We aim to promote and encourage an active seminar series for the benefit of all centre members.
We welcome all visiting astronomers to Sydney to come and give us a Seminar and are especially keen for any overseas visitors to give us a talk.
Overnight accommodation can be provided if necessary.
Please contact Jan Staff our seminar organiser (firstname.lastname@example.org) for further information and assistance.
The Seminars usually take place at 3pm in room E6B 2.300, which is located on the second floor of the E6B building. It is a quick walk from the Macquarie University train station and the location of the building can be found using the campus map.
This week’s Seminar
December 12, 2014
Speaker: Michael Cowley
Title: A multi-wavelength study of the impact of AGN on their host galaxies
Abstract: An active galactic nucleus, or AGN, refers to the existence of energetic phenomena at the central region of galaxies, which cannot be attributed directly to stellar emission alone. Extensive local surveys in the radio, infrared and X-ray domains have revealed a substantial population of these active galaxies, which are now known to be powered by the accretion processes of supermassive black holes. This raises the question if the enormous amounts of energy liberated by accretion has any impact on host galaxies. In light of this, many galaxy evolution models now incorporate AGN processes and have been successful in reproducing key observables for the co-evolution of AGN and galaxies. However, a reoccurring suggestion that AGNs play a role in the quenching of star formation in blue disk-like galaxies and their transition to red-dead ellipticals, remains a topic of hot debate.
In an effort to help address this, we cross-match our near-infrared ZFOURGE catalogues with radio, x-ray and far-infrared sources to perform a multi-wavelength identification and investigation into the impact of AGNs on their host galaxies out to a redshift of z = 3.2. We compare the host galaxy properties (stellar populations, colours and morphology) of our AGN to those of a mass-similar sample of non-active hosts. In this talk, I will summarise my approach and present preliminary findings of the study.
Speaker: Danica Draskovic
Title: Multi-wavelength Quest for New Planetary Nebulae in the Small Magellanic Cloud and its Outskirts
Abstract: Planetary Nebulae (PNe) represents one of the final evolutionary stages of low- and intermediate-mass stars, lasting for just 25000 to 50000 years. Most stars from 1 to 8 solar masses will at some point go through the PN phase. However, the brevity of this phase limits the number of PNe visible at any one time, and there are currently ~3500 known in the Galaxy. The story with a local group galaxies is quite similar: ~800 in the Large Magellanic Cloud, ~80 in the Small Magellanic Cloud, and only 4 confirmed PN in the nearby Sagittarius dwarf galaxy, where numbers scale with size and mass. Studies of PNe in the local group galaxies are of huge importance because of the different host environments and metallicities that can shed light on the different galactic evolutionary processes in these systems.
PNe play a crucial role in understanding mass loss for low to intermediate mass stars and the chemical evolution of galaxies due to interstellar medium (ISM) enrichment via PNe ejecta. Their ionized shells exhibit numerous emission lines – excellent laboratories for understanding plasma physics. PNe are visible to great distances due to these strong lines that permit determination of the size, expansion velocity and age. The significance in studying PNe in local-group galaxies is that they are still sufficiently close to be amenable to individual scrutiny. In this project we concentrate on the SMC PNe population that are effectively co-located in a coherent and separate system at known distance. Furthermore, the SMC is sufficiently small in angular size and can be studied in its entirety.