Professor Alis Deason's Outputs (94)

The Nature of Ionized Gas in the Milky Way Galactic Fountain (2019)
Journal Article
Werk, J. K., Rubin, K., Bish, H., Prochaska, J., Zheng, Y., O’Meara, J., Lenz, D., Hummels, C., & Deason, A. (2019). The Nature of Ionized Gas in the Milky Way Galactic Fountain. Astrophysical Journal, 887(1), Article 89. https://doi.org/10.3847/1538-4357/ab54cf

We address the spatial scale, ionization structure, mass, and metal content of gas at the Milky Way disk–halo interface detected as absorption in the foreground of seven closely spaced, high-latitude halo blue horizontal branch stars with heights z =... Read More about The Nature of Ionized Gas in the Milky Way Galactic Fountain.

The total stellar halo mass of the Milky Way (2019)
Journal Article
Deason, A. J., Belokurov, V., & Sanders, J. L. (2019). The total stellar halo mass of the Milky Way. Monthly Notices of the Royal Astronomical Society, 490(3), 3426-3439. https://doi.org/10.1093/mnras/stz2793

We measure the total stellar halo luminosity using red giant branch (RGB) stars selected from Gaia data release 2. Using slices in magnitude, colour, and location on the sky, we decompose RGB stars belonging to the disc and halo by fitting two-dimens... Read More about The total stellar halo mass of the Milky Way.

Simulating cosmological substructure in the solar neighbourhood (2019)
Journal Article
Simpson, C. M., Gargiulo, I., Gómez, F. A., Grand, R. J., Maffione, N., Cooper, A. P., Deason, A. J., Frenk, C., Helly, J., Marinacci, F., & Pakmor, R. (2019). Simulating cosmological substructure in the solar neighbourhood. Monthly Notices of the Royal Astronomical Society: Letters, 490(1), L32-L37. https://doi.org/10.1093/mnrasl/slz142

We explore the predictive power of cosmological, hydrodynamical simulations for stellar phase-space substructure and velocity correlations with the AURIGA simulations and AURIGAIA mock Gaia catalogues. We show that at the solar circle the AURIGA simu... Read More about Simulating cosmological substructure in the solar neighbourhood.

Galactic Gas Flows from Halo to Disk: Tomography and Kinematics at the Milky Way’s Disk–Halo Interface (2019)
Journal Article
Bish, H. V., Werk, J. K., Prochaska, J. X., Rubin, K. H., Zheng, Y., O’Meara, J. M., & Deason, A. J. (2019). Galactic Gas Flows from Halo to Disk: Tomography and Kinematics at the Milky Way’s Disk–Halo Interface. Astrophysical Journal, 882(2), Article 76. https://doi.org/10.3847/1538-4357/ab3414

We present a novel absorption-line survey using 54 blue horizontal branch stars in the Milky Way halo as background sources for detecting gas flows at the disk–halo interface. Distance measurements to high-latitude (b > 60°) background stars at 3.1–1... Read More about Galactic Gas Flows from Halo to Disk: Tomography and Kinematics at the Milky Way’s Disk–Halo Interface.

Space Telescope and Optical Reverberation Mapping Project. VIII. Time Variability of Emission and Absorption in NGC 5548 Based on Modeling the Ultraviolet Spectrum (2019)
Journal Article
Kriss, G., De Rosa, G., Ely, J., Peterson, B., Kaastra, J., Mehdipour, M., Ferland, G., Dehghanian, M., Mathur, S., Edelson, R., Korista, K., Arav, N., Barth, A., Bentz, M., Brandt, W., Crenshaw, D., Bontà, E. D., Denney, K., Done, C., Eracleous, M., …Zu, Y. (2019). Space Telescope and Optical Reverberation Mapping Project. VIII. Time Variability of Emission and Absorption in NGC 5548 Based on Modeling the Ultraviolet Spectrum. Astrophysical Journal, 881(2), https://doi.org/10.3847/1538-4357/ab3049

We model the ultraviolet spectra of the Seyfert 1 galaxy NGC 5548 obtained with the Hubble Space Telescope during the 6 month reverberation mapping campaign in 2014. Our model of the emission from NGC 5548 corrects for overlying absorption and deblen... Read More about Space Telescope and Optical Reverberation Mapping Project. VIII. Time Variability of Emission and Absorption in NGC 5548 Based on Modeling the Ultraviolet Spectrum.

