Michael Boylan-Kolchin
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View article: Central densities of dark matter haloes in <scp>fire-2</scp> simulations of low-mass galaxies with cold dark matter and self-interacting dark matter
Central densities of dark matter haloes in <span>fire-2</span> simulations of low-mass galaxies with cold dark matter and self-interacting dark matter Open
We investigate the central density structure of dark matter haloes in cold dark matter (CDM) and self-interacting dark matter (SIDM) models using simulations that are part of the Feedback In Realistic Environments (fire) project. For simul…
View article: How do Massive Primordial Black Holes Impact the Formation of the First Stars and Galaxies?
How do Massive Primordial Black Holes Impact the Formation of the First Stars and Galaxies? Open
We investigate the impact of massive primordial black holes (PBHs; m BH ∼ 10 6 M ⊙ ) on the star formation and first galaxy assembly process using high-resolution hydrodynamical simulations from z = 1100 to z ∼ 9. We find that PBH accretio…
View article: The Absolute Age of Milky Way Globular Clusters
The Absolute Age of Milky Way Globular Clusters Open
Globular clusters (GCs) provide statistically significant coeval populations of stars spanning various evolutionary stages, allowing robust constraints on stellar evolution model parameters and ages. We analyze eight old Milky Way GCs with…
View article: Pickles on FIRE: The 3D Shape Evolution of Simulated Milky Way-Mass Galaxies
Pickles on FIRE: The 3D Shape Evolution of Simulated Milky Way-Mass Galaxies Open
JWST and HST observations have revealed numerous elongated, pickle-shaped galaxies at high to intermediate redshifts, with masses close to those expected for Milky Way progenitors. Here we use reduced-mass eigentensors to quantify the elli…
View article: The Absolute Age of Milky Way Globular Clusters
The Absolute Age of Milky Way Globular Clusters Open
Globular clusters (GCs) provide statistically significant coeval populations of stars spanning various evolutionary stages, allowing robust constraints on stellar evolution model parameters and ages. We analyze eight old Milky Way GCs with…
View article: How do Massive Primordial Black Holes Impact the Formation of the First Stars and Galaxies?
How do Massive Primordial Black Holes Impact the Formation of the First Stars and Galaxies? Open
We investigate the impact of massive primordial black holes (PBHs; $m_{\rm BH}\sim 10^6~M_{\odot}$) on the star formation and first galaxy assembly process using high-resolution hydrodynamical simulations from $z = 1100$ to $z \sim 9$. We …
View article: Accelerated by dark matter: a high-redshift pathway to efficient galaxy-scale star formation
Accelerated by dark matter: a high-redshift pathway to efficient galaxy-scale star formation Open
In the local Universe, star formation is typically inefficient both globally and when considered as the fraction of gas converted into stars per local free-fall time. An important exception to this inefficiency is regions of high gravitati…
View article: Bloodhound Unleashed: Particle-based Substructure Tracking for Cosmological Simulations
Bloodhound Unleashed: Particle-based Substructure Tracking for Cosmological Simulations Open
Modern studies of galaxy formation rely heavily on numerical simulations, which in turn require tools to identify and track self-bound structures in stars and dark matter. In this paper, we present Bloodhound, a new halo tracking algorithm…
View article: Primordial Rotating Disk Composed of ≥15 Star Forming Clumps at Cosmic Dawn
Primordial Rotating Disk Composed of ≥15 Star Forming Clumps at Cosmic Dawn Open
Early galaxy formation, initiated by the dark matter and gas assembly, evolves through frequent mergers and feedback processes into dynamically hot, chaotic structures1. In contrast, dynamically cold, smooth rotating disks have been observ…
View article: Central densities of dark matter halos in FIRE-2 simulations of low-mass galaxies with cold dark matter and self-interacting dark matter
Central densities of dark matter halos in FIRE-2 simulations of low-mass galaxies with cold dark matter and self-interacting dark matter Open
We investigate the central density structure of dark matter halos in cold dark matter (CDM) and self-interacting dark matter (SIDM) models using simulations that are part of the Feedback In Realistic Environments (FIRE) project. For simula…
View article: The Hubble Space Telescope Survey of M31 Satellite Galaxies. IV. Survey Overview and Lifetime Star Formation Histories
The Hubble Space Telescope Survey of M31 Satellite Galaxies. IV. Survey Overview and Lifetime Star Formation Histories Open
