Tenure-track position

Apply – deadline Monday, 16 Oct 2017
The School of Physics at the University of Melbourne is seeking the appointment of an outstanding female academic to a continuing (tenure-track) position of Lecturer or Senior Lecturer in astrophysics. The successful applicant will also be awarded an ASTRO 3D Fellowship within the ARC Centre of Excellence for All Sky Astrophysics in 3-Dimensions (ASTRO 3D), which allows for full time research during the first six years of the appointment.

ASTRO 3D spans six (6) Australian universities, three (3) national infrastructure facilities, and seven (7) international partner institutions. ASTRO 3D combines Australia’s leading optical, infrared and radio telescope technologies with sophisticated theoretical simulations and ambitious new data intensive science techniques to build a comprehensive picture of the evolution of matter, the chemical elements, and ionizing radiation in the Universe from the Epoch of Reionization to the present day.

The position is open to female researchers in any area of ASTRO 3D science. The appointee is expected to attract postgraduate students, engage collaborative links, and secure competitive research funding. The lecturer will supervise research students at MSc and PhD levels. At the conclusion of their ASTRO 3D fellowship, they will also have a core commitment to teaching within the School’s undergraduate and MSc programs.

The University seeks to increase the representation of women in areas where they have been traditionally under-represented. Pursuant to a Special Measure under Section 12 (1) of the Equal Opportunity Act 2010 (Vic), The School will, therefore, only consider applications from suitably qualified female candidates for this position.



Big Screen Science: Star Trek III: The Search for Spock

Sun 7 Oct, 2018 @3.30 PM, Cinema Nova
Dr. Rachael Livermore, DECRA fellow
University of Melbourne

Email: rlivermore[at]unimelb.edu.au


Celebrate space and stars with a fun event for the whole family! Revisit classic sci-fi films on the big screen, followed by fascinating presentation and discussion on how space is depicted in cinema with Astrophysicist Dr Rachael Livermore (The University of Melbourne).

More details are here: Star Trek III



Big Screen Science: Contact

Sun 30 Sep, 2018 @3.30 PM, Cinema Nova
Dr. Rachael Livermore, DECRA fellow
University of Melbourne

Email: rlivermore[at]unimelb.edu.au


Celebrate space and stars with a fun event for the whole family! Revisit classic sci-fi films on the big screen, followed by fascinating presentation and discussion on how space is depicted in cinema with Astrophysicist Dr Rachael Livermore (The University of Melbourne).

More details are here: Contact



Black Hole Mass Scaling Relations for Spiral Galaxies

Wed 19th September, 2018 @12:00 PM, level 7
Dr Benjamin Davis, Swinburne University

Email:  benjamindavis[at]swin.edu.au

Abstract

For almost a century now, the Hubble-Jeans sequence of galaxies has classified spiral galaxies into morphological classes based on their bulge sizes and the tightness of winding present in their spiral arms. These qualitative morphologies also inform us about the mass of the black hole residing at a spiral galaxy’s centre. Specifically, spiral galaxies that typically possess the largest black holes have large bulges and tightly wound spiral arms. My research focusses on studying spiral galaxy structure and providing accurate, quantitative measurements of their bulge masses and logarithmic spiral arm pitch angles. I will present the details of my recent study of all the known supermassive black holes with directly measured dynamical masses in the literature. For this sample, I have measured their pitch angles and conducted extensive multicomponent decomposition analyses of their surface brightness profiles to determine accurate bulge masses. I will report on the resulting black hole mass scaling relations and discuss their usefulness in predicting unknown black hole masses to generate mass functions and identifying galaxies that might harbour intermediate mass black holes.


