Julie Hlavacek-Larrondo

Jorge Barrera Barrera-Ballesteros

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Current Students

Independent visiting researcher - National Autonomous University of Mexico

Mathieu Marquis

Master's Research - Université de Montréal

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Olivia Pereira

Master's Research - Université de Montréal

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Marine Prunier

PhD - Université de Montréal

Benjamin Vigneron

PhD - Université de Montréal

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Publications

The Cluster Evolutionary Reference Ensemble at Low- <i>z</i> (CEREAL) Sample of Galaxy Clusters. I. X-Ray Morphological Properties and Demographics

L. V. White

Michael McDonald

S. J. Allen

Marshall W. Bautz

Michael S. Calzadilla

G. P. Garmire

Ralph Kraft

Adam B. Mantz

Taweewat Somboonpanyakul

Alexey Vikhlinin

Abstract With rapid improvements in the assembly of large samples of galaxy clusters, we are approaching the ability to study clusters at z … (see more)≳ 2. Evolutionary studies comparing these distant clusters to the clusters in our local Universe depend heavily on the reliability of low-redshift cluster samples, most of which are subject to X-ray selection effects, biasing them to relaxed, cool-core clusters. Here, we introduce the Cluster Evolutionary Reference Ensemble at Low- z (CEREAL) sample, composed of Chandra X-ray observations of 169 galaxy clusters that have been selected from the Planck Sunyaev–Zel’dovich catalog. CEREAL has a simple and well-understood selection function, spans an order of magnitude in mass at z ∼ 0.15, and has uniform, high-resolution X-ray follow-up. We present the full sample and provide results based on X-ray surface brightness properties, finding significantly more non-cool-core systems than in X-ray-selected samples. We use surface brightness concentration ( c SB ) as a proxy for cool-core strength and centroid shift ( w ) to measure dynamical state. Over the full sample, we find a cool-core ( c SB > 0.075) fraction of 0.3 9 − 0.04 + 0.04 , a strong cool-core ( c SB > 0.155) fraction of 0.1 3 − 0.03 + 0.03 , and a dynamically relaxed ( w < 0.01) frac

2026-03-26

Astrophysical Journal (published)

SPT-CL J0417–4748: A Deep Chandra Study of a Relaxed Galaxy Cluster without Central Star Formation

Taweewat Somboonpanyakul

A. Mantz

S. W. Allen

Anthony M. Flores

R. Glenn Morris

Haley R. Stueber

L. E. Bleem

B. Floyd

Keunho Kim

Abstract We present an in-depth Chandra X-ray analysis of the galaxy cluster SPT-CL J0417−4748 (hereafter SPT J0417) at z = 0.58 with a fo… (see more)cus on its thermodynamic properties and the apparent absence of central star formation. Utilizing a total Chandra exposure of 103 ks, we find that the large-scale X-ray morphology is consistent with a dynamically relaxed cool-core system. The intracluster medium shows a central density of 0.08 ± 0.01 cm −3 , a central pseudoentropy of 2 6 − 5 + 6 keV cm 2 , and a central cooling time of 51 5 − 75 + 96 Myr, values typical of massive cool-core clusters. Despite these conditions, no evidence of recent or ongoing star formation is detected in the brightest cluster galaxy (BCG). Spectral energy di

2026-03-10

Astrophysical Journal (published)

Mapping the Perseus galaxy cluster with XRISM

Congyao Zhang

Irina Zhuravleva

Hannah McCall

Elena Bellomi

Nhut Truong

John ZuHone

Eugene Churazov

Megan E. Eckart

Yutaka Fujita

Yuto Ichinohe

Maxim Markevitch

Kyoko Matsushita

François Mernier

Eric D. Miller

Koji Mori

Hiroshi Nakajima

Anna Ogorzalek

Frederick S. Porter

Ayşegül Tümer … (see 3 more)

