ORCID Profile
0000-0002-3324-4824
Current Organisation
Swinburne University of Technology
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Astronomical sciences | Cosmology and extragalactic astronomy |
Publisher: American Astronomical Society
Date: 26-11-2021
Abstract: We present a follow-up analysis examining the dynamics and structures of 41 massive, large star-forming galaxies at z ∼ 0.67 − 2.45 using both ionized and molecular gas kinematics. We fit the galaxy dynamics with models consisting of a bulge, a thick, turbulent disk, and an NFW dark matter halo, using code that fully forward-models the kinematics, including all observational and instrumental effects. We explore the parameter space using Markov Chain Monte Carlo (MCMC) s ling, including priors based on stellar and gas masses and disk sizes. We fit the full s le using extracted 1D kinematic profiles. For a subset of 14 well-resolved galaxies, we also fit the 2D kinematics. The MCMC approach robustly confirms the results from least-squares fitting presented in Paper I: the s le galaxies tend to be baryon-rich on galactic scales (within one effective radius). The 1D and 2D MCMC results are also in good agreement for the subset, demonstrating that much of the galaxy dynamical information is captured along the major axis. The 2D kinematics are more affected by the presence of noncircular motions, which we illustrate by constructing a toy model with constant inflow for one galaxy that exhibits residual signatures consistent with radial motions. This analysis, together with results from Paper I and other studies, strengthens the finding that massive, star-forming galaxies at z ∼ 1 − 2 are baryon-dominated on galactic scales, with lower dark matter fractions toward higher baryonic surface densities. Finally, we present details of the kinematic fitting code used in this analysis.
Publisher: Public Library of Science (PLoS)
Date: 17-07-2019
Publisher: AIP Publishing
Date: 2019
DOI: 10.1063/1.5110134
Publisher: EDP Sciences
Date: 05-2021
DOI: 10.1051/0004-6361/202039704
Abstract: We present new Atacama Large Millimeter/Submillimeter Array observations of the [C II ] 158 μm transition and the dust continuum in HZ4, a typical star-forming galaxy when the Universe was only ∼1 Gyr old ( z ≈ 5.5). Our high ≈0.3″ spatial resolution allows us to study the relationships between [C II ] line emission, star formation rate, and far-infrared emission on spatial scales of ∼2 kpc. In the central ∼4 kpc of HZ4, the [C II ]/FIR is ∼3 × 10 −3 on global scales as well as on spatially resolved scales of ∼2 kpc, comparable to the ratio observed in local moderate starburst galaxies such as M 82 or M 83. For the first time in an in idual normal galaxy at this redshift, we find evidence for outflowing gas from the central star-forming region in the direction of the minor axis of the galaxy. The projected velocity of the outflow is ∼400 km s −1 , and the neutral gas-mass outflow rate is ∼3 − 6 times higher than the star formation rate in the central region. Finally, we detect a diffuse component of [C II ] emission, or [C II ] halo, that extends beyond the star-forming disk and has a diameter of ∼12 kpc. The outflow, which has a velocity approximately half of the escape velocity of the system, most likely partly fuels the [C II ] extended emission. Together with the kinematic analysis of HZ4 (presented in a forthcoming paper), the analysis supports the hypothesis that HZ4 is a typical star-forming disk at z ∼ 5 with interstellar medium conditions similar to present-day galaxies forming stars at a similar level, driving a galactic outflow that may already play a role in its evolution.
Publisher: American Astronomical Society
Date: 02-03-2015
Publisher: EDP Sciences
Date: 09-2022
DOI: 10.1051/0004-6361/202142562
Abstract: We present a kinematic analysis of the main-sequence galaxy HZ4 at z = 5.5. Our study is based on deep, spatially resolved observations of the [C II ] 158 μm transition obtained with the Atacama Large Millimeter/Submillimeter Array (ALMA). From the combined analysis of the disk morphology, the 2D velocity structure, and forward modeling of the 1D velocity and velocity dispersion profiles, we conclude that HZ4 has a regular rotating disk in place. The intrinsic velocity dispersion in HZ4 is high ( σ 0 = 65.8 −3.3 +2.9 km s −1 ), and the ratio between the rotational velocity and the intrinsic velocity dispersion is V rot / σ 0 = 2.2. These values are consistent with the expectations from the trends of increasing σ 0 and decreasing V rot / σ 0 as a function of the redshift observed in main-sequence galaxies up to z ≈ 4. Galaxy evolution models suggest that the high level of turbulence observed in HZ4 can only be achieved if, in addition to stellar feedback, there is radial transport of gas within the disk. Finally, we find that HZ4 is baryon-dominated on galactic scales (≲2 × R e ), with a dark-matter fraction at one effective radius of f DM ( R e ) = 0.41 −0.22 +0.25 . This value is comparable to the dark-matter fractions found in lower redshift galaxies that could be the descendants of HZ4: massive ( M ⋆ ≈ 10 11 M ⊙ ), star-forming galaxies at z ∼ 2, and passive, early-type galaxies at z ≈ 0.
