Completing the picture of the black hole population in the Milky Way with microlensing.

October 10, 2019

When: October 10, 2019 3:30PM

Warsaw University

Most of about 50 known stellar-mass black holes are (or were) in binaries (X-ray binaries and GW mergers). Single black holes, also those constituting a fraction of Dark Matter in the Milky Way, can be detected using the gravitational microlensing technique.

I will present the current status of the black hole hunt using OGLE and Gaia projects, which survey millions of stars in order to spot rare temporal brightenings due to black holes passing in front of distant stars.

I will present how astrometric measurements from the Gaia mission being collected now will yield measurement of the mass of the lens in the currently on-going events. However, in order to correctly recognise a lensing black hole the dense photometric coverage, lasting months to years, as well as high-res spectroscopy of the source are necessary. LCO has been a key contributor to this effort providing well-sampled light curves for black hole lens candidates.

I will also present the OPTICON network of small (<2m) telescopes scattered mostly around Europe, which would benefit from coordinated observations in the time-domain astronomy. The LCO's expertise in that field and, in particular, TOM Toolkit and AEON system, will be crucial elements in the planned improvements of the network's operation.

Łukasz Wyrzykowski

Lukasz Wyrzykowski (pronounced: woo-cash vi-shi-kov-ski) obtained his PhD in 2005 at the Astronomical Observatory of the University of Warsaw in Poland on studies of various aspects of gravitational microlensing towards the Galactic Centre with OGLE data. His research interests have been linked with the OGLE project (he is the member of OGLE project since 2000) and include studies of variable stars, quasars, supernovae and other transients, and search for dark matter and black holes with gravitational microlensing. He is also interested in machine learning approaches to the vast astronomical data sets.

In years 2006-2015 he was a postdoc at the Institute of Astronomy in Cambridge, where in 2008 he joined Gaia DPAC/CU5/DU17. Together with Simon Hodgkin, Sergey Koposov, Guy Rixon and other researchers from Cambridge and Warsaw, he designed, developed and implemented the Gaia Photometric Science Alerts system, called AlertPipe. The system is operational since 2014 and detects various transient astrophysical events like supernovae and microlensing events.

Lukasz has also initiated the ground-based network of telescopes to conduct follow-up of Gaia alerts, the network is organised under the umbrella of EC's OPTICON grant. He was also the main organiser of a series of seven Gaia Science Alerts workshops, held in Cambridge, Paris, Warsaw and other places.

Currently he is back in Poland as a Lecturer at the Warsaw University Astronomical Observatory and continues his involvement in Gaia Alerts. He is looking for on-going microlensing events in Gaia and exploring the possibility of using Gaia's astrometric time-series to find black holes in the Milky Way via astrometric microlensing effect. Recently he has led the observing campaign of a spectacular binary microlensing event, Gaia16aye, see ESA's note and Gaia Image of the Week. He is also leading OGLE's search for supernovae and tidal disruption events.

Seminar