Simulations of the merging galaxy cluster Abell 3376uspconference.if.usp.br/wp-content/uploads/Rubens_Machado_2013.… · gas sloshing and cooling ﬂows, ZuHone et al. (2010) Rubens

Simulations of the merginggalaxy cluster Abell 3376

Rubens Machado, IAG/USPGastão Lima Neto, IAG/USP

USP Conference: Cosmology, Large Scale Structure and First Objects, 05/02/2013

Summary

Rubens Machado (IAG/USP) Simulations of the merging galaxy cluster Abell 3376 2 / 30

Cluster mergers

Cluster mergers are the mechanismsby which clusters assemble

Mvir ∼ 1014 M�

Rvir ∼ 1 Mpc

b ∼ 100 kpcv ∼ 1000 km/s∆t ∼ 1 Gyr

Mach ∼ 1− 3Egrav ∼ 1063 erg


Simulations of cluster mergers: examples

transient structures, Poole et al. (2006)



gas sloshing and cold frontsAscasibar & Markevitch (2006)



gas sloshing and cooling flows, ZuHone et al. (2010)



parameter space exploration of mergers to study entropyZuHone (2011)



radio relics, van Weeren et al. (2011)



triple merger, Brüggen et al. (2012)



the Bullet Cluster:Springel & Farrar (2007), Mastropietro & Burkert (2007)Takizawa (2005, 2006), Milosavljevic et al. (2007)


Cluster mergers

clusters in which gashas become dissociatedfrom dark matter

1) 1E 0657-56 (Clowe et al. 2006), “Bullet Cluster”2) MACS J0025.4-1222 (Bradac et al. 2008)3) Abell 520 (Mahdavi et al. 2007), “Train Wreck”4) Abell 2744 (Merten et al. 2011), “Pandora’s Cluster”5) Abell 2163 (Okabe et al. 2011)6) Abell 1758 (Ragozzine et al. 2011)7) DLSCL J0916.2+2951 (Dawson 2012), “Musket Ball Cluster”


Abell 3376

Mvir = 5.2 × 1014 M�

z = 0.0456


Abell 3376: a nearby merging cluster

X-ray emission

XMM-Newton

radio relics

ROSAT (X-ray) + VLA (radio)Bagchi, Durret, Lima Neto & Paul (2006)



X-ray emission

XMM-Newton

radio relics




X-ray emission

XMM-Newton

radio relics



Abell 3376: radio

giant (2 Mpc) radio lobes around clusterno associated jetsmagnetic field ∼ 1µG


Abell 3376: brightest cluster galaxies

optical (galaxies)



optical (galaxies)



X-ray (intracluster gas)

second BCG coincides with X-ray peak; BCG does not



X-ray (intracluster gas)

second BCG coincides with X-ray peak; BCG does notseparation: 970 kpc


Numerical simulations: initial conditions

initial parameters:

• DM density profile • mass ratio• gas density profile • gas fraction• initial relative velocity • impact parameter



initial parameters:




initial parameters:




initial parameters:


a posteriori :

• time after central passage• projection angles


Numerical simulations: alphacrucis, 2304 cores


Numerical simulations: evolution

X-ray surface brightness

emission-weighted temperature

time


Numerical simulations: evolution


Numerical simulations: parameter space sample


Numerical simulations: parameter space of IC

initial parameters:

• DM density profile

: Hernquist (similar to NFW)

• gas density profile

: Dehnen γ=0 (similar to β-model)

• initial relative velocity• mass ratio• gas fraction

: fgas = 0.18

• impact parameter



initial parameters:

• DM density profile : Hernquist (similar to NFW)• gas density profile

: Dehnen γ=0 (similar to β-model)

• initial relative velocity• mass ratio• gas fraction

: fgas = 0.18




initial parameters:

• DM density profile : Hernquist (similar to NFW)• gas density profile : Dehnen γ=0 (similar to β-model)• initial relative velocity• mass ratio• gas fraction

: fgas = 0.18




initial parameters:

• DM density profile : Hernquist (similar to NFW)• gas density profile : Dehnen γ=0 (similar to β-model)• initial relative velocity• mass ratio• gas fraction : fgas = 0.18• impact parameter



initial parameters:

• DM density profile : Hernquist (similar to NFW)• gas density profile : Dehnen γ=0 (similar to β-model)• initial relative velocity• mass ratio• gas fraction : fgas = 0.18• impact parameter• temperature profile : from hydrostatic equilibrium



initial parameters:

• DM density profile : Hernquist (similar to NFW)• gas density profile : Dehnen γ=0 (similar to β-model)• initial relative velocity• mass ratio• gas fraction : fgas = 0.18• impact parameter• temperature profile : from hydrostatic equilibrium


Numerical simulations: mass ratio

MBMA

= 1/2 1/4 1/6 1/8


Numerical simulations: impact parameter

b = 0 150 kpc 350 kpc 500 kpc


Numerical simulations: initial relative velocity

vo = 500 km/s 1000 km/s 1500 km/s 2000 km/s


Numerical simulations: relative gas concentration

• central gas density of the minor cluster

ρBρA

= 1 2 4 6


Numerical simulations: inclination

i = 0◦ 30◦ 40◦ 60◦


Comparison to observations

observed simulated


Mach number


Mach number: Rankine-Hugoniot jump conditions

emissionmap

temperaturemap

temperature

density

pressure

entropy

streaminggas velocity

T2

T1=

5M4 + 14M2 − 3

16M2

n2

n1=

4M2

M2 + 3

P2

P1=

5M2 − 1

4

S2

S1=

(5M2 − 1

4

)(4M2

M2 + 3

)−5/3

(vx,2 − vx,1

)= (vs − u)

(3M2 − 3

4M2

)


Mach number: inclination

i = 0◦

M = 3.9

i = 40◦

M = 2.9


Mach number: inclination

i = 0◦

M = 3.9

i = 40◦

M = 2.9


Dark matter

How is the dark matter distributed?


Dark matter

projected mass (total)


BCG separation and dark matter


Summary

reproduced featuresvirial massintegrated X-ray fluxapproximate X-ray morphologytemperature range(proxy of) BCG separation

approximate constraintscollision axis inclined by i=40◦ wrt plane of the skyobserved ∼0.5 Gyr after central passagemass ratio 1/6 – 1/8Mach ∼3–4small impact parameter (b<150 kpc), if any


Summary

We have proposed a specific scenario of a dynamical history for themerging event of Abell 3376.

We have offered a possible combination of parameters that accountsfor several of its features.

Machado & Lima Neto (2013)


Perspectives

• Distribution of dark matter:• Mass maps from gravitational weak lensing• either corroborate this scenario or necessitate its improvement

acknowledgement:


Perspectives

• Distribution of dark matter:• Mass maps from gravitational weak lensing• either corroborate this scenario or necessitate its improvement

+ “All models are wrong; some models are useful.”Box & Draper (1987)

acknowledgement:


Documents

Simulations of the merging galaxy cluster Abell 3376uspconference.if.usp.br/wp-content/uploads/Rubens_Machado_2013.… · gas sloshing and cooling ﬂows, ZuHone et al. (2010) Rubens