I am a member of the JWST Mid-Infrared Instrument (MIRI) instrument and Guaranteed Time Observation (GTO) teams as well as the Near-Infrared Camera (NIRCam) GTO team.  I have participated in the detector testing and characterization of MIRI ongoing at JPL and in the integrated facility testing that occurred at Goddard Space Flight Center in 2015 and at Johnson Space Center in 2017.  With the GTO teams, I plan, design, and will eventually carry out JWST Cycle 1 GTO extragalactic science programs, a few of which you can read about below.

JWST/MIRI imaging in the HUDF

The Hubble Ultra Deep Field (HUDF) and surrounding area is the most well-studied patch of the sky, containing some of the deepest data (and farthest and youngest galaxies!) ever seen spanning the X-ray to the optical to the infrared to the radio. This area will be targeted by the NIRCam and NIRSpec GTO teams for the extensive JWST Advanced Deep Extragalactic Survey (JADES), which will provide early, extremely deep and wide near-infrared imaging and spectroscopy.  Mid-infrared MIRI imaging will be obtained as part of JADES and US and EC lead GTO programs.  Together these surveys will demonstrate the power of JWST to expand our science horizons.
MIRI imaging in the HUDF region will be obtained by the European Consortium MIRI GTO team, the United States MIRI GTO team, and the JADES team.  I am involved in the latter two efforts.  The MIRI HUDF Survey will image with the MIRI photometric bands (5-25.5μm, excepting the 11.3μm filter) over an area of 30 sq. arcmin centered on the HUDF.  The unprecedented photometric coverage and high resolution of MIRI imaging in the mid-infrared will allow us to carry out a census of obscured AGN activity,  star formation activity down to ~10 Msun/yr, and model mid-infrared aromatic features in statistical samples of galaxies up to cosmic noon (z~1-3).  The combination of MIRI and NIRCam imaging will allow us to push to low masses and lower metallicities.  As part of the JADES program, MIRI imaging will be obtained in parallel at 7.7 and 12.8μm.  7.7μm imaging to 27.4 AB mag obtained over 40 hours exposure time will allow us to constrain the stellar masses of z~5-6 galaxies, informing stellar mass modeling.  Wider, shallower 7.7 and 12.8μm imaging to 25.6 and 25 AB mag will probe stellar features, including emission from TP-AGB stars, at z~1-4 and serve as discovery space, with a 1000x improvement in sensitivity at 12.8μm over existing facilities (the Wide-field Infrared Explorer).

The Mystery of Jellyfish Galaxies

Jellyfish galaxies are galaxies that are falling into galaxy clusters.  In addition to being dense "cities" of galaxies, galaxy clusters use their deep gravity well to hold on to deep pools of hot gas.  This gas creates a "wake" for the galaxies that are falling into or through the cluster, stripping off materials like gas and stars to create spectacular jellyfish tails.

This process is one of the leading contenders to explain why galaxies that live in clusters shut down their star formation earlier than galaxies outside - this process may strip off the precious gas they need to form stars.   In Cycle 1, we will look at the well-studied local galaxy ESO 137-001 (right), obtaining high resolution MIRI IFU spectroscopy over 5-25.5μm at several locations spanning the galaxy-tail interface to the mid-tail.   This spectral range covers multiple rotational transition of H2 and additional fine structure lines, probing shock heated hot and warm gas at and around star forming currently proceeding in the tail.  These diagnostics will establish if the star formation is occurring in situ and/or was stripped from the galaxy.   For more information on our JWST program, check out this press release.
ESO 137-001
Image Credit:  X-ray: NASA/CXC/UAH/M.Sun et al; Optical: NASA, ESA, & the Hubble Heritage Team (STScI/AURA)
Arp220 on APOD

Supermassive black holes in the most dusty galaxies

Supermassive black holes are thought to play a vital role in the evolution of galaxies, particularly the most massive, luminous galaxies.  However, galaxies contain dust which can obscure our view of their components.  One class in particular, the Ultraluminous Infrared Galaxies (ULIRGs), are so dusty the light we normally see from the black hole (from the accretion disk and surrounding gas) cannot escape in a way we can currently see!  Enter JWST, which will reveal the mid-infrared light of these galaxies, where neon gas excited by the black hole will be emitted.  This signature and others provided by JWST will prove whether these ultra dusty galaxies host the black holes we expect them to.
In Cycle 1, we will target 5 local ULIRGs (including Arp220, above) which have ambiguous evidence for an accreting central black hole.  We will obtain both NIRSpec and MIRI IFU of the nucleus, with the primary goal of detecting the forbidden line [NeVI] at 7.65μm.  ​[NeVI] is similarly extincted as hard X-ray and comes from an extended region around the central engine, making it a unique indicator.  However, the existence of featureless spectra such as that of Mrk 231 necessitate additional indicators, such as stellar features at 3-5μm.