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The hierarchical build-up of the Tully-Fisher relation

(2010)

Authors:

Chiara Tonini, Claudia Maraston, Bodo Ziegler, Asmus Böhm, Daniel Thomas, Julien Devriendt, Joseph Silk
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The hierarchical build-up of the Tully-Fisher relation

ArXiv 1006.0229 (2010)

Authors:

Chiara Tonini, Claudia Maraston, Bodo Ziegler, Asmus Böhm, Daniel Thomas, Julien Devriendt, Joseph Silk

Abstract:

We use the semi-analytic model GalICS to predict the Tully-Fisher relation in the B, I and for the first time, in the K band, and its evolution with redshift, up to z~1. We refined the determination of the disk galaxies rotation velocity, with a dynamical recipe for the rotation curve, rather than a simple conversion from the total mass to maximum velocity. The new recipe takes into account the disk shape factor, and the angular momentum transfer occurring during secular evolution leading to the formation of bulges. This produces model rotation velocities that are lower by ~20-25% for the majority of the spirals. We implemented stellar population models with a complete treatment of the TP-AGB, which leads to a revision of the mass-to-light ratio in the near-IR. I/K band luminosities increase by ~0.3/0.5 mags at redshift z=0 and by ~0.5/1 mags at z=3. With these two new recipes in place, the comparison between the predicted Tully-Fisher relation with a series of datasets in the optical and near-IR, at redshifts between 0 and 1, is used as a diagnostics of the assembly and evolution of spiral galaxies in the model. At 0.4
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Photometric redshift estimation using Gaussian processes

\mnras 405 (2010) 987-994-987-994

Authors:

DG Bonfield, Y Sun, N Davey, MJ Jarvis, FB Abdalla, M Banerji, RG Adams
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The environments of z 1 active galactic nuclei at 3.6μm

\mnras 405 (2010) 347-358-347-358

Authors:

JT Falder, JA Stevens, MJ Jarvis, MJ Hardcastle, M Lacy, RJ McLure, E Hatziminaoglou, MJ Page, GT Richards
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Jet-regulated cooling catastrophe

ArXiv 1004.1851 (2010)

Authors:

Yohan Dubois, Julien Devriendt, Adrianne Slyz, Romain Teyssier

Abstract:

We present the first implementation of Active Galactic Nuclei (AGN) feedback in the form of momentum driven jets in an Adaptive Mesh Refinement (AMR) cosmological resimulation of a galaxy cluster. The jets are powered by gas accretion onto Super Massive Black Holes (SMBHs) which also grow by mergers. Throughout its formation, the cluster experiences different dynamical states: both a morphologically perturbed epoch at early times and a relaxed state at late times allowing us to study the different modes of BH growth and associated AGN jet feedback. BHs accrete gas efficiently at high redshift (z>2), significantly pre-heating proto-cluster halos. Gas-rich mergers at high redshift also fuel strong, episodic jet activity, which transports gas from the proto-cluster core to its outer regions. At later times, while the cluster relaxes, the supply of cold gas onto the BHs is reduced leading to lower jet activity. Although the cluster is still heated by this activity as sound waves propagate from the core to the virial radius, the jets inefficiently redistribute gas outwards and a small cooling flow develops, along with low-pressure cavities similar to those detected in X-ray observations. Overall, our jet implementation of AGN feedback quenches star formation quite efficiently, reducing the stellar content of the central cluster galaxy by a factor 3 compared to the no AGN case. It also dramatically alters the shape of the gas density profile, bringing it in close agreement with the beta model favoured by observations, producing quite an isothermal galaxy cluster for gigayears in the process. However, it still falls short in matching the lower than Universal baryon fractions which seem to be commonplace in observed galaxy clusters.
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