Assessing the Suitability of H4RG Near Infrared Detectors for Precise Doppler Radial Velocity Measurements

TL;DR

This paper evaluates the noise characteristics of H4RG HgCdTe detectors for near-infrared Doppler radial velocity measurements, providing insights into their suitability for high-precision astronomical spectroscopy.

Contribution

It offers a comprehensive noise analysis of H4RG detectors using simulations, informing their potential use in precise NIR RV instruments.

Findings

Quantified noise sources affecting RV precision.

Assessed impact of detector nonlinearities and dark current.

Provided implications for instrument noise floors.

Abstract

At wavelengths longwards of the sensitivity of silicon, hybrid structured mercury-cadmium-telluride (HgCdTe) detectors show promise to enable extremely precise radial velocity (RV) measurements of late-type stars. The most advanced near infrared (NIR) detector commercially available is the HAWAII series (HxRG) of NIR detectors. While the quantum efficiency of such devices has been shown to be approx ninety percent, the noise characteristics of these devices, and how they relate to RV measurements, have yet to be quantified. We characterize the various noise sources generated by H4RG arrays using numerical simulations. We present recent results using our end-to-end spectrograph simulator in combination with the HxRG Noise Generator, which emulates the effects of read noise, parameterized by white noise, correlated and uncorrelated pink noise, alternating column noise, and picture frame noise. The effects of nonlinear pixel response, dark current, persistence, and interpixel capacitance (IPC) on RV precision are also considered. Our results have implications for RV error budgets and instrument noise floors that can be achieved with NIR Doppler spectrographs that utilize this kind of detector.