Why? Workshop aim

Stellar streams are the most promising tools we have for studying the dark matter distribution around the Milky Way in detail. The last decade has seen an explosion in the number of detected streams, substantial progress in developing new modeling frameworks, new constraints on dark matter (on large and small scales) from streams, and new revelations about the complexity and time dependence of the Galactic mass distribution, largely thanks to precise astrometry from the Gaia mission. With new Gaia data releases on the near horizon, the time is ripe to ask: What is next for stellar streams? How can streams in the Milky Way provide lasting constraints that inform dark matter theories?


What? Discussion topics



Stream & substructure discovery


How near a complete census are we? Are we missing disrupted structure which isn’t stream-like? Do we need more streams or a more detailed view of the current streams? Do we understand the progenitors of streams well enough?


Large-scale structure of the Milky Way


Are we nearing a standard Milky Way potential model? Are streams still the best tools for measuring the global shape of the dark matter halo? What was the effect of the satellites on the Milky Way and its streams?


Small-scale structure in the Milky Way


What will it take to reliably detect a dark matter subhalo interacting with a stream? What information do we need to rule out all baryonic explanations? Are we missing important effects which produce additional stream structure?


Going beyond the Milky Way


What do streams around other galaxies provide? How do we improve collaboration with other communities (dark matter models, cosmological simulations, ...)? How do dark matter constraints from streams compare to other methods?


Community recommendations


What do we need as a community going forward? Do we need standardised tests and 'challenges’ for large and small-scale dark matter constraints? Do we need a common protocol for reporting stream discoveries and member stars?


How? Workshop format

The aim of the meeting is to gather the majority of the Milky Way streams research community to discuss progress and the future of the field. With international travel not currently possible, the meeting will be held entirely online. The meeting will take a discussion-oriented approach with contributors pre-recording research talks and the majority of the 'contact' week devoted to discussion. Every participant of the meeting may contribute a talk. Contributed talks will be approximately 10 minutes in length and will be made available prior to the meeting. During the workshop, discussions will center around groups of talks organized by topic, to be summarized by discussion moderators at the beginning of each session.

The meeting will be conducted primarily over Zoom. There will also be an opportunity for more informal 'coffee-time chats' using wonder.

We expect all participants to abide by the Flatiron Code of Conduct.

There are no fees associated with the workshop.

This is a difficult time for international science collaboration but we really hope that many of you will feel excited and inspired by the opportunities an online workshop will present.


When? Schedule

The full schedule for the workshop and associated talks are available via the Indico page. The password has been shared via email with all participants.

The workshop will take place from Monday 22nd to Friday 26th February 2021. Each day will run from 2pm until 5pm GMT. We will announce a detailed schedule nearer the time.

Key dates
15th January 2021: Application deadline
15th February 2021: Pre-recorded talk submission deadline
22nd–26th February 2021: Workshop


Get involved Apply

Applications for the workshop have now closed.

We have contacted all chosen speakers via email with guidelines for submitting their recorded talks. Speakers are required to submit their talks by 15th February 2021 (a week before the workshop).


What next? Legacy

We hope this workshop will lead to new ideas and research directions. During the workshop we plan to record the discussion sessions on Zoom and keep a written record of the discussions through a collaborative Google Doc.

In the longer term we would like the meeting to provide a legacy perhaps as the first in a longer series of meetings. We plan to produce a document detailing the proceedings of the meeting along with recommendations for the community for future targets and goals. If you have ideas on what structure this could take, please contact the organizers.