Log in

Computational and Theoretical Gravity, Astrophysics, and Cosmology

Principal Investigators: Prof. Amanda Weltman (University of Cape Town) & Prof. Aroonkumar Beesham (University of Zululand)

Scientific Question and Goal

Our overarching goal is to use astrophysical observations to help us understand the large-scale structure of the universe and the nature of gravity. Using observations of pulsars, FRBs, gravitational waves and the early universe we use computational techniques to rule out theories or confirm their viability.  

Institutions

  • University of Cape Town
  • University of KwaZulu-Natal
  • University of Johannesburg
  • North-West University
  • Rhodes University
  • Stellenbosch University
  • University of the Witwatersrand
  • Mangosuthu University of Technology
  • University of the Western Cape
  • University of Pretoria
  • University of South Africa

Some recent publications

In early November there were already 54 publications from the Research Focus Area in 2026, including:

  • Mfulwane, L.L. et al. A MeerKAT search for persistent radio sources towards twenty-five localized fast radio bursts. MNRAS 546, 1 (2026). https://doi.org/10.1093/mnras/stag166
  • Sarieddine, L., et al. The Atacama Cosmology Telescope: Constraints on local non-Gaussianity from the ACT cluster catalog. JCAP 08, 070 (2026). https://doi.org/10.1088/1475-7516/2026/08/070
  • Dixit, K., Mohlabeng, G. & Razzaque, S. Searching for dark matter signals with high energy astrophysical neutrinos in IceCube. Physical Review D 114, 043048 (2026). https://doi.org/10.1103/9zgv-fg7g
  • Kakkat, V., et al. Gravitational wave propagation through viscous matter. International Journal of Modern Physics D. https://doi.org/10.1142/S021827182641018X
  • Huang, Y., Lin, S., Razzaque, S., Yang, L., Huang, Z., Catching TeV emission from GRB 221009A and alike with LHAASO, LACT and SWGO. The European Physical Journal C 86, 195 (2026). https://doi.org/10.1140/epjc/s10052-026-15450-4
  • Aldowma, T.K.M. et al. Implications of joint spectral analysis of gamma-ray bursts detected by Fermi Large Area Telescope and Gamma-ray Burst Monitor on phenomenological correlations. MNRAS 546, stag060 (2026). https://doi.org/10.1093/mnras/stag060
  • Gupta, R., et al. Extremely Luminous Optical Afterglow of an Energetic Gamma-Ray Burst GRB 230204B. ApJ 997, 246 (2026). https://doi.org/10.3847/1538-4357/ae2794
  • Pradhan, C., Sharma, K., Roy, A., & Joshi, J.C. Constraints on GRB Jet properties from IceCube upper limits: Insights from GRB 221009A and GRB 240825A. Astroparticle Physics 178, 103226 (2026). https://doi.org/10.1016/j.astropartphys.2026.103226
  • Swain, V., et al. GRB 230204B: GIT Discovery of a Fast Fading Afterglow Associated with an Energetic Gamma-Ray Burst from a Massive Star Progenitor. ApJ 1000, 58 (2026). https://doi.org/10.3847/1538-4357/ae459f
  • Mondal, T., Razzaque, S., Joshi, J.C., Majumder, S., & Bose, D. Multi messenger study of GRB 221009A with VHE gamma-ray and neutrino Afterglow from a Gaussian structured jet. JHEAp 53, 100636 (2026). https://doi.org/10.1016/j.jheap.2026.100636
  • Ghosh, A., et al. Photometric and late-time spectropolarimetric observations of GRB 250129A afterglow. MNRAS 551, stag1391 (2026). https://doi.org/10.1093/mnras/stag1391
  • Das, S., et al. Modeling the Imprints of Large-scale Magnetized Structures on γ-Rays from Extragalactic Transients. ApJ 1008, 165 (2026). https://doi.org/10.3847/1538-4357/ae9546
  • Xu, R., Cui, Y., Shi, Y., & Yang, L. Time-dependent multienergy neutrino emission from symbiotic recurrent novae: The role of accretion disks. Physical Review D 114, 063011 (2026). https://doi.org/10.1103/c82p-pw9r
  • Shi, Y., Cui, Y., & Yang, L. LHAASO J1849−0002: A hybrid lepto-hadronic interpretation of PeV γ-ray emission. A&A 713, A35 (2026). https://doi.org/10.1051/0004-6361/202660244
