6 papers
Spectroscopic redshifts of selected flat-spectrum radio sources I
Dmitry Blinov, Alberto Floris, Andreas Zezas +5
We present the first results of a spectroscopic campaign carried out as part of the Search for Milli-Lenses (SMILE) program, which aims to constrain the prevalence of gravitational…
EP260321a/SN 2026gzf: The Faintest Shock Breakout Associated with a Broad-Lined Supernova
Brendan O'Connor, Xander J. Hall, Malte Busmann +33
The explosion of a star is first marked by the shock wave breaking out of the stellar surface, producing a burst of ultraviolet and X-ray radiation. These events are observationall…
HALO II: Constraining Hubble constant through continuum delay fitting of Fairall 9
Amit Kumar Mandal, Francisco Pozo Nuñez, Vikram Kumar Jaiswal +28
The Hubble tension remains one of the most significant unresolved problems in modern cosmology. A key question is whether it may arise from underestimated systematic uncertainties…
Observations of a Possible Transient Magnetically Arrested Accretion State in a Nearby Quasar: OQ208
Brian Punsly, Cormac Reynolds, Paola Marziani +12
OQ208 is a nearby, partially obscured quasar (z=0.077) that is a young, bright, parsec scale radio source. We assemble archival and new high frequency VLBA and VLA observations and…
Tracking down the broadband polarimetric properties of PG 1553+113
Riccardo Middei, Svetlana G. Jorstad, Alan P. Marscher +78
We report on a nine-month monitoring campaign of the blazar PG 1553+113, relying on three observations carried out in 2025 with the Imaging X-ray Polarimetry Explorer (IXPE) and su…
Super-Eddington Accretion in Quasars
P. Marziani, K. Garnica Luna, A. Floris +5
This review provides an observational perspective on the fundamental properties of super-Eddington accretion onto supermassive black holes in quasars. It begins by outlining the se…