ORCID Profile
0000-0001-9336-2825
Current Organisations
University of Amsterdam
,
Max-Planck-Institute for Astrophysics
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Astronomical sciences | Space instrumentation | Cosmology and extragalactic astronomy | Lasers and quantum electronics | General relativity and gravitational waves |
ANZSRC Socio-Economic Objective (SEO)
Related Links
Publications
Extinction Maps and Dust-to-gas Ratios in Nearby Galaxies with LEGUS
Publisher: American Astronomical Society
Date: 16-03-2018
The Mystery of CEMPs+r Stars and the Dual Core-Flash Neutron Superburst
Publisher: Cambridge University Press (CUP)
Date: 2009
DOI: 10.1071/AS08068
Abstract: Carbon-enhanced metal-poor (CEMP s + r ) stars show large enhancements of elements produced both by the slow and the rapid neutron capture processes (the s and r process, respectively) and represent a relatively large fraction, 30% to 50%, of the CEMP population. Many scenarios have been proposed to explain this peculiar chemical composition and most of them involve a binary companion producing the s -process elements during its Asymptotic Giant Branch (AGB) phase. The problem is that none of the proposed explanations appears to be able to account for all observational constraints, hence, alternatives are needed to be put forward and investigated. In this spirit, we propose a new scenario for the formation of CEMP s + r stars based on S. W. C bell's finding that during the ‘dual core flash’ in low-mass stars of extremely low metallicity, when protons are ingested in the He-flash convective zone, a ‘neutron superburst’ is produced. Further calculations are needed to verify if this neutron superburst could make the r -process component observed in CEMP s + r , as well as their Fe abundances. The s -process component would then be produced during the following AGB phase.
JWST Imaging of Earendel, the Extremely Magnified Star at Redshift z = 6.2
Publisher: American Astronomical Society
Date: 11-2022
Abstract: The gravitationally lensed star WHL 0137–LS, nicknamed Earendel, was identified with a photometric redshift z phot = 6.2 ± 0.1 based on images taken with the Hubble Space Telescope. Here we present James Webb Space Telescope (JWST) Near Infrared Camera images of Earendel in eight filters spanning 0.8–5.0 μ m. In these higher-resolution images, Earendel remains a single unresolved point source on the lensing critical curve, increasing the lower limit on the lensing magnification to μ 4000 and restricting the source plane radius further to r 0.02 pc, or ∼4000 au. These new observations strengthen the conclusion that Earendel is best explained by an in idual star or multiple star system and support the previous photometric redshift estimate. Fitting grids of stellar spectra to our photometry yields a stellar temperature of T eff ≃ 13,000–16,000 K, assuming the light is dominated by a single star. The delensed bolometric luminosity in this case ranges from log ( L ) = 5.8 to 6.6 L ⊙ , which is in the range where one expects luminous blue variable stars. Follow-up observations, including JWST NIRSpec scheduled for late 2022, are needed to further unravel the nature of this object, which presents a unique opportunity to study massive stars in the first billion years of the universe.
A comprehensive comparative test of seven widely used spectral synthesis models against multi-band photometry of young massive-star clusters
Publisher: Oxford University Press (OUP)
Date: 03-03-2016
DOI: 10.1093/MNRAS/STW150
Formation of the first three gravitational-wave observations through isolated binary evolution
Publisher: Springer Science and Business Media LLC
Date: 05-04-2017
DOI: 10.1038/NCOMMS14906
Abstract: During its first four months of taking data, Advanced LIGO has detected gravitational waves from two binary black hole mergers, GW150914 and GW151226, along with the statistically less significant binary black hole merger candidate LVT151012. Here we use the rapid binary population synthesis code COMPAS to show that all three events can be explained by a single evolutionary channel—classical isolated binary evolution via mass transfer including a common envelope phase. We show all three events could have formed in low-metallicity environments ( Z =0.001) from progenitor binaries with typical total masses ≳160 M ⊙ , ≳60 M ⊙ and ≳90 M ⊙ , for GW150914, GW151226 and LVT151012, respectively.
