Estimate of the Mass and Radial Profile of the Orphan-Chenab Stream's Dwarf Galaxy Progenitor Using MilkyWay@home

Abstract

We fit the mass and radial profile of the Orphan-Chenab Stream's (OCS) dwarf galaxy progenitor by using turnoff stars in the Sloan Digital Sky Survey (SDSS) and the Dark Energy Camera (DEC) to constrain N-body simulations of the OCS progenitor falling into the Milky Way on the 1.5 PetaFLOPS MilkyWay@home distributed supercomputer. We infer the internal structure of the OCS's progenitor under the assumption that it was a spherically symmetric dwarf galaxy comprised of a stellar system embedded in an extended dark matter halo. We optimize the evolution time, the baryonic and dark matter scale radii, and the baryonic and dark matter masses of the progenitor using a differential evolution algorithm. The likelihood score for each set of parameters is determined by comparing the simulated tidal stream to the angular distribution of OCS stars observed in the sky. We fit the total mass of the OCS's progenitor to ($2.0\pm 0.3$) $\times 10^7{M}_{\odot }$ with a mass-to-light ratio of $\gamma =73.5\pm 10.6$ and ($1.1\pm 0.2$)$\times 10^6{M}_{\odot }$ within 300 pc of its center. Within the progenitor's half-light radius, we estimate total a mass of ($4.0\pm 1.0$)$\times 10^5{M}_{\odot }$. We also fit the current sky position of the progenitor's remnant to be $(\alpha ,\delta )=((166.0\pm 0.9{)}^{\circ },(-11.1\pm 2.5{)}^{\circ })$ and show that it is gravitationally unbound at the present time. The measured progenitor mass is on the low end of previous measurements, and if confirmed lowers the mass range of ultrafaint dwarf galaxies. Our optimization assumes a fixed Milky Way potential, OCS orbit, and radial profile for the progenitor, ignoring the impact of the Large Magellanic Cloud.

arXiv comment33 pages, 53 figures, to be published by ApJ

References in corpus (56)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• On the variation of the Initial Mass Function
• The Dartmouth Stellar Evolution Database
• Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
• The Sixteenth Data Release of the Sloan Digital Sky Surveys: First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra
• Searching for Dark Matter Annihilation from Milky Way Dwarf Spheroidal Galaxies with Six Years of Fermi-LAT Data
• The Dark Energy Camera
• Compact Remnant Mass Function: Dependence on the Explosion Mechanism and Metallicity
• The Field of Streams: Sagittarius and its Siblings
• The Ghost of Sagittarius and Lumps in the Halo of the Milky Way
• A common mass scale for satellite galaxies of the Milky Way
• A comprehensive Maximum Likelihood analysis of the structural properties of faint Milky Way satellites
• Great Circle tidal streams: evidence for a nearly spherical massive dark halo around the Milky Way
• Constraining the Milky Way potential with a 6-D phase-space map of the GD-1 stellar stream
• Dynamical modelling of the Galactic bulge and bar: the Milky Way's bar pattern speed, stellar, and dark matter mass distribution
• The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: IV. Modeling the Sagittarius Tidal Tails
• The White Dwarf Initial-Final Mass Relation for Progenitor Stars From 0.85 to 7.5 M${}_{\odot }$
• An Orphan in the "Field of Streams"
• Stellar Streams Discovered in the Dark Energy Survey
• Detection of a 60 Degree-Long Dwarf Galaxy Debris Stream
• How Lumpy is the Milky Way's Dark Matter Halo?
• N-body modeling of globular clusters: Masses, mass-to-light ratios and intermediate-mass black holes
• Search for Gamma-Ray Emission from DES Dwarf Spheroidal Galaxy Candidates with Fermi-LAT Data
• The Mass of the Milky Way: Limits from a Newly Assembled Set of Halo Objects
• The shape of the inner Milky Way halo from observations of the Pal 5 and GD-1 stellar streams
• Galactic Globular and Open Clusters in the Sloan Digital Sky Survey. I. Crowded Field Photometry and Cluster Fiducial Sequences in ugriz
• Willman 1 - a probable dwarf galaxy with an irregular kinematic distribution
• Piercing the Milky Way: an all-sky view of the Orphan Stream
• The Orbit of the Orphan Stream
• Triangulum II: Not Especially Dense After All
• Internal kinematics and dynamical models of dwarf spheroidal galaxies around the Milky Way
• Kinematic study of the disrupting globular cluster Palomar 5 using VLT spectra
• Measuring Consistent Masses for 25 Milky Way Globular Clusters
• The information content in cold stellar streams
• The Densest Galaxy
• Results from the search for dark matter in the Milky Way with 9 years of data of the ANTARES neutrino telescope
• Search for dark matter signals towards a selection of recently-detected DES dwarf galaxy satellites of the Milky Way with H.E.S.S
• Triangulum II: Possibly a Very Dense Ultra-Faint Dwarf Galaxy
• Discovery of an Ultra-Faint Stellar System near the Magellanic Clouds with the DECam Local Volume Exploration (DELVE) Survey
• Observed Properties of Dark Matter: dynamical studies of dSph galaxies
• A hydrodynamical study of multiple-shell planetary nebulae. III. Expansion properties and internal kinematics: Theory versus observation
• On the genealogy of the Orphan Stream
• CCD time-series photometry of the globular cluster NGC 5053: RR Lyrae, Blue Stragglers and SX Phoenicis stars revisited
• The Metal-poor non-Sagittarius (?) Globular Cluster NGC 5053: Orbit and Mg, Al and Si Abundances
• Ursa Major II - Reproducing the observed properties through tidal disruption
• The course of the Orphan Stream in the Northern Galactic Hemisphere traced with Gaia DR2
• SMHASH: Anatomy of the Orphan Stream using RR Lyrae stars
• An Orphan No Longer? Detection of the Southern Orphan Stream and a Candidate Progenitor
• Life and death of a hero - Lessons learned from modeling the dwarf spheroidal Hercules: an incorrect orbit?
• The ACTIONFINDER: An unsupervised deep learning algorithm for calculating actions and the acceleration field from a set of orbit segments
• Search for gamma-ray emission from the 12 nearby dwarf spheroidal galaxies with 12 years of Fermi-LAT data
• Fitting the density substructure of the stellar halo with MilkyWay@home
• An Algorithm for Reconstructing the Orphan Stream Progenitor with MilkyWay@home Volunteer Computing

Cited by in corpus (2)

• $S^5$: Probing the Milky Way and Magellanic Clouds potentials with the 6-D map of the Orphan-Chenab stream
• On the Hunt for the Origins of the Orphan--Chenab Stream: Detailed Element Abundances with APOGEE and Gaia