Publisher: American Astronomical Society
Date: 28-11-2019
Publisher: Oxford University Press (OUP)
Date: 27-03-2017
DOI: 10.1093/MNRAS/STX727
Publisher: American Astronomical Society
Date: 07-2023
Abstract: Luminous quasars are powerful targets to investigate the role of feedback from supermassive black holes (BHs) in regulating the growth phases of BHs themselves and of their host galaxies, up to the highest redshifts. Here we investigate the cosmic evolution of the occurrence and kinematics of BH-driven outflows, as traced by broad absorption line (BAL) features, due to the C iv ionic transition. We exploit a s le of 1935 quasars at z = 2.1–6.6 with bolometric luminosity log( L bol /erg s −1 ) ≳ 46.5, drawn from the Sloan Digital Sky Survey and from the X-Shooter legacy survey of Quasars at the Reionization Epoch (XQR-30). We consider rest-frame optical bright quasars to minimize observational biases due to quasar selection criteria. We apply a homogeneous BAL-identification analysis, based on employing composite template spectra to estimate the quasar intrinsic emission. We find a BAL quasar fraction close to 20% at z ∼ 2–4, while it increases to almost 50% at z ∼ 6. The velocity and width of the BAL features also increase at z ≳ 4.5. We exclude the possibility that the redshift evolution of the BAL properties is due to differences in terms of quasar luminosity and accretion rate. These results suggest significant BH feedback occurring in the 1 Gyr old universe, likely affecting the growth of BHs and, possibly, of their host galaxies, as supported by models of early BH and galaxy evolution.
Publisher: Oxford University Press (OUP)
Date: 25-03-2015
DOI: 10.1093/MNRAS/STV343
Publisher: American Astronomical Society
Date: 12-03-2018
Publisher: American Astronomical Society
Date: 10-10-2017
Publisher: Oxford University Press (OUP)
Date: 18-09-2014
Publisher: Cambridge University Press (CUP)
Date: 2016
DOI: 10.1017/PASA.2016.47
Abstract: This paper presents the first major data release and survey description for the ANU WiFeS SuperNovA Programme. ANU WiFeS SuperNovA Programme is an ongoing supernova spectroscopy c aign utilising the Wide Field Spectrograph on the Australian National University 2.3-m telescope. The first and primary data release of this programme (AWSNAP-DR1) releases 357 spectra of 175 unique objects collected over 82 equivalent full nights of observing from 2012 July to 2015 August. These spectra have been made publicly available via the WISEREP supernova spectroscopy repository. We analyse the ANU WiFeS SuperNovA Programme s le of Type Ia supernova spectra, including measurements of narrow sodium absorption features afforded by the high spectral resolution of the Wide Field Spectrograph instrument. In some cases, we were able to use the integral-field nature of the Wide Field Spectrograph instrument to measure the rotation velocity of the SN host galaxy near the SN location in order to obtain precision sodium absorption velocities. We also present an extensive time series of SN 2012dn, including a near-nebular spectrum which both confirms its ‘super-Chandrasekhar’ status and enables measurement of the sub-solar host metallicity at the SN site.
Publisher: Springer Science and Business Media LLC
Date: 11-05-2022
DOI: 10.1038/S41586-022-04608-1
Abstract: Bright quasars, powered by accretion onto billion-solar-mass black holes, already existed at the epoch of reionization, when the Universe was 0.5-1 billion years old
Publisher: AIP Publishing LLC
Date: 2015
DOI: 10.1063/1.4937705
Publisher: American Astronomical Society
Date: 25-09-2023
Publisher: Oxford University Press (OUP)
Date: 16-02-2016
DOI: 10.1093/MNRAS/STW287
Publisher: American Astronomical Society
Date: 06-2022
Abstract: We present a new investigation of the intergalactic medium near reionization using dark gaps in the Ly β forest. With its lower optical depth, Ly β offers a potentially more sensitive probe to any remaining neutral gas compared to the commonly used Ly α line. We identify dark gaps in the Ly β forest using spectra of 42 QSOs at z em 5.5, including new data from the XQR-30 VLT Large Programme. Approximately 40% of these QSO spectra exhibit dark gaps longer than 10 h −1 Mpc at z ≃ 5.8. By comparing the results to predictions from simulations, we find that the data are broadly consistent both with models where fluctuations in the Ly α forest are caused solely by ionizing ultraviolet background fluctuations and with models that include large neutral hydrogen patches at z 6 due to a late end to reionization. Of particular interest is a very long ( L = 28 h −1 Mpc) and dark ( τ eff ≳ 6) gap persisting down to z ≃ 5.5 in the Ly β forest of the z = 5.85 QSO PSO J025−11. This gap may support late reionization models with a volume-weighted average neutral hydrogen fraction of 〈 x H I 〉 ≳ 5% by z = 5.6. Finally, we infer constraints on 〈 x H I 〉 over 5.5 ≲ z ≲ 6.0 based on the observed Ly β dark gap length distribution and a conservative relationship between gap length and neutral fraction derived from simulations. We find 〈 x H I 〉 ≤ 0.05, 0.17, and 0.29 at z ≃ 5.55, 5.75, and 5.95, respectively. These constraints are consistent with models where reionization ends significantly later than z = 6.
