Following the completion of his graduate studies, Ishak-Boushaki began work as a research associateatPrinceton University until later entering a professorship at the University of Texas at Dallas in 2005.
While at the University of Texas at Dallas, he formed an active group of cosmologists and astrophysicists,[9] and received the Outstanding Teacher of the Year Award in the years 2007 and 2018,[10][11] as well as the University President's Excellence in Teaching Award [12] and the University of Texas System Regents Outstanding Teacher Award in 2022 [13]
He is an active member of the Dark Energy Science Collaboration[14] and the Dark Energy Spectroscopic Instrument.[15]
In 2005, Ishak-Boushaki and collaborators proposed a procedure to distinguish between dark energy and modification to general relativity at cosmological scales as a cause of cosmic acceleration.
The idea was based on the fact that cosmic acceleration affects both the expansion rate and the growth rate of large-scale structures in the universe.
These two effects must be consistent one with another since they are based on the same underlying theory of gravity.
The publication was one of the first to: (1) contrast dark energy versus modified gravity as cause of cosmic acceleration, (2) use inconsistencies between Lambda-CDM modelcosmological parameters to test gravitational theory at cosmological scales.[4][17]
He and collaborators wrote then a series of publications on testing general relativity at cosmological scales (see Bibliography), and his work on the subject was recognized by an invitation to write in 2018 a review article [5] on the current state of research in the field of testing general relativity in the journal Living Reviews in Relativity.
Ishak-Boushaki and collaborators made a first detection of the large-scale intrinsic alignment of galaxies [18] of type『intrinsic shear – gravitational shear』using a spectroscopic galaxy sample from the Sloan Digital Sky Survey.
He and collaborators also made a first detection of these intrinsic alignments using a self-calibration method in the photometric galaxy sample in Kilo-Degree Survey.[19]
Ishak-Boushaki and collaborator wrote a review article on the intrinsic alignment of galaxies and its impact on weak gravitational lensing.
Ishak-Boushaki and a collaborator proposed a new mathematical measure of inconsistency between cosmological datasets called the index of inconsistency (IOI) as well as a novel Bayesian interpretation of the level of significance of such measures.[20][3][21]
2021 – Elected as Fellow of American Association for the Advancement of Science (AAAS).
[6]
2021 – Department of Energy Excellence Award for DESI (Dark Energy Spectroscopic Instrument) Collaboration.[23]
2021 – President's Excellence in Teaching Award at University of Texas at Dallas.
[12]
2020 – Granted Builder Status Recognition for the Legacy Survey of Space and Time (LSST) – Dark Energy Science Collaboration (DESC) (26 recognized members over 1005 members in July 2020).[14]
2018 – Award for Outstanding Teacher of the Year from the School of Natural Sciences and Mathematics. University of Texas at Dallas.[10]
2013 – Robert S. Hyer Research Award from the Texas Section of the American Physics Society.[24]
2007 – Award for Outstanding Teacher of the Year from the School of Natural Sciences and Mathematics, University of Texas at Dallas.[10]