Tracing high-z galaxy kinematics from turbulent disks to quenched spheroids

Wed 12th September, 2018 @12:00 PM, level 7
Dr Emily Wisnioski, ANU

Email:  emily.wisnioski[at]anu.edu.au

Abstract

The depth of the KMOS3D Survey has allowed us to study in unprecedented detail rare galaxies at z>1 that are likely in the process of quenching. The short timescales associated with the quenching process make it difficult to catch galaxies “in the act” of shutting down their star formation. Compact star-forming galaxies, making-up ~7% of our sample, are selected to have properties aligned with already quenched galaxies at the same or lower redshifts but forming stars at rates 2-10x higher. We measure resolved kinematics of ~30 of these galaxies within the KMOS3D survey. Our results – the first resolved spectral data of such objects – show that compact star-forming galaxies are rotationally-dominated systems, providing strong evidence that recently quenched galaxies at these epochs are likely to be “fast rotators” . The majority of compact star-forming galaxies show evidence of low molecular gas fractions from ALMA observations and nuclear activity indicative of secular quenching processes that may retain the rotation observed in the star-forming phase. The KMOS3D survey, an integral field survey of over 600 galaxies at z=0.7-2.7 using KMOS at the VLT, will make their data public this year. In addition to the above science (Wisnioski et al. 2018) I will describe the survey and data products that will soon be available to the Australian community.


Are neutron stars turbulent?

Fri 7th September, 2018 @11:00 PM, level 7
Dr Anthony Van Eysden, Montana State University

Email:  anthonyvaneysden[at]montana.edu

Abstract

Instabilities and turbulence in neutron stars have been suggested as the origin of timing irregularities in pulsars such as glitches and timing noise. I will examine the case for turbulence in neutron stars, comparing the conditions in these stars with those in known turbulent astrophysical systems. Particular attention is given to instabilities arising from conditions unique to neutron stars, such as two-stream instabilities driven by the relative rotation between the proton and neutron condensates in the core. We show that magnetic stresses have a stabilizing effect on these instabilities, making them unlikely to be connected with turbulence.


Designing for Discovery in Astronomy’s Data-Intensive Era

Wed 29 August, 2018 @12:00 PM, level 7
Sarah Hegarty, PhD Student
Swinburne University

Email:  shegarty[at]swin.edu.au

Abstract

The dawning era of data-intensive astronomy offers us unprecedented potential for discovery. However, the immense data rates of new-generation telescopes mean that we won’t be able to make these discoveries using established approaches. In this presentation, I will look at how our work practices need to change as we adapt to the data-intensive era – and discuss how we can use what we know about astronomical discovery-making to build more effective workflows. I will present a case study from the field of fast transient science, discussing the development of intelligent workflows for the Deeper, Wider, Faster transient search program, and describing the new eResearch platform PerSieve. I will discuss lessons learned about how astronomers work – and the implications for how we can capitalise on the vast discovery potential of coming data-intensive telescopes.


Constraining asymmetry in Europa’s oceans

Wed 22 August, 2018 @12:00 PM, level 7 Conference Room
Marshall Styczinski, PhD student
University of Washington

Email:  mjstyczi[at]uw.edu

Abstract

Induced magnetic fields from Europa, measured by the Galileo spacecraft, provide the strongest evidence we have for the presence of a salty water ocean beneath the outer ice shell. The observed field is consistent with a global ocean layer with a high dissolved salt content. However, ice layer thickness, ocean depth, and salinity determined from induced magnetic field measurements are dependent on the model applied to represent the interior structure. Past studies attempting to constrain ocean properties have all assumed spherical symmetry, which is not expected for Europa and restricts the validity of the derived constraints. Quantifying the degree of potential asymmetry in the ocean and ice layer is critical to future exploration. Interpretation of magnetic measurements by the upcoming Europa Clipper mission, especially considering plume activity that may have degenerate signals, may be impossible without asymmetric interior models. In this work, we aim to identify constraints on the spatial asymmetry that may be present in Europa’s oceans. Constraints will be determined as extremes in low-order spherical harmonics describing the ice-ocean boundary that are consistent with Galileo gravity and magnetometer measurements and realistic ocean parameters, assuming uniform ocean conductivity. Preliminary results and plans for future work will be presented.
 


Exploring the effects of crystallographic orientation on shock features in Martian meteorites: how does the orientation of a crystal affect how it bends or breaks?

Thurs 16 August, 2018 @14:00 PM, level 6 Opat Room
Dr Lucy Forman, Research Associate
Curtin University

Email:  lucy.forman[at]curtin.edu.au

Abstract

Shock features within Martian samples are thought to result primarily from the impact that launched them from the surface of Mars, and so exploring the material response can help constrain shock parameters, related impact processes and locate candidate launch craters on the Martian surface. Different minerals have varied material responses to stress and, more specifically in this case, the stress applied by a propagating shockwave. Slip systems must be activated in each grain so that the crystal lattice can be deformed. However, often the dominant activated slip system is dependent upon the orientation the stress is applied in, with relation to the crystallographic orientation of the grain, and the physical conditions of the material at the time of impact. Here we explore the effect of crystallographic orientation on the quantifiable amount of crystal deformation that is generated in an impact scenario on the Martian surface.

