Colloq Abstract - Plotkin

April 5, 2019

11:00am Mountain

Richard Plotkin (Curtin/Nevada)

 

Relativistic Jets from Weakly Accreting Black Holes

 

Abstract

Transient black hole X-ray binaries (BHXBs) spend the vast majority of their time in a 'quiescent' spectral state, emitting low levels of radiation (L_xray < 1e-5 Ledd, where L_edd is the Eddington luminosity). Over the last decade, the Very Large Array has started to reveal that BHXBs launch compact relativistic jets in quiescence, which emit (relatively) large amounts of synchrotron radiation in the radio waveband. At higher luminosities, in the so-called 'hard state' (1e-5 L_edd < L_xray < 1e-2 L_edd), BHXBs appear to always launch compact radio jets. However, hard state BHXB jets display a larger than expected range in (radiative) radio powers at a given X-ray luminosity, suggesting that there is diversity in their jet properties. Furthermore, there is still uncertainty whether physical properties of jets are different between the hard state and quiescence (e.g., efficiency of particle acceleration, energy equipartition in the jet base, etc). In this talk I will discuss recent multiwavelength observations of BHXB systems that bridge the boundary between the hard state and quiescence, with a focus on new and archival observations by the Very Large Array. I will discuss how our results are yielding new insights into how jets evolve as accretion rate decreases, and the implications for both stellar mass and supermassive black holes in our Galaxy and beyond.

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