The relation between star formation and ram pressure in jellyfish galaxies

Lunch Colloquium
Ms. Iveth Gaspar-Gorostieta
SCHEDULED
Instituto de Radioastronomia y Astrofisica (IRyA, UNAM)

I will present the analysis of the stellar population properties in a sample of the so-called jellyfish galaxies observed with MUSE@VLT in the frame of the GASP project. These galaxies take their name from the morphological resemblance to jellyfishes, displaying long tails of gas and newly born stars provoked by the interaction, via ram pressure stripping, between the hot intracluster medium and the gas with the galaxy itself. According to numerical simulations, ram pressure has a double effect: firstly, by compressing the gas within the galaxy, it might provoque an enhancement of the star formation activity, which can lead to an increment in the star formation rate within the galactic disk by up to a factor of 3-5. Later on in the interaction, ram pressure will push the gas that was once inside the galactic disk away, creating long (up to ~80 kpc) tails where star formation can occur. The aim of my work is to study the relation between the “enhanced” star formation activity, and the properties of both the galaxy (stellar mass, morphology, gas content, position within the cluster, velocity) and the cluster it is accreting onto.

The Global Star Formation Laws in Galaxies

Special Colloquium
Prof. Yu Gao
SCHEDULED
Purple Mountain Observatory

The dense molecular gas mass, traced by HCN J = 1-0, correlates linearly with the far-infrared (FIR) luminosity (star formation rate, SFR) for essentially all star-forming systems near and far. The spatially resolved FIR-HCN correlation in the disks of spiral galaxies, a local star formation law in terms of dense molecular gas across the spiral disks, appears also to be linear and is essentially the same as that established globally from the Galactic dense molecular cloud cores and the galaxies. And this linear correlation is valid for all other dense molecular gas tracers, e.g., CS, HCO+ and high-J CO. Such linear correlations suggest that the SFR depends linearly upon the mass of dense molecular gas. This is drastically different from the traditionally established Kennicutt-Schmidt (K-S) laws that relate the total gas to SFR in galaxies since there is no unique correlation in these K-S laws. Finally, we introduce the first results of the MALATANG large program on the JCMT to map the HCN and HCO+ J = 4 - 3 line emission in 20 nearest and FIR-brightest galaxies. MALATANG bridges the gap, in terms of physical scale and luminosity, between extragalactic (i.e., galaxy-integrated) and Galactic (i.e., giant molecular clouds) observations, showing again such linear correlation in FIR - high-J HCN/HCO+ emission.

MHD disks and jets - simulations of the accretion-ejection structure

Main Colloquium
Dr. Christian Fendt
SCHEDULED
MPIA Heidelberg

I will present recent MHD simulations investigating the launching of astrophysical jets. The simulations treat the time-dependent evolution of the accretion-ejection structure and the subsequent collimation of the disk wind into a high-velocity jet. I will discuss simulations considering (i) a mean-field accretion disk dynamo and the launching of outflows by a self-generated disk magnetic field, (ii) a general interrelation between the disk magnetization and the jet dynamics, and (iii) relativistic jet launching.

TBD

Special Colloquium
Prof. Yashwant Gupta
SCHEDULED
National Centre for Radio Astrophysics, India

TBD