The initial focus of this study is the lherzolitic Shergottite Roberts Massif (RBT) 04262, which comprises poikilitic pyroxenes amongst a pyroxene and olivine-rich mineralogy. We initially examined a large (10 x 7 mm) twinned pyroxene grain. At the macro scale, shock is heterogeneous but no mineral phase changes have been observed, therefore overall shock is limited. Electron backscatter diffraction (EBSD) techniques were used to determine pyroxene orientation to constrain spectral characteristics and understand the style of deformation within the grains. The data comprise crystallographic information from all mineral phases at a step size of 12.2 µm.

The twinned pyroxene grain is primarily pigeonite based on the composition, and was divided into twins A & B. Twin A shows very little internal deformation in the pigeonite region (<2 º), but a consistently greater amount of misorientation is present in the augite rim. However, twin B, which is twinned on the [001] plane with twin A, shows a variable amount of misorientation throughout the crystal, which appears to undulate in contrast to the radial trend in deformation in twin A.

This sample has a very low porosity, which would have also been true at the time of impact, and therefore heterogeneities in shock are not due to shockwave interactions arising from interaction with pores. We subsequently infer the crystallographic orientation of each grain dictated the degree of crystal-plastic deformation generated by the shock wave. Further EBSD microstructural analysis will be used to constrain the slip systems that have been activated in the pigeonite, and subsequently constrain the physical conditions at the time of impact. This approach may allow determination of the shockwave propagation direction with respect to the plane of the sample. Further Martian samples have been investigated using this analytical approach. This study will contribute directly to our understanding of impact-induced deformation in a suite of rocks ejected from the Martian surface at the same time, and potentially by the same impact event.

 

 


New frontiers in exoplanetary and stellar astrophysics with Australian observational facilities

Wed 08 August, 2018 @12:00 PM, level 7
Associate Professor Rob Wittenmyer, MINERVA Observatory, University of South Queensland

Email:  rob.wittenmyer[at]usq.edu.au

Abstract

Mount Kent Observatory at the University of Southern Queensland is host
to Australia’s newest astronomical research facilities.
MINERVA-Australis is the only Southern hemisphere precise radial
velocity facility wholly dedicated to follow-up of thousands of planets
to be identified by NASA’s Transiting Exoplanet Survey satellite
(TESS). Mass measurements of these planets are critically necessary to
maximise the scientific impact of the TESS mission, to understand the
composition of exoplanets and the transition between rocky and gaseous
worlds. MINERVA-Australis is now operational. I present first-light
results and give an update on the status of the project, which will
ultimately host six 0.7m telescopes feeding a stabilised spectrograph.

The Stellar Observations Network Group (SONG) is establishing a node at
Mount Kent. SONG-Australia will complete the global longitude coverage,
delivering breakthroughs in fundamental understanding of the interiors
of stars for decades to come. SONG-Australia is designed on a “MINERVA”
model, whereby fibres from multiple small telescopes feed a single
high-resolution spectrograph. This approach provides expandability and
reduces cost by using factory-built components that have been
well-tested by the MINERVA teams. As a result of these innovations,
SONG-Australia is expected to be fully operational by late 2019.


Pulsar glitches and vortex tangles: a neutron star super-mixture

Wed 1 August, 2018 @12:00 PM, level 7
Lisa Drummond, PhD Student
University of Melbourne

