Simula'ng*Self-Interac'ng* Dark*Ma5er* - - PowerPoint PPT Presentation

Simula'ng*Self-Interac'ng* Dark*Ma5er*

Andrew*Robertson*(Durham*University)* Supervisors:*Richard*Massey,*Vincent*Eke*and* Richard*Bower*

9th*June*2014,*DMUK*Mee'ng,*Durham*

What*is*Self-Interac'ng*Dark*Ma5er?*

• Dark*Ma5er*that*is*strongly*coupled*to*itself.*
• Natural*in*models*with*a*rich*dark*sector*which*has*new*gauge*forces.*
• Examples*include:*
• “Dark*Electromagne'sm”*(Ackerman*et*al.*2006)*
• “Fluid*Dark*Ma5er”*(Peebles,*2000)**
• “Q-balls”*(Kusenko*and*Steinhardt,*2001)*
• “Light*Asymmetric*Dark*Ma5er”*(Frandsen*et*al.*2011)*

DM* DM* DM* DM*

Astrophysical*Consequences*

Core-Cusp*(Weinberg*et*al.*2013)* Too*Big*to*Fail*

Garrison-Kimmel*et*al.*2014*

Missing*Satellites*(Klypin*et*al.*1999)*

Modified*GADGET-2* (Springel,*2005)*

• What*is*GADGET-2*?*
• “Freely*available*code*for*cosmological*N-body/SPH*simula'ons*on*massively*parallel*

computers”*

• Computes*gravita'onal*forces*using*a*hierarchical*tree*algorithm*for*short-range*forces*and*a*

par'cle*mesh*on*large*scales.*

• Sca5ering*rate*given*by:*
• Probability*of*par'cle*i*sca5ering*from*par'cle*j,*in*'me*Δt*is:*

Γ = dn dt = f v1

( )ρσ DM v0 − v1

∫

d3v1 P

ij = σ DM vi − v j Δt 4π 3 h3

Tests*of*Sca5ering*Kinema'cs*

ˆ σ =

σ m

( )M

a2

Kahlhoefer*et*al.*2014*

Major*Mergers*

Clowe*et*al.*2006* Bradac*et*al.*2008* Jee*et*al.*2012* Clowe*et*al.*2013* Merten*et*al.*2011*

Minor*Mergers:*“Bulle'city”*

Harvey*et*al.*2014*

Kahlhoefer*et*al.*2014*

Thanks*for*listening*