steve rawlings2nd skads workshop, paris, october 2007 science simulations steve rawlings (oxford)...

Steve Rawlings2nd SKADS Workshop, Paris, October 2007

Science Simulations

Steve Rawlings (Oxford)

Richard Wilman, Sadegh Khochfar, Hans-Rainer Klöckner, Tom Mauch, Lance Miller,

Danial Obreschkow (Oxford)

Matt Jarvis (Herts),Filipe Abdalla (UCL)


In this talk......

• Emphasise how imminent delivery of SKADS `simulated skies’ will provide standard input for quantified comparison of `competing’ SKA design concepts - needs high quality product, i.e. refereed papers (mostly to be published by next DS2-T1 meeting; Jan 2008)

• Use `continuum’ simulations (not described elsewhere) as example - last chance for input!


DS2-T1 Short-Term Deliverables: T0=July2006

• Continuum Surveys – Oxford, Leiden, (Herts, UCL):

Richard Wilman (Oxford); simulation deliverable T0+18

Ilse van Bemmel (Leiden); deliverable to be finalised (MeqTree Ionosphere module?)

• Line HI Surveys – Oxford, Groningen, Swinburne

Danail Obreschkow (Oxford); simulation deliverable T0+12

Rense Boomsa (Groningen); deliverable to be finalised (High-res HI module?)

• Magnetism – Cambridge, Bonn

Martin Krause+replacement (Cambridge); simulation deliverable T0+18

Tigran Arshakian (Bonn); deliverable to be finalised (Galactic Foreground module?)

• Pulsar Surveys – Manchester

Roy Smits (Manchester), simulation deliverable T0+15

• EOR – Paris, Lisbon;

Paola Di Matteo (Paris), simulation deliverable T0+21


Continuum simulations

• Rationale different from ‘Line’ approach (Obreschkow)

Not DM haloes from Millennium Simulation ascribed HI, star formation rates and AGN properties, because insufficient FOV for SKADS benchmark

• But DM density field evolved under linear theory, populated with objects from known radio luminosity functions, and with other important physics (e.g. non-linear structures, source models) `pasted on’


Basic methodology

(Δρ/ρ)DM evolved under linear theory in each 20 Mpc/h cell

Redshift In each cell, for each source type:

• Define DM halo mass for each source type and compute bias b(M,z)

• Compute mean number of sources above flux limit, n0, in absence of clustering

• Amplify fluctuations in underlying DM density field:

n/n0 ~ exp[ b(M,z) (Δρ/ρ)DM ]

• Poisson sample the LF

Wilman et al, 2007


Parent Source Types

• Radio-quiet quasars: Mhalo = 3E12/h M tied

to XLF of Ueda et al. (2003) • `FRI’ radio sources: Mhalo = 1E13/h M

Willott et al. (2001) 151 MHz LF

• `FRII’ radio sources: Mhalo = 1E14/h M Willott et al. (2001) 151 MHz LF

• Normal star-forming galaxies: Mhalo = 1E11/h M Yun et al. (2001) 1.4 GHz LF (low-L component) + PLE

• Starburst galaxies: Mhalo = 5E13/h M Yun et al. (2001) 1.4 GHz LF (high-L component) + PLE

Wilman et al, 2007


• Double Schechter-fn fit representing normal galaxies and starbursts

• We assume LF flattens below L1.4 GHz = 1020.5 W/Hz and integrate down to 1019

W/Hz (SFR ~ 0.01 M/yr)

• No need for an extra population of normal galaxies via an optical LF (à la Hopkins/Windhorst)

L(60 μm)

‘normal’ galaxies

starbursts

Two populations of star-forming galaxies

Wilman et al, 2007


Results: 1.4 GHz source counts

Wilman et al, 2007


Results: HI mass functions

Log M(HI) = 0.48 + 0.44*log L1.4 GHz +- 0.3 dex scatter

From M(HI)-SFR relations of Lah et al. 2007, Doyle & Drinkwater 2006

Increasing z

Wilman et al, 2007


March 2007 Release

• v2: 20 x 20 deg2 down to 1 micro-Jy @1.4 GHz • v3: 10 x 10 deg2 down to 10 nano-Jy @1.4 GHz• Simulations stop at z=4• Simple P(k), i.e. no Baryon Wiggles• See the WIKI for full details and catalogue

download

Wilman et al, 2007


Faint source uncertainty

Star-forming galaxies

AGN

Hopkins et al. 2000 model

• Models diverge below 1 micro-Jy due mainly to inclusion of an extra population of ‘normal galaxies’ in the Hopkins/Windhorst models

