374 citations · 2.5k across the 52 of their papers we have counts for
7 papers · 1 filter
Extreme Black Hole Anabasis
Shahar Hadar, Alexandru Lupsasca, Achilleas P. Porfyriadis
We study the transformation properties of spherically symmetric perturbations of the Bertotti-Robinson universe and identify an invariant that characterizes th…
Photon Emission from Circular Equatorial Kerr Orbiters
Delilah E. A. Gates, Shahar Hadar, Alexandru Lupsasca
We consider monochromatic and isotropic photon emission from circular equatorial Kerr orbiters. We derive analytic expressions for the photon escape probability and the redshift-de…
Photon Ring Autocorrelations
Shahar Hadar, Michael D. Johnson, Alexandru Lupsasca +1
In the presence of a black hole, light sources connect to observers along multiple paths. As a result, observed brightness fluctuations must be correlated across different times an…
The Shape of the Black Hole Photon Ring: A Precise Test of Strong-Field General Relativity
Samuel E. Gralla, Alexandru Lupsasca, Daniel P. Marrone
We propose a new test of strong-field general relativity (GR) based on the universal interferometric signature of the black hole photon ring. The photon ring is a narrow ring-shape…
Maximum Observable Blueshift from Circular Equatorial Kerr Orbiters
Delilah E. A. Gates, Shahar Hadar, Alexandru Lupsasca
The region of spacetime near the event horizon of a black hole can be viewed as a deep potential well at large gravitational redshift relative to distant observers. However, matter…
On the Observable Shape of Black Hole Photon Rings
Samuel E. Gralla, Alexandru Lupsasca
Motivated by the prospect of measuring a black hole photon ring, in previous work we explored the interferometric signature produced by a bright, narrow curve in the sky. Interfero…