  • Ntshatsha, M., Böttcher, M., & Razzaque, S. Compton-induced HE -- VHE γ-rays from pair cascade emissions in the SEDs of radio galaxies: NGC 1275. MNRAS 552, stag1716 (2026). https://doi.org/10.1093/mnras/stag1716
  • Liu, X., et al. Data-driven modeling of Galactic diffuse emission with multi-wavelength observations. The European Physical Journal C 86, 1135 (2026). https://doi.org/10.1140/epjc/s10052-026-16408-2
  • Sampath, A., et al. Primary Beam Chromaticity in HIRAX. I. Characterization from Simulations and Power Spectrum Implications. ApJ 997, (2026). https://doi.org/10.3847/1538-4357/ae1b89
  • Bhattacharrya, A., Gool, S., Haque, S.S. Krylov complexity for open quantum system: dissipation and decoherence. JHEP 2026, 140 (2026). https://doi.org/10.1007/JHEP08(2026)140
  • Bhattacharrya, A., Haque, S.S., Murugan, J., Tladi, M., Van Zyl, H.J.R. Stochastic Krylov dynamics: revisiting operator growth in open quantum systems. JHEP 2026, 127 (2026). https://doi.org/10.1007/JHEP09(2026)127
  • Aguena, M., et al. The Atacama Cosmology Telescope: DR6 Sunyaev-Zel'dovich Selected Galaxy Clusters Catalog. The Open Journal of Astrophysics 09, 55863 (2026). https://doi.org/10.48550/arXiv.2507.21459
  • Coulton, W., et al. Atacama Cosmology Telescope: A measurement of galaxy cluster temperatures through relativistic corrections to the thermal Sunyaev-Zeldovich effect. Physical Review D 113, 043520 (2026). https://doi.org/10.1103/n7p5-pc66
  • Dalal, N., et al. Deciphering baryonic feedback from ACT tSZ galaxy clusters. JCAP 2026, 36 (2026). https://doi.org/10.48550/arXiv.2507.04476
  • Ragavan, D., et al. The Atacama Cosmology Telescope: stellar mass growth in massive galaxy clusters from DR5 over the past 7 billion years. MNRAS 549, stag778 (2026). https://doi.org/10.1093/mnras/stag778
  • Sarieddine, L., et al. The Atacama Cosmology Telescope: Constraints on local non-Gaussianity from the ACT cluster catalog. JCAP 2026, 070 (2026). https://doi.org/10.1088/1475-7516/2026/08/070
  • Adam, J., Maartens, R., Larena, J., Clarkson, C., & Durrer, R. Probing the Cosmological Principle with CMB lensing and cosmic shear. Journal of Cosmology and Astroparticle Physics 2026, 023 (2026). https://doi.org/10.1088/1475-7516/2026/01/023
  • Guedezounme, S.L., Dinda, B.R., & Roy Maartens, R. Phantom crossing or dark interaction? Journal of Cosmology and Astroparticle Physics 2026, 062 (2026). https://doi.org/10.1088/1475-7516/2026/01/062
  • Kalbouneh et al. The anisotropic expansion rate of the local Universe and its covariant cosmographic interpretation. Journal of Cosmology and Astroparticle Physics 2026, 084 (2026). https://doi.org/10.1088/1475-7516/2026/03/084
  • Dube, Y., Dinda, B.R., Jolicoeur, S., & Maartens, R. Turnover detection using the power spectrum and bispectrum. Journal of Cosmology and Astroparticle Physics 2026, 021 (2026). https://doi.org/10.1088/1475-7516/2026/04/021
  • Sarma, M., Marinoni, C., Kalbouneh, B., Clarkson, C., & Maartens, R. Covariant cosmography in the presence of local structures: comparing exact solutions and perturbation theory. Journal of Cosmology and Astroparticle Physics 2026, 069 (2026). https://doi.org/10.1088/1475-7516/2026/04/069
  • Dinda, B.R., Maartens, R., & Clarkson, C. Calibration-independent consistency test of BAO and SNIa data: update. Journal of Cosmology and Astroparticle Physics 2026, 051 (2026). https://doi.org/10.1088/1475-7516/2026/05/015
  • Mfulwane et al. A MeerKAT search for persistent radio sources towards twenty-five localized fast radio bursts. MNRAS 546, stag166 (2026). https://doi.org/10.1093/mnras/stag166
  • Prayag, V., et al. The TRAPUM Large Magellanic Cloud pulsar survey with MeerKAT ─ II. 12 new discoveries and timing solutions for 7 pulsars. MNRAS 545, staf2193 (2026). https://doi.org/10.1093/mnras/staf2193
  • Kundu, A., et al. The Swept-back Multipolar Magnetic Field of Neutron Stars: Application to NICER MSP J0030+0451. ApJ 1008, 215 (2026). https://doi.org/10.3847/1538-4357/ae8e6f
