black holes and accreting systems, in particular active galactic nuclei (AGN). She uses X-ray spectroscopy to study the accretion, emission, and ejection processes in AGN, combining it with X-ray polarimetry to investigate the geometry and physical conditions of X-ray coronae. Her work also explores the properties and variability of obscuring media in AGN, including cases where X-ray and optical classifications diverge.
She obtained dual Ph.D. degrees in Astrophysics and Diluted Media from Université Grenoble Alpes (France) and in Physics from Roma Tre University (Italy) in 2024.
Indrani Pal
Indrani Pal is a postdoctoral fellow at Clemson University since 2024. Her primary area of research is focused on characterizing the X-ray corona in radio-quiet Active Galactic Nuclei (AGN), namely Seyfert 1 and Seyfert 2 galaxies. This is accomplished by performing spectral, timing, and polarimetric analysis of X-ray data from the Nuclear Spectroscopic Telescope Array (NuSTAR), XMM-Newton, Chandra, Swift-XRT and the X-ray polarization observations from the Imaging X-ray Polarimetry Explorer (IXPE). She is interested in investigating the properties of obscuring material around Compton Thick (CT) sources by modeling and analyzing their torus properties.
Indrani earned her Ph.D. in High Energy Astrophysics from the Indian Institute of Astrophysics in 2024. Click here to visit her personal website
Andrealuna Pizzetti
Andrealuna Pizzetti is a second year graduate student of Physics and Astronomy department at Clemson University in Clemson, USA. Her research focuses on X-ray analysis and modeling of obscured active galactic nuclei (AGN) and on the study of the variability of their tori properties over time using different models.
She obtained her Bachelor’s degree in Astronomy at the University of Bologna in 2018 and she joined Dr. Ajello group in 2020.
Dhrubojyoti Sengupta
Dhrubojyoti Sengupta is a postdoctoral researcher based at CNRS in Gif-sur-Yvette, in association with AIM at CEA Paris-Saclay, France. He completed his Ph.D. in Astrophysics at the University of Bologna in 2024. Following his Ph.D., he worked with the University of Maryland, Baltimore County, and NASA Goddard Space Flight Center on projects related to AGN variability.
At CNRS, he is currently studying X-ray emission from local dwarf galaxies. His broader research focuses on obscured and changing-look AGN in the local Universe, using multi-epoch X-ray observations and mid-infrared SED modeling. Combining multi-wavelength data spanning the X-ray, infrared, and optical/UV bands he explore s AGN variability, the structure of the dusty torus, and the physical connection between supermassive black holes and their host galaxies.
Ross Silver
Ross Silver is a postdoctoral researcher at the NASA Goddard Space Flight Center (GSFC). His research revolves around active galactic nuclei and uses both surveys and targeted observations to study them. He has analyzed over 2 Ms of NuSTAR and XMM-Newton observations of the JWST North Ecliptic Pole (NEP) Time Domain Field (TDF) in an effort to understand AGN variability and the AGN obscured fraction. Additionally, he has used machine learning with X-ray and Infrared data to identify specific targets which bare the most promise of being heavily obscured AGN.
He obtained his undergraduate degree in Physics at Gettysburg College in Gettysburg, USA. Ross joined Dr. Marco Ajello’s group in 2018 and graduated from Clemson in 2023. He continues his work with the Clemson-INAF team to this day.
Xiurui Zhao
Xiurui Zhao was a PhD student of Physics and Astronomy department at Clemson University (Clemson, USA) graduated in Aug. 2021. He joined Dr. Ajello’s group in 2017. He obtained his Bachelor degree in Physics at Lanzhou University (Lanzhou, China) in 2016. Now he is a postdoctoral research Fellow at the Center for Astrophysics | Harvard & Smithsonian (Cambridge, USA). His research focus on the physics of the active galactic nuclei (AGN) in X-rays, both in terms of obscuration and accretion. His most recent work focuses on using flux variability to constrain the size of the X-ray AGN corona. Here is his Personal Website.
Previous Members
Alberto Traina
Alberto Traina is a PostDoctoral Fellow at the Italian National Institute for Astrophysics in Bologna (INAF-OAS). His main interest is in extragalactic astrophysics of small and large galaxy samples, in the near and distant Universe. In his works he makes use of synergies between different type of observations in different parts of the electromagnetic spectrum (e.g., infrared and X-ray) to investigate both the physical and statistical properties of AGN samples.
He obtained his Bachelor degree in Astronomy in 2018 and a Master degree in Astrophysics and Cosmology in 2020, both at the University of Bologna.
