Terapix Star Formation Region IC 1396, © 2002 CFHT
Minutes for the VIRMOS science meeting in Bologna 12th-13th July 2005
by HJMCC - Updated February 24th, 2006

Olivier LeFevre Bianca Garilli Paolo Franzetti Theirry Contini Laurence Tresse (from Olivier Ilbert) Olivier Ilbert Angela Iovino Micol Bolzonella Fabrice Lamareille Baptiste Menuex (from Olivier Le Fevre)

Minutes for the VIRMOS science meeting in Bologna

Present: Gianni Zamorani, Henry Joy McCracken, Micol Bolzanello, Olivier Le Fevre, Sandro Bardelli, Alessandra Zanichelli, Mario Radovich, Alberto Cappi, Angela Bongiorno, Paolo Franzetti, Theirry Contini, Bianca Garilli, Christian Marinoni, Angela Iovino, Elena Zucca, Sandro Bardelli, Marco Scodeggio, Alberto Cappi, Fabrice Lamereille

Actions from this meeting:

-  The old R-band catalogue prepared by Stephen should be forwarded to Marseille for distribution to the consortium and integration into the database (Henry)
-  The new combined VVDS-CFHTLS catalogue should be made available as soon as possible (Henry)
-  Get the complete set of models to compute masses up to z 2 (Charlot+Lamareille)
-  Produce zmin, zmax for Vmax calculation (Bolzonella, Lamareille)
-  Prepare for global mass function and mass function per type (Bolzonella, Ilbert, Pozetti)
-  Prepare for mass density plot (Bolzonella, Ilbert)
-  In parallel, start draft (Pozetti)
-  Try to parametrise the slope evolution as function of redshift and see impact on point at z 1.5 (Olivier Ilbert and Laurence Tresse)
-  Use same slope as Steidel for comparison at z 3 and z 4 (Olivier Ilbert and Laurence Tresse)
-  Can the slope alpha be parameterised as a function of redshift?

Data reduction status: Olivier Le Fevre (presentation). Current status of epoch 2 reductions.

-  There are only 10 pointings in total which are ready to be inserted in the database;

-  There are around 30 pointings which have been super-checked with seven super-check sessions;
-  25 pointings still to do, probably over five super-check sessions. Maybe all this can be finished before the end of the year?
-  Olivier suggests 16th-19th of August in Milan and 22nd-26th of August in Marseille, and Bologna in 17-22 November, 12-16 December in Marseille.

Wide data reduction status: Bianca Garilli (presentation)

-  F22 super-checked galaxies. There are 7423 super-checked galaxies in this field. (Side note: Henry points out that there is some F22R photometry which has been reduced by Stephen, and he will pass this catalogue to Vincent as soon as possible.)
-  The redshift distribution is different between the F10 and F22 fields, does this comes from the galactic extinction? Galactic extinction should be applied in a galaxy-by-galaxy basis.

Kbred/VIPGI (Bianca and Paolo Franzetti)

-  VIPGI is now public domain. Marco requests that everyone uses the latest version of the software, which has the most up-to-date list of lines. People will be supplied with also calibration-specific versions of the software which contains only the lines which are visible from any given survey.
-  Paolo and Stephane in Geneva have started work on a new version of KBRED software which will be public domain and easily modifiable. The software is still at the prototyping stage.

Upcoming observations: Thierry Contini (SIFONI): presentation

-  Theirry has four nights on SINFONI (near-infrared integral field spectroscopy) at the beginning of September. 1.5-  Objects were selected on equivalent width of OII lines and flux. Maybe we should simply observe the galaxies which are brightest in OII? Or a mass selection? Thierry will have to decide at the end of August.

Submitted proposals which are pending

-  For the high-zed galaxies, 1 mask has been observed in DDT mode in LR blue, which has not been processed yet. For the new proposal one pointing has been approved in service mode which was ranked "B".
-  However, the proposal from Gigi was completely wiped out by ESO scheduling [note added in editing: it turns out that after mails sent to ESO, 10 hours have been awarded on the 14hr field].
-  For Christian's proposal, 20 hours were requested, 11hrs awarded. How to best use the time? Olivier's suggestion: first, confirm the red sequence, then membership, and maybe velocity dispersion? How can we get a S/N 5 in 11hrs? Four or two pointings. This will be discussed further by email.
-  Olivier has sent a letter to ESO (C. Cesarsky) asking for clarification concerning how the scheduling was arranged. Olivier was present for the panel discussions at ESO and it was clear that the programs were ranked highly enough. In effect, our programs have been downgraded by the telescope scheduling staff.

Upcoming SOFI observations (Marco and Angela):

-  The idea is to make a shallower depth, larger area and to favour the brighter part of the spectroscopic sample where the colour bias is minimal.
-  This would enlarge the sample to around 4000 objects. If the current depth is maintained, we can get around 1.5 times the current depth. For a shallower survey to K 20 we can cover four times the area, and get K photometry for a lots of objects which have spectroscopic redshifts.

