Order-by-order Modeling of Exoplanet Radial Velocity Data
Abstract
Precise radial velocity (RV) measurements are a crucial tool for exoplanet discovery and characterization. Today, the majority of these measurements are derived from Echelle spectra in the optical wavelength region using cross-correlation techniques. Although for certain stars these approaches can produce RVs with sub-1 m~s measurement errors, for many others, we are now in a regime where instrumental precision is fundamentally below the intrinsic RV variations of the star that result from astrophysical processes that can be correlated in both time and wavelength. We explore new methods for measuring exoplanet orbital parameters that take advantage of the fact that RV data sets are fundamentally multi-wavelength. By analyzing NEID extremely precise radial velocity (EPRV) data of three known exoplanet systems, we show that fitting a single Keplerian model to multi-wavelength RVs can produce a factor of 1.5 -- 6.8 better uncertainties compared to fitting RVs that are derived from a weighted average across wavelength.
Cite
@article{arxiv.2510.16139,
title = {Order-by-order Modeling of Exoplanet Radial Velocity Data},
author = {Zachary Langford and Cullen Blake and Samuel Halverson and Eric B. Ford and Suvrath Mahadevan and Mark R. Giovinazzi and Arvind F. Gupta and Paul Robertson and Jaime A. Alvarado-Montes and Chad F. Bender and Daniel M. Krolikowski and Arpita Roy and Christian Schwab and Ryan C. Terrien and Jason T. Wright},
journal= {arXiv preprint arXiv:2510.16139},
year = {2025}
}
Comments
14 pages, 6 figures, 2 tables. Corrected manuscript accepted to Publications of the Astronomical Society of the Pacific. Correction to Figure 3. The code used in this work is available at https://github.com/langfzac/obo-paper