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Extragalactic
Astrophysics &
Observational Cosmology Group
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This page is outdated and no longer maintained
I am working now at the Fermi National Accelerator Laboratory
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| Robert
Feldmann |
Postal Address:
ETH Hoenggerberg
Campus
Physics
Department, HIT J12.3
CH-8093 Zurich
Switzerland
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Phone: +41 (0)44
633-6450
Fax: +41 (0)44 633-1238
email: feldmann@phys.ethz.ch |
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| Curriculum
Vitae |
Education:
| 08/2009 |
PhD in Physics |
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Title: "The Evolution of Massive Galaxies - A Numerical Perspective" |
| 06/2005 |
Diploma degree (Master) in Computer Science |
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Title: "Planning with preferences - Solving
partial satisfaction problems" |
| 09/2004 |
Diploma degree (Master) in Physics |
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Title: "Phase structure and photon propagator in
3D abelian lattice Higgsmodels"
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Honours/Awards:
2008 ETH Extragalactic Astrophysics Excellence Award
2004-2005 PhD fellowship from the Studienstiftung
des deutschen Volkes
2001-2004 Scholarship from the Studienstiftung
des deutschen Volkes
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Employment:
Jul 2005 - Aug 2009 PhD student at the Institute of Astronomy, ETH Zürich,
Switzerland
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| Research
Interests |
My PhD advisor was Prof.
C. M. Carollo. Most of my research has been focused on the numerical study
of galaxy formation/evolution with SPH, AMR or N-body simulations and the comparison to observations. My
thesis is focussed on:
- how galaxies form, evolve
and interact in galaxy groups
- the mass and size
evolution of massive elliptical galaxies
- binary mergers between
elliptical galaxies and disk galaxies
- classification of
galaxy properties, e.g. the derivation
of accurate
photometric redshifts
Accurate photometric redshifts: ZEBRA
Observational
studies of galaxy evolution are increasingly dependent on accurate
photometric redshifts. In collaboration also with C.
Porciani and S.
Lilly I have designed
and built
ZEBRA,
the Zurich
Extragalactic Bayesian Redshift Analyzer, as my first PhD project. ZEBRA is a
publicly available software package that allows to compute photometric
redshifts with outstanding accuracy and has been successfully employed
in many publications. You can find more information about ZEBRA on its
dedicated website or in arXiv:0609044.
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A simple
Maximum-Likelihood estimate of redshifts: (top)
spectroscopic vs. photometric redshifts; (bottom) the error in the
redshift estimation as function of spectroscopic redshift for different
template
types; The standard deviation of dz/1+z is ~
0.043 and the outlier fraction ~ 2.1 %. Systematic biases at z~1
are visible.
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ZEBRA's
Bayesian
estimate of redshifts with template
optimization. Top and
bottom panels
as in a). Both the standard
deviation of dz/1+z ~ 0.027 and the outlier fraction ~ 0.8 % are
improved. Systematic biases are minimized.
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The formation of massive early type galaxies
Massive elliptical
galaxies are the most massive stellar systems in the Universe. Yet
their exact formation mechanism and time of mass assembly remains a
puzzle. In my first numerical part of my PhD program I performed in
collaboration with Co-advisor L.
Mayer a set of
high-resolution N-body simulations of binary galaxy
mergers to show that the morphologies of tidal features that are seen
around a large fraction of nearby, massive field ellipticals cannot be
reproduced by equal-mass dissipationless mergers; rather, we find them
to be consistent with the accretion of less massive disk-dominated
galaxies (arXiv:0801.4764).
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Morphological
signatures of mergers. (a) Observed image of
an elliptical galaxy that shows red tidal tails at large galactocentric
distances; (b-d) Mock images of: a simulated 1:4 merger between an
elliptical galaxy and a disk+bulge system 600 Myrs after the
merger; a simulated 1:10 merger between an elliptical galaxy and
a disk 500 Myrs after the merger; a simulated 1:4 merger between
elliptical galaxies 380 Myrs after the merger.
The tidal features originating in mergers between ellipticals and
those involving a disk-dominated companion are strikingly different,
independent of the mass ratio and orbit characteristics. While all
mergers can lead to shells and diffuse features, only the mergers
involving disks show strong tidal arms and loops, similar to the
observed features around bright ellipticals.
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The evolution of galaxies in group-sized halos
In collaboration
with L.
Mayer I have conducted
several high resolution
SPH simulations of galaxies in groups. One of our aims is to study the
structural
and kinematic evolution of galaxies in groups
and to work out the relative
importance of internal and external mechanisms in the star
formation and mass assembly histories of galaxies, and in their
morphological
transformations.
Our numerical campaign is also designed to provide a theoretical anchor
to
interpret
the
results from observational surveys that we are conducting at the ETH to
study
galaxy properties as a function of their group environment through
cosmic time.
