The ensemble emission from all sources outside of the Milky Way is known as the extragalactic background light (EBL). At optical and near-infrared (NIR) wavelengths, the EBL is primarily stellar emission tracing back to the Epoch of Reionization (EOR) at redshifts z > 6 when the first luminous structures formed. Given the large uncertainties in our understanding of the EOR, measurements of the EBL provide an important probe of the galaxies that were responsible for reionization. Direct observations of the EBL are challenging due to contamination from bright local foregrounds. In recent years, intensity mapping has emerged as a successful technique in which EBL fluctuations are measured on large angular scales where the known foreground contributions are minimal or well-modeled. To isolate the signals from EOR structures, intensity mapping can be applied to optical and NIR data to probe rest-frame UV emission in galaxies at z > 6.

Multiple intensity mapping studies including the first Cosmic Infrared Background ExpeRiment (CIBER-1) have found that the optical/NIR EBL intensity and its large-scale fluctuations exceed predictions from galaxy models. The excess is above EOR level and also persists at wavelengths < 1 μm where we do not expect to see reionization signals. To explain the excess, a number of astrophysical sources have been proposed including intra-halo light (IHL) from low-mass stars at the outskirts of galaxies. Observations at 1.1 and 1.8 μm from CIBER-1 second and third flights suggest that the excess can be best described by a level of IHL comparable to the integrated light from known galaxy populations. While this result is intriguing, given CIBER-1 spectral coverage, the IHL and EOR components could not be distinguished, prompting interest in a new mission, CIBER-2.

CIBER-2 is designed to disentangle the IHL and EOR signals using broader spectral coverage from 0.5 - 2.0 μm in six wavebands and larger light-gathering power. The wavebands are selected to provide 21 auto- and cross-spectra to probe the Lyman break that can distinguish EOR contributions from low-redshift foregrounds. CIBER-2 comprises a 28.5-cm telescope cooled to < 100K using liquid nitrogen, and three HAWAII-2RG detectors coupled with dual- band filters to obtain data in six wavebands simultaneously. CIBER-2 is planned for four flights on the Black Brant IX sounding rocket, with the first flight in mid-2021.

In this dissertation, I present my work on the CIBER-2 design, characterization and payload integration, as well as constructing the EBL fluctuation power spectra from the data taken from CIBER-1’s final flight. This analysis relies on a previously developed pipeline for use with earlier flights, but has been revised to capture the hardware changes in the final flight and the corresponding systematic uncertainties. I will also outline the expected development of CIBER-2 post-flight analysis and highlight the advantage of CIBER-2 data for EOR studies.

Publication Date


Document Type


Student Type


Degree Name

Astrophysical Sciences and Technology (Ph.D.)

Department, Program, or Center

School of Physics and Astronomy (COS)


Dorin Patru

Advisor/Committee Member

Michael Richmond

Advisor/Committee Member

Richard Arendt


RIT – Main Campus