2025/11/18 by von Fellenberg, Sebastiano D., Michail, Joseph M., Willner, S. P. +10
Physics and Astronomy · #Astrophysics and Star Formation Studies #Astrophysical Phenomena and Observations #Galaxies: Formation, Evolution, Phenomena
paper · doi:10.48550/arxiv.2511.14850
We determine the mid-infrared (MIR, ∼5~μm--22~μm) extinction towards the Galactic center using MIRI/MRS integral field unit (IFU) observations of the central 3''×3'' region (near 5~μm) to 7''×7'' region (near 22~μm). To measure the MIR extinction, we employ two approaches: modeling the intrinsic-to-observed dust thermal spectrum and assessing the differential extinction between hydrogen recombination lines. Expanding on prior work, we directly model the dust-opacity distribution along the line of sight, and we make available a Python code that provides a flexible tool for deriving intrinsic dust emission spectra. We confirm the spatial variability of extinction across the field, demonstrating that dusty sources--such as IRS~29N--exhibit higher local extinction. Furthermore, we verify the absence of PAH emission features in the Galactic center MIR spectra. Using the two complementary methods, we derive a refined ``best guess'' MIR extinction law for Sgr A* and the surrounding Galactic-center region. By applying the extinction law to a MIR flare measurement discussed in a companion paper Michail et al. 2025, we estimate a residual relative extinction uncertainty for the short MIRI/MRS grating on the order of 0.2~mag from ∼5 to ∼18~μm and ∼0.3~mag from ∼18 to ∼22~μm, consistent with our uncertainty estimate.