Publications (61)
On the mass assembly history of the Milky Way: clues from its stellar halo
Danny Horta, Ricardo P. Schiavon
Stellar halos of galaxies retain crucial clues to their mass assembly history. It is in these galactic components that the remains of cannibalised galactic building blocks are depo…
Measuring Dwarf Galaxy Intrinsic Abundance Scatter with Mid-resolution Spectroscopic Surveys: Calibrating APOGEE Abundance Errors
Jennifer Mead, Melissa Ness, Eric Andersson +2
The first generations of stars left their chemical fingerprints on metal-poor stars in the Milky Way and its surrounding dwarf galaxies. While instantaneous and homogeneous enrichm…
The chemical characterisation of halo substructure in the Milky Way based on APOGEE
Danny Horta, Ricardo P. Schiavon, J. Ted Mackereth +21
Galactic haloes in a -CDM universe are predicted to host today a swarm of debris resulting from cannibalised dwarf galaxies. The chemo-dynamical information recorded in their s…
Overview of The SDSS-V Magellanic Genesis Survey
David L. Nidever, Danny Horta, Steven R. Majewski +14
The Sloan Digital Sky Survey-V (SDSS-V) Magellanic Genesis survey is a spectroscopic program designed to map the kinematic and chemical structure of the Magellanic Clouds using APO…
Measuring and modelling the Splash with APOGEE/Gaia and ARTEMIS
Shobhit Kisku, Ricardo P. Schiavon, Andreea S. Font +6
Using combined data from SDSS-IV/APOGEE and Gaia, we study the chemo-dynamical properties of the Splash population in comparison with those of the high-alpha disc. We investigate a…
The Sixteenth Data Release of the Sloan Digital Sky Surveys: First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra
Romina Ahumada, Carlos Allende Prieto, Andres Almeida +310
This paper documents the sixteenth data release (DR16) from the Sloan Digital Sky Surveys; the fourth and penultimate from the fourth phase (SDSS-IV). This is the first release of…
The Nineteenth Data Release of the Sloan Digital Sky Survey
SDSS Collaboration, Gautham Adamane Pallathadka, Mojgan Aghakhanloo +209
Mapping the local and distant Universe is key to our understanding of it. For decades, the Sloan Digital Sky Survey (SDSS) has made a concerted effort to map millions of celestial…
The Milky Way's circular velocity curve measured using element abundance gradients
Danny Horta, Adrian M. Price-Whelan, Sergey E. Koposov +4
Spectroscopic surveys now supply precise stellar label measurements such as element abundances for large samples of stars throughout the Milky Way. These element abundances are kno…
Stellar Mergers or Truly Young? Intermediate-Age Stars on Highly-Radial Orbits in the Milky Way's Stellar Halo
Danny Horta, Yuxi, Lu +3
Reconstructing the mass assembly history of the Milky Way relies on obtaining detailed measurements of the properties of many stars in the Galaxy, especially in the stellar halo. O…
Evidence of Truly Young high- Dwarf Stars
Yuxi Lu, Isabel L. Colman, Maryum Sayeed +14
The existence of high- stars with inferred ages < 6 Gyr has been confirmed recently with large spectroscopic and photometric surveys. However, stellar mergers or binary interac…
The Seventeenth Data Release of the Sloan Digital Sky Surveys: Complete Release of MaNGA, MaStar and APOGEE-2 Data
Abdurro'uf, Katherine Accetta, Conny Aerts +337
This paper documents the seventeenth data release (DR17) from the Sloan Digital Sky Surveys; the fifth and final release from the fourth phase (SDSS-IV). DR17 contains the complete…
A slow spin to win -- the gradual evolution of the proto-Galaxy to the old disc
Akshara Viswanathan, Danny Horta, Adrian M. Price-Whelan +1
Observational studies are identifying stars thought to be remnants from the earliest stages of the hierarchical mass assembly of the Milky Way, referred to as the proto-Galaxy. We…
An enquiry on the origins of N-rich stars in the inner Galaxy basedon APOGEE chemical compositions
