KPKevin A. Pimbblet

Kevin A. Pimbblet

*This is an algorithmically generated author record based on publicly available information.

Current Organizations / Institutes

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Previous Organizations / Institutes

The organizations / institutes from the scholar's other articles in the past ten years


Kevin A. Pimbblet has a total of 931 co-authors. Here are the top co-authors by number of shared publications:


Latest Publications

  • Open Access

    EMU/GAMA: Understanding the link between dust geometry and star formation rate in galaxies

    by U T Ahmed, A M Hopkins, B Farley, M Cowley, S Phillipps, Y A Gordon, B W Holwerda, D J Bomans, K A Pimbblet, S Casura, et al.

    We investigate the link between dust obscuration and star formation rate (SFR) estimators using Hα luminosities, LHα and radio luminosities, Lradio. While the Balmer Decrement (BD) is the standard tool for attenuating Hα, it can fail to account for optically thick dust regions from which Hα cannot escape. The ratio of SFRs estimated from radio luminosity and LHα corrected for dust attenuation using the BD can be used as a probe of the degree of optically thick dust affecting Hα. We explore this combining Evolutionary Map of the Universe (EMU) Early Science data at 887.5 MHz in the Galaxy and Mass Assembly (GAMA) G23 field with the GAMA data. We draw on dust estimates using both the BD and the dust mass, Md, demonstrating systematic underlying dependencies with Lradio/LHα. By combining the BD and Md, we quantify how they relate to Lradio/LHα and other galaxy properties. We use this approach to establish an Hα SFR (SFRHα) estimator that accounts for optically thick dust, demonstrating its consistency with conventional SFR indicators. Rather than proposing a replacement for standard correction methods, we aim to demonstrate the effectiveness of a dust geometry model that integrates both BD and Md parameters. This Hdust parameter provides a more physically complete representation of optically thick environments that traditional methods may overlook, and can produce SFR estimates consistent with traditional techniques.

  • Open Access

    Identification of cosmic chronometers in the GAMA survey

    by Laura J Hunt, Kevin A Pimbblet, David M Benoit

    We present a pure sample of 231 massive, passively evolving elliptical galaxies as cosmic chronometer candidates selected from the Galaxy and Mass Assembly survey between $0.03\lt z\lt 0.4$. The goal of this work is to increase the pool of high-purity cosmic chronometer candidates available in the literature and assess the effect of purity on statistical uncertainty to make $H(z)$ and $H_0$ calculations more robust in future studies. We use traditional selection criteria to identify cosmic chronometers (CCs) using photometry and spectroscopy in conjunction with modelled parameters such as stellar mass and velocity dispersion. We use an NUVrJ photometric selection to identify quiescent galaxies and identify a number of spectral features, including H $\alpha$, [O ii], and H $\delta$ to use as tracers for ongoing or recently halted star formation. Additionally, as part of the selection, we calculate the ratio between the Ca ii H and K lines to determine whether a galaxy’s stellar population is dominated by older or younger stars. We confirm CC candidacy by selecting only the most massive galaxies and perform a visual inspection of the spectra and images of CC candidates. We provide an analysis of the parent sample in comparison to the CC sample and confirm CCs have much lower specific star formation rate (sSFR), with a median sSFR of $10^{-12} \,\text{Myr}^{-1}$. Additionally, we find their median ages are ${\sim} 2\, \text{Gyr}$ older than the parent sample.

  • Open Access

    SPINE : symbolic models to predict the evolution of the ΛCDM non-linear power spectrum

    by Manvi Chauhan, Daniel J Farrow, Ariel G Sánchez, Kevin A Pimbblet, Marika Asgari, David M Benoit

    We present SPINE and SPINEX, a pair of analytical emulators developed to predict the non-linear power spectrum based on its linear counterpart and several essential cosmological parameters within the range of $0.01\,\,h\,\,\mathrm{Mpc}^{-1} \lt k\lt 2\,\,h\,\,\mathrm{Mpc}^{-1}$. The primary difference between the two models is their parametrization. Our methodology is grounded in the mapping originally proposed by J. A. Peacock and S. J. Dodds. Both models are defined by clear mathematical expressions derived from symbolic regression, a machine learning technique that utilizes genetic programming to identify analytical equations that accurately represent the underlying data. This approach provides a more interpretable and efficient alternative to conventional numerical methods that should also exhibit superior extrapolation behaviour beyond the training range. The emulators have been trained on the Lambda cold dark matter ($\Lambda$CDM) Quijote Latin Hypercube simulations. We provide fits for both emulators across three distinct scenarios: cosmologies within 20$\sigma$ of the Planck-2018 observations, a designated fiducial cosmology, and a broader range of cosmologies sampled from the Quijote simulations. Our findings indicate that SPINE and SPINEX maintain an accuracy of better than 5 per cent in the majority of cases. These emulators provide a rapid alternative to numerical methods, and future initiatives will focus on developing expressions that incorporate galaxy bias and redshift-space distortions. This advancement aims to enhance the modelling of redshift space power spectra across multiple redshifts, enabling their application in large-scale cosmological surveys.

