Neutrino clustering in interacting Dark Energy cosmologies

1
Neutrino clustering in interacting Dark Energy
cosmologies

• Valeria Pettorino
• (ITP, Heidelberg)

4th International Workshop on the Dark Side of
the Universe 05.06.08 Cairo
astro-ph/0802.1515 D.F.Mota, V.P., G.Robbers,
C.Wetterich
2
Hopes and troubles

• Why so small?
• Why important just today?

Cosmological constant
Quintessence

• DE/M4 6.5 ?10-121
• ?m/M4 3.5 ?10-121
• M 2.44?1018 GeV

Wetterich 1988, Ratra Peebles 1988
Tracker fields

• Solutions are independent on the initial
  conditions for ? and ?

Steinhardt, Wang and Zlatev 1999, Liddle
Scherrer 1999
Details depend on V(?) or on the kinetic term
Valeria Pettorino, ITP Heidelberg The Dark Side
of the Universe, BUE, Cairo, 5th June 2008
3
Coupling dark energy

• The stringent difficulties of minimal coupling
  models and the lack of a clear explanation of the
  dark issue, encourage to pursue new ways of
  approaching the Dark Energy problem

Valeria Pettorino, ITP Heidelberg The Dark Side
of the Universe, BUE, Cairo, 5th June 2008
4
Interacting Dark Energy

• Coupling to atoms
• Tiny, small influence on cosmology
• Coupling to dark matter
• cosmological bounds
• role in clustering?
• Coupling to gravity
• Cosmological bounds
• role in clustering?

Amendola 2000 Maccio etal 2005 PerrottaBaccigalu
pi 2002 Mangano Miele VP 2005
PettorinoBaccigalupi 2008 and references therein
Valeria Pettorino, ITP Heidelberg The Dark Side
of the Universe, BUE, Cairo, 5th June 2008
5
Interacting Dark Energy

• Coupling to neutrinos
• can be big and can have a significant
  influence in cosmology (wetterich 2007)

?
MAVANS Fardon etal 2004, Afshordi etal 2005,
Bjaelde etal 2008, Brookfield etal 2007
Growing neutrinos Amendola etal 2007, Wetterich
2007, Mota etal 2008, Brouzakis etal 2007
Valeria Pettorino, ITP Heidelberg The Dark Side
of the Universe, BUE, Cairo, 5th June 2008
6
Exponential potential

• V(?) M4 exp(- ??)
• Solutions independent of the initial conditions
• DE scales as a constant fraction tracking the
  background
• ?? n/?2
• with n 3(4) in MDE (RDE)

?? has to increase in recent time! Need a
cosmological event that triggers the acceleration
Steinhardt, Wang and Zlatev 1999, Liddle
Scherrer 1999, Wetterich 1995, Amendola 2000
Valeria Pettorino, ITP Heidelberg The Dark Side
of the Universe, BUE, Cairo, 5th June 2008
7
Neutrinos become non relativistic
Attractor with constant fraction of DE coupling
Neutrino mass grows (? lt 0)
Neutrinos become non relativistic
Neutrinos become non relativistic
The coupling to DE turns on and almost stops ?
Transition to the future attractor acceleration
acceleration
Valeria Pettorino, ITP Heidelberg The Dark Side
of the Universe, BUE, Cairo, 5th June 2008
8
Coupling Dark Energy to neutrinos
Valeria Pettorino, ITP Heidelberg The Dark Side
of the Universe, BUE, Cairo, 5th June 2008
9
Dark energy - neutrino connection

• Dark energy and neutrino properties are related

The present amount of DE is set by a cosmological
event and not by ground state properties
DE-? fluid equation of state
Valeria Pettorino, ITP Heidelberg The Dark Side
of the Universe, BUE, Cairo, 5th June 2008
10
Neutrino clustering

• Neutrino structures become non linear at z 1
  for supercluster scales
• (Mota, Pettorino, Robbers, Wetterich 2008)

• At small scales
• neutrinos reduce CDM
• structures

• Stable neutrino lumps
• (Brouzakis etal 2007)

Valeria Pettorino, ITP Heidelberg The Dark Side
of the Universe, BUE, Cairo, 5th June 2008
11
Future prospects

• Use CMB and other data to constrain the coupling
  (or the neutrino mass)
• Non linear analysis of structure formation,
  spherical collapse, N-body simulations

Valeria Pettorino, ITP Heidelberg The Dark Side
of the Universe, BUE, Cairo, 5th June 2008
12
Conclusions

• When neutrinos become non relativistic, they
  activate the coupling and trigger the
  acceleration.
• Transition from attractor to an almost static
  dark energy, independent of ground state
  properties.
• Neutrinos first cluster at z 1 at supercluster
  scales and beyond.
• At small scales, neutrinos dont contribute to
  the clumping but they reduce cdm structures.
• Detection of such a population of large scale
  structures via gravitational potential or
  correlation with CMB can be an indication for a
  new attractive force stronger than gravity.

Valeria Pettorino, ITP Heidelberg The Dark Side
of the Universe, BUE, Cairo, 5th June 2008