• This extra population may not be needed- at least locally, the radio LF of infrared-selected galaxies accounts for all normal galaxies


Extensions: (i) small-scale clustering

• Aim, to `paint on ‘ clustering on co-moving scales < 20 Mpc/h (cell-size)

• Uses a smaller size cell (5 Mpc/h) and a ‘mass filtering’ method to identify cluster-sized over-densities (which we have checked follow Press-Schechter-like mass distributions)

• FRI/II sources (and relic/halo sources) added to the clusters following `known’ occupancies (although problem due to differences before/after virialization).

• Star-formation to be suppresed in cluster cores.

Wilman et al, 2007


Extension (ii) FRI/II structures: simple

prescriptions

PLS

PLS

FRI:

Log R(core:lobe) = 10.8 – 0.55logL151 + scatter

Γ=6 (for beaming)

FRII:

Log R(core:lobe) = -2 + scatter

Γ=8.5 for beaming

Hotspot:lobe ratio ~ 0.4*logL178 + const

• Cores and hotspots: point sources •lobes: uniform ellipses with varying axial ratio

• Pick-out blazars, core-dominated quasars, quasars and radio galaxies by angle


Extensions: (iii) multi-frequency information

• SF-galaxies: -thermal free-free emission (α=0.1) -synchrotron emission (α=0.75 + scatter)

-free-free absorption for starbursts (τff=1 at 1 GHz) -dust emission

• Radio-loud AGN:-distribution in intrinsic linear size (ie simple radio source evolution model), spectral curvature (including CSS/GPS sources) -core-lobe-hotspot morphologies and flux division (lobes modelled as ellipses; spectral gradients+IC losses; environmental asymmetries) -Beaming of the steep-spectrum parent population (checked for consistency with high-frequency source counts)

Wilman et al, 2007


Extensions: (iv) Full P(k)

Now (thanks to Filipe Abdalla) with added wiggles


Simulation Deliverable (1st Dec release)

• 20 x 20 deg2 (released as overlapping 4x4 deg2 tiles plus catalogues)

• Flux densities at 151 MHz, 610 MHz, 1.4 GHz, 5 GHz and 20 GHz• All sources included down to limits of LF (allowing user to add own

flux density limits)• Simulation performed out to high-z (z~10)• Galaxy clusters with assigned radio source content• Realistic source morphologies and SEDs: cores,lobes,hotspots, a

simple source evolution and a beaming model

Wilman et al, 2007


Catalogue format

• A common standard for SKADS extragalactic simulation catalogues • Galaxy index to identify sub-component sources

(cores/lobes/hotspots) to parent galaxy• Source type (AGN/SF) and sub-component type• Cluster Index • Millennium catalogue halo and galaxy indices• Continuum I[QUV] flux densities @0.15, 0.61, 1.4, 5 and 20 GHz• HI fluxes and profile descriptions• Morphological info: ellipse PA, major+minor axes


MAIN TABLE#0 Unique source index#1 Cluster index (0-no member, cluster index#2 Galaxy index (0-cluster halo, otherwise number)#3 SF type (0-no SF, 1-normal SF, 2-SB)#4 AGN type (0-no AGN, 1-RQQ, 2-FRI, 3-FRII)#5 Structure type (1-core, 2-lobe, 3-hotspot, 4-SFdisk, 5-HI disk, 6-diffuse halo)#6 RA#7 DEC#8 Redshift (cosmological)#9-11 Shape (PA, major axis, minor axis) (arcsec)#12-27 Cont FD IQUV (200MHz, 1GHz, 5 GHz, 25 GHz) x4#28-33 HI Flux IQUV, centre apparent velocity, linewidth#34 Millennium galaxy index#35 Millennium halo index

MILLENNIUM TABLE#1 Unique source index#2 Millennium galaxy index#3 Millennium halo index

CLUSTER TABLE#1 Cluster index#2 RA centre#3 DEC centre#4 Redshift#5 mass#6 Radius#7 Velocity dispersion

steve rawlings2nd skads workshop, paris, october 2007 science simulations steve rawlings (oxford)...

Documents