Journal Club


"Directed search for continuous gravitational wave signals from the Galactic Center"

Ornella Juliana Piccinni (INFN - Istituto Nazionale di Fisica Nucleare, Rome)

In this work we present the results of a search for continuous gravitational waves from the Galactic Center using LIGO O2 data. The search uses the Band-Sampled-Data directed search pipeline, which performs a semi-coherent wide-parameter-space search, exploiting the robustness of the FrequencyHough transform algorithm. The search targets signals emitted by isolated asymmetric spinning neutron stars, located within 25-150 parsecs from the Galactic Center. The talk will be based on:


"Big and young SMBHs in the early Universe: The first blazar observed at z>6"

Tullia Sbarrato (INAF - Osservatorio Astronomico di Brera (Merate, Italy))

The existence of extremely massive black holes at very high redshift is a true challenge to the commonly accepted black hole formation and evolution models. The quasars found at z>4 host extremely massive black holes and are particularly problematic: there is not enough time to accrete such large masses in a standard scenario. The presence of a jet could speed up the accretion process enough to assemble 10^9 solar masses black holes before z~6 from a reasonable black hole seed. Studying the population of jetted quasars is hence necessary. The peculiar orientation of blazars makes them the most effective tracers of the whole jetted population. Do relativistic jets really have a role in the early formation of extremely massive black holes? To explore the matter, we present the discovery of PSO J0309+27, a source selected by cross-matching NVSS and PanSTARRS PS1, whose high-z nature was confirmed by a dedicated spectroscopic observation at LBT. Swift/XRT, VLA and VLBA observations allowed us to classify this source as the farthest blazar currently known, putting even more extreme constraints on the formation and evolution of the first supermassive black holes in our Universe.