UR: The Silence of the Lambda: Tracking the Disruption of Satellites around Milky Way-Mass Galaxies in Cosmological Simulations

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Nguyễn Bình (Binh Nguyen)

University of Arizona

Binh Nguyen (Nguyễn Bình) is a senior undergraduate pursuing a dual bachelor’s degree in Astronomy and Linguistics at the University of Arizona. Their main interests are in the dark matter profiles of dwarf galaxies and what they can reveal to us about the evolution of galaxies in the universe. Outside astronomy, Binh is a published poet and translator, specialized in literary and historical works from Vietnam’s dynastical era.

Many Milky Way-mass galaxies have been observed to be surrounded by faint stellar halos that extend beyond the main disk. These are the remnants of smaller satellite galaxies that once orbited the larger galaxy, but were disrupted by its tidal forces. Using the FOGGIE cosmological hydrodynamic simulations, we track the evolution of a Milky Way-mass galaxy and its satellites over cosmic time to understand when the tidal disruption of the satellites begins, and whether it leaves any detectable evidence in the present-day stellar halo of the host galaxy. Our analysis shows that while nearly all early-infalling (before z = 1) satellites are completely disrupted by the present, those that fall in after z = 1 may retain a large fraction of their stellar populations, along with a dark matter subhalo that is identifiable by the halo-finder at the present. We also discover a match in time between the peaks in mass loss from the satellites and the peaks in tidal force experienced by these satellites from the central Milky Way-mass galaxy (Figure 1). This suggests that most of the satellites are not undergoing significant pre-processing in other groups prior to falling in.

Figure 1: Plot showing the total mass of an infalling satellite galaxy before (solid blue line) and after (dotted blue line) entering the more massive host galaxy. The pink peaked line show the tidal force experienced by the satellite. You can see that each peak corresponds with a big drop in satellite mass! Image Credit: Binh et al.

This work will be presented as iPoster 407.06 on Thursday at AAS241!

Astrobite edited by: Isabella Trierweiler

Featured Image Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration

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