Email:  l.drummond[at]student.unimelb.edu.au

Abstract

Pulsar glitches are a unique window into the dynamics of neutron matter at extreme densities. Modelling the physical mechanism that produces these glitches is an endeavour that spans many scales: from the quantum mechanical, microscopic interaction of vortices in the superfluid interior to the macroscopic motion of the rigid stellar crust. We can simulate vortex-avalanche-induced glitches by constructing a Gross-Pitaevskii model from first-principles, thereby incorporating the microscopic physics of superfluid vortices (Warszawski, Melatos, 2011; Melatos, Douglass & Simula, 2015). A complementary approach is to model pulsar glitches as a state-dependent Poisson process, thereby capturing the global behaviour of glitching pulsars (Fulgenzi, Melatos & Hughes, 2017). Bridging the stellar and microscopic scales described in these two approaches is an enormous computational and theoretical challenge. These models can each be extended in various ways, for example by including the interaction with the proton superconductor in the core (Drummond & Melatos, 2017). Competition between vortex-vortex repulsion and vortex-flux-tube attraction (pinning) leads to “glassy” behaviour characterized by multiple metastable states spaced closely in energy. Vortex tangles emerge as a consequence of the frustration in the system. The tangles evolve in a complicated fashion when driven out of equilibrium and a three-dimensional investigation reveals new vortex behaviours for misaligned magnetic and rotation axes.


Pulsars as gravitational wave sources

Wed 25 July, 2018 @12:00 PM, level 7
Dr Matthew Pitkin, Post-doctoral Research Fellow
University of Glasgow

Email:  matthew.pitkin[at]glasgow.ac.uk

Abstract

Transient sources of gravitational waves, such as coalescing black holes and neutron stars, have obviously been at the forefront of gravitational wave astronomy. But, there are still many intriguing sources that have yet to be detected, and these include continuous quasi-monochromatic signals from individual rapidly-rotating neutron stars. Known pulsars therefore are intriguing targets for searches for such signals. In this talk I will give an overview of searches for gravitational waves from pulsars using the LIGO and Virgo detectors. I will describe some recent work that may provide some evidence that millisecond pulsars have a minimum ellipticity, which makes detection of these sources more plausible with future gravitational detectors. I will also describe how hierarchical Bayesian inference can potentially be used to detect signals from an ensemble of pulsars and infer the distribution of pulsar ellipticities.


Titans of the Early Universe: The origin of the most massive, high-redshift quasars

Wed 18 July, 2018 @12:00 PM, level 7
Dr. Tyrone Woods, Post-doctoral Research Fellow
Monash University

Email:  tyrone.woods[at]monash.edu

Abstract

The discovery of billion solar mass quasars at redshifts of 6-7 challenges our understanding of the early Universe; how did such massive objects form in the first billion years? Observational constraints and numerical simulations increasingly favour the “direct collapse” scenario. In this case, an atomically-cooled halo of primordial composition accretes rapidly onto a single protostellar core, ultimately collapsing through the Chandrasekhar-Feynman instability to produce a supermassive (~100,000 solar mass) “seed” black hole. In this talk, I’ll present a systematic study of the lives and deaths of these objects, using the 1D implicit hydrodynamics and stellar evolution code KEPLER. We include post-Newtonian corrections to gravity and a detailed treatment of nuclear burning processes using an adaptive network. We find a simple relation between the infall rate and the final mass at collapse, and rule out the existence of rapidly-rotating supermassive stars. I’ll also discuss the possibility of early chemical enrichment from these objects, observational prospects in the era of the JWST, and briefly summarize other future directions agreed upon at our workshop “Titans of the Early Universe” held at the Monash Prato Centre in Italy, in November of last year.


Detectability of 21cm signal during the Epoch of Reionization with 21cm-LAE cross correlation

Wed 11 July, 2018 @12:00 PM, level 7
Shintaro Yoshiura,
Kumamoto University

Email:  161d9002[at]st.kumamoto-u.ac.jp

Abstract

The 21cm signal is a powerful tool to probe the Epoch of Reionization. However the detection of the redshifted 21cm signal is difficult due to the bright foregrounds. For mitigating the foreground contamination, the cross correlation with other observable is useful. Here, we predict the detectability of the cross power spectrum between 21cm signal and Lyman-alpha emitter (LAE) by using numerical reionization simulation and assuming ongoing and future observations. For 21cm observation, we assume radio survey by the Murchison Widefield Array (MWA) and Square Kilometre Array (SKA). The LAEs are detected at z=5.7, 6.6 and 7.3 by Subaru Hyper Suprime-Cam (HSC).  In this work, we find that the MWA can detect the signal by combining the spectroscopic survey with the Prime Focus Spectrograph (PFS). In practice, however, the error of cross power spectrum is dominated by the foregrounds, and moderate foreground removal is required.  


