About me

I am a graduate student in Astronomy and Astrophysics at the University of California, Los Angeles. My principle research interest is gravitational lensing and cosmology. I am currently working with Professor Tommaso Treu on time-delay cosmography.

I was born and raised in Bangladesh. I moved to Japan after graduating high school and received my B.S. degree in physics from the University of Tokyo in 2014. When I am not researching, studying, or doing outreach, I enjoy sightseeing, self-defense training, watching movies, and playing video games.


Time-delay cosmography

Strong gravitational lensing is the phenomenon of light from a background object being deflected by the gravitational potential of a massive foreground object to form multiple images of the background object. If the background object is a quasar, then the delay between the arrival times of photon for different images can be measured using the intrinsic quasar variablity. This time-delay measurement can be used to estimate the so-called "time-delay distance". The time-delay distance constraints cosmological parameters, specially the Hubble's parameter \(H_0\).

Integrated Sachs-Wolfe effect

In a dark-energy-dominated universe, the large-scale potential well decays with time. CMB photons gain a little amount of energy after crossing such a decaying potential well, which is the integrated Sachs-Wolfe (ISW) effect. I analyzed WISE and WMAP data to detect the ISW effect signal at \(3.4\sigma\) S/N. (Picture at the left shows the galaxy overdensity from AllWISE data.)


First author publications:
  1. Shajib, A. J. and Wright, E. L. Measurement of the integrated Sachs-Wolfe effect using the AllWISE data release. ApJ, 827:116, 2016.
  2. Shajib, A. J., Treu, T., and Agnello, A. Improving time-delay cosmography with spatially resolved kinematics. MNRAS, 473, 210-226, 2018.
  3. Shajib, A. J., et al. Is every strong lens model unhappy in its own way? Uniform modelling of a sample of 12 quadruply+ imaged quasars. arXiv:1807.09278, 2018.
Contributing author publications:
  1. Williams, P. R., et al. Discovery of three strongly lensed quasars in the Sloan Digital Sky Survey. MNRAS: Letters, sly043, 2018.
  2. Ding, X., Treu, T., Shajib, A. J., et al. Time Delay Lens Modeling Challenge: I. Experimental Design. eprint arXiv:1801.01506, 2018.
  3. Chen, G. C.-F., et al. Constraining the microlensing effect on time delays with new time-delay prediction model in \(H_0\) measurements. eprint arXiv:1804.09390, 2018.


I have taught the following courses as a teaching assistant at UCLA. I have also been a guest lecturer in Physics 127 and Astro 81.

  • Astronomy 3 - Nature of Universe
  • Physics 1C - Electrodynamics, Optics and Special Relativity
  • Physics 127 - General Relativity
  • Physics 6C - Physics for Life Sciences Majors: Light, Fluids, Thermodynamics, Modern Physics
  • Astronomy 81 - Astrophysics I: Stars and Nebulae
  • Astronomy 140 - Stellar Systems and Cosmology
  • Physics 12 - Physics of Sustainable Energy


Find my CV here.