From >1000 orbits of HST imaging, we present deep homogeneous resolved star color–magnitude diagrams that reach the oldest main-sequence turnoff and uniformly measured star formation histories (SFHs) of 36 dwarf galaxies (−6 ≥ M V ≥ −17) a…
View article: The Hubble Space Telescope Survey of M31 Satellite Galaxies IV. Survey Overview and Lifetime Star Formation Histories
The Hubble Space Telescope Survey of M31 Satellite Galaxies IV. Survey Overview and Lifetime Star Formation Histories Open
From $>1000$ orbits of HST imaging, we present deep homogeneous resolved star color-magnitude diagrams that reach the oldest main sequence turnoff and uniformly measured star formation histories (SFHs) of 36 dwarf galaxies ($-6 \ge M_V \ge…
View article: Elevated UV luminosity density at Cosmic Dawn explained by non-evolving, weakly mass-dependent star formation efficiency
Elevated UV luminosity density at Cosmic Dawn explained by non-evolving, weakly mass-dependent star formation efficiency Open
Recent observations with JWST have uncovered unexpectedly high cosmic star formation activity in the early Universe, mere hundreds of millions of years after the big bang. These observations are often understood to reflect an evolutionary …
View article: Stellar Metallicities and Gradients in the Faint M31 Satellites Andromeda XVI and Andromeda XXVIII
Stellar Metallicities and Gradients in the Faint M31 Satellites Andromeda XVI and Andromeda XXVIII Open
We present ∼300 stellar metallicity measurements in two faint M31 dwarf galaxies, Andromeda XVI ( M V = −7.5) and Andromeda XXVIII ( M V = –8.8), derived using metallicity-sensitive calcium H and K narrowband Hubble Space Telescope imaging…
View article: Early galaxies and early dark energy: a unified solution to the hubble tension and puzzles of massive bright galaxies revealed by <i>JWST</i>
Early galaxies and early dark energy: a unified solution to the hubble tension and puzzles of massive bright galaxies revealed by <i>JWST</i> Open
JWST has revealed a large population of UV-bright galaxies at $z\gtrsim 10$ and possibly overly massive galaxies at $z\gtrsim 7$, challenging standard galaxy formation models in the ΛCDM cosmology. We use an empirical galaxy formation mode…
View article: Evidence for a Shallow Evolution in the Volume Densities of Massive Galaxies at z = 4–8 from CEERS
Evidence for a Shallow Evolution in the Volume Densities of Massive Galaxies at z = 4–8 from CEERS Open
We analyze the evolution of massive (log 10 [ M ⋆ / M ⊙ ] > 10) galaxies at z ∼ 1–4 selected from JWST Cosmic Evolution Early Release Survey (CEERS). We infer the physical properties of all galaxies in the CEERS NIRCam imaging through spec…
View article: An attractive model: simulating fuzzy dark matter with attractive self-interactions
An attractive model: simulating fuzzy dark matter with attractive self-interactions Open
Fuzzy dark matter (FDM), comprised of ultralight ($m \sim 10^{-22}\,{\rm eV}$) boson particles, has received significant attention as a viable alternative to cold dark matter (CDM), as it approximates CDM on large scales (${\gtrsim}1$ Mpc)…
View article: Sliding into DM: determining the local dark matter density and speed distribution using only the local circular speed of the galaxy
Sliding into DM: determining the local dark matter density and speed distribution using only the local circular speed of the galaxy Open
We use FIRE-2 zoom simulations of Milky Way size disk galaxies to derive easy-to-use relationships between the observed circular speed of the Galaxy at the Solar location, v c , and dark matter properties of relevance for direct detection …
View article: Accelerated by Dark Matter: a High-redshift Pathway to Efficient Galaxy-scale Star Formation
Accelerated by Dark Matter: a High-redshift Pathway to Efficient Galaxy-scale Star Formation Open
In the local Universe, star formation is typically inefficient both globally and when considered as the fraction of gas converted into stars per local free-fall time. An important exception to this inefficiency is regions of high gravitati…
View article: Stellar Metallicities and Gradients in the Faint M31 Satellites Andromeda XVI and Andromeda XXVIII
Stellar Metallicities and Gradients in the Faint M31 Satellites Andromeda XVI and Andromeda XXVIII Open
We present $\sim300$ stellar metallicity measurements in two faint M31 dwarf galaxies, Andromeda XVI ($M_V = -7.5$) and Andromeda XXVIII ($M_V = -8.8$) derived using metallicity-sensitive Calcium H & K narrow-band Hubble Space Telescope im…
View article: Elevated UV luminosity density at Cosmic Dawn explained by non-evolving, weakly mass-dependent star formation efficiency