Shobhit Kisku, Ricardo P. Schiavon, Danny Horta +10
Recent evidence based on APOGEE data for stars within a few kpc of the Galactic centre suggests that dissolved globular clusters (GCs) contribute significantly to the stellar mass…
OTI on FIRE: Testing the Efficacy of Orbital Torus Imaging to Recover the Galactic Potential
Micah Oeur, Sarah R. Loebman, Adrian M. Price-Whelan +3
Orbital Torus Imaging (OTI) is a dynamical inference method for determining the Milky Way's gravitational potential using stellar survey data. OTI uses gradients in stellar astroph…
GALATEA: The 15-m Galactic Archaeology Spectroscopic Surveyor
Borja Anguiano, David Valls-Gabaud, Andrés del Pino +5
\textsc{GALATEA} (the \emph{Galactic Archaeology and Local-group Astrophysics Telescope for Extended Areas}) is a concept for a dedicated 15-m, wide-field, 10,000-fibre spectroscop…
NANCY: Next-generation All-sky Near-infrared Community surveY
Jiwon Jesse Han, Arjun Dey, Adrian M. Price-Whelan +206
The Nancy Grace Roman Space Telescope is capable of delivering an unprecedented all-sky, high-spatial resolution, multi-epoch infrared map to the astronomical community. This oppor…
Tidal Debris Candidates from the Centauri Accretion Event and its Role in Building Up the Milky Way Halo
Borja Anguiano, Arik Mitschang, Takanobu Kirihara +11
We identify stellar tidal debris from the Centauri ( Cen) system among field stars in the APOGEE survey via chemical tagging using a neural network trained on APOGEE obser…
The contribution of N-rich stars to the Galactic stellar halo using APOGEE red giants
Danny Horta, J. Ted Mackereth, Ricardo P. Schiavon +13
The contribution of dissolved globular clusters (GCs) to the stellar content of the Galactic halo is a key constraint on models for GC formation and destruction, and the mass assem…
The Extremely Metal Rich Knot of Stars at the Heart of the Galaxy
Hans-Walter Rix, Vedant Chandra, Gail Zasowski +15
We show with Gaia XP spectroscopy that extremely metal-rich stars in the Milky Way (EMR; ) - but only those - are largely confined to a tight "knot" at the center…
Counterculture Stars: Slow and Retrograde Stars with Low-Alpha Disk Abundances
Carrie Filion, Michael S. Petersen, Danny Horta +3
The Milky Way is home to a thin disk that can be defined via kinematics and/or elemental abundances. The elemental abundance-defined thin disk, also called the low-alpha disk, is g…
The Milky Way tomography with APOGEE: intrinsic density distribution and structure of mono-abundance populations
Jianhui Lian, Gail Zasowski, Ted Mackereth +11
The spatial distribution of mono-abundance populations (MAPs, selected in [Fe/H] and [Mg/Fe]) reflect the chemical and structural evolution in a galaxy and impose strong constraint…
The Chemical Compositions of Accreted and {\it in situ} Galactic Globular Clusters According to SDSS/APOGEE
Danny Horta, Ricardo P. Schiavon, J. Ted Mackereth +16
Studies of the kinematics and chemical compositions of Galactic globular clusters (GCs) enable the reconstruction of the history of star formation, chemical evolution, and mass ass…
Spectacular nucleosynthesis from early massive stars
Alexander P. Ji, Sanjana Curtis, Nicholas Storm +39
Stars formed with initial mass over 50 Msun are very rare today, but they are thought to be more common in the early universe. The fates of those early, metal-poor, massive stars a…
Is Terzan 5 the remnant of a building block of the Galactic bulge? Evidence from APOGEE
Dominic J. Taylor, Andrew C. Mason, Ricardo P. Schiavon +16
It has been proposed that the globular cluster-like system Terzan 5 is the surviving remnant of a primordial building block of the Milky Way bulge, mainly due to the age/metallicit…
The observable properties of galaxy accretion events in Milky Way-like galaxies in the FIRE-2 cosmological simulations
Danny Horta, Emily C. Cunningham, Robyn E. Sanderson +7