Publisher: American Astronomical Society
Date: 24-03-2015
Publisher: Wiley
Date: 08-12-2023
DOI: 10.1111/JPC.16305
Abstract: To describe the epidemiology and clinical profile of children and adolescents with acute rheumatic fever (ARF) and rheumatic heart disease (RHD) in Victoria, Australia. A retrospective audit was undertaken of children and adolescents with ARF and RHD attending the Royal Children's and Monash Children's Hospitals in Victoria, Australia between 2010 and 2019. Potential cases were identified by searching multiple sources for relevant ICD‐10‐AM codes and keywords, then reviewed manually. For confirmed cases, we collected data on patient demographics, clinical features, comorbidities and management. Of 179 participants included, there were 108 Victorian residents and 71 non‐Victorian residents. 126 had at least one episode of ARF during the study period and 128 were diagnosed with RHD. In the Victorian resident group, the overall incidence of ARF was 0.8 per 100 000 5–14 year olds. This incidence was higher in Victorian Aboriginal and/or Torres Strait Islander (3.8 per 100 000) and Pacific Islander (32.1 per 100 000) sub‐populations. Of 83 Victorian residents who had an ARF episode, 11 (13%) had a recurrence. Most Victorian residents with RHD had mixed aortic and mitral valve pathology (69.4%) and moderate to severe disease (61.9%). Most non‐Victorian residents were Aboriginal and/or Torres Strait Islander people (80.3%) and were commonly transferred for tertiary or surgical management of RHD (83.1%). ARF and RHD continue to affect the health of significant numbers of children and adolescents living in Victoria, including severe and recurrent disease. Specialised services and a register‐based control program may help to prevent complications and premature death.
Publisher: American Astronomical Society
Date: 03-2021
Abstract: We present a detailed study of the molecular gas content and stellar population properties of three massive galaxies at 1 z 1.3 that are in different stages of quenching. The galaxies were selected to have quiescent optical/near-infrared spectral energy distribution and relatively bright emission at 24 μ m, and show remarkably erse properties. CO emission from each of the three galaxies is detected in deep NOEMA observations, allowing us to derive molecular gas fractions M gas / M * of 13%–23%. We also reconstruct the star formation histories by fitting models to the observed photometry and optical spectroscopy, finding evidence for recent rejuvenation in one object, slow quenching in another, and rapid quenching in the third system. To better constrain the quenching mechanism we explore the depletion times for our s le and other similar s les at z ∼ 0.7 from the literature. We find that the depletion times are highly dependent on the method adopted to measure the star formation rate: using the UV+IR luminosity we obtain depletion times about 6 times shorter than those derived using dust-corrected [O ii ] emission. When adopting the star formation rates from spectral fitting, which are arguably more robust, we find that recently quenched galaxies and star-forming galaxies have similar depletion times, while older quiescent systems have longer depletion times. These results offer new, important constraints for physical models of galaxy quenching.
Publisher: Oxford University Press (OUP)
Date: 08-06-2017
Publisher: American Astronomical Society
Date: 16-01-2019
Publisher: American Astronomical Society
Date: 15-10-2020
Publisher: American Astronomical Society
Date: 03-2021
Abstract: We investigate what drives the redshift evolution of the typical electron density ( n e ) in star-forming galaxies, using a s le of 140 galaxies drawn primarily from KMOS 3D (0.6 z 2.6) and 471 galaxies from SAMI ( z 0.113). We select galaxies that do not show evidence of active galactic nucleus activity or outflows to constrain the average conditions within H ii regions. Measurements of the [S ii ] λ 6716/[S ii ] λ 6731 ratio in four redshift bins indicate that the local n e in the line-emitting material decreases from 187 cm −3 at z ∼ 2.2 to 32 cm −3 at z ∼ 0, consistent with previous results. We use the H α luminosity to estimate the rms n e averaged over the volumes of star-forming disks at each redshift. The local and volume-averaged n e evolve at similar rates, hinting that the volume filling factor of the line-emitting gas may be approximately constant across 0 ≲ z ≲ 2.6. The KMOS 3D and SAMI galaxies follow a roughly monotonic trend between n e and star formation rate, but the KMOS 3D galaxies have systematically higher n e than the SAMI galaxies at a fixed offset from the star-forming main sequence, suggesting a link between the n e evolution and the evolving main sequence normalization. We quantitatively test potential drivers of the density evolution and find that n e (rms) , suggesting that the elevated n e in high- z H ii regions could plausibly be the direct result of higher densities in the parent molecular clouds. There is also tentative evidence that n e could be influenced by the balance between stellar feedback, which drives the expansion of H ii regions, and the ambient pressure, which resists their expansion.