How stellar rotation shapes the colour−magnitude diagram of the massive intermediate-age star cluster NGC 1846
Publisher: Oxford University Press (OUP)
Date: 23-12-2019
Abstract: We present a detailed study of stellar rotation in the massive 1.5 Gyr old cluster NGC 1846 in the Large Magellanic Cloud. Similar to other clusters at this age, NGC 1846 shows an extended main-sequence turn-off (eMSTO), and previous photometric studies have suggested it could be bimodal. In this study, we use MUSE integral-field spectroscopy to measure the projected rotational velocities (vsin i) of around $1400$ stars across the eMSTO and along the upper main sequence of NGC 1846. We measure vsin i values up to $\\sim 250\\, {\\rm km\\, s^{-1}}$ and find a clear relation between the vsin i of a star and its location across the eMSTO. Closer inspection of the distribution of rotation rates reveals evidence for a bimodal distribution, with the fast rotators centred around $v\\sin i=140\\, {\\rm km\\, s^{-1}}$ and the slow rotators centred around $v\\sin i=60\\, {\\rm km\\, s^{-1}}$. We further observe a lack of fast rotating stars along the photometric binary sequence of NGC 1846, confirming results from the field that suggest that tidal interactions in binary systems can spin-down stars. However, we do not detect a significant difference in the binary fractions of the fast and slowly rotating sub-populations. Finally, we report on the serendipitous discovery of a planetary nebula associated with NGC 1846.
Ultraviolet Detection of the Binary Companion to the Type IIb SN 2001ig
Publisher: American Astronomical Society
Date: 27-03-2018
Gravitational Wave Sources in Our Galactic Backyard: Predictions for BHBH, BHNS, and NSNS Binaries Detectable with LISA
Publisher: American Astronomical Society
Date: 10-2022
Abstract: Future searches for gravitational waves from space will be sensitive to double compact objects in our Milky Way. We present new simulations of the populations of double black holes (BHBHs), BH neutron stars (BHNSs), and double neutron stars (NSNSs) that will be detectable by the planned space-based gravitational-wave detector called Laser Interferometer Space Antenna (LISA). For our estimates, we use an empirically informed model of the metallicity-dependent star formation history of the Milky Way. We populate it using an extensive suite of binary population-synthesis predictions for varying assumptions relating to mass transfer, common-envelope, supernova kicks, remnant masses, and wind mass-loss physics. For a 4(10) yr LISA mission, we predict between 30–370(50–550) detections over these variations, out of which 6–154 (9–238) are BHBHs, 2–198 (3–289) are BHNSs, and 3–35 (4–57) are NSNSs. We expect that about 50% (60%) can be distinguished from double white dwarf sources based on their mass or eccentricity and localization. Specifically, for about 10% (15%), we expect to be able to determine chirp masses better than 10%. For 13% (13%), we expect sky-localizations better than 1°. We discuss how the variations in the physics assumptions alter the distribution of properties of the detectable systems, even when the detection rates are unchanged. We further discuss the possibility of multimessenger observations of pulsar populations with the Square Kilometre Array and assess the benefits of extending the LISA mission.
THE BRIGHTEST YOUNG STAR CLUSTERS IN NGC 5253
Publisher: American Astronomical Society
Date: 24-09-2015
On the fate of the secondary white dwarf in double-degenerate double-detonation Type Ia supernovae
Publisher: Oxford University Press (OUP)
Date: 09-11-2022
Abstract: The progenitor systems and explosion mechanism of Type Ia supernovae are still unknown. Currently favoured progenitors include double-degenerate systems consisting of two carbon-oxygen white dwarfs with thin helium shells. In the double-detonation scenario, violent accretion leads to a helium detonation on the more massive primary white dwarf that turns into a carbon detonation in its core and explodes it. We investigate the fate of the secondary white dwarf, focusing on changes of the ejecta and observables of the explosion if the secondary explodes as well rather than survives. We simulate a binary system of a $1.05\\, \\mathrm{M_\\odot }$ and a $0.7\\, \\mathrm{M_\\odot }$ carbon-oxygen white dwarf with $0.03\\, \\mathrm{M_\\odot }$ helium shells each. We follow the system self-consistently from inspiral to ignition, through the explosion, to synthetic observables. We confirm that the primary white dwarf explodes self-consistently. The helium detonation around the secondary white dwarf, however, fails to ignite a carbon detonation. We restart the simulation igniting the carbon detonation in the secondary white dwarf by hand and compare the ejecta and observables of both explosions. We find that the outer ejecta at $v~\\gt ~15\\, 000$ km s−1 are indistinguishable. Light curves and spectra are very similar until $\\sim ~40 \\ \\mathrm{d}$ after explosion and the ejecta are much more spherical than violent merger models. The inner ejecta differ significantly slowing down the decline rate of the bolometric light curve after maximum of the model with a secondary explosion by ∼20 per cent. We expect future synthetic 3D nebular spectra to confirm or rule out either model.