In the -Cold Dark Matter model of the Universe, galaxies form in part through accreting satellite systems. Previous work have built an understanding of the signatures of these…
The proto-galaxy of Milky Way-mass haloes in the FIRE simulations
Danny Horta, Emily C. Cunningham, Robyn Sanderson +9
Observational studies are finding stars believed to be relics of the earliest stages of hierarchical mass assembly of the Milky Way (i.e., proto-Galaxy). In this work, we contextua…
Orbital Torus Imaging: Acceleration, density, and dark matter in the Galactic disk measured with element abundance gradients
Danny Horta, Adrian M. Price-Whelan, David W. Hogg +5
Under the assumption of a simple and time-invariant gravitational potential, many Galactic dynamics techniques infer the Milky Way's mass and dark matter distribution from stellar…
Stellar Birth Radii in the LMC: Insights into Chemodynamics, Radial Migration, and Star Formation Across the Disk
Yuxi Lu, Bethany Garver, David L. Nidever +4
The LMC and SMC are interacting dwarf galaxies that offer a valuable testbed for studying the effects of galactic mergers. We investigate the chemodynamic history of the LMC in the…
On the co-rotation of Milky Way satellites: LMC-mass satellites induce apparent motions in outer halo tracers
Nicolas Garavito-Camargo, Adrian M. Price-Whelan, Jenna Samuel +8
Understanding the physical mechanism behind the formation of a co-rotating thin plane of satellite galaxies, like the one observed around the Milky Way (MW), has been challenging.…
The homogeneity of the star forming environment of the Milky Way disk over time
Melissa K. Ness, Adam J. Wheeler, Kevin McKinnon +4
Stellar abundances and ages afford the means to link chemical enrichment to galactic formation. In the Milky Way, individual element abundances show tight correlations with age, wh…
APOGEE Chemical Abundance Patterns of the Massive Milky Way Satellites
Sten Hasselquist, Christian R. Hayes, Jianhui Lian +42
The SDSS-IV Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey has obtained high-resolution spectra for thousands of red giant stars distributed among the massi…
Chemical tagging with APOGEE, MUSE, and HST: constraints on the formation of Centauri
Andrew C. Mason, Ricardo P. Schiavon, Sebastian Kamann +9
A plethora of evidence suggests that Centauri ( Cen) is the nuclear star cluster of a galaxy that merged with the Milky Way in early times. We use APOGEE, Gaia, MUSE, and…
[X/Fe] Marks the Spot: Mapping Chemical Azimuthal Variations in the Galactic Disk with APOGEE
Zoe Hackshaw, Keith Hawkins, Carrie Filion +4
Chemical cartography of the Galactic disk provides insights to its structure and assembly history over cosmic time. In this work, we use chemical cartography to explore chemical gr…
Payne4GAIN: NLTE Corrections for Red Giants in Milky Way Mapper using H-Band Neural Network Emulators
Pierre Thibodeaux, Alexander P. Ji, Nicholas Storm +12
The majority of spectroscopic surveys assume local thermodynamic equilibrium (LTE) during the modeling of stellar spectra. This assumption begins to break down for luminous stars,…
Neutron-capture elements record the ordered chemical evolution of the disc over time
Danny Horta, Melissa K. Ness, Jan Rybizki +2
An ensemble of chemical abundances probing different nucleosynthetic channels can be leveraged to build a comprehensive understanding of the chemical and structural evolution of th…
The structure and evolution of the Galactic high- disc I. Chemical and age orbital cartography
Furkan Akbaba, Danny Horta, Olcay Plevne
We present a comprehensive chemical and age orbital cartography of the Galactic high- disc using subgiant stars with precise ages, element abundances, and full phase-space info…
The Debris of the "Last Major Merger" is Dynamically Young
Thomas Donlon, Heidi Jo Newberg, Robyn Sanderson +4
The Milky Way's (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the "last major merger." Hypotheses for the origin of t…
