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Detection of Accretion Shelves Out to the Virial Radius of a Low-mass Galaxy with JWST (2024)
Journal Article
Conroy, C., Johnson, B. D., van Dokkum, P., Deason, A., Tacchella, S., Belli, S., …Emami, R. (2024). Detection of Accretion Shelves Out to the Virial Radius of a Low-mass Galaxy with JWST. The Astrophysical Journal, 968(2), Article 129. https://doi.org/10.3847/1538-4357/ad414a

We report the serendipitous discovery of an extended stellar halo surrounding the low-mass galaxy Ark 227 (M * = 5 × 109 M ⊙; d = 35 Mpc) in deep JWST NIRCam imaging from the Blue Jay Survey. The F200W–F444W color provides robust star–galaxy separati... Read More about Detection of Accretion Shelves Out to the Virial Radius of a Low-mass Galaxy with JWST.

The Hubble Space Telescope Survey of M31 Satellite Galaxies. II. The Star Formation Histories of Ultrafaint Dwarf Galaxies (2023)
Journal Article
Savino, A., Weisz, D. R., Skillman, E. D., Dolphin, A., Cole, A. A., Kallivayalil, N., …van der Marel, R. P. (2023). The Hubble Space Telescope Survey of M31 Satellite Galaxies. II. The Star Formation Histories of Ultrafaint Dwarf Galaxies. Astrophysical Journal, 956(2), Article 86. https://doi.org/10.3847/1538-4357/acf46f

We present the lifetime star formation histories (SFHs) for six ultrafaint dwarf (UFD; M V > − 7.0, 4.9

HALO7D. III. Chemical Abundances of Milky Way Halo Stars from Medium-resolution Spectra (2023)
Journal Article
McKinnon, K. A., Cunningham, E. C., Rockosi, C. M., Guhathakurta, P., Escala, I., Kirby, E. N., & Deason, A. J. (2023). HALO7D. III. Chemical Abundances of Milky Way Halo Stars from Medium-resolution Spectra. Astrophysical Journal, 951(1), Article 43. https://doi.org/10.3847/1538-4357/acd33d

The Halo Assembly in Lambda Cold Dark Matter: Observations in 7 Dimensions (HALO7D) survey measures the kinematics and chemical properties of stars in the Milky Way (MW) stellar halo to learn about the formation of our Galaxy. HALO7D consists of Keck... Read More about HALO7D. III. Chemical Abundances of Milky Way Halo Stars from Medium-resolution Spectra.

The progenitor galaxies of stellar haloes as ‘failed’ Milky Ways (2023)
Journal Article
Bose, S., & Deason, A. J. (2023). The progenitor galaxies of stellar haloes as ‘failed’ Milky Ways. Monthly Notices of the Royal Astronomical Society, 522(4), 5013-5021. https://doi.org/10.1093/mnras/stad1123

The stellar halo of the Milky Way records the history of its interactions with dwarf galaxies, whose subsequent destruction results in the formation of an extended stellar component. Recent works have suggested that galaxies with masses comparable to... Read More about The progenitor galaxies of stellar haloes as ‘failed’ Milky Ways.

Overview of the DESI Milky Way Survey (2023)
Journal Article
Cooper, A. P., Koposov, S. E., Allende Prieto, C., Manser, C. J., Kizhuprakkat, N., Myers, A. D., …Zou, H. (2023). Overview of the DESI Milky Way Survey. Astrophysical Journal, 947(1), Article 37. https://doi.org/10.3847/1538-4357/acb3c0

We describe the Milky Way Survey (MWS) that will be undertaken with the Dark Energy Spectroscopic Instrument (DESI) on the Mayall 4 m telescope at the Kitt Peak National Observatory. Over the next 5 yr DESI MWS will observe approximately seven millio... Read More about Overview of the DESI Milky Way Survey.

Constraining the shape of dark matter haloes with globular clusters and diffuse stellar light in the E-MOSAICS simulations (2023)
Journal Article
Reina-Campos, M., Trujillo-Gomez, S., Pfeffer, J. L., Sills, A., Deason, A. J., Crain, R. A., & Diederik Kruijssen, J. M. (2023). Constraining the shape of dark matter haloes with globular clusters and diffuse stellar light in the E-MOSAICS simulations. Monthly Notices of the Royal Astronomical Society, 521(4), 6368–6382. https://doi.org/10.1093/mnras/stad920

We explore how diffuse stellar light and globular clusters (GCs) can be used to trace the matter distribution of their host halo using an observational methodology. For this, we use 117 simulated dark matter (DM) haloes from the periodic volume of... Read More about Constraining the shape of dark matter haloes with globular clusters and diffuse stellar light in the E-MOSAICS simulations.

