Letters of Intent for 2015

LoI 2015-203
Galaxies in the Early Universe and the Growth of Structure over Cosmic Time


3 August 2015 to 10 August 2015


Honolulu, United States


Sugata Kaviraj (s.kaviraj@herts.ac.uk)

Coordinating division:

Division J Galaxies and Cosmology

Co-Chairs of SOC:

Sugata Kaviraj (University of Hertfordshire and University of Oxford)
Henry Ferguson (Space Telescope Science Institute)

Co-Chairs of LOC:

Sugata Kaviraj (University of Hertfordshire and University of Oxford)
Henry Ferguson (Space Telescope Science Institute)



(1) Properties of emergent galaxies in the early Universe (e.g. star-formation rates, stellar ages, metallicities, masses, sizes)

(2) Interplay between gas and star formation at z>1

(3) Co-evolution of galaxies and black holes and the role of AGN feedback at early epochs

(4) Origin of the Hubble sequence

(5) Confrontation of observations and galaxy-formation models (e.g. hydro-cosmological simulations, semi-analytical models) in the early Universe

(6) Linking studies of early galaxies with the existing literature at z<1, to construct a coherent picture of galaxy evolution over ~90% of cosmic time

(7) Exploitation of new and future facilities, e.g. multi-object spectrographs (KMOS, MUSE, etc.), JWST, ELTs, ALMA and SKA precursors (LOFAR, e-MERLIN, etc.)

(8) Key post-2015 goals and challenges, in the context of future instrumentation

(9) The role of citizen-science projects (e.g. Galaxy Zoo) in widening the scientific impact of astronomical datasets and performing public outreach



Coordinating Division: Division J (Galaxies and Cosmology)

Divisions that are aligned with the themes of this meeting (in alphabetical order):
Division B: Facilities, Technologies and Data Science
Division C: Education, Outreach and Heritage
Division D: High-Energy Phenomena and Fundamental Physics
Division G: Stars and Stellar physics
Division H: Inter-stellar matter and Local Universe

Over the last two decades, a convergence of powerful observational facilities and high-performance computing has significantly advanced our understanding of galaxy evolution. While our current knowledge is still largely based on the nearby Universe, an explosion of multi-wavelength data at high redshift is revolutionising our understanding of emergent galaxies at z>1. Since the bulk of stellar mass assembly takes place at these redshifts, a comprehensive analysis of galaxies at these epochs is fundamental to our overall understanding of galaxy evolution.

HST surveys like CANDELS, combined with facilities like Spitzer and Herschel, are now constraining galaxy parameters such as star-formation rates, ages, metallicities, masses and sizes around z~2 and beyond. Together with deep Chandra observations, these data are probing the co-evolution of galaxies and their black holes at z>1 and the role of AGN in shaping their host systems at these early epochs. High-resolution near-infrared imaging from the HST is quantifying the origin and evolution of the Hubble sequence, for the first time, in the early Universe. This growing empirical literature is motivating an array of theoretical work, based on high-resolution hydro-simulations, which is elucidating the processes that drive early stellar-mass buildup, black-hole growth and morphological transformations.

Our current understanding of emergent galaxies will shortly be bolstered by new instruments with multiplexing capabilities, such as KMOS, MUSE and MOSFIRE, and those that offer high-resolution imaging in the long-wavelength regime, such as ALMA and the SKA precursors (e-MERLIN, LOFAR, etc.). These will enable unprecedented studies of stellar and gas kinematics at high redshift and allow us to investigate the poorly-understood interplay between gas and star formation in the early Universe. Looking further ahead to the turn of the decade, the field is poised for yet another revolution, both in terms of the ground-breaking depth and area offered by future imaging and spectroscopic surveys (e.g. LSST, Euclid, DES, 4MOST, MOONS), and our ability to comprehensively probe galaxy evolution all the way up to the epoch of reionization, using instruments like the JWST and the ELTs.

The time will be ripe in 2015 for a meeting that critically reviews our current and ongoing studies of the early Universe and identifies the community’s key challenges and goals in the context of future instrumentation. The overall aim of this Symposium will be to bring together theorists, observers and instrumentalists to (1) showcase the community’s accumulating knowledge of the early Universe (2) connect these high-redshift studies to the past literature to construct a coherent picture of galaxy evolution over ~90% of cosmic time and (3) lay the groundwork for the exploitation of the ground-breaking instruments that will become available post-2015.

The themes of this Symposium are strongly aligned with several IAU Divisions. The proposed coordinating Division is Division J (Galaxies and Cosmology). The principal topics of this meeting include high-energy phenomena like AGN (Division D), star formation (Division G) and inter-stellar matter (Division H), the exploitation of current and future facilities (Division B) and the role of citizen-science projects such as Galaxy Zoo in widening the scientific impact of astronomical datasets and performing public outreach (Division C).

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