Sloan Digital Sky Survey-V: Pioneering Panoptic Spectroscopy
Juna A. Kollmeier, Hans-Walter Rix, Conny Aerts +217
The Sloan Digital Sky Survey-V (SDSS-V) is pioneering panoptic spectroscopy: it is the first all-sky, multi-epoch, optical-to-infrared spectroscopic survey. SDSS-V is mapping the s…
Data-driven Dynamics with Orbital Torus Imaging: A Flexible Model of the Vertical Phase Space of the Galaxy
Adrian M. Price-Whelan, Jason A. S. Hunt, Danny Horta +4
The vertical kinematics of stars near the Sun can be used to measure the total mass distribution near the Galactic disk and to study out-of-equilibrium dynamics. With contemporary…
Modelling the density and mass of the Milky Way's proto-galaxy components with -
Danny Horta, Ricardo P. Schiavon
Unravelling galaxy formation theory requires understanding galaxies both at high and low redshifts. A possible way to connect both realms is by studying the oldest stars in the Mil…
APOGEE Detection of N-rich stars in the tidal tails of Palomar 5
Sian G. Phillips, Ricardo P. Schiavon, J. Ted Mackereth +15
Recent results from chemical tagging studies using APOGEE data suggest a strong link between the chemical abundance patterns of stars found within globular clusters, and chemically…
Chemodynamically Characterizing the Jhelum Stellar Stream with APOGEE-2
Allyson A. Sheffield, Aidan Z. Subrahimovic, Mohammad Refat +15
We present the kinematic and chemical profiles of red giant stars observed by the APOGEE-2 survey in the direction of the Jhelum stellar stream, a Milky Way substructure located in…
Evidence from APOGEE for the presence of a major building block of the halo buried in the inner Galaxy
Danny Horta, Ricardo P. Schiavon, J. Ted Mackereth +13
We report evidence from APOGEE for the presence of a new metal-poor stellar structure located within 4~kpc of the Galactic centre. Characterised by a chemical composition res…
Is Liller 1 a building block of the Galactic bulge? -- Evidence with APOGEE
Anna Liptrott, Ricardo P. Schiavon, Andrew C. Mason +10
Liller 1 is a stellar system orbiting within the inner 0.8kpc of the Galactic centre, characterised by a wide spread in age and metallicity, indicating a high mass. Liller 1 has be…
Radial phase spirals in the Solar neighbourhood
Jason A. S. Hunt, Adrian M. Price-Whelan, Kathryn V. Johnston +4
The second data release of ESA's mission revealed numerous signatures of disequilibrium in the Milky Way's disc. These signatures are seen in the planar kinematics of stars,…
The Twentieth Data Release of the Sloan Digital Sky Survey: First All-Sky BOSS Spectra, eROSITA-SDSS-V Mapper Coordinated Observations, and a Preview of the Local Volume Mapper
SDSS Collaboration, Mojgan Aghakhanloo, David Aguilar +273
The paper describes the twentieth data release (DR20) of the Sloan Digital Sky Survey, providing over 3 million new optical spectra from the SDSS‑V Milky Way, Black Hole, and Local…
Cosmological predictions for minor axis stellar density profiles in the inner regions of Milky Way-mass galaxies
Madeline Lucey, Robyn Sanderson, Danny Horta +5
CDM cosmology predicts the hierarchical formation of galaxies which build up mass by merger events and accreting smaller systems. The stellar halo of the Milky Way has proven t…
Hydrostatic and explosive -element chemical abundances of Milky Way globular clusters, halo substructures, and satellite galaxies
Danny Horta, Melissa K. Ness
Stellar atmospheric element abundance ratios of stars retain information about their birth conditions, helping elucidate their origin and nature. In this letter, we analyse and con…
RomAndromeda: The Roman Survey of the Andromeda Halo
Arjun Dey, Joan Najita, Carrie Filion +50
As our nearest large neighbor, the Andromeda Galaxy provides a unique laboratory for investigating galaxy formation and the distribution and substructure properties of dark matter…
