ESO Greatest Hits

The H Index

Rank papers by citations. H is the paper for which numberof citations equals the rank. H increases with time.

Some Statistics

Year La SillaVLT

Papers

2001 324 (18) 103 (40)

2002 291 (19) 161 (32)

2003 314 (17) 260 (29)

2004 326 (13) 340 (23)

2005 275 (6) 356 (10)

2006 (*) 246 370 (**)

(*) Until December 12. (**) Apex: 21; archive: 61

La Silla Statistics

Mean statistics

CES 28 0.13EFOSC 135 0.20EMMI 209 0.24FEROS 189 0.25HARPS 22 0.06SOFI 239 0.21SUSI 48 0.22TIMMI2 53 0.14WFI 146 0.10

Paranal statistics

Mean statisticsAMBER 2 0.15FLAMES 48 0.12FORS1 477 0.42FORS2 297 0.32ISAAC 364 0.26MIDI 15 0.22NACO 92 0.16SINFONI 10 0.08UVES 449 0.34VISIR 5 0.01VMOS 30 0.28

Science Highlights 2006 Science Highlights 2006 (326 April - September papers)(326 April - September papers)

Themes

The Primordial Lithium Abundance

Lithium Isotopic Abundances in Metal-Poor Halos StarsAsplund et al. Ap.J. (June 10 - UVES)

First stars VII. Lithium in extremely metal poor dwarfsBonifacio et al. astro-ph (October 9 - UVES)

A probable stellar solution to the cosmological lithium discrepancyKorn et al. Nature (August 10 - FLAMES+UVES)

The Mass Assembly of Galaxies

3D spectroscopy with VLT/Giraffe. I. The true Tully-Fisher relationshif at z0.6Flores et al. A&A (June - GIRAFFE)

SINFONI Integral Field Spectroscopy of z2 UV-Selected Galaxies: Rotation Curves and Dynamical EvolutionFoerster Scheriber et al Ap.J. (July 10 - SINFONI)

The rapid formation of a large rotating disk galaxy three biliion years after the Big Bang. - Genzel et al. Nature, (August 17 - SINFONI)

The VIMOS VLT Deep Survey: Evolution of the luminosity functions by galaxy type up to z=1.5 from first epoch data.Zucca et al. A&A (September; VIMOS)

Themes

The Galactic Center

The Two Young Star Disks in the Central Parsec of The Galaxy: Properties, Dynamics, and Formation. - Paumard et al. Ap.J., (June 1 - SINFONI)

Variations in the Spectral Slope of Sagittarius A* during a Near-Infrared FlareGillessen et al. Ap. J., (April 1 - NACO)

Clockwise Stellar Disk and the Dark Mass in the Galactic CenterBeloborodov et al. Ap.J. (Septermber 1)

The flare activity of Sagittarius A* - Eckart et al. A&A, (April - NACO)

Polarimetry of near-infrared flares from Sagittarius A*Eckart et al. A&A. (May - NACO)

K-band polarimatry of an Sgr A* flare with a clear sub-flare activityMeter et al. A&A (astro-ph/0610147 - NACO)

Near-infradrd polarimetry setting constraints on the orbiting spot model for Sgr A* flares. - Meyer et al. A&A (astro-ph/0610104 - NACO)

Cosmic Variation of the Fundamental Constants of Physics

Indication of a Cosmological Variation of the Proton-Electron Mass Ratio Based on Laboratory Measurement and Reanalysis of H2 Spectra Reinhold et al. Phys. Rev. Letters, (April 21 - UVES)

Most precise redshift bound to /. - Levshakov et al. A&A, (April - UVES)

Variation of the fine-structure constant: very high resolution spectrum of QSO HE 0515-4414. - Chand et al. A&A, (May - UVES)

Themes

The GRB - Supernova connection

Supernova 2006aj and the associated X-ray Flash 060218Sollerman et al (A&A 454) The assicuation of GRB060218 with a supernova and the evolution of the shockwave - Campana et al (Nature, August 31)

Optical observations of GRB 060218/SN 2006aj and its host galaxyFerrero et al. (astro-ph)

The GRB 060218/SN 2006aj event in the context of other gamma-ray burst supernovae - Ferrero et al. (A&A, 457)

Extrasolar Planets

An extrasolar planetary system with three Neptune-mass planetsLovis et al. Nature, (May 18 - HARPS)

Abundance ratios of volatile vs. refractory elements in planet-harbouring stars: hints of pollution? - Ecuvillon et al. A&A, (April - CORALIE+FEROS)

Abundaces of refractory elements in the atmospheres of stars with extrasolar planets - Gilli et al. A&A, (449 - FEROS+UVES+other)

Discovery of a Young Planetary-Mass BinaryJayawardhana & Ivanov Science, (September 1 - FORS2+ISAAC)

Anatomy of a Flaring Proto-Planetary Disk Around a Young Intermetiate-Mass StarLagage et al. ScienceExpress, (September 28 - VISIR)

Primordial Lithium Abundance

Asplund et al. (ApJ)

Korn et al. (Nature)

Primordial Lithium Abundance

Bonifacio et al. (A&A preprint)Model: Richard, Michaud & Richer (2005)

Conclusions

The gap between the Spite plateau and the Big-Bang Nucleosynthesis model predictions is still a challenge both observationally and theoretically.

