MISFIT: Misaligned Kinematic Fitting

Description

misfit is a package for the 2D fitting and 1D modeling of kinematic observations taken with galaxy-slit misalignments, using structural information derived from spatially-resolved ancillary imaging to model the effects of the misalignments.

Simple analytic profiles for galaxy rotation curves, velocity dispersions, and light intensity distributions are used to construct 3D spatial models (including line-of-sight projection). These 3D models are used to construct a 4D model of the galaxy over three spatial and one spectral dimension.

For 2D fitting, this model is then collapsed along the line-of-sight, convolved with the PSF, integrated over the slit spatial direction, and finally convolved in the spectral direction by the instrumental resolution.

When interpreting spatially unresolved 1D line profiles, the 3D rotation, dispersion and intensity models are used to derive a correction from an observed line velocity dispersion to an intrinsic RMS velocity (combining both rotation and random dispersion). These correction factors depend on the galaxy structure and orientation relative to the slit, and also require the assumption of a fixed ratio of ordered-to-disordered motion ($V/σ$).

This code was developed for the analysis of Keck/MOSFIRE spectra from MOSDEF survey, and used in the analysis presented in Price et al. (2016) and Price et al. (2020). Modifications have been made in prepartion for extending this code for use with JWST/NIRSpec MSA spectra.

Full details about this code can be found in Appendices A & B of Price et al. (2016). Testing of the 2D fitting algorithm is presented in Appendix A of Price et al. (2020).

Dependencies

• python (version >= 3.6)
• numpy
• scipy
• matplotlib
• numba
• astropy
• emcee
• lmfit
• acor
• corner
• dill

Acknowledgement

If you use misfit in a publication, please cite Price et al., 2016, ApJ 819 80 (presenting the methodology) and Price et al., 2020, ApJ 894 91 (testing of the 2D fitting).

License

This project is Copyright (c) Sedona Price and licensed under the terms of the BSD 3-Clause license. See the LICENSE for more information.