  • Open Access

    A search for H i absorption in distant star-forming galaxies with ASKAP-FLASH – II. Direct observations and stacking of 21 cm line

    by Sophie L Eden, Elaine M Sadler, Kevin A Pimbblet, Stephen J Curran, Julia Healy, Filippo M Maccagni, Elizabeth K Mahony, Hyein Yoon

    We present results of a search for associated and intervening H i 21 cm absorption in star-forming galaxies and a control sample of radio galaxies at 0.4 < z < 1.0, using ASKAP’s FLASH H i 21 cm absorption survey. We report the detection of a new H i 21 cm absorption line in radio galaxy NVSS J214954-004657 at $z_{\mathrm{H\,{\small I}}}$ = 0.863. Additionally, we present results of H i 21 cm stacking for associated and intervening star-forming and radio galaxy catalogues. For the first time at these redshifts, we report tentative detections of stacked H i 21 cm absorption for associated galaxies when stacked in order of descending radio source brightness, and show that these tentative detections become buried as optical depth increases as progressively weaker sources are co-added into the stack. No stacked signal is detected when co-adding intervening galaxy spectra. We speculate that the ability to detect a stacked H i 21 cm detection is dependent on the background source optical depth limits, as well as source covering factors. Covering factor has a greater impact when stacking intervening systems, and can be considered to effectively weaken the observed flux density of a radio source. We find no significant difference in detection rate for associated H i 21 cm absorption in star-forming galaxies versus the general radio-source population at the same redshift. Although detection rates are low, from a meta-analysis of H i 21 cm surveys we find that 1 detection is expected given the survey parameters.

  • Open Access

    Extended structure in E+A galaxies via image stacking

    by Kieran Broadbelt, Kevin Pimbblet, Daniel J Farrow, Sugata Kaviraj

    Small-scale interactions such as minor mergers, flybys and harassment are considered common driving mechanisms that can both initiate and quench star-forming processes within post-starburst (PSB) galaxies. PSBs have been linked to disturbed morphologies and faint tidal features in numerous works. We aim to independently study these features in E+A galaxies found in the Galaxy and Mass Assembly Fourth Data Release (GAMA DR4). Using image stacking techniques, we derive the averaged radial surface brightness profiles of E+A image stacks alongside the Sérsic parameters that best fit these profiles. These E+A stacks consist of 57 images extracted from the Sloan Digital Sky Survey (SDSS) in g, r & i bands. The E+A stacks are shown to have brighter extended regions than similar non-PSB galaxies, which is indicative of faint tidal features that could be caused by small-scale interactions. Additionally, we make use of Dark Energy Spectroscopic Instrument (DESI) Legacy Survey imaging, which is deeper than SDSS, to further support our conclusions and find that the Legacy Survey images independently strengthen the evidence for excess light at extended radii relative to the comparison samples. We discuss these findings in the context of future surveys such as the Vera C. Rubin Legacy Survey of Space and Time (LSST) survey.

  • Finding “Balance” Between AI and Culture as Drivers of Development in Burkina Faso

    by Harriet Deacon, Freda Owusu-Sekyere, Avril Joffe, Léonce Ki, Bhupesh Mishra, Kevin Pimbblet

    In achieving development objectives, the balance between innovation and protection is perceived as a lever or seesaw in AI policies, as in intellectual property law. However, innovation in the technology sector that uses online content without consent or attribution poses risks to both innovation and rights protection in the culture sector. Generative AI technologies have fundamentally altered the economic and social context for cultural production and practice. Communal cultural identity and meaning maintained through intangible cultural heritage, such as traditional knowledge, music, craft, and performance, are affected by increased opportunities for misrepresentation, misappropriation, and misattribution. Strengthening intellectual property protections and/or extending them to cultural heritage in sui generis regimes are insufficient to address these problems. This article analyzes African continental policy to understand how culture is represented in AI policy and what challenges are faced in addressing generative AI risks. The article suggests that to foster development that benefits the culture sector, “balance” could be better understood as a four-legged chair than a lever, supporting not only innovation and rights protection (including human rights to cultural participation) but also access to technologies and empowerment of creators. Examples from Burkina Faso are used to illustrate the need to supplement sui generis intellectual property rights protection for national cultural heritage with more direct support, such as subsidies or tailored marketing and capacity-building training programs.

