Astrophysical jets at the highest-angular resolution with very long baseline interferometry

Abstract

Astrophysical jets are a ubiquitous and powerful phenomenon in astronomy. Their emission ranges over a wide scale, from young stellar objects (YSO) to super-massive black holes (SMBH) and Active Galactic Nucleii (AGN). Jets are believed to play a central role in regulating protostellar and black hole mass-accretion as well galaxy growth via AGN feedback; despite their importance, their driving mechanism is still largely unknown. This is chiefly due to observational limitations: their launching and collimation occurs in the innermost regions of the driving engine, requiring extremely high-angular resolutions to observe them. In this context, radio-interferometry, and particularly Very Long Baseline Interferometry (VLBI), applied to the shortest radio wavelengths (1 mm or shorter), yields the highest angular resolution presently achievable in ground-based astronomy. De facto, sub-mm VLBI is the only technique that can reach sufficiently high angular resolution to test theoretical predictions of jet launching models. The proposed project aims to observationally study AGN and protostellar jets at the highest angular resolution using the most powerful radio interferometers on Earth. The latter will include the Atacama Large Millimeter Array (ALMA) and the Event Horizon telescope (EHT), which has made a historic breakthrough publishing the first image of a black hole (released on Apr 2019). Together, EHT and ALMA are truly paving the way to groundbreaking new science. In particular, the observing programme proposed here will enable a major leap forward in our understanding of the mass-accretion/mass-loss processes in Galactic high-mass star formation, the role of magnetic fields in launching relativistic jets and regulating black-hole mass accretion in AGN, and black hole physics in general. We ask for the support of FAPESP to start a leading research group at IAG USP in the field of radio-interferometry and observational astrophysics of jets. The PI has a 20 years experience with VLBI, has been supporting and commissioning the ALMA observatory for the last 10 years, and has been part of the EHT project for the past 6 years. He has robust knowledge on data analysis and radio-sky astrophysics. This expertise will be applied to set up and train the nascent interferometry group at IAG-USP, which will be comprised of graduate students at the master and Ph.D. level. Such a group will be the first in Brazil to join the EHT Collaboration. The PI will also lead the efforts for the inclusion of the new Argentine-Brazil Large Latin American Millimeter Array (LLAMA) in the EHT network, which will enable new groundbreaking science in the field of SMBHs and relativistic jet astrophysics. This project is of strategic importance for Brazil in view of the new Ibero-American VLBI Initiative (IVIA), which aims at establishing the first VLBI network in South-America. As such, it will have broader implications, as recently pointed out in the Annals of the Brazilian Academy of Sciences. (AU)