Future proposals (Olivier)

-  Olivier's experience at the OPC seems to indicate that large programs have a better chance of being approved as there is a large block of time already reserved and the pressure on large programs is smaller.
-  For the next set of proposals perhaps it is better to go back applying for single large programs. Some discussion about whether or not to apply in visitor or service mode. There is pressure from other groups to observe the F02 field (XMM/LSS and SWIRE).
-  One suggestion is to make LARGE program on the wide (F22/F14) and then two other smaller programs to add more data in the F02 field. Probably at least the SWIRE team can be co-opted.
-  Christian argues that the sampling rate should be increased in the centre of the F02 field.
-  OLF will try to find out from the OPC what the current status of large proposals is.

Future science directions for the VVDS

-  What the competition is doing: based on talks OLF saw at Ringberg: DEEP2 have a large spectroscopic sample and our most direct competitors.
-  There are also many groups doing rapid analysis with photometric redshifts. There is also the GMASS survey which is a sample limited at K 21.
-  Luminosity density and mass function
-  High redshift galaxies: it seems that the population we have is a mix of all types of galaxies

Lunch Break

Science Presentations

Stellar mass functions (Micol; (presentation).

-  Actions from telecon include computing all masses for all objects taking into account complex SFHs and including models with secondary bursts;
-  There are three methods: purely photometric (Lucia and Micol); Photometry and spectroscopy (Paolo and Marco); and Fabrice and Schedule distributed by Olivier before the meeting;
-  Comparisons made between masses computed by Fabrice and Micol: there is some systematic offset;
-  Using the two component dust model you get a very good agreement with masses computed by Fabrice; simulated catalogues seem to back up this;
-  Apparently also the secondary bursts have less importance;
-  Mass function plots shown by Micol;
-  Some questions from Gianni: should we stop when you are complete in mass and not luminosity? Of course this limits the number of galaxies a lot.
-  Mass function by spectral type: this is a very important point which needs to be investigated.
-  Can we use the SWIRE data?

-  Olivier insists that Lucia starts writing and that a draft should be circulated by the end of July.

-  One other interesting plot to make is the 'mass density' which shows the evolution of mass as a function of cosmic time.

High redshift galaxies: Olivier

-  Some discussion about what the objects are outside the UGR lyman-break selection box;
-  It seems that the numbers of these objects outside the box is equivalent to the number of BZK objects;
-  It could be that the vvds high redshift population is the 'missing link' between the different populations (UGR selected and BZK).
-  It would be interesting as well to stack the X-ray data around these objects to get an upper limit on their x-ray flux.

Mass functions: Fabrice Lamereille
-  Quality check of the measurements with platefit;
-  OLF points out that around half the spectra have not been cleaned;
-  It's not clear that all the cleaned spectra made their way into the database: this point should be checked;
-  Some discussion about what the priority in the catalogues should
-  be, and what parameters should be included;
-  OLF asks what the principal results from this work will be: Theirry suggests a study of the Mass / metallicity relation, which doesn't exist in the literature.

Luminosity density: Olivier Ilbert for Laurence Tresse (presentation)

-  The luminosity density shows a decline at z 1, but this last point is strongly dependent on assumed slope for the luminosity function which unfortunately cannot be determined directly from our data because we don't go deep enough;
-  At z 3 there seems to be a decrease in the luminosity density;
-  The key difficulty seems to be measuring the luminosity function slope at faintmagnitudes to get the integrated luminosity density.

Luminosity function as a function of environment: Olivier Ilbert (presentation).
-  Two classes have been defined: objects in under-dense regions and over-dense regions;
-  Cumulative distribution of objects and shows that brighter objects are in over-dense regions;
-  Bluer objects are present in over-dense region;
-  Global LF also shown as function of environment;
-  LF shown as a function of environment and type. The same trend is visible for the two types;
-  To do list: add CFHTLS data, try with CDF, maybe add second F02 epoch data? OLF strongly suggests that we stick with existing data;
-  Some plots shown by Croton et al (2DF) and Tully et al. The 2DF results seem to be the reverse of what we find.

Other matters: comparisons with deep2: Olivier Ilbert (presentation)

-  Plots showing comparison with DEEP2 with the VVDS paper from Faber et al.
-  It's not clear how Faber et al got our points: they were not published anywhere, although do seem to be consistent with the points we published.
-  However, the COMBO-17 points are different from the points in the literature.

Other matters: Colour-morphology-density relation: Angela Iovino (presentation)

-  Objects selected with (U-R) < 1.0 and (U-R)>2.0;
-  redshift range was 0.1-  Fraction of objects as a function as a function of over-density in 4h^-1MPC gaussian scales.
-  Fraction of blue objects decreases in over dense regions.

(VVDS Dinner in an excellent restaurant in Altedo 25 km from Bologna!)

