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Laura Wolz - Galaxy evolution with HI intensity Mapping (Experiment (GBT,…
Laura Wolz - Galaxy evolution with HI intensity Mapping
HI intensity mapping
Integrated line flux over entire HI mass function
Tomographic maps of the universe for 0<z<6
Observe large cosmological volumes for wide redshifts with high z and low spatial resolution
measurement of large scale tructure
Temperature power spectrum
Amplitude tests mean HI density and thus Omega_HI
Non-linear effects: environments and galaaxy formation
Experiment
GBT
Parkes
SKA
ASKAP
CHIME
Tianlai
MeerKAT
BINGO
Challenges
Receiver noise: amplitude comparable to signal - isotropic, manageable in power spectrum space
Instrumental errors: calibration uncertainties, beam and pointing errors, polarization leakage - simulations of instrument response
RFI : contaminates in spatial and frequency space - go to the desert
foreground contaminations: galactic emission and extra-glaactic point sources - avoidence and removal strategies
GBT X EBOSS data analysis
GBT updated intensty mapping data in 0.6<z<1
eBOSS ELGs: 0.7<z<1.1;LRGs:0.6<z<.9
Area overlap: 100 square degrees
Goal: etimate th HI content of eBOSS ELGs and LRGs via cross-correlation eith GBT HI intensity maps
Goal: constrain HI density and bias at z=0.8
Goal: compare different foreground removal methods
Neutral Hydrogen Evolution: HI auto-correlation
Require HI distribution to do correct cosmology
Measure HI evolution to discover connection to galaxy formation processes
SKA Low Intensity Mapping
SKA low observation between 200-350MHz - 3.05<z<6.1
Core and central configurations with 224/296 stations in 500m/1750m radius
Deep survey with 100sq deg with 5000hrs
Medium survey with 100 sq deg with 2500hrs
Instrumental Simulations
Meraxes galaxy formation model of the DRAGONS simulation including high particle and redshift resolution
Blitz-Rosolowsky HI partitioning scheme
z=5.0
OSKAR visibility simulatr for core and central areas of HI signal and diffuse foreground
fastICA: solving the coctail party problem
Independent component analysis (ICA) seperates a multicomponent signal into subcomponents such that components are statistically independent
Central limit theorum: PDF of a mixture of independent components is more gaussian than the PDF of any individual component
Components with gaussian PDFs can not be indentified
Galaxy Evolution: HI-galaxy cross-correlations
HI only detected for low redshift
String selection effects toward HI rich objects\
HI intensity maps are complete - Global HI density
HI-galaxy cross-correlations sensitive to galaxy properties
cross shot noise measures HII contents in galaxy samples
Poisson noise scales as HI brightness temperature of the optical galaxy sample
Maths
Hydro-simulations
Subgrid models include gas cooling and heating, feedback processes, star evolution etc
Neutral hydrogen partition
Phenomenological and theoretical partitioning models
Analytic models
Semi analytic and hydrodynamical models very complex
Computationally expensive for one cosmology
Analytic halo model framework based on I maass per halo
Predict observables such as power spectra, HI mass functions, column densities
Fit parameters of HI-halo-mass relation to observables
discrete model: HI associated to galaxy