Publisher: American Astronomical Society
Date: 24-07-2019
Publisher: Oxford University Press (OUP)
Date: 28-07-2016
Publisher: Public Library of Science (PLoS)
Date: 30-09-2021
DOI: 10.1371/JOURNAL.PONE.0258039
Abstract: Soil-transmitted helminths (STH) infect up to one-quarter of the global population, with a significant associated disease burden. The main human STH are: Ancylostoma spp. and Necator americanus (hookworms) Ascaris lumbricoides , Trichuris trichiura , and Strongyloides stercoralis . The aim of this study was to establish a scalable system for stool STH multiplex quantitative real-time polymerase chain reactions (qPCR). Stool s les collected in Fiji and preserved in potassium dichromate were transferred to Melbourne at ambient temperature. S les were washed to remove potassium dichromate and DNA was extracted with the Mini-Beadbeater-24 and a column-based kit. A SYBR green qPCR to detect the vertebrate mitochondrial gene was used as a DNA extraction control. S les were tested using a probe-based multiplex qPCR targeting A . lumbricoides , T . trichiura and S . stercoralis , and in a second multiplex reaction to detect hookworms to the species level ( A . duodenale , A . ceylanicum , N . americanus ). An internal lification control in both multiplex assays was included to prevent false-negative results due to PCR inhibitors. S les were homogenised for a single cycle of 40 seconds to release STH DNA and washed stool was stored for up to 15 weeks at -30°C without compromising DNA. Our multiplex qPCR detected multiple species of STH without reduced sensitivity compared to singleplex. qPCR data from 40 stools was validated against STH-positive stools determined by microscopy. We have developed and validated an efficient and staged system for detecting six clinically important STH affecting humans that could be easily implemented without advanced automation in any qPCR-capable laboratory.
Publisher: American Geophysical Union (AGU)
Date: 29-12-2021
DOI: 10.1029/2021GL094051
Abstract: The tropical Pacific influences climate patterns across the globe, yet robust constraints on decadal to centennial‐scale climate variations are difficult to extract from sparse instrumental observations in this region. Oxygen isotope (δ 18 O) records from long‐lived corals enable the quantitative reconstruction of tropical Pacific climate variability and trends over the twentieth century and beyond, but such corals are exceedingly rare. Here, we use multiple short coral δ 18 O records to create a coral ‘ensemble’ reconstruction of twentieth century climate in the central tropical Pacific. Ten U/Th‐dated fossil coral δ 18 O records from Kiritimati Island (2°N, 157°W) span 1891 CE to 2006 CE, with the younger s les enabling quantitative comparison to a large ensemble of modern coral records and instrumental sea surface temperature. A composite record constructed of modern and fossil Kiritimati coral δ 18 O records shows a shift toward warmer and fresher conditions from 1970 CE onward, consistent with previously published records in this region.
Publisher: Springer International Publishing
Date: 2016
Publisher: Oxford University Press (OUP)
Date: 03-05-2023
Abstract: Proximity zones of high-redshift quasars are unique probes of their central supermassive black holes as well as the intergalactic medium (IGM) in the last stages of reionization. We present 22 new measurements of proximity zones of quasars with redshifts between 5.8 and 6.6, using the enlarged XQR-30 s le of high-resolution, high-SNR quasar spectra. The quasars in our s le have ultraviolet magnitudes of M1450 ∼ −27 and black hole masses of 109–1010 M⊙. Our inferred proximity zone sizes are 2–7 physical Mpc, with a typical uncertainty of less than 0.5 physical Mpc, which, for the first time, also includes uncertainty in the quasar continuum. We find that the correlation between proximity zone sizes and the quasar redshift, luminosity, or black hole mass, indicates a large ersity of quasar lifetimes. Two of our proximity zone sizes are exceptionally small. The spectrum of one of these quasars, with z = 6.02, displays, unusually for this redshift, d ing wing absorption without any detectable metal lines, which could potentially originate from the IGM. The other quasar has a high-ionization absorber ∼0.5 pMpc from the edge of the proximity zone. This work increases the number of proximity zone measurements available in the last stages of cosmic reionization to 87. This data will lead to better constraints on quasar lifetimes and obscuration fractions at high redshift, that in turn will help probe the seed mass and formation redshift of supermassive black holes.