Day 2: Wednesday Jul 13 2005 XMM-VVDS: Dario Maccagni (no presentation)
-  New catalogue of cross-matched sources with XMM-LSS sources has been loaded into the Milano database;
-  Some work is being done on stacking the high-redshift sources;
-  Only two or three X-ray sources have no optical counterpart;
-  Olivier suggests producing combined X-ray / radio postage stamps to investigate various galaxy populations, for example the population z 3.

OLF: Reddest galaxies in the VVDS (presentation)
-  Take the reddest galaxies in VVDS in several redshift bins and stack the spectra to see if you can say anything about the stellar populations;
-  Average of around 10-15 galaxies in redshift range 0.7;
-  Try to fit with B/C model;
-  Fit looks pretty good, in fact the s/n on the stacked spectra is higher than the s/n of the the model (need to use better models!).

Bimodality: Paolo Franzetti (presentation)
-  Plots have been re-done with U-V colour which is easier to compare with the literature;
-  Nice plot shown the evolution of colours for high and low luminosity galaxies as a function of redshift;
-  Colour-magnitude diagram shown in U-V vs V space which seems less "bimodal" than before. Is this an artifact of template fitting?
-  Discussion follows in which OLF insists that any paper must provide quantitative arguments and either extend or refute papers such as those of Bell et al. What's really new in our results?

Galaxy clustering by type: Olivier Le Fevre (for Baptiste) (presentation)

-  Galaxies have been divided into types 1,2, 3 and 4. The combined type 1+2 and 3+4 have a very different clustering amplitudes;
-  The clustering amplitude by type as a function of redshift shown: early and late types have different clustering amplitudes;
-  One important question is to disentangle the effects of type and absolute magnitude on clustering amplitude;
-  Could we see what the clustering amplitudes are in the plane of absolute magnitude / type / redshift?
-  Baptiste is currently working a draft of a paper describing these results;
-  Agnieska is moving to Marseille for an GALEX post-doc but may be able to continue to work on this topic;

Galaxy clustering statistics and CFHTLS-VVDS match: Henry Joy McCracken (presentation)

-  VVDS photometry re-extracted using cfh12k images re-swarped onto the CFHTLS data: this produces a NEW photometric catalogue with ugrizBVRI;
-  Some plots showing the difference in projected clustering amplitude over the four fields of the CFHTLS;
-  It seems the field-to-field variance is very high, maybe higher than you would expect: around a factor of 3.5 over the four fields;
-  Is the VVDS-F02 field representative? We need some robust estimates of how cosmic variance varies as a function of size.

AGNs : Angela Bongiorno (presentation)
-  74 deep and 57 AGN in the wide;
-  AGN counts shown which agree well with CFRS and COMBO-17;
-  Morphological and AGN colour selection plot shown;
-  If we had used the 2df selection function we would be around 45% incomplete.
-  Faint end of the AGN luminosity function computed from the wide and deep surveys;
-  Templates used from LBQS and FBQS;
-  Comparisons shown with 2DF and Combo-17;
-  The data is in better agreement with the steep luminosity function from Boyle et al (and not the shallower slope found from Croom et al using half of the full 2df quasar sample);
-  Also comparison shown with quasars measured with the 2DF but selected using the SDSS;
-  Luminosity and density evolution shown using fixed alpha and M*;
-  The evolution of the LF seen in our data is better described by combined luminosity and density evolution (it's not just pure luminosity evolution).
-  Comparison with the Barger et al X-ray LF and this optical LF;
-  Gianni comments that is slightly annoying to publish the first papers without the FORS1 data, which would help a lot with the objects with uncertain redshifts.

New photometric redshifts: Olivier Ilbert
-  Offsets calculated between the fields;
-  New templates computed based on the new ugrizBVRI catalogue at 21.5
-  Adaptive correction applied;
-  Using the new data between 3.5 and 4.5 the agreement with the spectroscopic redshifts is very good for the first time, probably because of the new super-deep u* data;
-  There seems to be no systematic in the photometric redshifts;
-  At high redshift bins we see the can see that the zphots are incomplete;
-  0.2 and 1.0 very secure;
-  Classification between stars and galaxies shows;
-  Redshift distributions;
-  List of what to do: add J,K, maybe swire
-  Don't use the zphot at z<0.2 and 1.5

(Lunch break)

Other matters

-  SWIRE data is now available on the VVDS database. It is also possible to retrieve unmatched swire objects. Projects in luminosity function selected at 3.6u and 24u underway.

Current status of papers: Olivier Le Fevre (presentation)

-  What to do with Christian's paper that was rejected from Nature? One suggestion is to resubmit the article (in an essentially unchanged fashion) to Science.
-  17 papers are accepted
-  List of papers in preparation and submitted was updated.
-  A list of 8 high priority papers for September has been established.

End of meeting at 15.00

The next (10th anniversary!) virmos science meeting 6th-7th October on the island of Porquerolles (availability to be confirmed).

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