Reading the CARDs: the Imprint of Accretion History in the Chemical Abundances of the Milky Way's Stellar Halo
Emily C. Cunningham, Robyn E. Sanderson, Kathryn V. Johnston +7
In the era of large-scale spectroscopic surveys in the Local Group (LG), we can explore using chemical abundances of halo stars to study the star formation and chemical enrichment…
2-process Model and Residual Abundance Analysis of the Milky Way Massive Satellites
Sten Hasselquist, Christian R. Hayes, Emily J. Griffith +4
The ``2-process Model'' is a promising technique for interpreting stellar chemical abundance data from large-scale surveys (e.g., SDSS-IV/V, GALAH), enabling more quantitative empi…
Variations in the Milky Way's Stellar Mass Function at [Fe/H] < -1
Jiadong Li, Hans-Walter Rix, Yuan-Sen Ting +14
We present the first determination of the Galactic stellar mass function (MF) for low-mass stars (0.2-0.5 M_sun) at metallicities [Fe/H] < -1. A sample of ~53,000 stars was selecte…
CAPOS: The bulge Cluster APOgee Survey I. Overview and initial ASPCAP results
Doug Geisler, Sandro Villanova, Julia E. O'Connell +39
Context. Bulge globular clusters (BGCs) are exceptional tracers of the formation and chemodynamical evolution of this oldest Galactic component. However, until now, observational d…
The imprint of dark matter on the Galactic acceleration field
Arpit Arora, Robyn E. Sanderson, Sukanya Chakrabarti +6
Measurements of the accelerations of stars enabled by time-series extreme-precision spectroscopic observations, from pulsar timing, and from eclipsing binary stars in the Solar Nei…
: A generative, multi-output, latent-variable model for astronomical data with noisy labels
Danny Horta, Adrian M. Price-Whelan, David W. Hogg +2
The large volume of spectroscopic data available now and from near-future surveys will enable high-dimensional measurements of stellar parameters and properties. Current methods fo…
The APOGEE Value Added Catalogue of Galactic globular cluster stars
Ricardo P. Schiavon, Siân G. Phillips, Natalie Myers +17
We introduce the SDSS/APOGEE Value Added Catalogue of Galactic Globular Cluster (GC) Stars. The catalogue is the result of a critical search of the APOGEE data release 17 (DR17) ca…
The GALAH Survey: Chemical tagging and chrono-chemodynamics of accreted halo stars with GALAH+ DR3 and eDR3
Sven Buder, Karin Lind, Melissa K. Ness +27
Since the advent of astrometry, it is possible to identify massive accreted systems within the Galaxy through their unique dynamical signatures. One such system, -Saus…
Linking globular cluster formation at low and high redshift through the age-metallicity relation in E-MOSAICS
Danny Horta, Meghan E. Hughes, Joel L. Pfeffer +4
We set out to compare the age-metallicity relation (AMR) of massive clusters from Magellanic Cloud mass galaxies in the E-MOSAICS suite of numerical cosmological simulations with a…
A Comparative Analysis of the Chemical Compositions of Gaia-Enceladus/Sausage and Milky Way Satellites using APOGEE
Laura Fernandes, Andrew C. Mason, Danny Horta +11
We use data from the 17th data release of the Apache Point Observatory Galactic Evolution Experiment (APOGEE 2) to contrast the chemical composition of the recently discovered Gaia…
Disentangling the Galaxy's Gordian knot: evidence from for a knotted and slower bar in the Milky Way
Danny Horta, Michael S. Petersen, Jorge Peñarrubia
The inner kiloparsec (kpc) region of the Milky Way is complex. Unravelling the evolution of the Galaxy requires precise understanding of the formation of this region. We re…
Cosmological Simulations of Stellar Halos with Gaia Sausage-Enceladus Analogues: Two Sausages, One Bun?
Dylan Folsom, Mariangela Lisanti, Lina Necib +3
Observations of the Milky Way's stellar halo find that it is predominantly comprised of a radially biased population of stars, dubbed the Gaia Sausage--Enceladus, or GSE. These sta…