Science vs Cinema: Star Trek II – Wrath of Khan

Sun 8 Jul, 2018 @3.30 PM, NOVA cinema
Dr. Rachael Livermore, DECRA fellow
University of Melbourne

Email: rlivermore[at]unimelb.edu.au


Celebrate space and stars with a fun event for the whole family! Revisit classic sci-fi films on the big screen, followed by fascinating presentation and discussion on how space is depicted in cinema with Astrophysicist Dr Rachael Livermore (The University of Melbourne).

More details are here: Star Trek II – Wrath of Khan



Science vs Cinema: Apollo 13

Sun 17 Jun, 2018 @3.30 PM, NOVA cinema
Dr. Rachael Livermore, DECRA fellow
University of Melbourne

Email: rlivermore[at]unimelb.edu.au


Celebrate space and stars with a fun event for the whole family! Revisit classic sci-fi films on the big screen, followed by fascinating presentation and discussion on how space is depicted in cinema with Astrophysicist Dr Rachael Livermore (The University of Melbourne).

More details are here: Apollo 13


Precession measurability in black hole binary coalescences

Wed 13 June, 2018 @12:00 PM, level 7
Dr. Grant David Meadors, Postdoctoral Researcher
Monash University

Email:  grant.meadors[at]monash.edu

Abstract

Rotating bodies precess, and black holes should be no exception. Black hole spin has so far been inferred largely from electromagnetic observations of surrounding matter. Gravitational-wave observations of coalescences can probe the spin and precession of the black holes themselves. Using a Bayesian parameter estimatin pipeline, we characterize a method for detecting evidence of precession. Precession might conceivably be seen in either high-signal-to-noise ratio events with favorably parameters, or in a statistical ensemble of many events. We use simulated events with numerical-relativity approximant waveforms to estimate the detectability of precession.


Enhancing EoR limits – spectral accuracy of the MWA

Wed 6 June, 2018 @12:00 PM, level 7
Dr. Nichole Barry, Postdoctoral Researcher
University of Melbourne 

Email:  nichole.barry[at]unimelb.edu.au

Abstract
Epoch of Reionization observations have the potential to be transformative in the field of cosmology, but this is impossible without unprecedented levels of accuracy in calibration. We enhance EoR upper limits from the Murchison Widefield Array through the improvement of instrumental calibration with in situ simulations, and the reduced limit highlights the precision and accuracy that we must achieve. An in situ calibration simulation verifies our experimental findings, and identifies the fundamental limits of sky-based calibration. We set a precedent for required bandpass accuracy to one part in 105

Our improved EoR upper limit is (80 mK)2 at k=0.2 h Mpc-1 for z=7, an improvement of over a factor of 4 compared to a previous analysis using the exact same data set. These spectral accuracy techniques will influence future pipeline advances in the search for the EoR.


The lithium-rich giant star puzzle

Wed 23 May, 2018 @12:00 PM, level 7
Dr. Andy Casey, Postdoctoral Fellow
Monash University

Email:  andrew.casey[at]monash.edu

Abstract

All theoretical models of stellar evolution predict that most of the lithium inside a star is destroyed as the star becomes a red giant. However, observations reveal that about 1% of red giants are peculiarly rich in lithium, often exceeding the amount in the interstellar medium or predicted from the Big Bang. With only 151 lithium-rich giants discovered in the past four decades, and no distinguishable properties other than lithium enhancement, the origin of lithium-rich giant stars is one of the oldest problems in stellar astrophysics. In this talk I will report on the discovery of 2,330 low-mass lithium-rich giant stars, and a likely solution to this longstanding puzzle.


Closing in on the HIdden universe

Thurs 17 May, 2018 @12:00 PM, level 7
Dr. Michelle Cluver, ARC Future Fellow
Swinburne University

Email:  mcluver[at]swin.edu.au

Abstract

As the experiments looking to detect dark matter close in (coming from different directions on the Feynman Diagram), a small fraction of the baryon community is quietly anticipating a window on the universe (21cm neutral hydrogen) to de-fog a little. While theoretical simulators continue to grapple with the challenges of “mocking the universe”, observers can focus on refining (or even just beginning to understand) the prescriptive, previously sub-grid, physics and chemistry that made the universe great. I will talk about how star formation and stellar mass in galaxy groups can possibly make more sense if we can see the faint stuff (stars and gas) that everyone assumed was unimportant.


