Date of Award


Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy in Physics (PhD)

Administrative Home Department

Department of Physics

Advisor 1

Robert Nemiroff

Committee Member 1

Jon Hakkila

Committee Member 2

Petra Huentemeyer

Committee Member 3

Elena Giusarma


In this dissertation, I explore the existence of Compact Object (CO) Dark Matter (DM), examining its predicted millilensing impact on the light curves of Gamma-Ray Bursts (GRBs). The hypothesis under investigation is that if CO DM exists, it will act as a gravitational lens, influencing light emanating from GRBs and creating a measurable gravitational echo. The detection of this echo is conditional on several factors, including the spatial alignment of the observer, lens, and source and the mass of the CO DM.

Recent studies have reported the potential detection of millilensing in several GRBs, including GRB 950830, GRB 081122A, GRB 081126A, GRB 090717A, GRB 110517B, GRB 200716C, and GRB 210812A. Two millilensing tests were implemented to evaluate these findings: a light-curve similarity test and a hardness similarity test. According to this analysis, none of these GRBs passed both tests convincingly, with some GRBs even dismissing millilensing above an 8-σ confidence level.

Using data from the Fermi satellite, I examined numerous GRBs to identify possible gravitational echoes. Although no clear gravitational lensing events were detected, the absence of detections still provided important constraints on the presence of CO DM within specific mass ranges. In particular, if CO DM accounts for 6.9% of the total DM, equivalent to a CO DM density value of roughly 0.0183, the mass range between 105.95 M⊙ to 106.3 M⊙ can be ruled out as a viable CO DM candidate. This conclusion is supported by confidence greater than 90%. In addition, when the CO DM density parameter is 0.256, the mass range that can be eliminated as a viable CO DM candidate extends from 104.6 M⊙ to 107.1 M⊙ with a 90% confidence. Therefore, this mass range cannot constitute the majority of DM, narrowing the possibilities for CO DM's contribution to the overall DM composition.

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Creative Commons Attribution-Share Alike 4.0 License
This work is licensed under a Creative Commons Attribution-Share Alike 4.0 License.