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Marcin Sawicki
Canada Research Chair in Astronomy


I seek to understand how galaxies formed and evolved when the Universe was only a fraction of its present age. My research is focused through three key projects:

  1. (1)The massive, 200-hour JWST Guaranteed Time Observations CANUCS program that will let us investigate in detail the inner workings of thousands of low-mass galaxies at Cosmic Noon (z~2) and Cosmic Dawn (z>6). Following the successful JWST launch on 25 December 2021, we obtained the first batch of our CANUCS data in October 2022! 

  1. (2)The 68-night CFHT CLAUDS survey that together with affiliated deep surveys from other telescopes lets us use several million galaxies over a wide redshift range to do enormously large statistical studies of the processes that drive galaxy evolution.  CLAUDS is now joined by its newer sibling, DEUS, which aims to cover 10 sq degrees in the Euclid Deep Field North and study how galaxy properties relate to their location within the high-redshift Cosmic Web.

  1. (3)The GIRMOS AO-fed, multi-IFU spectrograph now under construction by a partnership of Canadian institutions, including our team at Saint Mary’s. GIRMOS will let us do detailed, spatially-resolved studies of 100’s of distant galaxies when commissioned at Gemini-North later this decade.

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2023 February 1: CLAUDS public data release, catalog paper, and new website, all at once! 

Our CLAUDS (+HSC+NIR) photometric catalogs go public, accessible to anyone who would like to use them!  The paper that describes these catalogs (led by group member Guillaume!) is now in press (see it here) in Astronomy & Astrophysics.  And, at the same time, we have a new version of the CLAUDS project website, www.clauds.net.


I am so excited by the amazing amount of very cool science that has already relied on CLAUDS data (22 papers as of today, with more submitted and in prep!), and the science still to come with the data in the hands of the community.  And, now underway, the DEEP project with which, together with partners, we are building a contiguous 10 square-degree, multi-wavelength dataset in Euclid’s Northern Deep Field. 

2022 December 16: JWST witnesses the assembly of a ultra-low-mass galaxy at z~5 

In a paper just submitted to MNRAS (and posted to arXiv here), we used our JWST imaging of the gravitationally-lensing MACS 0417 cluster field  to find a doubly-lensed pair of ultra-low-mass galaxies at z~5.1 that are undergoing coordinated bursts of star formation.  This system provides a first detailed look at the merger of two galaxies of the type thought to be responsible for reionizing the Universe at high redshift.  Much new stellar mass is made by the interaction-induced bursts of star formation, and much ionizing radiation is produced in the process.  To read more about this system, see the paper on arXiv here.

2022 December 15: NIRISS triples the number of redshifts in Webb’s First Deep Field

Today we submitted to MNRAS (and arXiv, here) a paper that describes our just-released catalog of spectroscopic redshifts in the cluster field SMACS 0723, a piece of the extragalactic sky famously observed by JWST as its First Deep Field. The work, led by Gaël and involving a number of our team members, uses NIRISS to triple the number of secure redshifts in this field.  We are making our catalog public so that the community can make the best use of this resource for their science -- go here to download.

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