— in detail? How can we translate detailed reconstructions of nearby galaxy evolution into meaningful insights about galaxy formation and evolution in the broader universe? THE BIG QUESTIONS THAT MOTIVATE ME:
Situ Population • Constraints on Formation Avenues • Relative importance of in situ and accretion Mass of Halo: Comparing Observations with Simulated Halos Tidal Debris Features: Recent Accretion Events • Stellar properties of recently accreted satellites • Modeling of collision: time of accretion, mass of progenitor and host galaxy • Orbits of satellites Global Properties: Accretion History • Luminosity Function, Time of Accretion of destroyed dwarf galaxy population • Relative Importance of major/minor mergers over time Key Observables: stellar density, stellar velocities, chemical abundances, star formation histories
velocity distributions of stars resolve spatially overlapping streams discover faint streams identify connections between photometric substructures help tease the needles (M31 stars) out of the haystack (contaminants) CONSTRAIN THE ORBITS OF PROGENITORS K. M. Gilbert et al. 2009b K. M. Gilbert et al. 2009b Velocity Distribution (km/s) SPECTROSCOPY IS CRUCIAL FOR RECONSTRUCTING RECENT ACCRETION EVENTS M31$ N185$ N147$ M33$ 30$kpc$ 90$kpc$ 150$kpc$ 60$kpc$ N$ E$ M31$dSphs$ Giant$Southern$ Stream$ M31$Halo$Fields$ PAndAS$M31$Map$ (McConnachie$et$al.)$ Dwarf$Galaxy$Fields$
STELLAR HALO INWARDS Combine contiguous spectroscopic and photometric datasets SPLASH: spectra of > 5000 M31 Stars PHAT: imaging of > 100 Million M31 stars Model M31’s structural components from 4 kpc; Investigate dynamics as a function of stellar age Significant rotation in inner spheroid Evidence for a population of former disk stars heated into halo Increasing asymmetric drift with age: evidence M31’s stellar disk dynamically heated over time Dorman et al. (+KMG) 2013 Dalcanton et al. (+KMG) 2012 M31$ N185$ N147$ M33$ 30$kpc$ 90$kpc$ 150$kpc$ 60$kpc$ N$ E$ M31$dSphs$ Giant$Southern$ Stream$ M31$Halo$Fields$ PAndAS$M31$Map$ (McConnachie$et$al.)$ Dwarf$Galaxy$Fields$ Dorman et al. 2012, 2013, 2015; Quirk et al. 2019
to a few relatively massive (>109 M⊙ ) accretion events • M31 likely experienced a prolonged accretion history. May require many recent low-mass accretions at large radii. • M31 likely has a more massive dominant progenitor and larger accreted stellar halo than the typical MW-mass galaxy SIMULATIONS HAVE NOW PRODUCED GSS MORPHOLOGY WITH MERGER MASS RATIOS RANGING FROM 2:1 TO 300:1 PAndAs Starcount Map (McConnachie et al. 2018) Inner Halo: In Situ Population • Inner region of M31’s halo has a significant population of stars that once belonged to the disk • Multiple lines of evidence indicate an active recent accretion history impacting the disk Tidal Debris Features: Recent Accretion Events • Giant Stellar Stream related debris found throughout the inner halo • Minor merger simulations indicate an LMC to M33 mass progenitor disrupted ~750 Myr ago • Modeling full halo velocity distribution: improved constraints on substructure kinematics and uncertainties For more, see my STScI May 2019 colloquium
DEGENERACY LUMINOSITY FUNCTION OF ACCRETED SATELLITES TIME OF ACCRETION Image Credit Sanjib Sharma Stellar Surface Density Metallicity [Fe/H] Alpha Element Abundances [ /Fe] Stellar luminosity Time of infall Stellar luminosity plus time since disruption e.g., K. M. Gilbert et al. 2009a, Lee et al. 2015
CORRELATE WITH TIME OF INFALL [ /Fe] provides a clock First Star Formation Core Collapse SNe – element rich ejecta (e.g., Si, Ti, Ca, Mg) Type Ia SNe – Fe rich ejecta [ /Fe] [Fe/H]
CORRELATE WITH TIME OF INFALL [ /Fe] provides a clock [ /Fe] vs. [Fe/H] encodes the efficiency of star formation over time First Star Formation Core Collapse SNe – element rich ejecta (e.g., Si, Ti, Ca, Mg) Type Ia SNe – Fe rich ejecta [ /Fe] [Fe/H]