Predicting the Presence of Companions for Stripped-envelope Supernovae: The Case of the Broad-lined Type Ic SN 2002ap
Publisher: American Astronomical Society
Date: 22-06-2017
Massive Stellar Mergers as Precursors of Hydrogen-rich Pulsational Pair Instability Supernovae
Publisher: American Astronomical Society
Date: 09-05-2019
LEGACY EXTRAGALACTIC UV SURVEY (LEGUS) WITH THEHUBBLE SPACE TELESCOPE. I. SURVEY DESCRIPTION
Publisher: American Astronomical Society
Date: 15-01-2015
Fluorine in carbon-enhanced metal-poor stars: a binary scenario
Publisher: EDP Sciences
Date: 15-05-2008
Legacy ExtraGalactic UV Survey with TheHubble Space Telescope: Stellar Cluster Catalogs and First Insights Into Cluster Formation and Evolution in NGC 628
Publisher: American Astronomical Society
Date: 05-06-2017
Impact of massive binary star and cosmic evolution on gravitational wave observations I: black hole–neutron star mergers
Publisher: Oxford University Press (OUP)
Date: 23-09-2021
Abstract: Mergers of black hole–neutron star (BHNS) binaries have now been observed by gravitational wave (GW) detectors with the recent announcement of GW200105 and GW200115. Such observations not only provide confirmation that these systems exist but will also give unique insights into the death of massive stars, the evolution of binary systems and their possible association with gamma-ray bursts, r-process enrichment, and kilonovae. Here, we perform binary population synthesis of isolated BHNS systems in order to present their merger rate and characteristics for ground-based GW observatories. We present the results for 420 different model permutations that explore key uncertainties in our assumptions about massive binary star evolution (e.g. mass transfer, common-envelope evolution, supernovae), and the metallicity-specific star formation rate density, and characterize their relative impacts on our predictions. We find intrinsic local BHNS merger rates spanning $\\mathcal {R}_{\\rm {m}}^0 \\approx$ 4–830 $\\, \\rm {Gpc}^{-3}$$\\, \\rm {yr}^{-1}$ for our full range of assumptions. This encompasses the rate inferred from recent BHNS GW detections and would yield detection rates of $\\mathcal {R}_{\\rm {det}} \\approx 1$–180$\\, \\rm {yr}^{-1}$ for a GW network consisting of LIGO, Virgo, and KAGRA at design sensitivity. We find that the binary evolution and metallicity-specific star formation rate density each impacts the predicted merger rates by order $\\mathcal {O}(10)$. We also present predictions for the GW-detected BHNS merger properties and find that all 420 model variations predict that $\\lesssim 5{{\\ \\rm per\\ cent}}$ of the BHNS mergers have BH masses $m_{\\rm {BH}} \\gtrsim 18\\, \\rm {M}_{\\odot }$, total masses $m_{\\rm {tot}} \\gtrsim 20\\, \\rm {M}_{\\odot }$, chirp masses ${\\mathcal {M}}_{\\rm {c}} \\gtrsim 5.5\\, \\rm {M}_{\\odot }$, and mass ratios qf ≳ 12 or qf ≲ 2. Moreover, we find that massive NSs with $m_{\\rm {NS}} \\gt 2\\, \\rm {M}_{\\odot }$ are expected to be commonly detected in BHNS mergers in almost all our model variations. Finally, a wide range of $\\sim 0{{\\ \\rm per\\ cent}}$ to $70{{\\ \\rm per\\ cent}}$ of the BHNS mergers are predicted to eject mass during the merger. Our results highlight the importance of considering variations in binary evolution and cosmological models when predicting, and eventually evaluating, populations of BHNS mergers.
Polluting the Pair-instability Mass Gap for Binary Black Holes through Super-Eddington Accretion in Isolated Binaries
Publisher: American Astronomical Society
Date: 07-07-2020
Controversial age spreads from the main sequence turn-off and red clump in intermediate-age clusters in the LMC
Publisher: EDP Sciences
Date: 02-2016
The Candidate Progenitor Companion Star of the Type Ib/c SN 2013ge
Publisher: American Astronomical Society
Date: 04-2022
Abstract: This Letter presents the detection of a source at the position of the Type Ib/c supernova (SN) 2013ge more than four years after the radioactive component is expected to have faded. This source could mark the first post-SN direct detection of a surviving companion to a stripped-envelope Type Ib/c explosion. We test this hypothesis and find the shape of the source’s spectral energy distribution is most consistent with that of a B5 I supergiant. While binary models tend to predict OB-type stars for stripped-envelope companions, the location of the source on a color–magnitude diagram places it redward of its more likely position on the main sequence (MS). The source may be temporarily out of thermal equilibrium, or a cool and inflated non-MS companion, which is similar to the suggested companion of Type Ib SN 2019yvr that was constrained from pre-SN imaging. We also consider other possible physical scenarios for the source, including a fading SN, circumstellar shock interaction, line-of-sight coincidence, and an unresolved host star cluster, all of which will require future observations to more definitively rule out. Ultimately, the fraction of surviving companions (“binary fraction”) will provide necessary constraints on binary evolution models and the underlying physics.
