AS THE FAINTEST LOWEST-LUMINOSITY AND MOST DARK-MATTER-DOMINATED EXTREMES OF THE GALAXY POPULATION DWARF GALAXIES PRESENT UNIQUE OPPORTUNITIES FOR STUDYING GALAXY FORMATION AND THE PROPERTIES OF DARK. ACCORDINGLY THEY HAVE BEEN OBSERVED IN DETAIL FROM THE GROUND AND (BY NASA MISSIONS) FROM SPACE WITH THE HOPES OF UNRAVELING HOW DWARF GALAXIES FORM THE EFFECTS OF REIONIZATION ON GALAXY FORMATION AND WHETHER SIGNATURES OF THE PARTICLE NATURE OF DARK MATTER (DM) INTERACTIONS CAN BE OBSERVED. SUCH WORK HAS GAINED INIMPORTANCE AS EFFORTS TO DIRECTLY DETECT DM HAVE SO FAR YIELDED ONLY UPPER LIMITS TO THE INTERACTION BETWEEN DM AND NORMAL MATTER LEAVING ASTROPHYSICAL TESTS AS THE PRIMARY MEANS OF INVESTIGATING THE NATURE OF DM. WE PROPOSE TO UNDERTAKE AN EXTENSIVE YET FOCUSED PROGRAM OF COSMOLOGICAL HYDRODYNAMIC SIMULATIONS AIMED AT UNDERSTANDING THEFORMATION OF DWARF GALAXIES. WE WILL FOCUS ON THE INTERPLAY BETWEEN GALAXY FORMATION AND DARK MATTER IN THESE GALAXIES POINTING TOWARD SPECIFIC OBSERVABLES TO DISENTANGLE THE EFFECTS OF GALAXY FORMATION PHYSICS FROM THE EFFECTS OF DM PHYSICS. OUR SIMULATION SUITE WILL EXPLORE COLLISIONLESS COLD DARK MATTER (CDM) AND BROAD CLASSES OF ALTERNATIVES WHERE DM HAS A NON-NEGLIGIBLE FREE-STREAMING LENGTH AND / OR SELF-SCATTERING CROSS SECTION. THE NOVEL ASPECTS OF THE PROPOSED WORK WILL INCLUDE: (1) A MODERN TREATMENT OF BARYONIC PHYSICS USING GIZMO A NEW CODE THAT USES ACCURATE MESHLESS METHODS FOR HYDRODYNAMICS (2) FEEDBACK IN REALISTIC ENVIRONMENTS (FIRE) A SUITE OF GALAXY FORMATION PARAMETRIZATIONS WITH WELL-TESTED EXPLICIT IMPLEMENTATIONS OF STELLAR FEEDBACK (3) AN EXPLORATION OF REALISTIC MODELS OF DM BEYOND CDM BASED ON AN EFFECTIVE THEORY OF STRUCTURE FORMATION WITH FULL BARYONIC PHYSICS AND (4) DETAILEDMOCK OBSERVATIONS OF THE SIMULATIONS IN ORDER TO IDENTIFY SPECIFIC DISTINGUISHING TESTS FOR CDM AND ITS ALTERNATIVES.OUR RESEARCH WILL PROVIDE A FRAMEWORK WITHIN WHICH ASTROPHYSICAL INFERENCES ABOUT THE NATURE OF DM CAN BE FAIRLY AND SELFCONSISTENTLY TESTED. CRUCIALLY WE WILL EXPLORE UNCERTAIN ASPECTS OF GALAXY FORMATION AND DM PHYSICS IN A CONTROLLED MANNER FOCUSING ON THE HALO MASS RANGE -- 9.5<LOG10(M/M_SUN)<10.5 -- WHERE CURRENT MODELS ARE MOST UNCERTAIN. THIS WILL MARK A MAJOR EFFORT TOSYSTEMATICALLY STUDY DIFFERENT DM MODELS COMBINED WITH REALISTIC TREATMENTS OF GALAXY FORMATION PHYSICS THAT ARE IMPLEMENTED IN AN IDENTICAL WAY FOR THE VARIOUS DM MODELS. THE RESULTS OF THE PROPOSED RESEARCH WILL BE DRAMATIC IMPROVEMENTS IN THE UNDERSTANDING OF HOW BARYONIC VERSUS DM PHYSICS AFFECT ASTROPHYSICAL OBSERVABLES. SUCH A STUDY IS VERY TIMELY AS OBSERVATIONS OF DWARF GALAXIES IN ANDBEYOND THE LOCAL GROUP HAVE PROGRESSED SUBSTANTIALLY IN RECENT YEARS WITH NEW REVELATIONS ABOUT DWARFS' DM CONTENT STAR FORMATION HISTORIES AND STELLAR METALLICITIES CHALLENGING PREVIOUS INTERPRETATIONS.

University Of Texas At Austin, Austin TX

Investigators