Ultra faint dwarfs: probing early cosmic star formation

Abstract

We investigate the nature of the newly discovered Ultra Faint dwarf spheroidal galaxies (UF dSphs) in a general cosmological context simultaneously accounting for various ``classical`` dSphs and Milky Way properties including their Metallicity Distribution Function (MDF). To this aim we extend the merger tree approach previously developed to include the presence of star-forming minihaloes, and an heuristic prescription for radiative feedback. The model successfully reproduces both the observed [Fe/H]-Luminosity relation and the mean MDF of UFs. In this picture UFs are the oldest, most dark matter-dominated (M/L > 100) dSphs with a total mass M= 10^{7-8}Msun; they are leftovers of H_2-cooling minihaloes formed at z > 8.5, i.e. before reionization. Their MDF is broader (because of a more prolonged SF) and shifted towards lower [Fe/H] (as a result of a lower gas metallicity at the time of formation) than that of classical dSphs. These systems are very ineffectively star-forming, turning into stars by z=0 only <3% of the potentially available baryons. We provide a useful fit for the star formation efficiency of dSphs.

5 pages, 4 figures, accepted for publication in MNRAS http://saveitalianbrains.wordpress.com

References in corpus (31)

• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• How Do Galaxies Get Their Gas?
• The Assembly and Merging History of Supermassive Black Holes in Hierarchical Models of Galaxy Formation
• The Kinematics of the Ultra-Faint Milky Way Satellites: Solving the Missing Satellite Problem
• Effect of Reionization on the Structure Formation in the Universe
• Massloss of galaxies due to a UV-background
• A common mass scale for satellite galaxies of the Milky Way
• First stars, very massive black holes and metals
• Cosmic Background Anisotropies in CDM Cosmology
• The Tidal Evolution of Local Group Dwarf Spheroidals
• Simulations of Pregalactic Structure Formation with Radiative Feedback
• The First Cosmic Structures and their Effects
• Early Metal Enrichment of the Intergalactic Medium by Pregalactic Outflows
• Uncovering Extremely Metal-Poor Stars in the Milky Way's Ultra-Faint Dwarf Spheroidal Satellite Galaxies
• Fragmentation of star-forming clouds enriched with the first dust
• Photoionization Feedback in Low--Mass Galaxies at High Redshift
• Formation Histories of Dwarf Galaxies in the Local Group
• A new view of the dwarf spheroidal satellites of the Milky Way from VLT/FLAMES: Where are the very metal poor stars?
• The distribution and kinematics of early high-sigma peaks in present-day haloes: implications for rare objects and old stellar populations
• The Invisibles: A Detection Algorithm to Trace the Faintest Milky Way Satellites
• Early Gas Stripping as the Origin of the Darkest Galaxies in the Universe
• H_2 Cooling of Primordial Gas Triggered by UV Irradiation
• Generating Hot Gas in Simulations of Disk-Galaxy Major Mergers
• Life and times of dwarf spheroidal galaxies
• The structural properties and star formation history of Leo T from deep LBT photometry
• Effects of the galactic winds on the stellar metallicity distribution of dwarf spheroidal galaxies
• Fossil remnants of reionization in the halo of the Milky Way
• The Influence of Galactic Outflows on the Formation of Nearby Dwarf Galaxies
• X-ray iron line variability for the model of an orbiting flare above a black hole accretion disc
• Radiation-Hydrodynamical Collapse of Pregalactic Clouds in the Ultraviolet Background
• Detectable Signatures of Cosmic Radiative Feedback

Cited by in corpus (105)