Unravelling the mass spectrum of destroyed dwarf galaxies with the metallicity distribution function (2023)
Journal Article
Deason, A. J., Koposov, S. E., Fattahi, A., & Grand, R. J. (2023). Unravelling the mass spectrum of destroyed dwarf galaxies with the metallicity distribution function. Monthly Notices of the Royal Astronomical Society, 520(4), 6091-6103. https://doi.org/10.1093/mnras/stad535

Accreted stellar populations are comprised of the remnants of destroyed galaxies, and often dominate the ‘stellar haloes’ of galaxies such as the Milky Way (MW). This ensemble of external contributors is a key indicator of the past assembly history o... Read More about Unravelling the mass spectrum of destroyed dwarf galaxies with the metallicity distribution function.

On the edge: the relation between stellar and dark matter haloes of Milky Way-mass galaxies (2023)
Journal Article
Genina, A., Deason, A., & Frenk, C. (2023). On the edge: the relation between stellar and dark matter haloes of Milky Way-mass galaxies. Monthly Notices of the Royal Astronomical Society, 520(3), 3767-3787. https://doi.org/10.1093/mnras/stad397

We investigate the build-up of the accreted stellar and dark matter haloes of Milky Way-like galaxies in APOSTLE suite of cosmological hydrodynamics simulations. We show that the stellar halo is made up primarily of stars stripped from a small number... Read More about On the edge: the relation between stellar and dark matter haloes of Milky Way-mass galaxies.

Energy wrinkles and phase-space folds of the last major merger (2022)
Journal Article
Belokurov, V., Vasiliev, E., Deason, A. J., Koposov, S. E., Fattahi, A., Dillamore, A. M., …Grand, R. J. (2023). Energy wrinkles and phase-space folds of the last major merger. Monthly Notices of the Royal Astronomical Society, 518(4), 6200-6215. https://doi.org/10.1093/mnras/stac3436

Relying on the dramatic increase in the number of stars with full 6D phase-space information provided by the Gaia Data Release 3, we resolve the distribution of the stellar halo around the Sun to uncover signatures of incomplete phase-mixing. We show... Read More about Energy wrinkles and phase-space folds of the last major merger.

Observing EAGLE galaxies with JWST: predictions for Milky Way progenitors and their building blocks (2022)
Journal Article
Evans, T. A., Fattahi, A., Deason, A. J., & Frenk, C. S. (2022). Observing EAGLE galaxies with JWST: predictions for Milky Way progenitors and their building blocks. Monthly Notices of the Royal Astronomical Society, 516(3), 3861-3877. https://doi.org/10.1093/mnras/stac2410

We present predictions, derived from the EAGLE ΛCDM cosmological hydrodynamical simulations, for the abundance and properties of galaxies expected to be detected at high redshift by the James Webb Space Telescope (JWST). We consider the galaxy popula... Read More about Observing EAGLE galaxies with JWST: predictions for Milky Way progenitors and their building blocks.

Structural Parameters and Possible Association of the Ultra-faint Dwarfs Pegasus III and Pisces II from Deep Hubble Space Telescope Photometry (2022)
Journal Article
Richstein, H., Patel, E., Kallivayalil, N., Simon, J. D., Zivick, P., Tollerud, E., …Sohn, S. T. (2022). Structural Parameters and Possible Association of the Ultra-faint Dwarfs Pegasus III and Pisces II from Deep Hubble Space Telescope Photometry. Astrophysical Journal, 933(2), Article 217. https://doi.org/10.3847/1538-4357/ac7226

We present deep Hubble Space Telescope (HST) photometry of the ultra-faint dwarf (UFD) galaxies Pegasus III (Peg III) and Pisces II (Psc II), two of the most distant satellites in the halo of the Milky Way (MW). We measure the structure of both galax... Read More about Structural Parameters and Possible Association of the Ultra-faint Dwarfs Pegasus III and Pisces II from Deep Hubble Space Telescope Photometry.

The chemo-dynamical groups of Galactic globular clusters (2022)
Journal Article
Callingham, T. M., Cautun, M., Deason, A. J., Frenk, C. S., Grand, R. J., & Marinacci, F. (2022). The chemo-dynamical groups of Galactic globular clusters. Monthly Notices of the Royal Astronomical Society, 513(3), 4107-4129. https://doi.org/10.1093/mnras/stac1145

We introduce a multicomponent chemo-dynamical method for splitting the Galactic population of globular clusters (GCs) into three distinct constituents: bulge, disc, and stellar halo. The latter is further decomposed into the individual large accretio... Read More about The chemo-dynamical groups of Galactic globular clusters.

