A5035360065- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Adaptive optics and wavefront sensing
- Pulsars and Gravitational Waves Research
- CCD and CMOS Imaging Sensors
- Calibration and Measurement Techniques
- Remote Sensing in Agriculture
- Astronomical Observations and Instrumentation
- Astrophysics and Star Formation Studies
- Impact of Light on Environment and Health
- Color Science and Applications
- Infrared Target Detection Methodologies
- Explainable Artificial Intelligence (XAI)
- Cosmology and Gravitation Theories
- Image Enhancement Techniques
- Advanced Measurement and Metrology Techniques
- Advanced Optical Sensing Technologies
- Ocular and Laser Science Research
- Astrophysical Phenomena and Observations
- Adversarial Robustness in Machine Learning
- Thermography and Photoacoustic Techniques
- Laser-Plasma Interactions and Diagnostics
- Anomaly Detection Techniques and Applications
Swinburne University of Technology
2017-2024
Royal Astronomical Society
2024
ASTRO-3D
2019-2023
ARC Centre of Excellence for All-sky Astrophysics
2019-2023
South African Radio Astronomy Observatory
2007
The GLASS James Webb Space Telescope Early Release Science (hereafter GLASS-JWST-ERS) Program will obtain and make publicly available the deepest extragalactic data of ERS campaign. It is primarily designed to address two key science questions, namely, "what sources ionized universe when?" "how do baryons cycle through galaxies?", while also enabling a broad variety first look scientific investigations. In primary mode, it NIRISS NIRSpec spectroscopy galaxies lensed by foreground Hubble...
Here we present a sample of 12 massive quiescent galaxy candidates at [Formula: see text] observed with the James Webb Space Telescope (JWST) Near Infrared Spectrograph (NIRSpec). These galaxies were pre-selected from Hubble imaging and 10 our sources unable to be spectroscopically confirmed by ground based spectroscopy. By combining spectroscopic data NIRSpec multi-wavelength JWST Camera (NIRCam), analyse their stellar populations formation histories. We find that all classify as on...
Large scale imaging surveys will increase the number of galaxy-scale strong lensing candidates by maybe three orders magnitudes beyond known today. Finding these rare objects require picking them out at least tens millions images and deriving scientific results from quantifying efficiency bias any search method. To achieve objectives automated methods must be developed. Because gravitational lenses are reducing false positives particularly important. We present a description an open lens...
We train and apply convolutional neural networks, a machine learning technique developed to learn from classify image data, Canada–France–Hawaii Telescope Legacy Survey (CFHTLS) imaging for the identification of potential strong lensing systems. An ensemble four networks was trained on images simulated galaxy–galaxy lenses. The training sets consisted total 62 406 lenses 64 673 non-lens negative examples generated with two different methodologies. applied all 171 deg2 CFHTLS wide field...
We search Dark Energy Survey (DES) Year 3 imaging data for galaxy-galaxy strong gravitational lenses using convolutional neural networks. generate 250,000 simulated at redshifts > 0.8 from which we create a set training the networks with realistic seeing, sky and shot noise. Using simulations as guide, build catalogue of 1.1 million DES sources 1.8 < g - i 5, 0.6 -r 3, r_mag 19, g_mag 20 i_mag 18.2. train two ensembles on sets consisting lenses, non-lenses, real sources. use to score images...
We present a rest-frame optical morphological analysis of galaxies observed with the NIRCam imager on James Webb Space Telescope (JWST) as part GLASS-JWST Early Release Science program. select 388 sources at redshifts \(0.8 < z 5.4\) and use seven 0.9--5\micron\ filters to generate $gri$ composite color images, conduct visual classification. Compared HST-based work we find higher incidence disks bulges than expected $z>1.5$, revealed by rest frame imaging. detect 123 clear (58 $z>1.5$) which...