Publisher: American Astronomical Society
Date: 09-04-2019
Publisher: Informa UK Limited
Date: 02-10-2014
Publisher: Oxford University Press (OUP)
Date: 07-06-2022
Abstract: The presence of excess scatter in the Ly-α forest at z ∼ 5.5, together with the existence of sporadic extended opaque Gunn-Peterson troughs, has started to provide robust evidence for a late end of hydrogen reionization. However, low data quality and systematic uncertainties complicate the use of Ly-α transmission as a precision probe of reionization’s end stages. In this paper, we assemble a s le of 67 quasar sightlines at z & 5.5 with high signal-to-noise ratios of & per ≤15 km s−1 spectral pixel, relying largely on the new XQR-30 quasar s le. XQR-30 is a large program on VLT/X-Shooter which obtained deep (SNR & 20 per pixel) spectra of 30 quasars at z & 5.7. We carefully account for systematics in continuum reconstruction, instrumentation, and contamination by d ed Ly-α systems. We present improved measurements of the mean Ly-α transmission over 4.9 & z & 6.1. Using all known systematics in a forward modelling analysis, we find excellent agreement between the observed Ly-α transmission distributions and the homogeneous-UVB simulations Sherwood and Nyx up to z ≤ 5.2 (& σ), and mild tension (∼2.5σ) at z = 5.3. Homogeneous UVB models are ruled out by excess Ly-α transmission scatter at z ≥ 5.4 with high confidence (& .5σ). Our results indicate that reionization-related fluctuations, whether in the UVB, residual neutral hydrogen fraction, and/or IGM temperature, persist in the intergalactic medium until at least z = 5.3 (t = 1.1 Gyr after the big bang). This is further evidence for a late end to reionization.
Publisher: Oxford University Press (OUP)
Date: 02-03-2023
Abstract: Intervening metal absorption lines in the spectra of z ≳ 6 quasars are fundamental probes of the ionization state and chemical composition of circumgalactic and intergalactic gas near the end of the reionization epoch. Large absorber s les are required to robustly measure typical absorber properties and to refine models of the synthesis, transport, and ionization of metals in the early Universe. The Ultimate XSHOOTER legacy survey of quasars at z ∼ 5.8–6.6 (XQR-30) has obtained high signal-to-noise spectra of 30 luminous quasars, nearly quadrupling the existing s le of 12 high quality z ∼ 6 quasar spectra. We use this unprecedented s le to construct a catalogue of 778 systems showing absorption in one or more of Mg ii (360 systems), Fe ii (184), C ii (46), C iv (479), Si iv (127), and N v (13) which span 2 ≲ z ≲ 6.5. This catalogue significantly expands on existing s les of z ≳ 5 absorbers, especially for C iv and Si iv which are important probes of the ionizing photon background at high redshift. The s le is 50 per cent (90 per cent) complete for rest-frame equivalent widths W ≳ 0.03 Å (0.09 Å). We publicly release the absorber catalogue along with completeness statistics and a python script to compute the absorption search path for different ions and redshift ranges. This data set is a key legacy resource for studies of enriched gas from the era of galaxy assembly to cosmic noon, and paves the way for even higher redshift studies with JWST and 30 m-class telescopes.
Publisher: Oxford University Press (OUP)
Date: 12-10-0001
Abstract: We report on our combined analysis of HST, VLT/MUSE, VLT/SINFONI, and ALMA observations of the local Seyfert 2 galaxy, NGC 5728 to investigate in detail the feeding and feedback of the active galactic nucleus (AGN). The data sets simultaneously probe the morphology, excitation, and kinematics of the stars, ionized gas, and molecular gas over a large range of spatial scales (10 pc to 10 kpc). NGC 5728 contains a large stellar bar that is driving gas along prominent dust lanes to the inner 1 kpc where the gas settles into a circumnuclear ring. The ring is strongly star forming and contains a substantial population of young stars as indicated by the lowered stellar velocity dispersion and gas excitation consistent with H ii regions. We model the kinematics of the ring using the velocity field of the CO (2–1) emission and stars and find it is consistent with a rotating disc. The outer regions of the disc, where the dust lanes meet the ring, show signatures of inflow at a rate of 1 M$\\odot$ yr−1. Inside the ring, we observe three molecular gas components corresponding to the circular rotation of the outer ring, a warped disc, and the nuclear stellar bar. The AGN is driving an ionized gas outflow that reaches a radius of 250 pc with a mass outflow rate of 0.08 M$\\odot$ yr−1 consistent with its luminosity and scaling relations from previous studies. While we observe distinct holes in CO emission which could be signs of molecular gas removal, we find that largely the AGN is not disrupting the structure of the circumnuclear region.
