Day 1004

Tuesday.


1511.02231
Towards a self-consistent halo model for the nonlinear large-scale structure
Schmidt

Halo model suffer from two major deficiencies: (i) they do not enforce the stress-energy conservation of matter; (ii) they are not guaranteed to recover exact perturbation theory results on large scales.  Provide a formulation of the halo model ("EHM") that remedies both drawbacks in a consistent way, while attempting to maintain the productivity of the approach.  In the formulation presented here, mass and momentum conservation are guaranteed, and results of perturbation theory and the effective field theory can in principle be matched to any desired order on large scales.  Find that a key ingredient in the halo model PS is the halo stochasticity covariance, which has been studied to a much lesser extent than other ingredients such as MF, bias, and profiles of halos.  As written here, this approach still does not describe the transition regime between perturbation theory and halo scales realistically, which is left as an open problem.  Also show explicitly that, when implemented consistently, halo model predictions do not depend on any properties of low-mass haloes that are smaller than the scales of interest.


1511.02245
Galaxy and mass assembly (GAMA): growing up in a bad neighborhood - how do low-mass galaxies become passive?
Davies, et al

Both theoretical predictions and observations of the very nearby Universe suggest that low-mass galaxies (log10[M*/Msun]<9.5) are likely to remain SF unless they are affected by their local environment.  To test this premise, compare and contrast the local environment of both passive and SF galaxies as a function of stellar mass, using GAMA.  Find that passive fractions are higher in both interacting pair and group galaxies than the field at all stellar masses, and that this effect is most apparent in the lowest mass galaxies.  Also find that essentially all passive log10[M*/Msun]<8.5 galaxies are found in pair/group environments, suggesting that local interactions with a more massive neighbor cause them to cease forming new stars.  Find that the effects of immediate environment (local galaxy-galaxy interactions) in forming passive systems increases with decreasing stellar mass, and highlight that this is potentially due to increasing interaction timescales giving sufficient time for the galaxy to become passive via starvation.  Present a simplistic model to test this premise, and show that given the speculative assumptions, it is consistent with the observed results.


1511.02363
Frequentist tests for Bayesian models
Lucy

Analogues of the frequentist chi-square and F tests are proposed for testing goodness-of-fit and consistency for Bayesian models.  Simple examples exhibit these tests0' detection of inconsistency between consecutive experiments with identical parameters, when the first experiment provides the prior for the second.  In a related analysis, a quantitative measure is derived for judging the degree of tension between two different experiments with partially overlapping parameter vectors.


1511.02549
Quantifying the origins of life on a planetary scale
Scharf, Cronin

A simple, heuristic formula with parallels to the Drake Equation is introduced to help focus discussion on open questions for the origins of file in a planetary context.  This approach indicates a number of areas where quantitive progress can be made on parameter estimation for determining origins of life probabilities.  Also suggest that the probability of origin of life events can be dramatically increased on planets with parallel chemistries that can undergo the development of complexity, and in solar systems where more than one planet is available for chemical evolution, and where efficient impact eject exchange occurs, increasing the effective chemical search space and available time.