Compact massive spheroids in the local Universe

TBD



Zoom info:

Hi there,

Karl Glazebrook is inviting you to a scheduled Zoom meeting.

Time: Jul 14, 2020 10:30 AM Australia/Melbourne
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TBA

Most of the stars in the Universe are not single like our Sun but in binary stars systems. A binary star is composed of two stars in orbit around each other, as they age they can "get-in-each-others" way and experience very different evolution to that our stars like our Sun. Only over the last decade it has become clear that to accurately understand the Universe we need to take account of these interacting binary stars. In my talk I will go over a few examples showing how understanding binary stars allows us to understand the appearance of galaxies, the diversity of supernovae, the production of the most abundant and rarest elements and the production of gravitational wave transients.

TBA

TBA

The evolution of galaxies is driven by complex physical mechanisms that may have internal or environmental origins. As time passes galaxies become less star-forming and tend to acquire elliptical or lenticular morphologies. We have embarked in a simultaneous study of morphology and star formation in cluster and field galaxies with the aim of investigating the relationships between star-formation quenching and morphological transformations as a function of environment. In this talk I shall present the results of a study conducted on galaxies in the CLASH and CANDELS surveys at redshifts 0.2 < z < 0.9. By dividing galaxies into star-forming and quiescent we find that quiescent ellipticals are more abundant in clusters than in the field. Regardless of the environment, we observe an increase in the fraction of quiescent disc galaxies at low redshifts, supporting the notion that star-formation quenching precedes morphological changes, at least at low stellar masses. Star-forming field galaxies are mostly late type discs, while in clusters they present a diverse morphological composition with a non-negligible fraction of star-forming ellipticals that is detected in low-redshift clusters. I will discuss the implications of our results in the general context of galaxy evolution.

Confirmation of Candidature review for Geray Karademir.
Zoom password: 137484

October 2018 marked the beginning of a new large program at the Canada-France-Hawaii Telescope: SIGNALS, the Star-formation, Ionized Gas, and Nebular Abundances Legacy Survey. During the next four years and with 55 nights of telescope time in hands, our collaboration is observing more than 50,000 extragalactic HII regions located in different galactic environments using the Imaging Fourier Transform Spectrograph, SITELLE. In order to build such a sample, we cover 40 galaxies that are actively forming stars within a distance of 10 Mpc. SITELLE, with its FOV of 11 arcminutes and its 4 million spaxels, is the perfect instrument to survey these often extended objets. We are gathering spectral information over the strong emission lines of the visible (i.e. [OII]3727, Hbeta4861, [OIII]4959,5007, [NII]6548,6583, Halpha6563, HeI6678, [SII]6716,6731) with a spectral resolution of 5000 (on Halpha) at a mean spatial resolution of 15 parsecs. Along with ancestry data in the IR and UV, our collaboration aims at studying resolved star-formation activity, understanding the impact of the local environment on the star-formation process, and providing the science community with a unique dataset along with new tools to study star formation. During this presentation, I will introduce this ambitious project and will show some preliminary results from the M33 data and other galaxies.

Forming new generations of stars in galaxies critically depends on gas flows that can both fuel and deprive galaxies of their precious gas supply. Fresh cold gas must flow in to form new stars, while the explosive deaths of stars and supermassive black holes eject cold and hot gas into a galaxy’s surroundings. All of this is compounded by the fact that galaxies do not live in isolation; they form a veritable ecosystem, exchanging matter and energy, which dramatically impacts the evolution of galaxies therein. I will present observations of gaseous galaxy environments on both small and large scales that reveal this evolution in action, from dwarf galaxies to galaxy groups and clusters to the Cosmic Web. In the immediate vicinity of galaxies, the gaseous halo, or circumgalactic medium (CGM), serves as both a gas reservoir and mediator of all interactions between galaxies and their environments. On the largest scales, the intergalactic medium (IGM) filling the Cosmic Web is the Universe’s storehouse of gas that can feed the CGM and galaxies themselves. With even a little help from slime mold, I will show how we are beginning to reveal how galaxies, their CGM, and the IGM are intimately connected to the Cosmic Web and evolve within their ecosystem context.

