Conference photo. Click image for full-res version.
Scientific motivation

Accreting compact objects are among the most powerful sources of radiation in the Universe. The observed bright emission in X-rays would have been impossible without matter losing its energy to radiation on its way towards a black hole or neutron star. Conversely, emission at the extreme limits of the observed wavelength range, at radio frequencies and in the GeV energy range, is connected to ejection events where matter is accelerated to relativistic speeds. Since the initial discovery in the middle of the 20th century, spectral and timing properties of accreting sources, black hole and neutron star-hosting X-ray binaries and active galactic nuclei, have been studied in the entire available electromagnetic energy range. Yet, the geometry and physical properties of these objects remain highly debated, and different models compete to predict and explain the data. New instruments bring more surprises in the field, such as the recent discovery of the pulsed ultraluminous X-ray sources and transitional millisecond pulsars. With substantial advances in computer hardware and numerical algorithms, it has become possible to simulate the environments of the extreme gravitational field, close to the compact objects. It is now time for the simulations to meet observations.

Organised in a series of meetings devoted to accretion and ejection from compact objects, Time for accretion will cover spectral and timing aspects of black holes and neutron stars. The conference will bring together observers and theoreticians to discuss our present understanding of accretion, and what key questions we need to answer. The meeting will include topics such as:

X-ray timing and spectral observations and modelling

Multiwavelength observations and modelling

Simulations of accretion/ejection

The meeting will mix invited and contrubuted talks with ample time devoted to discussions.

Previous workshops of this series were organized in

Cambridge, UK, 1983

NORDITA, Denmark, 1986

Space Telescope Science Institute, USA, 1989

Koninki (aka Suhora), Poland, 1993 and 1996

Graftaavallen, Sweden, 1998

Warsaw, Poland, 2000

Kathmandu, Nepal, 2002

Fort William, Scotland, 2005

Kathmandu, Nepal, 2006

Funaesdalen, Sweden, 2008

Kathmandu, Nepal, 2008

Kathmandu, Nepal, 2010, 2013, 2016


The meeting will be held in Sigtuna, a small town north of Stockholm and close to Arlanda aiport. Founded in AD 970, Sigtuna is Sweden's oldest city and is full of history, with medieval churches, ruins, castles and rune stones from the Viking era. The venue is a conference hotel within a few minutes walk from the town center.

Accommodation can only be booked for the whole duration of the conference, and includes a single room and full board.


The meeting is supported by the Swedish Research Council (Vetenskapsr├ądet), the Wenner-Gren Foundations and the Nordic Institute for Theoretical Physics (NORDITA). It is organized in collaboration with a research network supported by JSPS KAKENHI (16H03954; PI: R. Matsumoto).