by Fidy A. RAMAMONJISOA MSc Project University of the Western Cape
description
Transcript of by Fidy A. RAMAMONJISOA MSc Project University of the Western Cape
by
Fidy A. RAMAMONJISOA
MSc Project
University of the Western Cape
Supervisor: Prof Catherine Cress
Modelling radio galaxies in simulations:
CMB contaminants and SKA / Meerkat sources
SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09
AimOne of CMB experiments goals
Counting clusters at different times (redshift)
Relevant to dark energy constraints
How?Use CMB observations
through Sunyaev- Zeldovich (SZ) effect
Counting is difficult because of point sources and radio sources
We aim at modelling spatial distribution (number density) and flux of radio sources using N-body
simulation
INTRODUCTION
SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09
Inte
nsity
(M
Jy/s
r)
Frequency (GHz) -0.05
0.00
0.05
ACT frequencies
145 GHz decrement
218 GHz null
270 GHz increment
Credit: Spergel D.
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TTelectronelectron = 10 = 1088 K K
Hot electron gas
Sunyaez-Zeldovich effect (SZE) in galaxy clusters
Distortion of CMB black body by inverse Compton scattering
2A
eSZE
D
TMdT
redshift independent effect
SZ surveys detect clusters
Thermal SZ270-300 microKelvin
Kinetic SZ10-20 microKelvin
SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09
Methodology
•Millennium Run and semi analytical modelsemi analytical model of galaxy formation and evolution (Croton et al. 2006, De Lucia & Blaizot 2007)
•Extend the semi analytical model to follow black hole follow black hole mass accretion and its conversion to radiationmass accretion and its conversion to radiation
Millennium Run: simulation of 1010 dark matter particles in a cubic region 500h-1Mpc on a side in the ΛCDM cosmological framework (Springel et al. 2005)
Particle mass:8.6x108h-1Mʘ
Outputs stored in a database: use Structured Query Language (SQL) to make a query
SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09
AGN feedbackRadiative accretion efficiency
(not yet well known)
Radio mode Quasar mode
SMBH growth triggered by mergers- cold disk gas driven onto black hole
(Kauffmann & Haeanelt 2000)
Hot gas from surrounding hot halo accretes onto SMBH
Efficient at
7.0z
sunBH MM 810
Efficient at
SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09
1z
2
1cML BHbol
)()(
)()(
21
21
ztzt
zMzMM BHBHBH
Find progenitors at z1of all galaxies at z2
bolfLL
24 Ld
LS
mJySS cut 1 cutL
BH Sfc
dM
2
241
Count radio source
MODELf fraction of conversion to radio
SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09
Fossati G. et al. (1998)
Average SED of blazars grouped by powers
Redshift distribution of blazars normalized
Flux density limit 1 mJy at 2.7 GHz
SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09
Results
Redshift distribution of blazars normalized
Flux density limit 1 mJy at 2.7 GHz
SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09
ResultsFossati G. et al. (1998)
Average SED of blazars grouped by powers
Redshift distribution of blazars normalized
Flux density limit 1 mJy at 2.7 GHz
SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09
ResultsFossati G. et al. (1998)
Average SED of blazars grouped by powers
200r
r
123 .10 HzWP
Total surface density of radio galaxies vs.
Simulation+observation
Lin & Mohr (2007)simulation
Luminosity
200r
r
at 1.4 GHz
ResultsRedshift up to 0.06Radio galaxies
galaxies
BL LacsFRI
SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09
Results
200r
rsunMh 11410
sunMh 11410
Surface density of radio sources vs.
2<Mvir<6
6<Mvir<10Mvir>10
Unit:
200r
r
Radio sources are concentrated in low mass clusters
Density of radio sources maximum near the centre
123 .10 HzWPLuminosity
at 1.4 GHz
Redshift 0.05
sunMh 11410
SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09
Temperature (microK) vs redshift z Flux (mJy) vs z
Temperature fluctuations and fluxes caused by blazars in clusters binned in cluster mass at 145 GHz
Results
CMB contamination by radio galaxies and quasars
SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09
Summary• The model is able to reproduce fairly well the observed redshift distribution of radio
sources
• The surface density of simulated blazars are in agreement with Lin & Mohr for small radial distance from the centre of the cluster.
• It predicts high concentration of radio sources close to the centre of clusters.
• Radio sources are more concentrated in low mass clusters .
• Contaminations by blazars are not negligible at local redshift (z<0.1).
• The average temperature fluctuation in CMB caused by BL Lacs is 5 microK at z=0.01
(almost at the same order as the kinetic SZ signature of an average cluster mass).
• At high redshift (z>1), the fluctuation in CMB temperature produced by blazars appears to be very significant (about 300-350 microK, similar to temperature fluctuations from the thermal SZ effect).
SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09
References• Croton D. J., Springel V. et al., 2006, MNRAS, 365, 11
• Dunlop J. S., Peacock J. A., 1990, MNRAS 247, 19-42
• Marulli F., Bonoli S., Branchini E., Moscardini L., Springel V., 2007, MNRAS, submitted
• Lin Y. T., Mohr J. J., 2007, astro-ph/0612521v2
SKA 4 th annual Bursary Conference, Stellenbosch Institute for Advanced Study 03/12/09