Energy and momentum from massive stars drives gas out of galaxies, regulating galaxy growth and cosmic evolution. Perhaps as important, ionizing photons from massive stars generate nebular emission lines and heat dust, which observationally diagnose the physical conditions of galaxies throughout cosmic time. These observations have shed light on the formation and evolution of galaxies, but they are founded upon the ability to determine the properties of the underlying massive star populations. Here, I present a far-ultraviolet stellar population synthesis analysis of 61 star-forming galaxies, both in the local Universe and at redshift 2. I fit their observed far-ultraviolet stellar continua with fully theoretical stellar continuum models to estimate the metallicities, ages, and star formation histories of the massive star populations. These fits predict the production of ionizing photons, which strongly varies from galaxy-to-galaxy. I will discuss the underlying stellar astrophysics that drives these fits and their relation to the inferred stellar properties. I conclude by discussing how the assumed star formation histories, stellar atmospheres, and stellar evolution models impact the production of ionizing photons and explore how certain we can constrain the production of ionizing photons.

The Laser Interferometer Gravitational-Wave Observatory (LIGO) has now reported numerous detections of transient gravitational-wave events from systems of merging binary black holes or neutron stars. However, many more potential gravitational-wave sources exist. In addition to looking for transient signals, there are a number of searches for persistent, quasi-monochromatic gravitational-wave emission from rapidly rotating neutron stars. Young supernova remnants containing neutron stars are a particularly promising source of these continuous gravitational waves. In this talk I will go over sources of continuous gravitational wave emission, outline current search methods and challenges, then present the results of a recent search for gravitational waves targeting twelve young supernova remnants.

Mid-term review

The correlation between stellar mass and metal abundance (or MZR, the mass-metallicity relation) reflects the balance between galactic feedback and galactic gravitational potential. We present stellar MZRs based on the stellar metallicities of individual quiescent galaxies in the Cl0024 and MS0451 galaxy cluster at redshifts 0.4 and 0.54 respectively. The measurements were made via full-spectrum stellar population synthesis models. The lower limit of our stellar mass range is log[M/Msun]=9.7. To our knowledge, this is the lowest galaxy mass at which individual stellar metallicity has been measured beyond the local universe. We detect an evolution of the stellar MZR with observed redshift when the metal is iron (Fe). We do not detect any significant evolution with observed redshift when the metal is Magnesium (Mg). We use a simple analytic chemical evolution model to constrain average outflow that these galaxies experience over their lifetime, via the calculation of mass-loading factor. We find that the average mass-loading factor is a power-law function of galaxy stellar mass. The measured mass-loading factors are consistent with the results of other observational methods for outflow measurements and with the predictions where outflow is caused by star formation feedback in turbulent disks.

The first stars and galaxies initiated the epoch of reionization (EoR) and provided the seeds from which all galaxy evolution grew. Knowledge of the properties of these galaxies are needed to understand ionizing photon production and escape, and will provide the crucial missing link needed to weave a coherent picture of galaxy evolution. I will present several programs that are establishing the needed framework to interpret galaxies from z~0‒10, bridging the present-day and early universe. These programs use multi-wavelength spectroscopy to disentangle the spectral signatures that characterize the interplay between massive stars and their surroundings, and allow us to interpret how radiative processes shape galaxies. I will show how precise measures of the stellar and nebular properties of both nearby and distant lensed galaxies directly link the ionizing stellar populations with the baryon+metal feedback cycle and the conditions of ionizing photon production and escape. My studies provide a detailed foundation of the diversity of local star-forming galaxies with which to interpret cosmic evolution, as well as unique laboratories of nearly pristine gas in which to test conditions analogous to the first galaxies. In preparation for the coming UV window onto the early universe with the advent of the James Webb Space Telescope and the extremely large telescopes, I will introduce the COS Legacy Archival Spectroscopic SurveY (CLASSY) - an upcoming large Hubble Space Telescope program that will produce the first high-resolution UV spectral atlas of star-forming galaxies. CLASSY will calibrate new tools that will allow us to completely describe the stars and interstellar medium in galaxies across redshift, setting the stage to study cosmic origins, ionizing production, and the evolution of galaxies in a unified framework.