• Star Formation Histories, Abundances and Kinematics of Dwarf Galaxies in the Local Group
• Accurate masses for dispersion-supported galaxies
• The Faintest Dwarf Galaxies
• The First Galaxies
• Keck Spectroscopy of Faint 3<z<7 Lyman Break Galaxies: - I. New constraints on cosmic reionisation from the luminosity and redshift-dependent fraction of Lyman-alpha emission
• The Quenching of the Ultra-Faint Dwarf Galaxies in the Reionization Era
• The Current Status of Galaxy Formation
• A Baryonic Solution to the Missing Satellites Problem
• A quantitative explanation of the observed population of Milky Way satellite galaxies
• The assembly of "normal" galaxies at z=7 probed by ALMA
• Galaxy Properties and UV Escape Fractions During Epoch of Reionization: Results from the Renaissance Simulations
• Luminosity function and radial distribution of Milky Way Satellites in a LCDM Universe
• Titans of the Early Universe: The Prato Statement on the Origin of the First Supermassive Black Holes
• Initial mass function of intermediate mass black hole seeds
• Multi-Element Abundance Measurements from Medium-Resolution Spectra. I. The Sculptor Dwarf Spheroidal Galaxy
• The ACS LCID Project: On the origin of dwarf galaxy types: a manifestation of the halo assembly bias?
• The population of Milky Way satellites in the LambdaCDM cosmology
• The stellar content of the Hamburg/ESO survey. V. The metallicity distribution function of the Galactic halo
• Connecting the first galaxies with ultra faint dwarfs in the Local Group: chemical signatures of Population~III stars
• From the first stars to the first black holes
• Local Group Dwarf Spheroidals: Correlated Deviations from the Baryonic Tully-Fisher Relation
• Simulating cosmic metal enrichment by the first galaxies
• Simulating high-redshift galaxies
• High-Resolution Spectroscopy of Extremely Metal-Poor Stars in the Least Evolved Galaxies: Leo IV
• Chronologically dating the early assembly of the Milky Way
• Chemical Signatures of the First Galaxies: Criteria for One-Shot Enrichment
• Descendants of the first stars: the distinct chemical signature of second generation stars
• Magnetic fields in Local Group dwarf irregulars
• Limits on Pop III star formation with the most iron-poor stars
• Carbon-enhanced metal-poor stars in dwarf galaxies
• Confined Population III Enrichment and the Prospects for Prompt Second-Generation Star Formation
• On the nature of the Milky Way satellites
• Escape Fraction of Ionizing Radiation from Starburst Galaxies at High Redshifts
• Decoding the stellar fossils of the dusty Milky Way progenitors
• Carbon-Enhanced Metal-Poor Stars: Relics from the Dark Ages
• Where are the Fossils of the First Galaxies? I. Local Volume Maps and Properties of the Undetected Dwarfs
• The oldest and most metal poor stars in the APOSTLE Local Group simulations
• The first carbon-enhanced metal-poor star found in the Sculptor dwarf spheroidal
• The predicted luminous satellite populations around SMC and LMC-mass galaxies - A missing satellite problem around the LMC?
• The First Galaxies: Assembly under Radiative Feedback from the First Stars
• Ultrafaint Dwarf Galaxies - the lowest mass relics from before reionization
• Metal Transport and Chemical Heterogeneity in Early Star Forming Systems
• Mining the Galactic Halo for Very Metal-Poor Stars
• Neutron-capture element deficiency of the Hercules dwarf spheroidal galaxy
• Lyman Alpha Emitter Evolution in the Reionization Epoch
• Probing the Epoch of Reionization with Milky Way Satellites
• The Brightest Ly$\alpha$ Emitter: Pop III or Black Hole?
• Probing the existence of very massive first stars
• A Keck/DEIMOS spectroscopic survey of the faint M31 satellites And IX, And XI, And XII, and And XIII
• Ultra-faint dwarf galaxies: unveiling the minimum mass of the first stars
• The first galaxies: simulating their feedback-regulated assembly
• Chemical enrichment of Damped Lyman Alpha systems as a direct constraint on Population III star formation
• First stars in Damped Lyman Alpha systems