  • Özansoy, M., Shukla, B.K., Sofuoğlu, D., Beesham, A., & Tripathi, R. Cosmic acceleration in f(Q) gravity: a nonlinear equation of state approach. European Physical Journal C 86, 134 (2026). https://doi.org/10.1140/epjc/s10052-026-15310-1
  • Tiwari, R.K., Beesham, A., & Jaiswal, A.K. Bulk Viscous Cosmological Model with varying Deceleration Parameter in Modified Gravity. International Journal of Geometric Methods in Modern Physics 23, 2650087 (2026) . https://doi.org/10.1142/S0219887826500878
  • Shukla, B.K., Sofuoglu, D., Beesham, A., Tiwari, R.K., & Msweli, M.S. Observational Diagnostics of a Parametrized Deceleration Parameter in FLRW Cosmology. Particles 09, 41 (2026). https://doi.org/10.3390/particles9020041
  • Sharma, S., Singh, K., Tiwari, R.K., Beesham, A.K. Bianchi Type-V Cosmological Model in f(R,T) Gravity: Exact Solutions and Dynamical Analysis. Palestine Journal of Mathematics 15, (2026). Preprint: https://www.preprints.org/manuscript/202503.1261
  • Bishop, N.T., Kakkat, V., & Naidoo, M. Gravitational wave interactions with a viscous fluid: Core collapse supernova, binary neutron star merger, and accretion around a black hole merger. Physical Review D 113, 64047 (2026). https://doi.org/10.1103/yndb-ysvp
  • Kakkat, V., et al. Gravitational wave propagation through viscous matter (Conference Proceedings). International Journal of Modern Physics D 2026, 2641018 (2026). https://dx.doi.org/10.1142/S021827182641018X
  • Venter, L.R. (supervised by Bishop, N.T.). The Kerr and Kerr-Newman Metrics in Bondi-Sachs Coordinates (PhD Thesis).
  • Pillay, D.S., et al. Radio timing constraints on the orbital orientation and component masses of PSR J1455−3330. A&A 708, A213 (2026). https://doi.org/10.1051/0004-6361/202556766
  • Singha, J., et al. Magneto-active environments in pulsar binaries with the MeerKAT telescope: I. Pulsar sample and their basic properties. MNRAS 551, stag928 (2026). https://doi.org/10.1093/mnras/stag968
  • Blecher, T., et al. Mining the time axis with TRON – III. Discovery of a nulling pulsar towards the SMC with MeerKAT. MNRAS 552, stag1704 (2026). https://doi.org/10.1093/mnras/stag1704
  • Singha, J., et al. Detection of relativistic orbital deformation from improved timing of PSR J1757−1854. MNRAS 553, stag1861 (2026). https://doi.org/10.1093/mnras/stag1861
  • Gasealahwe, K. Neutron star X-ray binaries with MeerKAT (PhD Thesis). University of Cape Town institutional repository.
  • Beckering Vinckers, U.K., & Bishop, N.T. Gravitational wave interactions with matter: Beyond quadrupolar perturbations. Physical Review D 114, 084080 (2026). https://doi.org/10.1103/32p5-845t
  • Chand, V., et al. A Search for GeV Emission from Magnetar Giant Flare Candidates with Fermi-LAT. The Astrophysical Journal 1011, 148 (2026). https://doi.org/10.3847/1538-4357/ae969d
  • Rahman, et al. Investigating the sensitivity of the MPTA and extended datasets to alternative gravitational wave polarisations using simulations. Submitted to MNRAS.
  • Fortunato, J., Marra, V., Hipolita-Ricaldi, W., & Weltman, A. A stochastic forward model for the intergalactic dispersion-measure distribution of Fast Radio Bursts. Submitted to MNRAS.
  • Kalita, S., Bhatporia, S., & Weltman, A. Understanding constraints on primordial mass black holes made of dark matter using fast radio bursts (Conference Proceedings). Proceedings of the International Astronomical Union 20 (A32). https://doi.org/10.1017/S1743921324003260
  • SKA Transients Working Group. Fast Radio Bursts as Cosmological Probes (White Paper). HAL Science Ouverte.
  • SKA Transients Working Group. Fast Radio Bursts as Cosmological Probes (White Paper). HAL Science Ouverte.
  • Curtin, A., et.al. Astrophysics of Fast Radio Bursts (White Paper). HAL Science Ouverte.
  • Fortunato, J., Kalita, S., & Weltman, A. Testing the cosmic distance-duality relation with localized fast radio bursts: a cosmological model-independent study. HAL Science Ouverte.

Coordinators

Amanda Weltman, Aroonkumar Beesham

Focus Area