Accretion disks around neutron and strange stars in $\mathcal{R}^2$   gravity
  We study the electromagnetic spectrum of accretion disks around neutron and strange stars in $\mathcal{R}^2$ gravity. Both static and rapidly rotating models are investigated. The results are compared with the General Relativistic results. We found difference between the results in both theories of about 50\% for the electromagnetic flux and about 20\% in the luminosity for models with equal mass and angular velocity in both theories. The observed differences are much lower for models rotating with Kelperian velocity and with equal masses. 
Kalin V. Staykov, Daniela D. Doneva, Stoytcho S. Yazadjiev
gr-qc astro-ph.HE