Shutaro Ueda

Norbert Werner

Annie Heinrich

We present extended gas kinematic maps of the Perseus cluster based on a combination of five new XRISM/Resolve pointings observed in 2025 wi… (see more)th four performance verification datasets from 2024, totaling a net exposure of 745 ks. To date, Perseus remains the only cluster that has been extensively mapped out to ≃0.7 r 2500 by XRISM/Resolve, while simultaneously offering sufficient spatial resolution to resolve gaseous substructures driven by mergers and active galactic nucleus (AGN) feedback. Our observations cover multiple radial directions and a broad range of dynamical scales, enabling us to characterize the kinematic properties of the intracluster medium up to a scale of ∼500 kpc. In the measurements, we detected high-velocity dispersions (≃300km s −1 ) in the eastern region of the cluster that are spatially coincident with the extended X-ray surface brightness excess and correspond to a nonthermal pressure fraction of ≃7 − 13%. The velocity field outside the AGN-dominant region can be effectively described by a single, large-scale kinematic driver based on the velocity structure function, which statistically favors an energy injection scale of at least a few hundred kpc. The estimated turbulent dissipation energy is comparable to the gravitational potential energy released by a recent merger, implying a significant role of turbulent cascade in the merger energy conversion. In the bulk velocity field, we observed a dipole-like pattern along the east-west direction with an amplitude of ≃ ± 200 − 300 km s −1 , indicating rotational motions induced by the recent merger event. This feature constrains the viewing direction to ≃30° −50° relative to the normal of the merger plane. Our hydrodynamic simulations suggest that Perseus has experienced at least two energetic mergers since redshift z ∼ 1, the most recent of which is associated with the radio galaxy IC310, in agreement with recent SRG/eROSITA findings. This study showcases exciting scientific opportunities for future missions with high-resolution spectroscopic capabilities (e.g., HUBS, LEM, and NewAthena).

2026-01-18

Astronomy & Astrophysics (published)

Observations of AGN-driven feedback: dynamics and ionization of the filaments in M87

Camille Poitras

Marie-Lou Gendron-Marsolais

Valeria Olivares

Yuan Li

Adrien Picquenot

Aurora Simionescu

Matteo Fossati

Alessandro Boselli

Laura Hermosa Muñoz

Sara Cazzoli

Annabelle Richard-Laferrière

We present a comprehensive kinematic and ionization analysis of the warm ionized filaments (…

2025-12-18

arXiv (preprint)

Disentangling AGN Feedback and Sloshing in the Perseus Cluster with XRISM: Insights from Simulations

Elena Bellomi

John A. ZuHone

Nhut Truong

Irina Zhuravleva

Rainer Weinberger

Christoph Pfrommer

Congyao Zhang

Annie Heinrich

Mateusz Ruszkowski

Brian McNamara

M. Gendron-Marsolais

Benjamin Vigneron

High-resolution X-ray spectroscopy with XRISM has revealed complex, non-monotonic velocity dispersion profiles in the Perseus cluster, point… (see more)ing to a complex interplay between at least two physical drivers of motions caused by dynamical processes within the intracluster medium (ICM). To further explore this conclusion, we perform a suite of idealized, controlled simulations targeting the relative roles of merger-induced sloshing and active galactic nucleus (AGN) feedback. Our models systematically isolate and combine these mechanisms to predict observable velocity profiles and X-ray line shapes, providing direct comparison to XRISM and Hitomi data. We find that neither sloshing nor AGN activity alone can reproduce the observed velocity dispersion profile; only their combined action matches the elevated dispersions both at the cluster core and outskirts. Power-spectrum analysis reveals distinct spatial signatures: sloshing generates large-scale coherent motions, while AGN feedback injects turbulence and broadens the velocity spectrum at small scales, especially in the core. By forward-modeling spectral line profiles, we show how these dynamics imprint unique observational signatures on X-ray emission. Our results underscore the necessity of accounting for both large-scale and small-scale drivers of gas motions in the ICM when interpreting high-resolution spectroscopic data, and provide guidance for the analysis of forthcoming XRISM observations.

2025-12-13

arXiv (preprint)

Massive Extremely High-velocity Outflow in the Quasar J164653.72+243942.2

Paola Rodríguez Hidalgo

Hyunseop Choi (최현섭)

Patrick B. Hall

Karen M. Leighly

Liliana Flores

Mikel M. Charles

Cora DeFrancesco

Laurence Perreault-Levasseur

We present the analysis of one of the most extreme quasar outflows found to date in our survey of extremely high velocity outflows (EHVO). J… (see more)164653.72+243942.2 (z ~ 3.04) shows variable CIV1548,1551 absorption at speeds larger than 0.1c, accompanied by SiIV, NV and Lya, and disappearing absorption at lower speeds. We perform absorption measurements using the Apparent Optical Depth method and SimBAL. We find the absorption to be very broad (Δv ~35,100 km/s in the first epoch and ~13,000 km/s in the second one) and fast (vmax ~ -50,200 km/s and -49,000 km/s, respectively). We measure large column densities (

2025-09-03

The Astrophysical Journal (published)