Publisher: Oxford University Press (OUP)
Date: 02-03-2023
Abstract: Intervening C iv absorbers are key tracers of metal-enriched gas in galaxy haloes over cosmic time. Previous studies suggest that the C iv cosmic mass density ($\\Omega _{\\rm C \\, \\small {IV}}$) decreases slowly over 1.5 $\\lesssim \\, z\\lesssim$ 5 before declining rapidly at z ≳ 5, but the cause of this downturn is poorly understood. We characterize the $\\Omega _{\\rm C \\, \\small {IV}}$ evolution over 4.3 ≲ z ≲ 6.3 using 260 absorbers found in 42 XSHOOTER spectra of z ∼ 6 quasars, of which 30 come from the ESO Large Program XQR-30. The large s le enables us to robustly constrain the rate and timing of the downturn. We find that $\\Omega _{\\rm C \\, \\small {IV}}$ decreases by a factor of 4.8 ± 2.0 over the ∼300 Myr interval between z ∼ 4.7 and ∼5.8. The slope of the column density (log N) distribution function does not change, suggesting that C iv absorption is suppressed approximately uniformly across 13.2 ≤ log N/cm−2 & 15.0. Assuming that the carbon content of galaxy haloes evolves as the integral of the cosmic star formation rate density (with some delay due to stellar lifetimes and outflow travel times), we show that chemical evolution alone could plausibly explain the fast decline in $\\Omega _{\\rm C \\, \\small {IV}}$ over 4.3 ≲ z ≲ 6.3. However, the C iv/C ii ratio decreases at the highest redshifts, so the accelerated decline in $\\Omega _{\\rm C \\, \\small {IV}}$ at z ≳ 5 may be more naturally explained by rapid changes in the gas ionization state driven by evolution of the UV background towards the end of hydrogen reionization.
Publisher: Oxford University Press (OUP)
Date: 05-12-2022
Abstract: This paper presents deep K-band spectroscopic observations of galaxies at z = 3 − 4 with composite photometric rest-frame H β+[O iii] 5007 equivalent widths (EW0) & 600 Å, comparable to the EW of galaxies observed during the epoch of reionization (EoR, z & 6). The typical spectroscopic [O iii] 5007 EW0 and stellar mass of our targets is ∼700 Å and log (M*/M⊙) = 8.98. By stacking the [O iii] 5007 emission profiles, we find evidence of a weak broad component with $\\rm F_{broad}/F_{narrow} \\sim 0.2$ and velocity width σbroad ∼ 170 km s−1. The strength and velocity width of the broad component does not change significantly with stellar mass and [O iii] 5007 EW0 of the stacked s le. Assuming similar broad component profiles for [O iii] 5007 and Hα emission, we estimate a mass loading factor ∼0.2, similar to low stellar mass galaxies at z & 1 even if the star formation rates of our s le is 10 times higher. We hypothesize that either the multiphase nature of supernovae driven outflows or the suppression of winds in the extreme star-forming regime is responsible for the weak signature of outflows in the EoR analogues.
Publisher: American Astronomical Society
Date: 2023
Abstract: We present a high-resolution kinematic study of the massive main-sequence star-forming galaxy (SFG) SDSS J090122.37+181432.3 (J0901) at z = 2.259, using ∼0.″36 Atacama Large Millimeter/submillimeter Array CO(3–2) and ∼0.″1–0.″5 SINFONI/VLT H α observations. J0901 is a rare, strongly lensed but otherwise normal massive ( log ( M ⋆ / M ⊙ ) ∼ 11 ) main-sequence SFG, offering a unique opportunity to study a typical massive SFG under the microscope of lensing. Through forward dynamical modeling incorporating lensing deflection, we fit the CO and H α kinematics in the image plane out to about one disk effective radius ( R e ∼ 4 kpc) at an ∼600 pc delensed physical resolution along the kinematic major axis. Our results show high intrinsic dispersions of the cold molecular and warm ionized gas ( σ 0,mol. ∼ 40 km s −1 and σ 0,ion. ∼ 66 km s −1 ) that remain constant out to R e a moderately low dark matter fraction ( f DM ∼ 0.3–0.4) within R e and a centrally peaked Toomre Q parameter—agreeing well with the previously established σ 0 versus z , f DM versus Σ baryon , and Q 's radial trends using large-s le non-lensed main-sequence SFGs. Our data further reveal a high stellar mass concentration within ∼1–2 kpc with little molecular gas, and a clumpy molecular gas ring-like structure at R ∼ 2–4 kpc, in line with the inside-out quenching scenario. Our further analysis indicates that J0901 had assembled half of its stellar mass only ∼400 Myr before its observed cosmic time, and the cold gas ring and dense central stellar component are consistent with signposts of a recent wet compaction event of a highly turbulent disk found in recent simulations.
