Multiline Spectropolarimetric Evidence for Photospheric Reconnection in Ellerman Bombs from DKIST

Abstract

Ellerman bombs (EBs) are compact, transient brightenings observed in the wings of Balmer lines and are believed to result from magnetic reconnection in the lower solar atmosphere. However, their signatures have rarely been observed simultaneously in multiple spectral lines sensitive to the lower atmosphere. We present novel high-resolution multiline spectropolarimetric observations of EBs obtained with the Visible Spectro-Polarimeter (ViSP) on the Daniel K. Inouye Solar Telescope (DKIST). Simultaneous observations reveal remarkable H$β$ wing enhancements extending up to $\sim$4~Å from the line core and intensity enhancements in the \ion{Na}{1}~D1 and \ion{Fe}{1}~6302 lines. Using multiline non-LTE inversion of the \ion{Na}{1} and \ion{Fe}{1} lines, we infer localized photospheric heating of up to $ΔT\sim$800~K, accompanied by weak upflows and downflows at EB locations. Comparing with synthetic observables from Bifrost radiative-MHD simulations, we find that synthetic spectra reproduce the observed H$β$ and \ion{Na}{1}~D wing enhancements and yield atmospheric stratification broadly consistent with those inferred from the non-LTE inversion. This study provides strong evidence that EBs are driven by photospheric magnetic reconnection below the temperature-minimum region, and places new constraints on the realistic EB models and small-scale energy release in the lower solar atmosphere.