My Research Interests

Research Interests

My research focuses on the interplay between galactic feedback and the intergalactic medium (IGM) and I am interested in the multiple ways that galactic winds affect the properties of the IGM.
During my PhD I have devised a new way to describe feedback by galactic winds in the Munich semi-analytic model for galaxy formation, which successfully describes the evolution of outflows powered by star formation into the IGM (astro-ph/0402044). I have used my model for galactic winds to investigate several ways in which outflows can impact on the IGM.
I have estimated the volume filling factor and the fraction of IGM mass affected by galactic winds: both these quantities give us a first order estimate of the probability to find signatures of winds in the Ly-alpha forest. The volume filling factor of winds also gives us information about the fraction of the universe that may have been polluted with metals by winds and about the IGM metallicity evolution (astro-ph/0402044).


A z=3 thin slice through one of my wind simulations. The white contours indicate the extension of the winds.

While the volume filling factor and the fraction of IGM mass affected by winds give a "theoretical" estimate of the influence of winds on the Ly-alpha forest, we can quantitatively determine these effects by calculating their contribution on the flux probability distribution function (PDF) and the flux power spectrum of the Ly-alpha forest.

Another effect that could be used to identify the presence of a galactic wind in the IGM is the so-called galaxy proximity effect: this means that when a wind blows out of a galaxy, the absorption features observed along a line of sight that intercepts the galaxy may be modified (astro-ph/0511028).

Example of signature of a (pressure-driven) galactic wind: the hot bubble of gas emerging from the galaxy increases the flux transmissivity of the gas inside the wind.

Example of signature of a (momentum-driven) galactic wind: the cold gas accumulating onto a thin shell expanding into the IGM creates narrow absorption lines and a cavity with reduced flux transmissivity along a line of sight intercepting the wind-blowing galaxy.

In collaboration with Corina Vogt and Torsten Ensslin I have attempted to estimate the level of seed magnetisation of the IGM, under the assumption that galactic winds can transport magnetic fields and cosmic rays together with mass and metals (see astro-ph/0604462).





The evolution of the magnetic fields ejected by galactic winds at z=3, z=1, z=0.5 and z=0, respectively. The figues shows slices through one of our simulated box.


The Sussex Millennium Galaxy Catalogue

See here.





Last modified: December 2007