Publisher: American Astronomical Society
Date: 17-05-2017
Publisher: American Astronomical Society
Date: 19-03-2020
Publisher: Oxford University Press (OUP)
Date: 04-03-2014
DOI: 10.1093/MNRAS/STU234
Publisher: American Astronomical Society
Date: 02-2022
Abstract: There is growing evidence for physical influence between supermassive black holes and their host galaxies. We present a case study of the nearby galaxy NGC 7582, for which we find evidence that galactic substructure plays an important role in affecting the collimation of ionized outflows as well as contributing to the heavy active galactic nucleus (AGN) obscuration. This result contrasts with a simple, small-scale AGN torus model, according to which AGN-wind collimation may take place inside the torus itself, at subparsec scales. Using 3D spectroscopy with the Multi Unit Spectroscopic Explorer instrument, we probe the kinematics of the stellar and ionized gas components as well as the ionization state of the gas from a combination of emission-line ratios. We report for the first time a kinematically distinct core (KDC) in NGC 7582, on a scale of ∼600 pc. This KDC coincides spatially with dust lanes and starbursting complexes previously observed. We interpret it as a circumnuclear ring of stars and dusty, gas-rich material. We obtain a clear view of the outflowing cones over kiloparsec scales and demonstrate that they are predominantly photoionized by the central engine. We detect the back cone (behind the galaxy) and confirm previous results of a large nuclear obscuration of both the stellar continuum and H ii regions. While we tentatively associate the presence of the KDC with a large-scale bar and/or a minor galaxy merger, we stress the importance of gaining a better understanding of the role of galaxy substructure in controlling the fueling, feedback, and obscuration of AGNs.
Publisher: Cambridge University Press (CUP)
Date: 07-2014
DOI: 10.1017/S1743921314009661
Abstract: Here we present the first results from the Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7) which aims to investigate the physics of ∼140 radio-detected southern active Galaxies with z .02 through Integral Field Spectroscopy using the Wide Field Spectrograph (WiFeS). This instrument provides data cubes of the central 38×25 arc sec. of the target galaxies in the waveband 340–710nm with the unusually high resolution of R =7000 in the red (530–710nm), and R =3000 in the blue (340–560nm). These data provide the morphology, kinematics and the excitation structure of the extended narrow-line region, probe relationships with the black hole characteristics and the host galaxy, measures host galaxy abundance gradients and the determination of nuclear abundances from the HII regions. From photoionisation modelling, we may determine the shape of the ionising spectrum of the AGN, discover whether AGN metallicities differ from nuclear abundances determined from HII regions, and probe grain destruction in the vicinity of the AGN. Here we present some preliminary results and modelling of both Seyfert galaxies observed as part of the survey.
Publisher: Oxford University Press (OUP)
Date: 27-06-2017
Publisher: Oxford University Press (OUP)
Date: 20-07-2016
Publisher: American Astronomical Society
Date: 10-06-2016
Publisher: EDP Sciences
Date: 06-2014
Publisher: American Astronomical Society
Date: 13-03-2019
Publisher: American Astronomical Society
Date: 05-2020
Publisher: EDP Sciences
Date: 10-2018
DOI: 10.1051/0004-6361/201832790
Abstract: Context . Although studying outflows in the host galaxies of active galactic nuclei (AGNs) have moved to the forefront of extragalactic astronomy in recent years, estimating the energy associated with these outflows has been a major challenge. Determining the energy associated with an outflow often involves an assumption of uniform density in the narrow line region (NLR), which spans a wide range in the literature, leading to large systematic uncertainties in energy estimation. Aims . In this paper we present electron density maps for a s le of outflowing and non-outflowing Seyfert galaxies at z 0.02 drawn from the Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7) and try to understand the origin and values of the observed density structures to reduce the systematic uncertainties in outflow energy estimation. Methods . We use the ratio of the [S II ] λ 6716,6731 emission lines to derive spatially resolved electron densities (≲50–2000 cm −3 ). Using optical Integral Field Unit observations from the Wide Field Spectrograph (WiFeS), we are able to measure densities across the central 2–5 kpc of the selected AGN host galaxies. We compare the density maps with the positions of the H II regions derived from the narrow H α component, ionization maps from [O III ] and spatially resolved BPT diagrams to infer the origin of the observed density structures. We also use the electron density maps to construct density profiles as a function of distance from the central AGN. Results . We find a spatial correlation between the sites of high star formation and high electron density for targets without an active ionized outflow. The non-outflowing targets also show an exponential drop in the electron density as a function of distance from the centre, with a mean exponential index of ∼0.15. The correlation between the star forming sites and electron density ceases for targets with an outflow. The density within the outflowing medium is not uniform and shows both low- and high-density sites, most likely due to the presence of shocks and highly turbulent medium. We compare these results in the context of previous results obtained from fibre and slit spectra.
Publisher: Springer Science and Business Media LLC
Date: 08-04-2008
Abstract: Rheumatic heart disease (RHD) is an important problem in developing countries however, many cases are detected only when the disease has progressed to cardiac failure. Screening can detect cases earlier, but there are no screening guidelines. We performed a cross-sectional screening study in Tonga among 5,053 primary school children, in whom auscultation followed by echocardiography of those with heart murmurs were used to identify RHD. We also analyzed whether a three-stage screening protocol of auscultation performed by a medical student to detect any heart murmur, second-stage auscultation performed by a local pediatrician to differentiate pathological from innocent murmurs and echocardiography of those with pathological murmurs altered outcomes. The prevalence of definite RHD was 33.2 per 1,000. The prevalence of RHD increased significantly with age, peaking at 42.6 per 1,000 in children aged 10-12 years. Most valve lesions (91 [54%] of 169) were mild. Auscultation to detect pathological murmurs was poorly sensitive (46.4%), and the finding of any murmur on auscultation did not affect the likelihood of detecting pathology on echocardiography. The finding of a pathological murmur did significantly increase the likelihood of detecting pathology on echocardiography, but still missed 54% of those with pathology (mainly RHD) detected on echocardiography. Screening is a useful method for detecting asymptomatic RHD in regions of high prevalence and we report a high echocardiographically confirmed prevalence. The most appropriate screening strategy remains to be confirmed, however, and implementation will depend on the availability of echocardiography and trained staff.