We use the GLASS-JWST Early Release Science NIRCam parallel observations to provide a first view of UV continuum properties NIRCam/F444W selected galaxies at 4<z<7. By combining multiwavelength observations, we constrain slope for sample 401 with stringent quality controls. find that >99% are blue star-forming very low levels dust (Avbeta~0.01+/-0.33). no statistically significant correlation redshift or magnitude. However, in general higher redshifts and fainter magnitudes have steeper...
Abstract We present spectroscopic confirmation of candidate strong gravitational lenses using the Keck Observatory and Very Large Telescope as part our ASTRO 3D Galaxy Evolution with Lenses ( AGEL ) survey. confirm that (1) search methods convolutional neural networks (CNNs) visual inspection successfully identify (2) are at higher redshifts relative to existing surveys due combination deeper higher-resolution imaging from DECam spectroscopy spanning optical near-infrared wavelengths....
Abstract Machine learning (automated processes that learn by example in order to classify, predict, discover, or generate new data) and artificial intelligence (methods which a computer makes decisions discoveries would usually require human intelligence) are now firmly established astronomy. Every week, applications of machine added growing corpus work. Random forests, support vector machines, neural networks having genuine impact for as diverse discovering extrasolar planets, transient...
Abstract We present a first look at the reddest 2–5 μ m sources found in deep images from GLASS Early Release Science program. undertake general search, i.e., not looking for any particular spectral signatures, detected only bands redder than is reachable with Hubble Space Telescope, and which would likely have been identified pre-JWST surveys. search down to AB ∼27 (corresponding >10 σ detection threshold) of F200W F444W filters, >1 magnitude excess relative F090W F150W bands. Fainter...
Gravitational lenses can magnify distant galaxies, allowing us to discover and characterize the stellar populations of intrinsically faint, quiescent galaxies that are otherwise extremely difficult directly observe at high redshift from ground-based telescopes. Here, we present spectral analysis two lensed, $z\gtrsim 1$ discovered by ASTRO 3D Galaxy Evolution with Lenses survey: AGEL1323 ($M_*\sim 10^{11.1}M_{\odot}$, $z=1.016$, $\mu \sim 14.6$) AGEL0014 10^{11.5}M_{\odot}$, $z=1.374$,...
We search Dark Energy Survey (DES) Year 3 imaging for galaxy-galaxy strong gravitational lenses using convolutional neural networks, extending previous work with new training sets and covering a wider range of redshifts colors. train two networks images simulated lenses, then use them to score postage stamp 7.9 million sources from the chosen have plausible lens colors based on simulations. examine 1175 highest-scored candidates identify 152 probable or definite lenses. Examining an...
Recent ground-based deep observations of the Universe have discovered large populations massive quiescent galaxies at z~3-5. With launch James Webb Space Telescope (JWST), on-board NIRSpec instrument will provide continuous 0.6-5.3 $\mu$ m spectroscopic coverage these galaxies. Here we show that NIRSpec/CLEAR spectroscopy is ideal to probe completeness photometrically selected such as ones presented by Schreiber et al. (2018b). Using a subset (2018b) sample with Keck/MOSFIRE Esdaile (2020),...
Abstract We present the formation histories of 19 massive (≳3 × 10 M ⊙ ) quiescent (specific star rate, sSFR < 0.15 Gyr −1 galaxy candidates at z ~ 3.0–4.5 observed using JWST/NIRSpec. This completes spectroscopic confirmation 24 K -selected sample from ZFOURGE and 3DHST surveys. Utilizing Prism 1–5 μ m spectroscopy, we confirm that all 12 sources eluded by ground-based spectroscopy lie > 3, resulting in a spectroscopically confirmed number density ~1.4 −5 Mpc −3 between 3 4....
Near-infrared photometry of 599 stars is used to calculate transformations from the South African Astronomical Observatory (SAAO) JHK system Two-Micron All-Sky Survey (2MASS) S system.Both several-term formal regression relations and simplified are presented.Inverse (i.e.2MASS SAAO) also given.The presence non-linearities in some colour terms highlighted.