Radial distributions of globular clusters trace their host dark matter halo: insights from the E-MOSAICS simulations (2022)
Journal Article
Reina-Campos, M., Trujillo-Gomez, S., Deason, A. J., Kruijssen, J. D., Pfeffer, J. L., Crain, R. A., …Hughes, M. E. (2022). Radial distributions of globular clusters trace their host dark matter halo: insights from the E-MOSAICS simulations. Monthly Notices of the Royal Astronomical Society, 513(3), 3925-3945. https://doi.org/10.1093/mnras/stac1126

Globular clusters (GCs) are bright objects that span a wide range of galactocentric distances, and can therefore probe the structure of dark matter (DM) haloes. In this work, we explore whether the projected number density radial profiles of GCs can... Read More about Radial distributions of globular clusters trace their host dark matter halo: insights from the E-MOSAICS simulations.

Fast, Slow, Early, Late: Quenching Massive Galaxies at z ∼ 0.8 (2022)
Journal Article
Tacchella, S., Conroy, C., Faber, S., Johnson, B. D., Leja, J., Barro, G., …Yesuf, H. M. (2022). Fast, Slow, Early, Late: Quenching Massive Galaxies at z ∼ 0.8. Astrophysical Journal, 926(2), Article 134. https://doi.org/10.3847/1538-4357/ac449b

We investigate the stellar populations for a sample of 161 massive, mainly quiescent galaxies at 〈zobs〉 = 0.8 with deep Keck/DEIMOS rest-frame optical spectroscopy (HALO7D survey). With the fully Bayesian framework Prospector, we simultaneously fit... Read More about Fast, Slow, Early, Late: Quenching Massive Galaxies at z ∼ 0.8.

Dwarf stellar haloes: a powerful probe of small-scale galaxy formation and the nature of dark matter (2021)
Journal Article
Deason, A. J., Bose, S., Fattahi, A., Amorisco, N. C., Hellwing, W., & Frenk, C. S. (2022). Dwarf stellar haloes: a powerful probe of small-scale galaxy formation and the nature of dark matter. Monthly Notices of the Royal Astronomical Society, 511(3), 4044-4059. https://doi.org/10.1093/mnras/stab3524

We use N-body cosmological simulations and empirical galaxy models to study the merger history of dwarf-mass galaxies (with Mhalo∼1010M⊙⁠). Our input galaxy models describe the stellar mass–halo mass relation, and the galaxy occupation fraction. The... Read More about Dwarf stellar haloes: a powerful probe of small-scale galaxy formation and the nature of dark matter.

Star Formation Histories of Ultra-faint Dwarf Galaxies: Environmental Differences between Magellanic and Non-Magellanic Satellites?* (2021)
Journal Article
Sacchi, E., Richstein, H., Kallivayalil, N., van der Marel, R., Libralato, M., Zivick, P., …Wetzel, A. (2021). Star Formation Histories of Ultra-faint Dwarf Galaxies: Environmental Differences between Magellanic and Non-Magellanic Satellites?*. Astrophysical Journal Letters, 920(1), Article L19. https://doi.org/10.3847/2041-8213/ac2aa3

We present the color–magnitude diagrams and star formation histories (SFHs) of seven ultra-faint dwarf galaxies: Horologium 1, Hydra 2, Phoenix 2, Reticulum 2, Sagittarius 2, Triangulum 2, and Tucana 2, derived from highprecision Hubble Space Telesco... Read More about Star Formation Histories of Ultra-faint Dwarf Galaxies: Environmental Differences between Magellanic and Non-Magellanic Satellites?*.

Discovery of a possible splashback feature in the intracluster light of MACS J1149.5+2223 (2021)
Journal Article
Gonzalez, A. H., George, T., Connor, T., Deason, A., Donahue, M., Montes, M., …Zaritsky, D. (2021). Discovery of a possible splashback feature in the intracluster light of MACS J1149.5+2223. Monthly Notices of the Royal Astronomical Society, 507(1), 963-970. https://doi.org/10.1093/mnras/stab2117

We present an analysis of the intracluster light (ICL) in the Frontier Field Cluster MACS J1149.5+2223 (z = 0.544), which combines new and archival Hubble WFC3/IR imaging to provide continuous radial coverage out to 2.8 Mpc from the brightest cluster... Read More about Discovery of a possible splashback feature in the intracluster light of MACS J1149.5+2223.

Detection of the LMC-induced sloshing of the Galactic halo (2021)
Journal Article
Erkal, D., Deason, A. J., Belokurov, V., Xue, X., Koposov, S. E., Bird, S. A., …Zhao, G. (2021). Detection of the LMC-induced sloshing of the Galactic halo. Monthly Notices of the Royal Astronomical Society, 506(2), 2677-2684. https://doi.org/10.1093/mnras/stab1828

A wealth of recent studies have shown that the LMC is likely massive, with a halo mass >1011M⊙. One consequence of having such a nearby and massive neighbour is that the inner Milky Way is expected to be accelerated with respect to our Galaxy’s outsk... Read More about Detection of the LMC-induced sloshing of the Galactic halo.