HALO7D II: The Halo Velocity Ellipsoid and Velocity Anisotropy with Distant Main-sequence Stars (2019)
Journal Article
Cunningham, E. C., Deason, A. J., Sanderson, R. E., Sohn, S. T., Anderson, J., Guhathakurta, P., Rockosi, C. M., van der Marel, R. P., Loebman, S. R., & Wetzel, A. (2019). HALO7D II: The Halo Velocity Ellipsoid and Velocity Anisotropy with Distant Main-sequence Stars. Astrophysical Journal, 879(2), Article 120. https://doi.org/10.3847/1538-4357/ab24cd

The Halo Assembly in Lambda Cold Dark Matter: Observations in 7 Dimensions (HALO7D) data set consists of Keck II/DEIMOS spectroscopy and Hubble Space Telescope–measured proper motions of Milky Way halo main-sequence turnoff stars in the CANDELS field... Read More about HALO7D II: The Halo Velocity Ellipsoid and Velocity Anisotropy with Distant Main-sequence Stars.

The Pisces Plume and the Magellanic wake (2019)
Journal Article
Belokurov, V., Deason, A. J., Erkal, D., Koposov, S. E., Carballo-Bello, J. A., Smith, M. C., Jethwa, P., & Navarrete, C. (2019). The Pisces Plume and the Magellanic wake. Monthly Notices of the Royal Astronomical Society: Letters, 488(1), L47-L52. https://doi.org/10.1093/mnrasl/slz101

Using RR Lyrae stars in the Gaia Data Release 2 and Pan-STARRS1 we study the properties of the Pisces overdensity, a diffuse substructure in the outer halo of the Milky Way. We show that along the line of sight, Pisces appears as a broad and long plu... Read More about The Pisces Plume and the Magellanic wake.

The effects of dynamical substructure on Milky Way mass estimates from the high-velocity tail of the local stellar halo (2019)
Journal Article
Grand, R. J., Deason, A. J., White, S. D., Simpson, C. M., Gómez, F. A., Marinacci, F., & Pakmor, R. (2019). The effects of dynamical substructure on Milky Way mass estimates from the high-velocity tail of the local stellar halo. Monthly Notices of the Royal Astronomical Society: Letters, 487(1), L72-L76. https://doi.org/10.1093/mnrasl/slz092

We investigate the impact of dynamical streams and substructure on estimates of the local escape speed and total mass of Milky-Way-mass galaxies from modelling the high-velocity tail of local halo stars. We use a suite of high-resolution magnetohydro... Read More about The effects of dynamical substructure on Milky Way mass estimates from the high-velocity tail of the local stellar halo.

HALO7D I. The Line-of-sight Velocities of Distant Main-sequence Stars in the Milky Way Halo (2019)
Journal Article
Cunningham, E. C., Deason, A. J., Rockosi, C. M., Guhathakurta, P., Jennings, Z. G., Kirby, E. N., Toloba, E., & Barro, G. (2019). HALO7D I. The Line-of-sight Velocities of Distant Main-sequence Stars in the Milky Way Halo. Astrophysical Journal, 876(2), Article 124. https://doi.org/10.3847/1538-4357/ab16cb

The Halo Assembly in Lambda-CDM: Observations in 7 Dimensions (HALO7D) data set consists of Keck II/DEIMOS spectroscopy and Hubble Space Telescope–measured proper motions of Milky Way halo main-sequence turnoff stars in the CANDELS fields. In this pa... Read More about HALO7D I. The Line-of-sight Velocities of Distant Main-sequence Stars in the Milky Way Halo.

