Publications (9)
Toward a concordance teleparallel Cosmology II: Linear perturbation
Mahmoud Hashim, Amr A. El-Zant, Waleed El Hanafy +1
Late time cosmic acceleration may be achieved by modifying gravity on large scales. This should also have consequences on the evolution of perturbations. We thus extend our study o…
Halo heating from fluctuating gas in a model dwarf
Mahmoud Hashim, Amr El-Zant, Jonathan Freundlich +2
The cold dark matter (CDM) structure formation scenario faces challenges on (sub)galactic scales, central among them being the `cusp-core' problem. A known remedy, driving CDM out…
Degeneracy between primordial non-Gaussianity and interaction in the dark sector
Mahmoud Hashim, Daniele Bertacca, Roy Maartens
If dark energy and dark matter interact via exchange of energy and momentum, then this may affect the galaxy power spectrum on large scales. When this happens, it may be degenerate…
Building stellar bulges and halo cores from massive clumps observed in the DYNAMO-HST sample
Mahmoud Hashim, Amr El-Zant, Antonino Del popolo
We present N-body simulations of the process of bulge formation in disc galaxies due to inward migration of massive stellar clumps. The process is accompanied by dark halo heating,…
Dissipative Unified Dark Fluid: Observational Constraints
Esraa Ali Elkhateeb, Mahmoud Hashim
We adopt a standard FRW cosmology with a unified scenario, where the usual dark matter and dark energy sectors are replaced by a single dissipative unified dark fluid (DUDF). The e…
Cosmological Viability of Exponential Infrared Gravity
Mahmoud Hashim, Eleonora Di Valentino, Jackson Levi Said +1
We investigate the cosmological viability of exponential infrared teleparallel gravity using current cosmological observations. This framework realizes late-time cosmic acce…
Revisiting Flat Rotation Curves in Chern-Simons Modified Gravity
Waleed El Hanafy, Mahmoud Hashim, G. G. L. Nashed
We revisit slow rotating black hole (BH) solutions in Chern-Simons modified gravity (CSMG) by considering perturbative solution about Schwarzschild BH. In particular, the case when…
Toward a concordance teleparallel Cosmology I: Background Dynamics
Mahmoud Hashim, Waleed El Hanafy, Alexey Golovnev +1
Assuming a spatially flat universe, we study the cosmological viability of an infrared corrected teleparallel gravity model, which accounts for late acceleration by weakening gravi…
Clustered unified dark sector cosmology: Background evolution and linear perturbations in light of observations
Mahmoud Hashim, Amr El-Zant
We consider unified dark sector models in which the fluid can collapse and cluster into halos, allowing for hierarchical structure formation to proceed as in standard cosmology. We…