Time: Apr 7, 2020 10:30 AM Canberra, Melbourne, Sydney

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How does the Ancient Music of the Spheres sounds under the conditions of Astrophysics of the 21th century? The Heaven’s Carousel presented from 20 March – 6 April in occasion of the World Science Festival and Curiocity Brisbane gives a contemporary answer. The kinetic artwork was developed by Tim Otto Roth in collaboration with Hubble Space Telescope. The 36 illuminated speakers rotating over the heads of the audience create a giant sound accelerator playing with the Doppler Effect and echoing the accelerated expansion of the universe as Adam Riess pointed out at the premiere 2014 in Rome.

Tim Otto Roth will speak not only as artist about his numerous astrophysical collaborations, but in his double role as art and science historian he will talk also about the strong tie between colour observation of the celestial spheres and the birth of astrophysics in the 19th century.
The highly sophisticated concept of colour in astrophysics inspired by colorimetric observations and the spectroscopic decomposition of starlight is complementary to the colour experiments of (Neo-)Impressionism emerging at about the same time. As immediate physical effect spectra challenge our concepts of image and visualization, so spectra in astronomy are at least as unsettling as the colourful explorations by the French painters.

Tim Otto Roth (*1974) is a German conceptual artist, composer and scholar. He is known and awarded for his large art & science projects in public space including scientists of top research institutions around the world, as ESO, CERN (Geneva) or IceCube in Antarctica. He considers his work as a plea for a physics of art. As art and science historian he published in 2015 the definite book »Cultural History of Shadow Pictures« (Fink).

Online via Zoom:
https://swinburne.zoom.us/j/238629203

Panel member; zoom link booked for 2 hours.

At this stage, Geoff plans to use the AR Tearoom to deliver his talk

Mohsen will give his CoC review on Millisecond pulsar timing with Parkes and MeerKAT.

Zoom link: Hi there,

Matthew Bailes is inviting you to a scheduled Zoom meeting.

Time: Mar 19, 2020 02:00 PM Canberra, Melbourne, Sydney
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Meeting ID: 671 742 743
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Meeting ID: 671 742 743

Time: Mar 17, 2020 10:00 AM Canberra, Melbourne, Sydney
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Meeting ID: 515 150 872

In this talk I will summarise recent results of the dependence of the galaxy stellar-to-halo mass relation on galaxy morphology. I use data from the Sloan Digital Sky Survey DR7 with morphological classifications from Galaxy Zoo, and also compare with the EAGLE cosmological simulation, to draw a coherent physical picture of the different evolutionary paths of discs and ellipticals. I will also explore possible scenarios of galaxies undergoing morphological transformation and quenching. To finalise I will discuss the limitations of current simulations such as EAGLE, and introduce the ongoing simulation project of EAGLE-2.

Sara's mid-candidature review

Dwarf galaxies with stellar masses of 10^9 Msun can be explored at high and low redshifts and they give a glimpse of the different conditions of galaxy formation at different epochs. Using a large sample of about 300 zoom-in cosmological hydrodynamical simulations of galaxy formation I will briefly describe the formation of dwarfs at this mass scale at 3 different epochs: cosmic dawn, cosmic noon, and today. I will describe the FirstLight simulations of first galaxies at redshifts 5-15. These first dwarfs have extremely high star formation efficiencies due to high gas fractions and high gas accretion rates. At cosmic noon, z = 2, galaxy formation is a violent process. The VELA simulations have generated a set of dispersion-dominated dwarfs that show an elongated morphology due to their prolate dark-matter halos. Between z =1-0, the AGORA simulation shows the formation of a low-mass disc due to slow gas accretion.

