Lessons from the Local Universe

 
Dynamical modeling based on z=0 disks:
 
  • Collisional perturbation
  • Self gravitating response
  • Gas inflow + activity
  • Merger


(Noguchi 1987;  Barnes 1988; Barnes & Hernquist 1991, 1996; Mihos etal 1992, 1993; Mihos & Hernquist 1994, 1996; Hernquist & Mihos 1995; Bekki 1998; Gerritsen 1999)

 
 
Star formation in interacting galaxies:
  • SFR enhancements of ~ few times
  • Nuclear star formation 
  • Starburst fractions ~ few % of stellar mass
(Larson & Tinsley 1978; Hummel 1981; Condon etal 1982; Joseph etal 1982; Lonsdale etal 1984; Keel etal 1985; Kennicutt etal 1987; Bushouse 1986; Liu & Kennicutt 1995; Barton etal 2000)

 
But the action is in the infrared!
  • luminous infrared galaxies 

    • (Lfir ~ 1011 - 1012 Lsun)
  • dust enshrouded
  • close mergers
  • nuclear gas concentrations and starbursts
(Soifer etal 1984; Sanders etal 1988; Lawrence etal 1989; Kim etal 1995; Solomon etal 1997; Mihos & Bothun 1998; Rigopoulou etal 1999)

from Hibbard and Yun 1997

So what determines the outcome of an interaction?
    Encounter parameters? Gas fraction? Galaxy type? Environment?

Back to the models...

Gaseous inflow and central activity are driven by gravitational torques:
(Noguchi 1987; Barnes & Hernquist 1991; Mihos & Hernquist 1996)
 
Gas Angular Momentum
Physical Torques
Gravitational Torques
(from Mihos & Hernquist 1996)

 
Inflow can be suppressed if instabilities are suppressed:
  • Including a central bulge (Mihos & Hernquist 1994, 1996)

    •  
  • Reducing the disk surface density (eg, LSBs; Mihos, McGaugh, & de Blok 1997; Mihos 1999)

    •  
  • Suppressing orbital resonances (Barnes & Hernquist 1996)

    •  
...but other influences (gas fraction, environment, etc) must surely also play a role...

So how do we translate this knowledge to the high redshift universe?