The Halo’s Ancient Metal-Rich Progenitor Revealed with BHB Stars (2019)
Journal Article
Lancaster, L., Koposov, S. E., Belokurov, V., Evans, N. W., & Deason, A. J. (2019). The Halo’s Ancient Metal-Rich Progenitor Revealed with BHB Stars. Monthly Notices of the Royal Astronomical Society, 486(1), 378-389. https://doi.org/10.1093/mnras/stz853

Using the data from the Sloan Digital Sky Survey and the Gaia satellite, we assemble a pure sample of ∼3000 Blue Horizontal Branch (BHB) stars with 7-D information, including positions, velocities and metallicities. We demonstrate that, as traced wit... Read More about The Halo’s Ancient Metal-Rich Progenitor Revealed with BHB Stars.

The local high-velocity tail and the Galactic escape speed (2019)
Journal Article
Deason, A. J., Fattahi, A., Belokurov, V., Evans, N. W., Grand, R. J., Marinacci, F., & Pakmor, R. (2019). The local high-velocity tail and the Galactic escape speed. Monthly Notices of the Royal Astronomical Society, 485(3), 3514-3526. https://doi.org/10.1093/mnras/stz623

We model the fastest moving (⁠v tot >300kms −1 vtot>300kms−1 ⁠) local (D ≲ 3 kpc) halo stars using cosmological simulations and six-dimensional Gaia data. Our approach is to use our knowledge of the assembly history and phase-space distribution of ha... Read More about The local high-velocity tail and the Galactic escape speed.

The mass of the Milky Way from satellite dynamics (2019)
Journal Article
Callingham, T. M., Cautun, M., Deason, A. J., Frenk, C. S., Wang, W., Gómez, F. A., Grand, R. J., Marinacci, F., & Pakmor, R. (2019). The mass of the Milky Way from satellite dynamics. Monthly Notices of the Royal Astronomical Society, 484(4), 5453-5467. https://doi.org/10.1093/mnras/stz365

We present and apply a method to infer the mass of the Milky Way (MW) by comparing the dynamics of MW satellites to those of model satellites in the EAGLE cosmological hydrodynamics simulations. A distribution function (DF) for galactic satellites is... Read More about The mass of the Milky Way from satellite dynamics.

The origin of galactic metal-rich stellar halo components with highly eccentric orbits (2019)
Journal Article
Fattahi, A., Belokurov, V., Deason, A. J., Frenk, C. S., Gómez, F. A., Grand, R. J., Marinacci, F., Pakmor, R., & Springel, V. (2019). The origin of galactic metal-rich stellar halo components with highly eccentric orbits. Monthly Notices of the Royal Astronomical Society, 484(4), 4471-4483. https://doi.org/10.1093/mnras/stz159

Using the astrometry from the ESA’s Gaia mission, previous works have shown that the Milky Way stellar halo is dominated by metal-rich stars on highly eccentric orbits. To shed light on the nature of this prominent halo component, we have analysed 28... Read More about The origin of galactic metal-rich stellar halo components with highly eccentric orbits.

The aftermath of the Great Collision between our Galaxy and the Large Magellanic Cloud (2018)
Journal Article
Cautun, M., Deason, A. J., Frenk, C. S., & McAlpine, S. (2018). The aftermath of the Great Collision between our Galaxy and the Large Magellanic Cloud. Monthly Notices of the Royal Astronomical Society, 483(2), 2185-2196. https://doi.org/10.1093/mnras/sty3084

The Milky Way (MW) offers a uniquely detailed view of galactic structure and is often regarded as a prototypical spiral galaxy. But recent observations indicate that the MW is atypical: it has an undersized supermassive black hole at its centre; it i... Read More about The aftermath of the Great Collision between our Galaxy and the Large Magellanic Cloud.

Aurigaia: mock Gaia DR2 stellar catalogues from the Auriga cosmological simulations (2018)
Journal Article
Grand, R., Helly, J., Fattahi, A., Cautun, M., Cole, S., Cooper, A., Deason, A., Frenk, C., Gómez, F., Hunt, J., Marinacci, F., Pakmor, R., Simpson, C., Springel, V., & Xu, D. (2018). Aurigaia: mock Gaia DR2 stellar catalogues from the Auriga cosmological simulations. Monthly Notices of the Royal Astronomical Society, 481(2), 1726-1743. https://doi.org/10.1093/mnras/sty2403

We present and analyse mock stellar catalogues that match the selection criteria and observables (including uncertainties) of the Gaia satellite data release 2 (DR2). The source are six cosmological high-resolution magneto-hydrodynamic ΛCDM zoom simu... Read More about Aurigaia: mock Gaia DR2 stellar catalogues from the Auriga cosmological simulations.