I will present new results on the formation and fate of discs of spiral galaxies from the New Horizon and Galactica simulations. The high-resolution simulations (>40pc) reveal the history of disc settling, build-up, and fading in great detail and provide hints to the origin of the thin and thick discs.

Grace Lawrence CoC review talk on detecting dark matter, all welcome

Apertif is the new phased-array feed receiver system on the Westerbork Synthesis Radio Telescope (WSRT). The substantially increased field of view of the telescope makes Apertif a great survey instrument. In July 2019, Apertif started survey observations for a two-tiered imaging survey, with a shallow and medium-deep component and a time domain survey searching for new (millisecond) pulsars and fast radio bursts (FRBs). The main science goals of the Imaging Survey are: the role of environment and interaction on galaxy properties, finding the smallest galaxies, connecting cold gas to AGN, understanding the faint radio population, and studying magnetic fields in galaxies. After a proprietary period, all survey data products will be publicly available through the Apertif Long Term Archive (ALTA, https://alta.astron.nl). I will describe the first seven months of the Imaging Survey, where the team is observing and automatically processing the data to produce radio continuum images, polarisation images, and HI (neutral hydrogen) line cubes. I will show examples of the survey data and highlight the first science results from the survey.

Title:

The role of angular momentum in the evolution of star forming galaxies

Abstract:

The age of the Universe at which star formation peaks is interesting, angular momentum (j) has been measured to be low and gas fractions (f_gas) are high (compared to local analogues). Both j and f_gas play an important role in the evolution of disk galaxies to the grand design spirals we observe today and so it is important to measure them accurately. Measuring j at high redshift is particularly difficult, one needs deep observations in both infrared photometry (stellar mass distribution) and integral field spectroscopy (emission line kinematics) in order to get an accurate description of the angular momentum content. Currently, most high-z IFS data are natural seeing (NS) limited, which prevents accurate morphological classification, introduces artefacts and hides small scale kinematic structures that affect the real shape of the rotation curves. On the other hand, adaptive optics (AO) assisted observations improve resolution but suffer from SN loss. One way to account for this is to combine data at the different resolutions: i) AO high resolution data for the inner parts where signal is enough to prevail over the SN loss introduced by the AO correction (and where the rotation curve rises rapidly) and ii) NS low resolution data for the outer parts since SN is high (and where the rotation curve has already flattened). We have analysed a sample of 10 galaxies with the combination method at z∼1.5 and z∼2 (the largest sample at high-z with combined j measurements to our knowledge) from Keck/OSIRIS + VLT/KMOS+SINFONI + HST and we have explored the capabilities of applying the combination method such as a decrease in uncertainty and a more realistic determination of shape and morphology for each galaxy.

The James Webb Space Telescope (JWST) will provide a great opportunity to explore
high redshift galaxies, and understand the role of galaxies in the reionization
of the Universe. I will present our observational plans for the Guaranteed Time
Observations of the NIRSpec Instrument Science Team, including those co-ordinated with the NIRCam
Team as part of the JADES survey. Determining the UV luminosity function to faint
magnitudes, coupled with more accurate determinations of the escape fraction (from
observations of the Balmer lines and UV continuum), will address the ionizing photon budget
from galaxies. The census of the fraction of high redshift star-forming galaxies with Lyman alpha in
emission will constrain the neutral fraction of the IGM at z>6, and the size of the ionized bubbles,
and the study of rest-UV absorption lines and nebular emission will shed light on the outflows
and the role of the circum-galactic medium. Working at between 1 and 5 microns, NIRSpec on JWST
has the capability to explore the star formation rates, metallicities and IGM surroundings of
galaxies within the epoch of reionization.