Rapid Stellar and Binary Population Synthesis with COMPAS
Publisher: American Astronomical Society
Date: 02-2022
Abstract: Compact Object Mergers: Population Astrophysics and Statistics (COMPAS compas.science ) is a public rapid binary population synthesis code. COMPAS generates populations of isolated stellar binaries under a set of parameterized assumptions in order to allow comparisons against observational data sets, such as those coming from gravitational-wave observations of merging compact remnants. It includes a number of tools for population processing in addition to the core binary evolution components. COMPAS is publicly available via the GitHub repository github.com/TeamCOMPAS/COMPAS/ , and is designed to allow for flexible modifications as evolutionary models improve. This paper describes the methodology and implementation of COMPAS. It is a living document that will be updated as new features are added to COMPAS the current document describes COMPAS v02.21.00.
The effects of stellar rotation along the main sequence of the 100-Myr-old massive cluster NGC 1850
Publisher: Oxford University Press (OUP)
Date: 04-11-2022
Abstract: Young star clusters enable us to study the effects of stellar rotation on an ensemble of stars of the same age and across a wide range in stellar mass and are therefore ideal targets for understanding the consequences of rotation on stellar evolution. We combine MUSE spectroscopy with HST photometry to measure the projected rotational velocities (Vsin i) of 2184 stars along the split main sequence and on the main sequence turn-off (MSTO) of the 100 Myr-old massive ($10^5\\, {\\rm M_{\\odot }}$) star cluster NGC 1850 in the Large Magellanic Cloud. At fixed magnitude, we observe a clear correlation between Vsin i and colour, in the sense that fast rotators appear redder. The average Vsin i values for stars on the blue and red branches of the split main sequence are $\\sim \\! 100\\, {\\rm km\\, s^{-1}}$ and $\\sim \\! 200\\, {\\rm km\\, s^{-1}}$, respectively. The values correspond to about $25-30{{\\ \\rm per\\ cent}}$ and $50-60{{\\ \\rm per\\ cent}}$ of the critical rotation velocity and imply that rotation rates comparable to those observed in field stars of similar masses can explain the split main sequence. Our spectroscopic s le contains a rich population of ∼200 fast rotating Be stars. The presence of shell features suggests that 23 per cent of them are observed through their decretion discs, corresponding to a disc opening angle of 15 degrees. These shell stars can significantly alter the shape of the MSTO, hence care should be taken when interpreting this photometric feature. Overall, our findings impact our understanding of the evolution of young massive clusters and provide new observational constraints for testing stellar evolutionary models.
The Redshift Evolution of the Binary Black Hole Merger Rate: A Weighty Matter
Publisher: American Astronomical Society
Date: 05-2022
Abstract: Gravitational-wave detectors are starting to reveal the redshift evolution of the binary black hole (BBH) merger rate, R BBH ( z ). We make predictions for R BBH ( z ) as a function of black hole mass for systems originating from isolated binaries. To this end, we investigate correlations between the delay time and black hole mass by means of the suite of binary population synthesis simulations, COMPAS . We distinguish two channels: the common envelope (CE), and the stable Roche-lobe overflow (RLOF) channel, characterized by whether the system has experienced a common envelope or not. We find that the CE channel preferentially produces BHs with masses below about 30 M ⊙ and short delay times ( t delay ≲ 1 Gyr), while the stable RLOF channel primarily forms systems with BH masses above 30 M ⊙ and long delay times ( t delay ≳ 1 Gyr). We provide a new fit for the metallicity-dependent specific star formation rate density based on the Illustris TNG simulations, and use this to convert the delay time distributions into a prediction of R BBH ( z ). This leads to a distinct redshift evolution of R BBH ( z ) for high and low primary BH masses. We furthermore find that, at high redshift, R BBH ( z ) is dominated by the CE channel, while at low redshift, it contains a large contribution (∼40%) from the stable RLOF channel. Our results predict that, for increasing redshifts, BBHs with component masses above 30 M ⊙ will become increasingly scarce relative to less massive BBH systems. Evidence of this distinct evolution of R BBH ( z ) for different BH masses can be tested with future detectors.
A high fraction of Be stars in young massive clusters: evidence for a large population of near-critically rotating stars
Publisher: Oxford University Press (OUP)
Date: 23-11-2016
Ultra-luminous X-ray sources and neutron-star–black-hole mergers from very massive close binaries at low metallicity
Publisher: EDP Sciences
Date: 08-2017
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Related Funding Activities
ARC Centres Of Excellence - Grant ID: CE230100016
Start Date: 04-2024
End Date: 03-2031
Amount: $35,000,000.00
Funder: Australian Research Council
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