[CII] as a SFR tracer in M31 and M51: A ~constant photoelectric heating efficiency links [CII] 158 um with young stars

Wed 9 May, 2018 @12:00 PM, level 7
Dr Maria Kapala, SARChI Postdoctoral Fellow
University of Cape Town

Email:  kapala[at]ast.uct.ac.za

Abstract

The energy balance sets the structure of the interstellar medium (ISM) phases, which in turn control the processes of star-formation (SF). We investigate the balance between the heating by stellar radiation, and neutral gas cooling dominated by [CII] emission line. [CII] is typically the brightest far-IR emission line from star-forming galaxies, and it has been proven to be a useful SFR tracer, both locally and at high redshifts, however, with some vital caveats. Specifically, we are interested wheather there are any changes in the efficiency of the photoelectric heating (PEeff), the dominant heating mechanism of the neutral gas, that might affect reliability of the [CII] as a SFR tracer.

To address these issues, we have assembled a unique set of observations in two nearby galaxies, M31 and M51. Multi wavelength FUV-FIR photometric coverage enables a well constrained SED modelling. Key observations of [CII] emission at high, 50pc, resolution in five SF regions in M31 (Herschel), and the first fully mapped galaxy at ~650pc resolution in M51 (SOFIA), enable a local and a global studies. Finally, we model individually resolved stars with 6 band HST photometry down to spectral type F0 with PHAT survey in M31 using BEAST (Bayesian Extinction and Stellar Tool) for an independent measurement of the heating at smallest scales.

A commonly used ratio [CII]/TIR (total IR emission), fails as a proxy for PEeff, because the TIR measures all dust heating, not just the FUV photons capable of ejecting electrons from dust grains (Kapala et al. 2017). We find [CII]/TIR to be strongly correlated with UVatt/TOTatt (inferred from MAGPHYS SED fitting), indicating that, in M31 at least, one of the dominant drivers for [CII]/TIR variation is the relative hardness of the absorbed stellar radiation field. We define PEeff(UV), [CII]/UVatt which should be more closely related to the true PE efficiency, which we find to be essentially constant (1.85 ± 0.8%) in all explored 700x700pc fields in M31, regardless of the value of [CII]/TIR (varying by a factor of 3).

I will present the above findings and the preliminary results of the [CII] – SFR relation, and the PEeff(UV) on 650pc scales in M51. I will also explore environmental dependencies on those relations.

 


When Galaxy Clusters Collide: Shocking tales of structure formation

Wed 2 May, 2018 @12:00 PM, level 7
Dr Andra Stroe, European Southern Observatory,
Garching

Email:  astroe[at]eso.org

Abstract

Red weather alert: dangerous cosmic weather forecast, in light of galaxy cluster mergers! Clusters grow through mergers with other clusters, events which give rise to the largest cosmic shock waves. Shocks travel like giant tsunamis through the electron plasma and shape the evolution of the intra-cluster medium. Giant radio relics trace these shock fronts and are thought to form when accelerated electrons emit synchrotron radiation in the presence of a magnetic field. I will present results from the widest frequency study of radio relics, where we combine, for the first time, data covering more than 2 order of magnitude in radio frequency. Our very low and very high radio frequency data challenge the simple, widely accepted model for relic formation. Using unique observations spanning the 150 MHz to 30 GHz range, I will derive physical parameters, such as Mach numbers and electron ages, as well as constrain injection mechanisms. I will also discuss how new models involving re-acceleration of aged seed electrons or evolving magnetic fields can alleviate the discrepancies between observations of relics and theory.


Science vs Cinema: Galaxy Quest

Sun 29 Apr, 2018 @3.30 PM, NOVA cinema
Dr. Rachael Livermore, DECRA fellow
University of Melbourne

Email: rlivermore[at]unimelb.edu.au


Celebrate space and stars with a fun event for the whole family! Revisit classic sci-fi films on the big screen, followed by fascinating presentation and discussion on how space is depicted in cinema with Astrophysicist Dr Rachael Livermore (The University of Melbourne).

