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Using Infrared Surface Brightness Fluctuation Measurements as a Tool to Probe Stellar Characteristics
  • Zachary Gibson, Utah State University
I present new measurements using the near-infrared Surface Brightness Fluctuations (SBF) distance measurement method for the F110W (J110) and F160W (H160) bandpasses of Hubble Space Telescope’s (HST) Wide Field Camera 3 Infrared Channel (WFC3/IR), and use the measurements of absolute fluctuation magnitude to compare to stellar population models. The galaxies studied are 16 early-type galaxies from the Virgo and Fornax clusters observed with WFC3/IR. The calibrations utilize data from these 16 galaxies and are provided as functions of both the optical (g475−z850) and near-infrared (J110−H160) colors. HST is a remarkably powerful tool for measuring extragalactic distances. Comparing data from this sample of 16 galaxies to stellar population models reveals interesting population differences that cause the calibration scatter to increase for bluer dwarf galaxies. Comparing our data to single-burst population models reveals the anticipated result that redder early-type galaxies are composed of old, metal-rich populations, while the bluer dwarf elliptical counterparts conatain a wider range of ages and lower metallicity. The gradients in IR color are revealed by radial SBF measurements to be largely an age effect. The bluer dwarfs have an opposite trend to those of redder giant ellipticals with bluer dwarfs having their youngest populations in the center, getting older moving out from the center and the opposite trend for their redder counterparts. Because the population varies much more in bluer galaxies, distance measurements in the near-IR should be limited to red early-type galaxies.
  • SBF,
  • Surface Brightness Fluctuations,
  • Stellar Characteristics,
  • Cosmology,
  • Distance Scale
Publication Date
Spring May, 2016
Citation Information
Zachary Gibson. "Using Infrared Surface Brightness Fluctuation Measurements as a Tool to Probe Stellar Characteristics" (2016)
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