Isaiah Santistevan, Ph.D.

I recently submitted my 4th first-author paper, which is focused on comparing the orbits of satellite galaxies around MW-mass hosts in the FIRE simulations, to a static potential model of the same hosts at z = 0, to better understand the pros and cons of this commonly used orbit modeling technique. Check the paper out here!

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We model the MW-mass hosts with an NFW profile for the halo, and two exponential disks for the inner disk/bulge region, and outer disk. A few of the main takeaways include:

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• Most of the mass growth of the host occurred at small distances (< 50 kpc), opposite to dark matter only results, which experience very little growth at small radii.

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• Orbital energy and angular momenta are not conserved very well throughout a satellite's history, and vary by 25% going back 1.6 - 4.7 Gyr ago.

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• Most orbit properties are conserved to within ~10% when averaged across the entire population, but have large uncertainties. Properties that happened recently, like the most recent pericenter distance, often have smaller uncertainties than properties that happened farther back in time, like the satellite infall time.