Camille Poitras

Université Laval

Camille Poitras is a first-year master’s student at Université Laval under the supervision of Dr. Marie-Lou Gendron-Marsolais. Her research focuses on the filamentary nebulae associated with the brightest cluster galaxies (BCGs), with a particular emphasis on M87, in order to better understand the dynamics of these structures. In parallel, she is finalizing a project initiated during her undergraduate research internship, conducted under the primary supervision of Pr. René-Pierre Martin (U. Hawaii), in collaboration with Prs L. Drissen, C. Robert, and H. Martel (U. Laval). This work investigates star formation and chemical enrichment in two well-known galaxies involved in a relatively recent collision: NGC 2207 and IC 2163.

Using data cubes targeting the main emission lines in the visible spectrum, obtained with the SITELLE/CFHT Fourier transform imaging spectrometer, Camille and her supervisors analyzed the physical properties of many HII region complexes within NGC 2207 / IC 2163. Their optimized detection method has resulted in an order-of-magnitude increase in the number of detected HII regions compared to previous studies. Several properties were extracted, and then, for the first time, the complexes were separated from the overlap region between the two galaxies based on criteria involving emission line ratios and extinction. This approach enabled a detailed analysis of the galaxies both individually and globally, leveraging BPT diagrams, metallicity gradients, luminosity functions, and system kinematics to explore how interactions influence these parameters.

In addition to observations, numerical simulations were developed using GCD+ (Galactic Chemo-Dynamics +), an algorithm that combines N-body modeling with smoothed particle hydrodynamics. This model accounts for the intrinsic gravity of dark matter disks, star formation, supernova feedback, metal enrichment, diffusion, and radiative cooling. These simulations aim to reproduce the system’s main morphological structures and model its chemical evolution throughout the interaction, providing insights into the current state of observations. A paper summarizing this work is currently in preparation to be submitted to MNRAS.

Left panel: SITELLE image of the NGC 2207/IC 2163 system, created using deep SN2 and SN3 images combined with the Hα map – the primary emission line associated with HII regions. Both galaxies are identified in the image. Right panel: A zoomed-in view of the HII region complex separation in the overlap region, highlighted by the colored areas. Complexes classified as part of IC 2163 are shown in orange, while those assigned to NGC 2207 appear in blue. Hatched regions indicate complexes with ambiguous classifications: the color represents the manual classification, whereas the hatching signifies that the unsupervised machine learning method assigns them to the other galaxy.