More details are here: Galaxy Quest


Vesta and the Chaotic Formation of Planets

Thurs 26 Apr, 2018 @12:00 PM, level 7
Brother Guy Consolmagno, Director of the Vatican Observatory
Vatican Observatory

Email:  director[at]specola.va

Abstract

NASA’s Dawn mission was sent to asteroid 4 Vesta to inspect, close up, “an intact protoplanet from the origin of the solar system”. But the Dawn data have revealed that Vesta’s overall density is too low, and its core and crust too big, to resemble anything like an intact protoplanet. Was Vesta ripped apart and re-assembled? It looks like Vesta is giving us new clues to planet formation and evolution in a violent early solar system.


The growing field of post-main-sequence exoplanetary science

Wed 18 Apr, 2018 @12:00 PM, level 7
Dr. Dimitri Veras, STFC Ernest Rutherford Fellow
University of Warwick

Email: d.veras[at]warwick.ac.uk

Abstract

Connecting planetary systems at different stages of stellar evolution helps us understand their formation, evolution and fate, as well as provides us with crucial insights about their dynamics and chemistry. Post-main-sequence stars — pulsars, white dwarfs and giant branch stars — all host planetary systems, which often include remnant debris discs. Here I provide a review of our current knowledge of these systems. I show how this interdisciplinary field incorporates several facets of stellar physics and chemistry as well as solar system physics and chemistry, and detail simulation-based efforts to understand the big picture.


Small scale structure of the IGM: A Dark Matter Tale

Wed 11 Apr, 2018 @12:00 PM, level 7
Dr. Vid Irsic, Postdoctoral Fellow
University of Washington

Email: irsic[at]uw.edu

Abstract

The intergalactic medium (IGM) plays a unique role in constraining the (small scale) matter power spectrum, since the low-density, high redshift IGM filaments are particularly sensitive to the small scale properties of dark matter. The main observable manifestation of the IGM, the Lyman-alpha forest, has provided important constraints on the linear matter power spectrum, especially when combined with cosmic microwave background data. This includes, most notably, the tightest constraints on warm dark matter (WDM) and fuzzy dark matter (FDM) models, that I will present in this talk.


The Hubble Space Telescope: 28 Years of Cosmic Discovery

Thu 29 Mar, 2018 @14:30 PM, level 7
Dr. Jennifer Wiseman, Senior Project Scientist for the Hubble Space Telescope
NASA Goddard Space Flight Center

Email: jennifer.j.wiseman[at]nasa.gov

Abstract

The Hubble Space Telescope is operating at peak scientific capability even 28 years after its launch, thanks to successful astronaut servicing missions and operations that keep the observatory in top condition.  I will review the premiere scientific advancements achieved by Hubble, including both those that were planned at launch (e.g. measuring the Hubble constant) and many that were never dreamed of at launch (e.g. finding evidence for dark energy; analyzing exoplanet atmospheres).  Hubble observations are now helping prepare for JWST and other future missions, and are contributing critical complementary observations for solar system probes like JUNO and New Horizons.  I will discuss how Hubble can be used in its coming final years to provide the best science return, complementing other space-based and ground-based observatories and setting the stage for future flagship missions.


Parameter Estimation and Model Selection of Gravitational Wave Signals Contaminated by Transient Detector Noise Glitches

Wed 28 Mar, 2018 @12 PM, level 7
Dr. Jade Powell, Postdoctoral Fellow
Swinburne University

Email: jpowell[at]swin.edu.au

Abstract

The number of astrophysical sources detected by Advanced LIGO and Virgo is expected to increase as the detectors approach their design sensitivity. Gravitational wave detectors are also sensitive to transient noise sources created by the environment and the detector, known as ‘glitches’. As the rate of astrophysical sources increases, the probability that a signal will occur at the same time as a glitch also increases. This has occurred previously in the gravitational wave binary neutron star merger detection GW170817. In this talk, we examine the effect of glitches on the measurement of signal parameters and Bayesian model selection. We include binary black holes similar to current detections, sine Gaussian bursts, and core-collapse supernovae. We examine if the effects of glitches are worse when there is a mis-match between the signal model and the data.


Number of posts found: 67