M31$dSphs$ Giant$Southern$ Stream$ M31$Halo$Fields$ PAndAS$M31$Map$ (McConnachie$et$al.)$ Dwarf$Galaxy$Fields$ M31$ N185$ N147$ M33$ 30$kpc$ 90$kpc$ 150$kpc$ 60$kpc$ N$ E$ M31$dSphs$ Giant$Southern$ Stream$ M31$Halo$Fields$ PAndAS$M31$Map$ (McConnachie$et$al.)$ Dwarf$Galaxy$Fields$ Deep DEIMOS spectra completed in progress DECIPHERING ANDROMEDA’S MERGER HISTORY: CHEMICAL ABUNDANCES BUILDING A STATISTICAL CENSUS OF CHEMICAL ABUNDANCES Existing SPLASH data Coadd low SNR spectra Mean [Fe/H], [ /Fe] abundances New Spectroscopic Campaign Obtain deep data in strategic dSph and halo fields Distributions of [Fe/H], [ /Fe] abundances M31’s halo: from 4 stars to 240 stars Extension of spectral synthesis method to lower resolution (R~3000) Jennifer Wojno Ivanna Escala Evan Kirby NSF AST-1614569 (PI K. M. Gilbert) and AST-1614081 (PI Kirby) M31$ N185$ N147$ M33$ 30$kpc$ 90$kpc$ 150$kpc$ 60$kpc$ N$ E$ M31$dSphs$ Giant$Southern$ Stream$ M31$Halo$Fields$ PAndAS$M31$Map$ (McConnachie$et$al.)$ Dwarf$Galaxy$Fields$ Escala et al. 2019 Gilbert et al. 2019, Escala et al. 2020, Kirby et al. 2019, + Wojno et al. subm.
al., 2019 FIRST ALPHA ABUNDANCES IN GSS GSS experienced higher efficiency of star formation than surviving M31 dwarf satellites [Fe/H] [ /Fe] And V, VII: Kirby, K. M. Gilbert et al., subm. N185: Vargas et al. 2014 PAndAS Starcount Ma (McConnachie et al. 20 50 kpc 100 kpc And I And III And II And X f130 H13s f207 GSS M33 M31$ N185$ N147$ M33$ 30$kpc$ 90$kpc$ 150$kpc$ 60$kpc$ N$ E$ M31$dSphs$ Giant$Southern$ Stream$ M31$Halo$Fields$ PAndAS$M31$Map$ (McConnachie$et$al.)$ Dwarf$Galaxy$Fields$
al., 2019 FIRST ALPHA ABUNDANCES IN GSS GSS experienced higher efficiency of star formation than surviving M31 dwarf satellites And than Sagittarius and the Magellanic Clouds PAndAS Starcount Ma (McConnachie et al. 20 50 kpc 100 kpc And I And III And II And X f130 H13s f207 GSS M33 M31$ N185$ N147$ M33$ 30$kpc$ 90$kpc$ 150$kpc$ 60$kpc$ N$ E$ M31$dSphs$ Giant$Southern$ Stream$ M31$Halo$Fields$ PAndAS$M31$Map$ (McConnachie$et$al.)$ Dwarf$Galaxy$Fields$ [Fe/H] [ /Fe]
LOW METALLICITY ENVIRONMENTS The evolution of low mass galaxies is strongly responsive to a wide array of physical processes: Reionization External Processes ram pressure stripping tidal stripping, stirring environmental triggering of star formation Dwarf-Dwarf interactions and mergers Internal Processes (stellar feedback) some unique to low-mass environment DDO 68 Fornax IC1613
HST IMAGING Disk kinematics as a function of stellar age Quantitative comparison with tracers of gas disk Chemo-dynamical analysis of older stellar populations Does M33 have a stellar halo? What forces have driven the disturbances in the stellar and gas disks? THE POWER OF RESOLVED STARS FOR REVEALING TRIANGULUM’S HISTORY NSF AST-1909066 (PI K. M. Gilbert) and AST-1909759 (PI P. Guhathakurta) Amanda Quirk Raja Guhathakurta PI Dalcanton; GO-14610 Proposed Existing Literature
DEFINITIVE EVIDENCE OF A WIDESPREAD KINEMATICALLY HOT COMPONENT K. M. Gilbert et al., in prep. >800 RGB stars; ≳30% in a ≳50 km/s component PI Dalcanton; GO-14610 Velocity Offset from HI Disk Model Probability Younger stars RGB stars HI Disk Model: Kam et al., 2017 THE POWER OF RESOLVED STARS FOR REVEALING TRIANGULUM’S HISTORY
AND ANGRRR TO LUVIT — ACS Nearby Galaxy Survey Treasury volume-limited sample of 69 galaxies within 3.5 Mpc plus M81 and NGC 253 groups (ACS/WFC and WFPC2) available on MAST Archive of Nearby Galaxies: Reduce, Reuse, Recycle ~700 ACS/WFC and WFPC2 datasets of ~150 galaxies within 5 Mpc homogeneously reduced with ANGST reduction pipelines (precursor to PHAT pipeline) within 3.5 Mpc on MAST; for remainder see me HST IMAGING SURVEYS OF THE LOCAL VOLUME ANGST Sample, Dalcanton et al. 2009
LOCAL ULTRAVIOLET IMAGING TREASURY UV observations with WFC3/UVIS in 22 dwarf galaxies on edge of LG and in LV (GO-15275) combined with archival broad-band imaging 4- or 6-band (UV-optical-IR) imaging Targets have wealth of ancillary data in other wavelengths Stellar SED fitting (BEAST): Teff , Lbol , AV , RV Improved constraints on recent SFH - spatially resolved (60 pc at 2.5 Mpc) maps of recent SF over last 300 Myr, time resolution better than all common SFR/stellar age indicators Generate resolved dust maps (MegaBEAST!) Infer unobscured UV flux of every resolved star ….