The Imprint of Cosmic Reionization on the Luminosity Function of Galaxies (2018)
Journal Article
Bose, S., Deason, A. J., & Frenk, C. S. (2018). The Imprint of Cosmic Reionization on the Luminosity Function of Galaxies. Astrophysical Journal, 863(2), Article 123. https://doi.org/10.3847/1538-4357/aacbc4

The (re)ionization of hydrogen in the early universe has a profound effect on the formation of the first galaxies: by raising the gas temperature and pressure, it prevents gas from cooling into small halos, thus affecting the abundance of present-day... Read More about The Imprint of Cosmic Reionization on the Luminosity Function of Galaxies.

Absolute Hubble Space Telescope Proper Motion (HSTPROMO) of Distant Milky Way Globular Clusters: Galactocentric Space Velocities and the Milky Way Mass (2018)
Journal Article
Sohn, S. T., Watkins, L. L., Fardal, M. A., van der Marel, R. P., Deason, A. J., Besla, G., & Bellini, A. (2018). Absolute Hubble Space Telescope Proper Motion (HSTPROMO) of Distant Milky Way Globular Clusters: Galactocentric Space Velocities and the Milky Way Mass. Astrophysical Journal, 862(1), Article 52. https://doi.org/10.3847/1538-4357/aacd0b

We present Hubble Space Telescope (HST) absolute proper motion (PM) measurements for 20 globular clusters (GCs) in the Milky Way (MW) halo at Galactocentric distances RGC » 10 100 – kpc, with a median per-coordinate PM uncertainty of 0.06 m - as yr 1... Read More about Absolute Hubble Space Telescope Proper Motion (HSTPROMO) of Distant Milky Way Globular Clusters: Galactocentric Space Velocities and the Milky Way Mass.

Apocenter Pile-up: Origin of the Stellar Halo Density Break (2018)
Journal Article
Deason, A. J., Belokurov, V., Koposov, S. E., & Lancaster, L. (2018). Apocenter Pile-up: Origin of the Stellar Halo Density Break. Astrophysical Journal Letters, 862(1), Article L1. https://doi.org/10.3847/2041-8213/aad0ee

We measure the orbital properties of halo stars using seven-dimensional information provided by Gaia and the Sloan Digital Sky Survey. A metal-rich population of stars, present in both local main sequence stars and more distant blue horizontal branch... Read More about Apocenter Pile-up: Origin of the Stellar Halo Density Break.

Evolution of LMC/M33-mass dwarf galaxies in the EAGLE simulation (2018)
Journal Article
Shao, S., Cautun, M., Deason, A., Frenk, C., & Theuns, T. (2018). Evolution of LMC/M33-mass dwarf galaxies in the EAGLE simulation. Monthly Notices of the Royal Astronomical Society, 479(1), 284-296. https://doi.org/10.1093/mnras/sty1470

We investigate the population of dwarf galaxies with stellar masses similar to the Large Magellanic Cloud (LMC) and M33 in the EAGLE galaxy formation simulation. In the field, galaxies reside in haloes with stellar-to-halo mass ratios of 1.03+0.50−0.... Read More about Evolution of LMC/M33-mass dwarf galaxies in the EAGLE simulation.

Co-formation of the disc and the stellar halo★ (2018)
Journal Article
Belokurov, V., Erkal, D., Evans, N., Koposov, S., & Deason, A. (2018). Co-formation of the disc and the stellar halo★. Monthly Notices of the Royal Astronomical Society, 478(1), 611-619. https://doi.org/10.1093/mnras/sty982

Using a large sample of main sequence stars with 7D measurements supplied by Gaia and SDSS, we study the kinematic properties of the local (within ∼10 kpc from the Sun) stellar halo. We demonstrate that the halo’s velocity ellipsoid evolves strongly... Read More about Co-formation of the disc and the stellar halo★.