Publisher: Public Library of Science (PLoS)
Date: 10-11-2021
DOI: 10.1371/JOURNAL.PMED.1003849
Abstract: Scabies is a neglected tropical disease hyperendemic to many low- and middle-income countries. Scabies can be successfully controlled using mass drug administration (MDA) using 2 doses of ivermectin-based treatment. If effective, a strategy of 1-dose ivermectin-based MDA would have substantial advantages for implementing MDA for scabies at large scale. We did a cluster randomised, noninferiority, open-label, 3-group unblinded study comparing the effectiveness of control strategies on community prevalence of scabies at 12 months. All residents from 35 villages on 2 Fijian islands were eligible to participate. Villages were randomised 1:1:1 to 2-dose ivermectin-based MDA (IVM-2), 1-dose ivermectin-based MDA (IVM-1), or screen and treat with topical permethrin 5% for in iduals with scabies and their household contacts (SAT). All groups also received diethylcarbamazine and albendazole for lymphatic filariasis control. For IVM-2 and IVM-1, oral ivermectin was dosed at 200 μg/kg and when contraindicated substituted with permethrin. We designated a noninferiority margin of 5%. We enrolled 3,812 participants at baseline (July to November 2017) from the 35 villages with median village size of 108 (range 18 to 298). Age and sex of participants were representative of the population with 51.6% male and median age of 25 years (interquartile range 10 to 47). We enrolled 3,898 at 12 months (July to November 2018). At baseline, scabies prevalence was similar in all groups: IVM-2: 11.7% (95% confidence interval (CI) 8.5 to 16.0) IVM-1: 15.2% (95% CI 9.4 to 23.8) SAT: 13.6% (95% CI 7.9 to 22.4). At 12 months, scabies decreased substantially in all groups: IVM-2: 1.3% (95% CI 0.6 to 2.5) IVM-1: 2.7% (95% CI 1.1 to 6.5) SAT: 1.1% (95% CI 0.6 to 2.0). The risk difference in scabies prevalence at 12 months between the IVM-1 and IVM-2 groups was 1.2% (95% CI −0.2 to 2.7, p = 0.10). Limitations of the study included the method of scabies diagnosis by nonexperts, a lower baseline prevalence than anticipated, and the addition of diethylcarbamazine and albendazole to scabies treatment. All 3 strategies substantially reduced prevalence. One-dose was noninferior to 2-dose ivermectin-based MDA, as was a screen and treat approach, for community control of scabies. Further trials comparing these approaches in varied settings are warranted to inform global scabies control strategies. Clinitrials.gov NCT03177993 and ANZCTR N12617000738325 .
Publisher: Public Library of Science (PLoS)
Date: 24-06-2019
Publisher: Oxford University Press (OUP)
Date: 18-05-2023
Abstract: The final phase of the reionization process can be probed by rest-frame UV absorption spectra of quasars at z ≳ 6, shedding light on the properties of the diffuse intergalactic medium within the first Gyr of the Universe. The ESO Large Programme ‘XQR-30: the ultimate XSHOOTER legacy survey of quasars at z ≃ 5.8–6.6’ dedicated ∼250 h of observations at the VLT to create a homogeneous and high-quality s le of spectra of 30 luminous quasars at z ∼ 6, covering the rest wavelength range from the Lyman limit to beyond the Mg ii emission. Twelve quasar spectra of similar quality from the XSHOOTER archive were added to form the enlarged XQR-30 s le, corresponding to a total of ∼350 h of on-source exposure time. The median effective resolving power of the 42 spectra is R ≃ 11 400 and 9800 in the VIS and NIR arm, respectively. The signal-to-noise ratio per 10 km s−1 pixel ranges from ∼11 to 114 at λ ≃ 1285 Å rest frame, with a median value of ∼29. We describe the observations, data reduction, and analysis of the spectra, together with some first results based on the E-XQR-30 s le. New photometry in the H and K bands are provided for the XQR-30 quasars, together with composite spectra whose characteristics reflect the large absolute magnitudes of the s le. The composite and the reduced spectra are released to the community through a public repository, and will enable a range of studies addressing outstanding questions regarding the first Gyr of the Universe.
Start Date: 2024
End Date: 12-2026
Amount: $441,700.00
Funder: Australian Research Council
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