Pre-galactic production of both Li(6) and Li(7) through the decay of a massive primordial particle, such as the Gravitino, remains one of the most attractive candidates.

Diffusive depletion of surface Li can explain the (7)Li gap, but may be in conflict with the photometric temperature scale. Determination of Teff to 50K is required. Interesting challenge for the VLTI?

The Mass Assembly of Galaxies

Flores et al. (A&A)

The Mass Assembly of Galaxies

Flores et al. (A&A): GTO program with FLAMES IFUs

The Mass Assembly of Galaxies

Weiner et al. (astro-ph/0609091): 1000 Galaxies to z=1.2 with Keck

UV-selected galaxies at z>2

Foerster Schreiber et al. (ApJ): SINFONI

SummarySpecific angular momentum consistent with that of late-type galaxies in the local universe.

Disks are thick and have v/ ratios about 10 times lower than local disk galaxies.

BzK-15504: A large protodisk galaxy at z=2.4?

Genzel et al. (Nature): SINFONI

A large protodisk galaxy at z=2.4

Summary

The strong deviations (a-c) from a simple rotation pattern indicate a (70-100km/s) radial component.

A large, massive protodisk is channelling gas towards a growing bulge hosting an accreting massive BH.

Star formation in the disk with no evidence for a major merger

Conclusions

• Integral-Field spectrographs such as FLAMES, VMOS, and SINFONIare already having a large impact on understanding the mass-assembly of galaxies in the Universe

• The T-F relation seems to develop already at redshifts z>2, although it is still not clear whether rotation of z=2 galaxies is due to mergers or to disks. The case of BzK-15594 observed with SINFONI in AO mode indicates the rapid formation of rotating stellar disk possibly followed by the formation of a Bulge from disk instabilities.

• The evolution of the Tully-Fisher relation since z=1.2 is still controversial and much larger samples of IFU data would be required to understand the impact of photometric miss-alignments in the existing slit data.

The Center of our Galaxy

There is a cluster of B stars in the central 1’’ of the galaxy, the so-called S-cluster. These high proper motion stars - in particular star S2 - show that Sgr A* is a black-hole of 3-4 million solar masses.

Large numbers of young stars, in particular O supergiants and WR stars are observed within 20’’ of the black-hole.

Surprinsingly, therefore, massive star formation has occurred near or at the Galactic Center within the past few million years. The most promissing explanations for this are:

1. Stars have formed in-situ out of the fragmentation of a very dense gas disk2. The young stars come from an in-spiralling massive (M>100,000Msun) star cluster

The formation of the central S-cluster of >15 B stars in the central light month may result from a the scattering of stars from the reservoir of massive, young stars further out.

The black-hole itself is very faint at IR and is observed to flare.

The Central Cluster

Paumard et al Ap.J..

The Central Cluster

The Central Cluster

=

The northern arm

=

=

=

=

Clockwise disk

CND molecular gas

Ionized mini-spiral

Counterclockwise disk

The Central Cluster

Summary

The large majority of early type stars in the central parsec reside in one of two pretty flat (H/r=14%) rotating disks

The disks have well defined inner edges (1’’ for CWS). CCWS resembles a ring

The stellar disks are coeval within 1Myr with ages 6+/-2 Myr. They must have formed in less than 2Myr.

The total mass of these disks does not exceed 10000 Msun.

Sagittarius A*

Typical duration: 100 min4+/-2 per day

Sagittarius A*

HKL - Eckart et al. A&A

Sagittarius A*

Eckart et al A&A - NACO K-band

Sagittarius A*

Meyer et al. (a,b) A&A astro-ph

Summary

Flares of typical duration 60-100 min apear about 2-6 times per day.

The IR emission from these flares is strongly polarized (>50%)

Polarized IR emission clearly shows quasi-periodicsub-flares with a periodicity of about 20min

NIR and X-ray flares appear simultaneously to within the time resolution of observations

The observations are in agreement with a combined hot spot/ring model. Highly polarized blobs of plasma orbiting the BH close to the horizon are responsible for the 20m quasi-periodic sub-flares (implying a spin parameter a>0.5 for the BH). The flares are due to sound waves propagaring azimuthally along the ring.

Conclusions

I

The central few parsecs of the Galaxy display most of the properties observed in AGN, but at a distance of only 7.6 kpc allowing exquisitly detailed investigations of the nuclear stellar populations, the nuclear accretion disk, and the properties of the central Black-Hole.

At least part of the young massive stars at the GC appear to have formed in-situ from a dense accretion disk. The disk has a hole in the center exactly where the S-stars are found. The size of this hole (1’’) agrees well with the size of the region where star formation is not expected. The origin of the CCWS disk is not so clear, and could be due to the infall of a very dense cluster, or to in-situ star formation.

The accretion of gas onto the BH is weak and powers flares arising from blobs of plasma near the last stable orbit around the BH. The emission is well modelled by SSC processes.

Quasi-periodic flares akin to those observed in massive X-ray binaries. These sub-flares show a periodicity of about 20min and may arise from a jet.

VLT is clear leading this field.

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