• Evidence for $\gtrsim 4$ Gyr timescales of neutron star mergers from Galactic archaeology
• Chemical evolution of classical and ultra-faint dwarf spheroidal galaxies
• Insights into Pre-Enrichment of Star Clusters and Self-Enrichment of Dwarf Galaxies from their Intrinsic Metallicity Dispersions
• On the faint-end of the high-$z$ galaxy luminosity function
• Chemical enrichment in very low-metallicity environments: Bootes I
• HST/WFPC2 Imaging of the Dwarf Satellites And XI and And XIII : HB Morphology and RR Lyraes
• Hubble Space Telescope Observations of NGC 253 Dwarf Satellites: Discovery of Three Ultra-faint Dwarf Galaxies
• Metals and ionizing photons from dwarf galaxies
• Galaxy formation with radiative and chemical feedback
• The star formation history of Eridanus II: on the role of SNe feedback in the quenching of ultra-faint dwarf galaxies
• On the R-Process Enrichment of Dwarf Spheroidal Galaxies
• Scaling Relations for Galaxies Prior to Reionization
• A CEMP-no star in the ultra-faint dwarf galaxy Pisces II
• The history of the dark and luminous side of Milky Way-like progenitors
• Origin of the CEMP-no Group Morphology in the Milky Way
• Low-mass suppression of the satellite luminosity function due to the supersonic baryon--cold-dark-matter relative velocity
• The earliest galaxies seen in 21 cm line absorption
• How much metals did the first stars provide to the ultra-faint dwarfs?
• The IGIMF and other IMFs in dSphs: the case of Sagittarius
• The eventful life of GS-z14-0, the most distant galaxy at redshift $z=14.32$
• Star Cluster Formation and Survival in the First Galaxies
• High-resolution three-dimensional simulations of gas removal from ultrafaint dwarf galaxies. I. Stellar feedback
• On the early evolution of Local Group dwarf galaxy types: star formation and supernova feedback
• A 3D view of dwarf galaxies with Gaia and VLT/FLAMES I. The Sculptor dwarf spheroidal
• Dwarf Spheroidal Satellite Formation in a Reionized Local Group
• The 21-cm forest as a simultaneous probe of dark matter and cosmic heating history
• Understanding the origin of CEMP-no stars through ultra-faint dwarfs
• The evolution of Lithium: implications of a universal Spite plateau
• True Pair-instability Supernova Descendant: Implications for the First Stars' Mass Distribution
• Tracing stars in Milky Way satellites with A-SLOTH
• Exploring Simulated Early Star Formation in the Context of the Ultrafaint Dwarf Galaxies
• Homogeneous Photometry VI: Variable Stars in the Leo I Dwarf Spheroidal Galaxy
• Extended OVI haloes of starforming galaxies
• Inhomogeneous Galactic Chemical Evolution: Modelling Ultra-Faint Dwarf Galaxies of the Large Magellanic Cloud
• Metal Enrichment in the Reionization Epoch
• Towards ultra metal-poor DLAs: linking the chemistry of the most metal-poor DLA to the first stars
• Local Group progenitors: Lyman Alpha bright?
• High redshift Lya emitters: clues on the Milky Way infancy
• Selecting ultra-faint dwarf candidate progenitors in cosmological N-body simulations at high redshifts
• Chemical evolution of ultra-faint dwarf galaxies: testing the IGIMF
• Neutron-capture elements in dwarf galaxies III: A homogenized analysis of 13 dwarf spheroidal and ultra-faint galaxies
• Chemodynamical study of two CEMP-no stars from the Hamburg/ESO Survey
• Searching for the earliest galaxies in the 21 cm forest
• Predicting the frequencies of young and of tiny galaxies
• Probing baryonic processes and gastrophysics in the formation of the Milky Way dwarf satellites: I. metallicity distribution properties
• Carbon-enhanced metal-poor stars in different environments
• Linking high-z and low-z: Are We Observing the Progenitors of the Milky Way with JWST?
• Stellar halos tracing the assembly of ultra-faint dwarf galaxies
• The metal-poorest tail of the Galactic halo: hypothesis on its origin from precise spectral analysis
• Stellar archeology: a cosmological view of dwarf galaxies
• Carbon measurements in two ultra-faint dwarf galaxies: Grus II and Tucana IV
• Forward-modelling the Luminosity, Distance, and Size distributions of the Milky Way Satellites