IAU2006

When do galaxies merge? The merger fraction does evolve lowly up to z=1.2 but at around 2-3, 50% of all high-mass systems are mergers. The small ones again have only slightly higer merging rate. So at z=1 most of the high-mass objects were in place.

Using the same methodology to find mergers on numerically simulated data (with C. Mihos), they derive absolute merger rates (per volume) and a sharp drop after z=1 is found for all masses. A typical massive elliptical galaxy (today) will have undergone 3-5 major mergers since z=3.

A significant fraction (maybe the majority) of SF at z

By looking at the Hubble Ultra Deep Field (UDF), one can classify galaxies by how they look. The number of clumpy and irregular looking galaxies increases as one looks at further and further distances. Disk galaxies seem to disappear at a certain redshift and only thick disks are found.

Clumpy galaxies seem to be more frequent at high z and it is basically the large star forming regions that are seen there. These clumps should dissolve and could build up a normal spirals. Indeed the “clump clusters” share several properties, altough they are less massive. The scale height of “clump chains” is found to be 1kpc, which could be connected to forming a thick disk.

A usual problem here is that one looks with a fixed set of filters (opitcal in this case), but due to the redshift, one looks at different wavelenths inside the galaxy. In this case, one admittedly only sees the regions that actively form stars and a much smoother underlying population of older stars would not be seen.

Thousands of UV-selected galaxies at z>1.5 with spectroscopic confirmation from Keck. 25% contain AGN. From clustering length (4 Mpc) the DM halo mass is derived to roughly 10^11.5-12 solar masses and these objects are presumably the progenitors of nowadays ellipticals (by following halo-evolution in simulations).

The highest X-ray detected cluster is at z=1.45. The speaker and collaborators find protoclusters at z>2 also from UV and measure/find the overdenities (factor 7) in a redshift subslice. The galaxies there have double stellar mass than the ones outside the cluster. They find the morphologies not to fall on the Hubble sequence, but I wonder if they took into account that even normal galaxies look very different in different wavelenth, especially in rest-frame UV which the HST images were made in, if I got it right.

Quasars are not found at very high redshift. The record holder has been at z=6.4 for quite an amount of time and at this redshift, the universe was about 870 Myr old.

A fun fact with redshifts is that you observe different wavelengths in objects when use use a certain wavelenth for observations. Because there is a large peak of emission from dust in the mid- and far-infrared, this gets shifted into the mm-rane at high redshifts and thereby, an object that is much further away may not appear fainter than a closer one at all.

Molecular emission has been detected to redshifts over 6 as well and of course only the highest concentrations can be detected at these large distances. One can get hold of the ionisations state of the IGM via the proximity effect, which presumably is due to a large ionised sphere (formation time=10^7 yr * neutral gas fraction) and lets emission a little blueward of the lyman-limit at the quasars redshift escape.

How quickly does the gas that is heated by the SSC cool? The larger the cluster the more radiative cooling (I did not understand why) and eventually there is a regime of “catastrophic cooling” where no equilibrium solution exists any more.

Studies in M82 which blows a huge bipolar wind perpendicular to the disk (pretty picture) show that …. I missed it because I fetched the link to the picture.

Im sitting in S237 and someone just tries to motivate people to go the big hall during coffee break to take a picture of the S237 attendants in from of a bis IAU logo.

This will never work.
Coffee breaks are sacred to people.

There is a whole schedule of social events that are organized around the meeting, mainly it’s sightseeing. I do not know when people find the time for this, but I would guess the ones during the week-end are the most popular.

I don’t think, I’ll join one of these and I am not even sure if I will make it to the concert on Friday evening since I have to move to a new place. You might have heard of the Hospitality Club, anyway, that’s how I’m going to stay over the week-end before I fly back home on Monday.

I somehow doubt that someone will show up and take over this blog to report from the second half of the meeting next week, so I think this blog will close already tomorrow…