Elevated UV luminosity density at Cosmic Dawn explained by non-evolving, weakly mass-dependent star formation efficiency Open
Recent observations with the James Webb Space Telescope (JWST) have uncovered unexpectedly high cosmic star formation activity in the early Universe, mere hundreds of millions of years after the Big Bang. These observations are often under…
View article: Testing the near-far connection with FIRE simulations: inferring the stellar mass function of the proto-Local Group at <i>z</i> &gt; 6 using the fossil record of present-day galaxies
Testing the near-far connection with FIRE simulations: inferring the stellar mass function of the proto-Local Group at <i>z</i> > 6 using the fossil record of present-day galaxies Open
The shape of the low-mass (faint) end of the galaxy stellar mass function (SMF) or ultraviolet luminosity function (UVLF) at $z \gtrsim 6$ is an open question for understanding which galaxies primarily drove cosmic reionization. Resolved p…
View article: Early Galaxies and Early Dark Energy: A Unified Solution to the Hubble Tension and Puzzles of Massive Bright Galaxies revealed by JWST
Early Galaxies and Early Dark Energy: A Unified Solution to the Hubble Tension and Puzzles of Massive Bright Galaxies revealed by JWST Open
JWST has revealed a large population of ultra-violet (UV)-bright galaxies at $z\gtrsim 10$ and possibly overly massive galaxies at $z\gtrsim 7$, challenging standard galaxy formation models in the $Λ$CDM cosmology. We use an empirical gala…
View article: Dissipative Dark Matter on FIRE. II. Observational Signatures and Constraints from Local Dwarf Galaxies
Dissipative Dark Matter on FIRE. II. Observational Signatures and Constraints from Local Dwarf Galaxies Open
We analyze the first cosmological baryonic zoom-in simulations of galaxies in dissipative self-interacting dark matter (dSIDM). The simulations utilize the FIRE-2 galaxy formation physics with the inclusion of dissipative dark matter self-…
View article: Confronting the Diversity Problem: The Limits of Galaxy Rotation Curves as a tool to Understand Dark Matter Profiles
Confronting the Diversity Problem: The Limits of Galaxy Rotation Curves as a tool to Understand Dark Matter Profiles Open
While galaxy rotation curves provide one of the most powerful methods for measuring dark matter profiles in the inner regions of rotation-supported galaxies, at the dwarf scale there are factors that can complicate this analysis. Given the…
View article: Hooks & Bends in the radial acceleration relation: discriminatory tests for dark matter and MOND
Hooks & Bends in the radial acceleration relation: discriminatory tests for dark matter and MOND Open
The radial acceleration relation (RAR) connects the total gravitational acceleration of a galaxy at a given radius, atot(r), with that accounted for by baryons at the same radius, abar(r). The shape and tightness of the RAR for rotationall…
View article: COSMOS-Web: Intrinsically Luminous z ≳ 10 Galaxy Candidates Test Early Stellar Mass Assembly
COSMOS-Web: Intrinsically Luminous z ≳ 10 Galaxy Candidates Test Early Stellar Mass Assembly Open
We report the discovery of 15 exceptionally luminous 10 ≲ z ≲ 14 candidate galaxies discovered in the first 0.28 deg 2 of JWST/NIRCam imaging from the COSMOS-Web survey. These sources span rest-frame UV magnitudes of −20.5 > M UV > −22, an…
View article: Stellar Metallicities and Gradients in the Isolated, Quenched Low-mass Galaxy Tucana
Stellar Metallicities and Gradients in the Isolated, Quenched Low-mass Galaxy Tucana Open
We measure the metallicities of 374 red giant branch (RGB) stars in the isolated, quenched dwarf galaxy Tucana using Hubble Space Telescope narrowband (F395N) calcium H and K imaging. Our sample is a factor of ∼7 larger than what is availa…
View article: The JWST Resolved Stellar Populations Early Release Science Program. V. DOLPHOT Stellar Photometry for NIRCam and NIRISS
The JWST Resolved Stellar Populations Early Release Science Program. V. DOLPHOT Stellar Photometry for NIRCam and NIRISS Open
We present NIRCam and NIRISS modules for DOLPHOT, a widely used crowded-field stellar photometry package. We describe details of the modules including pixel masking, astrometric alignment, star finding, photometry, catalog creation, and ar…
View article: Primordial Rotating Disk Composed of $\geq$15 Dense Star-Forming Clumps at Cosmic Dawn
Primordial Rotating Disk Composed of $\geq$15 Dense Star-Forming Clumps at Cosmic Dawn Open
Early galaxy formation, initiated by the dark matter and gas assembly, evolves through frequent mergers and feedback processes into dynamically hot, chaotic structures. In contrast, dynamically cold, smooth rotating disks have been observe…