Mock Córdoba�Galaxy formation for gravity and cosmology

Discussion session 1: Cosmology� 08.04.2019

The future of observational cosmology

• What will be a standard cosmological analysis in 10 or 15 years? �
• Multiple probes available:�- Clustering (BAO & RSD)�- Weak lensing (cosmic shear, galaxy-galaxy lensing)�- Galaxy Clusters�- Radio galaxies (Halpha and more)�- direct velocities catalogues�- GW sirens

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Image credit: Max Tegmark

Mock catalogues requirements

• What do we need mock catalogues for?�- Covariance matrices.�- Test cosmological/galaxy formation models with clustering measurements, environment, sat/central, etc�- Covariance of results inferred from different methods.�- Survey design & optimisation.
• What types of mocks are required for the analysis of current and future surveys?�- Optical common but HI soon to arrive
• Control against systematics effect, biases and degeneracies� �

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Mock catalogues for multi-probe analyses

• Joint clustering-lensing studies will require new mock catalogues�- (Galaxy) Halo + Density Field �
• Can we use existing codes to generate these mocks? �
• What else would we need?
• GW/Kilonova host galaxies
• velocity/radio surveys host (difficult selecyon functions)�

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Mock Córdoba�Galaxy formation for gravity and cosmology

Discussion session 2: Hydro-Galaxy Formation� 08.04.2019

Mocks from Hydro simulations

Galaxy clusters:

• Masses of BCGs? Mismatch between observations and both semianalytic models and hydro simulations?
• Dust? Modelling dust in simulations?

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Small-scale structure:

• Cosmological issues coming from small-scale structure: cores vs. cusps.
• Dwarf galaxies in semianalytic models vs. dwarfs in hydro simulations.
• Cosmological probes from low-mass galaxies.

Machine Learning:

• Give up on physical insight in favor of Machine Learning?

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Modified gravity

• Breaking the degeneracy between baryonic physics and MG. What are the further steps?�
• What are the key tests that we should focus on to rule out LCDM and /or a particular MG model?

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• Can we always parametrize deviations from GR into a single factor to be constrained with cosmological tests? (e.g. G factor in Cai’s talk)�
• Can/should we include MG for approximate methods (COLA, scaling,...)?

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• Include lensing for f(R) simulations�
• Many MG theories out there, not enough computational power. What should we simulate?

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Mock Córdoba�Galaxy formation for gravity and cosmology

Discussion session 3: Modified Gravity

09.04.2019

Mock Córdoba�Galaxy formation for gravity and cosmology

Discussion session 4: Hydro-Galaxy Formation II� 09.04.2019

Topics for discussion

Neutrino masses: Current upper limits from Lyman-alpha forest + CMB are close to the lower bounds from ground experiments. But this result depends on our good understanding of hydro-simulations. What are the requirements and tests to validate such simulations?

HI-studies: What are the possible ways to use 21cm measurements to constrain cosmology, besides intensity mapping? Cross-correlations with other tracers? Learn about gas content of different tracers? f(R) or wDM simulations to check assembly bias effect? Illustris vs EAGLE

Galaxy colors in simulations: How well they reproduce observations?

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Mock Córdoba�Galaxy formation for gravity and cosmology

Discussion session 5: Mocks/Assembly Bias� 10.04.2019

Topics for discussion

• How to improve SAMs to reproduce colours?
• Update on MD-Galacticus sSFR vs Mstar plot
• Multiple ways towards the same clustering, which one is right?
• Assembly Bias: Fake News? Do we care for cosmology (HOD good enough?) ? How do we detect this in the real world? Halo mass estimates? Central vs satellite? Real-redshift space?
• Approximate methods are fine (Martha et al.) for covariance for Euclid, do we stop worrying about running simulations?
• Gender Bias in Science?!
• The need to retune models when changing the N-body simulation. How do we improve the gender balance and diversity?
• Easter egg hunt

Mock Córdoba�Galaxy formation for gravity and cosmology

Discussion session 6: Voids, ELGs and lenses� 10.04.2019

Voids, ELGs and lenses

• Should we introduce the effect that baryons have over haloes when populating DM only simulations with galaxies?
• For cosmological studies, do we care about the physical details of nebular emission?
• Imagine that in some years we have characterised the DE, then what?
• Which new cosmological probes could be promising?
• Is there anything more to do with voids aside probes based on galaxy cross correlation or abundance studies?
• How much of the models that we want to test can be used in the treatment of systematics on cosmological probes?
• Void interior properties, pristine structure ?
• Feedback in void regions ?
• Any chance to probe magnetogenesis models?
• How extended are dark matter halos of small galaxy systems?
• Is the search/characterisation of voids too optical-centric?
• Anyone in favour of finish talks with the summary/conclusions?

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Discussion Session - Cosmology

• Competition/exchange lab experiments (e.g. testing gravity on small scales, quantum gravity, inhomogeneous DE)
• Galaxies without DM
• Combine cosmological probes -> galaxy clustering + lensing, intermediate scales, intrinsic alignments, systematic errors
• Goals of future simulations, mocks for multiprobe analysis, parametrization of small scale physics
• Do we have a small-scale problem?
• Which new probes are most promising e.g. void abundance problematic, void lensing profile
• Higher order statistics, BAO, Lyman-alpha gas physics, MG

Discussion Session - Cosmology

• “Out of the box” statistics, VPF, shape distribution of voids, Minkowski functionals, machine learning
• Machine learning applications, exchange with computer scientists

Galaxy Formation Group Session

Discussion Session: Galaxy Formation

Road map: HI-region / Angular momuntum / Bar formation / Environmental quenching / SAM improvement regarding HI / Bar formation in SAMs:

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Conclusion question:

How to bar structures influence the starformation and the AGN feedback in HI-rich galaxies?

Problem:

• Absence in HI in the center! HI-holes! Bars feed AGN or transport gas in the outskirts.
• Morphology quenching: real or fake?
• Bias in choosing galaxies! Blind survey!
• What are the issues which make the starformation efficent or inefficient?

How should SAMs be improved?

bar formation, angular momentum, HI region (circular velocity profles to construct rotations curves)��Idea: include bars in SAMs!

What to do: Push SAM into a more complex direction regarding to HI modelling. ��Others: How to relate magnetic fields with bars?