LOCAL ULTRAVIOLET IMAGING TREASURY UV observations with WFC3/UVIS in 22 dwarf galaxies on edge of LG and in LV (GO-15275) combined with archival broad-band imaging 4- or 6-band (UV-optical-IR) imaging Targets have wealth of ancillary data in other wavelengths Stellar SED fitting (BEAST): Teff , Lbol , AV , RV Improved constraints on recent SFH - spatially resolved (60 pc at 2.5 Mpc) maps of recent SF over last 300 Myr, time resolution better than all common SFR/stellar age indicators Generate resolved dust maps (MegaBEAST!) Infer unobscured UV flux of every resolved star …. NGC 4214 predicted unobscured FUV GALEX FUV contours Choi et al. 2017 SEE YUMI’S INTRO TALK!
STAR STUDIES: WIDE FIELDS WIDE FIELD SPECTROSCOPY IN ANDROMEDA CURRENT SPECTROSCOPIC COVERAGE PAndAs Starcount Map McConnachie et al. 2018 K. M. Gilbert & E. Tollerud, Astro2020 white paper Degrees from M31’s Center Degrees from M31’s Center
STAR STUDIES: WIDE FIELDS WIDE FIELD SPECTROSCOPY IN ANDROMEDA CURRENT SPECTROSCOPIC COVERAGE PAndAs Starcount Map McConnachie et al. 2018 K. M. Gilbert & E. Tollerud, Astro2020 white paper Degrees from M31’s Center Degrees from M31’s Center
STAR STUDIES: WIDE FIELDS WIDE FIELD SPECTROSCOPY IN ANDROMEDA CURRENT SPECTROSCOPIC COVERAGE PAndAs Starcount Map McConnachie et al. 2018 K. M. Gilbert & E. Tollerud, Astro2020 white paper Degrees from M31’s Center Degrees from M31’s Center
STAR STUDIES: WIDE FIELDS WIDE FIELD SPECTROSCOPY IN ANDROMEDA CURRENT SPECTROSCOPIC COVERAGE PAndAs Starcount Map McConnachie et al. 2018 K. M. Gilbert & E. Tollerud, Astro2020 white paper McConnachie et al. 2018 Degrees from M31’s Center Degrees from M31’s Center
STAR STUDIES: WIDE FIELDS WIDE FIELD SPECTROSCOPY IN ANDROMEDA CURRENT SPECTROSCOPIC COVERAGE POTENTIAL WIDE FIELD MOS SURVEY COVERAGE PAndAs Starcount Map McConnachie et al. 2018 K. M. Gilbert & E. Tollerud, Astro2020 white paper Degrees from M31’s Center Degrees from M31’s Center
HIGH RESOLUTION IMAGING IN ANDROMEDA Contiguous deep imaging to ancient Main Sequence turnoff will be enabled over significant areas of halo with WFIRST Existing HST imaging to the old Main Sequence Turnoff Brown et al. 2008, 2009 WFIRST Field of View Extended Disk 11 kpc Minor Axis Halo Field 21 kpc 21 kpc Giant Stellar Stream Field 35 kpc K. M. Gilbert & E. Tollerud, Astro2020 white paper
DISKS AND HALOS IN THE LOCAL VOLUME Combination of JWST, 30-m telescopes, WFIRST, and LUVOIR will: Extend current day M31-like studies to galaxies throughout the Local Volume Wide field studies of M31 will be crucial for correctly interpreting the observations JWST WFIRST TMT LUVOIR
konakalab
takusamar
.jpg){kind=avatar}
lychee1223
trycycle
mickey_0226
voginip
hanbao
institutdelelevage
naospon
akasan
livdayseo
palkan
tmiket
skoyamalab
nikkihalliwell
shpigford
cassininazir
mayatellez
reverentgeek
aleyda
joshbly
baasie