ABSTRACT Machine learning photo-z methods, trained directly on spectroscopic redshifts, provide a viable alternative to traditional template-fitting methods but may not generalize well new data that deviates from in the training set. In this work, we present Hybrid Algorithm for WI(Y)de-range estimation with Artificial neural networks and TEmplate fitting (hayate), novel method combines template data-driven approaches whose loss is optimized terms of both redshift point estimates probability...
Abstract The ability to quickly detect transient sources in optical images and trigger multi-wavelength follow up is key for the discovery of fast transients. These include events rare difficult such as kilonovae, supernova shock breakout, ‘orphan’ Gamma-ray Burst afterglows. We present Mary pipeline, a (mostly) automated tool discover transients during high-cadenced observations with Dark Energy Camera at Cerro Tololo Inter-American Observatory (CTIO). are part ‘Deeper Wider Faster’...
The formation of galaxies by gradual hierarchical co-assembly baryons and cold dark matter halos is a fundamental paradigm underpinning modern astrophysics predicts strong decline in the number massive at early cosmic times. Extremely quiescent (stellar masses $>10^{11}$ M$_\odot$) have now been observed as 1-2 billions years after Big Bang; these are extremely constraining on theoretical models they form 300-500 Myr earlier only some can this early. Here we report spectroscopic observations...
ABSTRACT We present a sample of 22 massive galaxies with stellar masses &gt;1010 M⊙ at 3 &lt; z 4 deep H and K-band high resolution spectra (R = 3500–3000) from Keck/MOSFIRE VLT/KMOS near-infrared spectrographs. find large fraction have strong [O iii] 5007 Hβ emission lines line widths (σ 100–450 km s−1). measure the sizes our Hubble Space Telescope images consider potential kinematic scaling relations sample, rule out an explanation for these broad in terms galaxy-wide kinematics....
We present the formation histories of 19 massive ($\gtrsim3\times10^{10}\text{M}_\odot$) quiescent galaxy candidates at $z\sim3.0-4.5$ observed using JWST/NIRSpec. This completes spectroscopic confirmation 24 $K$-selected sample from ZFOURGE and 3DHST surveys \citep{Schreiber2018}. Utilizing Prism $1-5\mu$m spectroscopy, we confirm that all 12 sources eluded by ground-based spectroscopy lie $z>3$, resulting in a spectroscopically confirmed number density $\sim1.4\times10^{-5}\text{Mpc}^{-3}$...
Here we present a sample of 12 massive quiescent galaxy candidates at z~3-4 observed with the James Webb Space Telescope (JWST) Near Infrared Spectrograph (NIRSpec). These galaxies were pre-selected from Hubble imaging and 10 our sources unable to be spectroscopically confirmed by ground based spectroscopy. By combining spectroscopic data NIRSpec multi-wavelength JWST Camera (NIRCam), analyse their stellar populations formation histories. We find that all classify as on reconstruction star...
Abstract We study the kinematics of interstellar medium (ISM) viewed “down barrel” in 20 gravitationally lensed galaxies during cosmic noon ( z = 1.5–3.5). use moderate-resolution spectra R ∼ 4000) from Keck’s Echellette Spectrograph and Imager Magellan/MagE to spectrally resolve ISM absorption these into ∼10 independent elements double Gaussian fits quantify velocity structure gas. find that bulk motion gas this galaxy sample is outflowing, with average centroid <?CDATA $\left\langle...
We use the GLASS-JWST Early Release Science NIRCam parallel observations to provide a first view of UV continuum properties NIRCam/F444W selected galaxies at 499% are blue star-forming with very low levels dust (Avbeta~0.01+/-0.33). find no statistically significant correlation for slope redshift or magnitude. However, we that in general higher redshifts and fainter magnitudes have steeper slopes. stellar mass, mass showing shallower Individual fits some our reach bluest slopes beta~-3.1...