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Modelling radio galaxies in simulations:
CMB contaminants and SKA / Meerkat sources
by
Fidy A. RAMAMONJISOA
MSc Project
University of the Western Cape
Supervisor: Dr Catherine Cress
Introduction
Square Kilometre array:resolution less than 1milliarcsecond
108μm
Why do we model radio galaxies?
Relevant for SKA/MeerKAT science (eg. dark energy probe)
http://www.nrao.edu/whatisra/radiotel.shtml
MeerKAT (Karoo Array Telescope): more than 50 dishes, use mid-frequency
galaxies evolution and large-scale structure
1965
1992
2003
Penzias and Wilson
COBE
WMAP
Cosmic Microwave Background (CMB) :
Predicted by Gamov in 1948 Discovered by Penzias and Wilson in 1964
Precise measurement of the fluctuations in CMB by COBE in 1989
WMAP improved with more data in 2001
PLANCK will be launched 2009
Atacama Cosmology Telescope (ACT) will measure fluctuations on arcminute angular scale
Cosmic Microwave Background (CMB)
CMB: relic radiation from the early universe emitted when the universe was about 400000 yrs old (z=1100), has a thermal black body of 2.73 K.
ACT
http://www.space.com/scienceastronomy
AimOne of CMB experiments goals
Counting clusters at different times (redshift)
Relevant to dark energy constraints
BUTWhy?
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
e-
e-
e-
e-
e-
e-
e-
e-
e-
TTelectronelectron = 10 = 1088 K K
Hot electron gas
Inte
nsity
(M
Jy/s
r)
Frequency (GHz) -0.05
0.00
0.05
ACT frequencies
145 GHz decrement
220 GHz null
270 GHz increment
What is Sunyaev Zeldovich (SZ) effect?
•Distortion of CMB spectrum by inverse Compton scattering
•SZ is redshift independent
Credit: D. Spergel
100 200 300
SZ
Point sources
synchrotron
Dust
BLAZAR
X ray OpticalRadio cont. 21 cm
e-
e-
e-
e-
e-
e-
e-
e-
e-
TTelectronelectron = 10 = 1088 K K
Hot electron gas
SZ contaminants
Inte
nsity
(M
Jy/s
r)
Frequency (GHz) -0.05
0.00
0.05
ACT frequencies
145 GHz decrement
220 GHz null
270 GHz increment
Credit: D. Spergel
Method
•Use Millennium Run and semi 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
Method Use the Millennium simulation (Virgo consortium) to build the modelMillennium 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
http://www.g-vo.org/Millennium
Method
1
1
1
1
1
2
2
3
3
4
4
4
4
4
5
5
6
6
6
7
7
1. Dark matter collapses under gravity and forms halos 1, 2, 3, 4.
2. Gas cools in halos 1, 2, 3, 4 and forms disks and stars. Halo 5 collapses.
3. Halos 2 and 3 merge with halo 1. Gas cools in halo 4 and 5 forming stars. Halo 6 collapses.
4.Galaxy 2 merges with galaxy 1 and form a spheroid (elliptical) as they have similar size. Galaxy 3 is a satellite. Halos 4 and 5 merge. Gas cools and stars form in halo 6. Halo 7 collapses.
5. More gas cools into disk in galaxy 1. Galaxy 5 merges with galaxy 4. Galaxy 5 is much smaller so no spheroid forms. Gas cools into halo 7 forming stars.
SEMI ANALYTICAL MODEL
z=3
z=2
z=1
z=0
N-body simulation
Method
Y
dt
dz
dz
dM
dt
dM BHBHBHM
GHz
GHz
GHz
GHzGHz
dL
dL
f 910
10
)15145(
)15145(145
0º<i<10º
Use SED of blazar
Use SED of normal radio galaxies
)()( 145 tLft bolGHzACTL
24
)(
L
ACT
d
tLS
Find the progenitors at later z2 of the whole galaxies at z1
Extract galaxies in halo centralMvir>2x1014h-1Mʘ at z1
Assume a random inclination i of radio source
Assume a fraction f of total Lbol (t) is radio luminosity
fluctuation in CMB at t
mJy
SK
3.010
N
2
1)( cMtL BHbol
(Marulli et al. 2007)
Obsevations
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-1.5
-1
-0.5
0
0.5
1
1.5RLF with luminosity cut off at 151 MHz (High luminosity part of the RLF)
Redshift z
Nu
mb
er
de
nsi
ty (
log
sca
le)
in G
pc-3
Radio luminosity function (number density of radio sources): obtained by fitting data from surveys of radio sources
Model ‘C’ of luminosity function (C.J. Willott et al. 2000).
Model of RLF (J.Jarvis et al.2001)
0 0.5 1 1.5 2 2.5 3 3.5 40
500
1000
1500
2000
2500
3000
3500RLF with luminosity cut off L=10
26 W.Hz
-1.sr
-1 at 151 MHz
Redshift z
Num
ber
de
nsi
ty in
Gp
c-3
Progenitors of the brightest galaxy (mag_v~-24.4) identified at z=0
Preliminary results
0 0.5 1 1.5 2 2.5 3 3.5 410
-4
10-3
10-2
10-1
Redshift z
Bla
ck h
ole
mas
s in
uni
ts o
f 101
0h-1
Msu
n (s
emilo
g pl
ot)
0 1 2 3 4 5 6 710
-4
10-3
10-2
10-1
Redshift z
Bla
ck h
ole
mas
s in
uni
ts o
f 101
0h-1
Msu
n (s
emilo
g pl
ot)
Progenitors of a galaxy at z=1 in the most massive halo (centralMvir~8x1014h-1Mʘ massive halos)
Preliminary results
MBH=0.43x1010h-1MʘMBH=0.09x1010h-1Mʘ
Preliminary results
0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.410
0
101
102
103
Redshift zTe
mp
era
ture
flu
ctu
atio
n (
mic
roK
elv
in)
z
σ (μK)
0.54
226
1.03
45
1.57
16
2.16
7
Temperature fluctuation (μK) from radio source vs redshift z
Preliminary results
0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4
100
Redshift z
Flu
x o
f ra
dio
so
urc
es
log
S (
mJy
)
z
Sν
(mJy)
0.54
6.8
1.03
1.4
1.57
0.5
2.16
0.2
Flux of radio sources at 145 GHz vs redshift z
Future objectives
3
18, .2001.010
skmVf
MMM virhotBH
AGNRBH
Radio mode: accretion of hot gas
Quasar mode : major merger and cold gas accretion
21, )/.280(1 vir
coldBHQBH Vskm
mfM
central
satBHBH m
mff
03.0BHf
Include Active Galactic Nuclei (AGN) feedbackInclude Active Galactic Nuclei (AGN) feedback
Model radio emission fromModel radio emission from star formationstar formation
16105.7
yrMAGNControl the efficiency of accretion
Efficient at low redshift Efficient at z>2
Conclusion The results constitute a first step for the investigation of the growth of
supermassive black hole
Currently we investigate how best to relate the black hole growth to the expected radio emission (as in Marulli et al. 2007)
The most massive black holes are present today (z=0) in simulations
References Croton D. J., Springel V. et al., 2006, MNRAS, 365, 11
Marulli F., Bonoli S., Branchini E., Moscardini L., Springel V., 2007, MNRAS, submitted
Willott C.J., Rawlings S., Blundell K. M., Lacy M., Eales S.A., 2000, MNRAS, 322 (2001) 536-552
http://chandra.harvard.edu/
http://cse.ssl.berkeley.edu/
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