Noise Reduction Methods for Large-scale Intensity-mapping Measurements with Infrared Detector Arrays

TL;DR

This paper presents advanced noise reduction techniques for large-scale intensity mapping using infrared detector arrays, enabling stable measurements crucial for upcoming space missions like SPHEREx.

Contribution

It introduces a specialized low-noise ASIC amplifier and analysis methods that effectively suppress 1/f noise in large infrared detector arrays for intensity mapping.

Findings

Achieved residual 1/f noise near photon noise levels for scales <30 arcminutes.

Designed and fabricated a novel low-noise ASIC Video8 amplifier.

Developed a noise model to optimize detector and amplifier parameters.

Abstract

Intensity mapping observations measure galaxy clustering fluctuations from spectral-spatial maps, requiring stable noise properties on large angular scales. We have developed specialized readouts and analysis methods for achieving large-scale noise stability with Teledyne 2048$\times$2048 H2RG infrared detector arrays. We designed and fabricated a room-temperature low-noise ASIC Video8 amplifier to sample each of the 32 detector outputs continuously in sample-up-the-ramp mode with interleaved measurements of a stable reference voltage that remove current offsets and $1/f$ noise from the amplifier. The amplifier addresses rows in an order different from their physical arrangement on the array, modulating temporal $1/f$ noise in the H2RG to high spatial frequencies. Finally, we remove constant signal offsets in each of the 32 channels using reference pixels. These methods will be employed in the upcoming SPHEREx orbital mission that will carry out intensity mapping observations in near-infrared spectral maps in deep fields located near the ecliptic poles. We also developed a noise model for the H2RG and Video8 to optimize the choice of parameters. Our analysis indicates that these methods hold residual $1/f$ noise near the level of SPHEREx photon noise on angular scales smaller than $\sim30$ arcminutes.