Letters of Intent for 2015

LoI 2015-191
From molecular gas to star forming galaxies

Date: 3 August 2015 to 7 August 2015
Location: Honolulu, United States
Contact: Pascale JABLONKA (pascale.jablonka@epfl.ch)
Coordinating division: Division J Galaxies and Cosmology
Chair of LOC: ()



A) Tracing H2
• H2 is not observed directly and its detection relies on the CO molecule. The conversion between CO and H2 is definitely a sensitive parameter. Does it vary with dust ? With metallicity ? With time ?
• The molecular (H2) and neutral (HI) phases of the galaxy interstellar medium are linked to star formation and feedback processes in different ways. To which extent do they trace each other ? How do they vary with redshift ?

B) The physical properties of the molecular gas
• Herschel has enabled the observatio of the high-excitation molecular gas. How does the CO SLEDs vary with different galaxy types ?
• Besides CO, there are a variety of molecules revealing a variety of physical properties of the galaxy interstellar medium.
• The mass distribution of the molecular clouds is a crucial piece of information to understand the origin of the stellar initial mass function: does it vary spatially ? From galaxy to galaxy ?

C) Turning gas into stars
• Star formation at small scale: mass, turbulence, and magnetic field play a significant role in star formation. Where do theories stand ?
• Star formation at galactic scales: is there any evidence for a variation with redshift of the conversion from gas to stars? Does it depend on the galaxy dynamical stage, on the strength of the star formation (LIRGs, ULIRGs) etc… ?

D) Cold gas and the galaxy star formation histories
• Can we link the gas content and dynamical status to the star formation histories of galaxies: from dwarf to massive systems ?
• Which role do the AGNs play in the accretion and feedback processes?

E) The impact of the environment:
• The galaxy star formation rates evolve with time but also with the galaxy environment, what about the cold and gas in galaxies ? Can ram-pressure, galaxy harassment etc.. impact the molecular gas as well ? How does this compare to HI?

F) Numerical simulations
• The challenges of the implementation of the star formation laws and different gas phases in numerical simulations: sub-grid galaxy or cosmological models, which include star formation and feedback require the physics of the interstellar medium.
• What do we learn from 3-D simulations including H2 at small scales and at high redshifts on the formation of the first stars and first structures ?



The launch of Far Infrared satellites (Spitzer, Herschel, Wise, Akari…) associated to much improved sensitivities of the sub-millimetre arrays has allowed a recent spectacular and decisive step forward in our understanding of the star formation modes in galaxies. Much has been learned on the conversion from gas to stars, at both small (pc) and global (kpc) scales, in nearby as well as distant galaxies. The goal of this Symposium is to start building a coherent picture of how star formation is fuelled in galaxies. It should gather researchers working on the question of star formation with different viewpoints: from theoretical studies at scale of the molecular clouds to high redshift detections of the first star forming galaxies in the Universe. Held nearly two years after ALMA has entered its full operation mode, a wealth of exciting results should be presented at this meeting.