Li: Direct Detection of Black Hole-Driven Turbulence in the Centers of Galaxy Clusters / Marcotulli: The Extremes of the Blazar Sequence

Nov 12, 2019 - 11:00 am to 12:00 pm
Location

Campus, Varian 355

Speaker
Yuan Li (UC Berkeley) / Lea Marcotulli (Clemson)

Marcotulli: Blazars are among the most luminous, persistent, sources in our Universe. With powerful relativistic jets closely pointed to our line of sight, they are detected at high redshifts (up to z=4-5) and seem to follow the so-called `blazar sequence’, i.e. the more luminous the source, the redder their SED appears. At one end of the sequence lie the most extreme of these sources, the MeV blazars. Found when the Universe was barely 1-2 billion years old, they harbor jets with power exceeding 10^47 erg s-1 and host billion solar masses black holes, questioning our understanding of the origin and growth of supermassive black holes. At the other end, lies the undetected population of high-frequency peaked and luminous blazars. If found, such sources not only will be crucial to understand the blazar evolution, but would also be excellent probes for the Extragalactic Background Light. At present, only few such sources are known and the detection of more is crucial to shed a light on this elusive population. Using the improved sensitivity of the Fermi Large Area Telescope (LAT), combined with the incredible capabilities of NuSTAR, we studied six powerful MeV blazars beyond redshift 3. Moreover, these facilities enabled us to find one more high-frequency high-luminosity BL Lac and study its properties in the broader blazar population scheme. Here, we present the results of our recent work on some of the most powerful and distant blazars ever detected.