In particular, we want to interpret the results from our ZEN Survey (Zurich
ENvironmental Survey), an ESO Large Program of wide-field imaging of
185 z~0
2dFGRS-2PIGG groups, and of the zCOSMOS survey,
the
ETH-led spectroscopic follow-up of COSMOS. More
details about this part of my PhD thesis can be found here.
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Composite
image of a simulated galaxy group of ~ 1013
solar masses at redshift 1. The different
colors show stellar (red), gaseous (green) and dark
matter (blue) components. The inset shows the central galaxy in more
detail revealing a spiral gas disk within the inner kpc. This
simulation is being run on the Swiss National Supercomputing center in
Manno.
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Student supervision
I supervised an undergraduate student project (E.
Weihs) to develop a C++ package for the morphological classification of
galaxies.
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| Refereed
Papers |
- R. Feldmann, L. Mayer, & C. M.
Carollo,
“Tidal Debris in Elliptical Galaxies as Tracers of Mergers with Disks”,
Astrophys.J. 684, 1062 (2008)
- C.
Scarlata, C. M. Carollo, S. J. Lilly, R.
Feldmann, et al.
“The Redshift Evolution of Early-Type Galaxies in COSMOS: Do Massive
Early-Type Galaxies Form by Dry Mergers?“,
Astrophys. J. Supp. 172, 494
(2007)
- M. T.
Sargent, C. M. Carollo, S. J. Lilly, ..., R. Feldmann, et al.
“The Evolution of the Number Density of Large Disk Galaxies in COSMOS”
Astrophys. J. Supp. 172, 434
(2007)
- C.
Scarlata, C. M. Carollo, S. J. Lilly, ..., R. Feldmann, et al.
“COSMOS Morphological
Classification with the Zurich Estimator of Structural Types (ZEST) and
the Evolution Since z = 1 of the Luminosity Function of Early, Disk,
and Irregular Galaxies”,
Astrophys. J. Supp. 172, 406
(2007)
- P.
Kampczyk, S. J. Lilly, C. M. Carollo, ..., R. Feldmann et al.
“Simulating the
Cosmos: The Fraction of Merging Galaxies at High Redshift”,
Astrophys. J. Supp 172, 329
(2007)
- B.
Mobasher, P. Capak, N. Z. Scoville, ..., R. Feldmann, et al.
“Photometric
Redshifts of Galaxies in COSMOS”
Astrophys. J. Supp. 172, 117
(2007)
- S. J.
Lilly, O. Le Fèvre, A. Renzini, ..., R. Feldmann et al.
“zCOSMOS: A Large
VLT/VIMOS Redshift Survey Covering 0 < z < 3 in the COSMOS Field”,
Astrophys. J. Supp. 172, 70 (2007)
- R. Feldmann, C. M. Carollo, C. Porciani et al. “The Zurich Extragalactic Bayesian
Redshift Analyzer and its first application: COSMOS”, Mon. Not.
Roy. Astron. Soc. 372, 564
(2006)
Publications related to my
Diploma Thesis:
- M.N.
Chernodub, R.
Feldmann, E.-M. Ilgenfritz, A.
Schiller
"Monopole
chains in the compact Abelian Higgs model
with doubly-charged matter field",
Phys.
Lett. B 605, 161-168 (2005), hep-lat/0406015
- M.N.
Chernodub, R. Feldmann, E.-M.
Ilgenfritz, A.
Schiller
"Compact
Q=2 Abelian Higgs model in the London limit:
Vortex-monopole chains and the photon propagator",
Phys.
Rev. D 71, 074502 (2005), hep-lat/0502009
- M.N.
Chernodub, R. Feldmann, E.-M.
Ilgenfritz, A.
Schiller,
"Phase
structure and gauge boson propagator in the
radially active 3D compact Abelian Higgs model",
Phys.
Rev. D 70, 074501 (2004), hep-lat/0405005
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| Conferences,
schools and workshops |
Frontiers
in Computational Astrophysics: The Origin of Stars, Planets and Galaxies
Conference, Ascona, Switzerland, July 2008 [Poster]
From Protostellar cores to
disk galaxies
Workshop, Zurich, Switzerland, September 2007 [Poster]
Dynamics of galaxies
Conference, St. Petersburg, Russia, August 2007
[Poster]
Helmholtz
Summerschool in Supercomputational Cosmology
School, AIP Potsdam, Germany, July 2006
Evolution of galaxies and their large-scale environment
School, Bad Honnef, Germany, July 2006
Galaxies
and Structures through Cosmic Time
Conference,
Venice, Italy, March 2006 [Poster]
Leilat04 - Lattice field theory: Present Results and Future Perspectives
Workshop, Leipzig, Germany, June 2004
[Talk]
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Collaborators
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| Links |
Much of
my numerical work is performed on the ETH Linux cluster Brutus
(formerly Gonzales). You can find
more information on our Group Brutus page.
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About
us 