  • Open Access

    EMU/GAMA: A statistical perspective on active galactic nuclei diagnostics

    by Jahang Prathap, Andrew Hopkins, Rodrigo Carvajal, Michael Cowley, Scott Croom, Duncan Farrah, Isabella Prandoni, Stanislav Shabala, Jacco Th. van Loon, Ciro Pappalardo, et al.

    While it is well known that galaxies are composites of many emission processes, quantifying the various contributions remains challenging. In this work, we use unsupervised machine learning based clustering algorithms to evaluate the agreement between the clustering tools and astrophysical classifications, and hence quantify the fractional contributions of star formation processes and nuclear black hole activity to the total galaxy energy budget of radio sources. We perform clustering on the multiwavelength (optical, infrared (IR), and radio) active galactic nuclei (AGN) diagnostic spaces, using the data from the G09 and G23 fields from the Galaxy and Mass Assembly (GAMA) survey, Evolutionary Map of the Universe (EMU) survey, and the Wide-field Infrared Survey Explorer. We find that the statistical clustering recovers $\approx$ 90% of the star forming galaxies (SFGs) and $\approx$ 80% of the AGN. We define a new IR-radio AGN diagnostic scheme that identifies radio AGN from IR SFGs and AGN, corresponding to the KMeans cluster with approximately 90% reliability. We demonstrate the superior power of radio AGN selection in higher dimensions using a three-dimensional space composed of directly observable parameters ( ${W_1-W_2}$ colour, ${W_2}$ magnitude, and the 1.4 GHz radio flux density). This novel three dimensional diagnostic shows immense potential in radio AGN selection that is close to 90% reliable and 90% complete. We also publish a catalogue of radio sources in the EMU survey with associated probabilities for them to be active in the optical regime, through which we emphasise the philosophy of considering a galaxy to be composed of various fractions rather than a binary classification of SFGs and AGN.

  • Open Access

    TCG-AI: AI Integration in Collectibles Grading for Trading Card Games and Sport Cards

    by Luke Warren, Kevin Pimbblett, Julius Mboli

    The grading of trading cards and collectibles remains a labour-intensive and subjective task, traditionally dependent on expert visual inspection. This paper investigates the integration of Artificial Intelligence (AI) into automated grading systems, with a focus on balancing accuracy, scalability and interpretability. We compare conventional image-processing methods based on OpenCV with modern Convolutional Neural Network (CNN) models and propose a hybrid framework that incorporates YOLOv8 with Oriented Bounding Box (OBB) support for localised defect detection. The system operates through a six-stage pipeline encompassing centring, corner wear, edge integrity, surface quality and holistic scoring. To support reproducibility and consistency, we developed a robotic imaging platform capable of capturing standardised high-resolution images (6000 × 4000 pixels) under controlled lighting conditions, enhanced by Flat Field Correction (FFC) for illumination normalisation. Using this platform, we constructed a large-scale dataset comprising over 43,000 training samples after augmentation, covering a wide range of real-world card conditions. Experimental evaluation using localisation accuracy, region-level grading agreement and professional grading consistency metrics demonstrates that CNN-based classification approaches significantly outperform traditional OpenCV pipelines in predictive accuracy but lack spatial interpretability. In contrast, the proposed hybrid framework achieves improved defect localisation and grading consistency relative to CNN-only baselines, while providing transparent visual explanations through YOLO-OBB detections. The integration of deterministic image analysis with deep learning enables both quantitative subgrades and interpretable defect localisation, offering an explainable and scalable solution for automated collectible card grading.

  • Open Access

    SARS: A Novel Face and Body Shape and Appearance Aware 3D Reconstruction System extends Morphable Models

    by Gulraiz Khan, Kenneth Y. Wertheim, Kevin Pimbblet, Waqas Ahmed

    Morphable Models (3DMMs) are a type of morphable model that takes 2D images as inputs and recreates the structure and physical appearance of 3D objects, especially human faces and bodies. 3DMM combines identity and expression blendshapes with a basic face mesh to create a detailed 3D model. The variability in the 3D Morphable models can be controlled by tuning diverse parameters. They are high-level image descriptors, such as shape, texture, illumination, and camera parameters. Previous research in 3D human reconstruction concentrated solely on global face structure or geometry, ignoring face semantic features such as age, gender, and facial landmarks characterizing facial boundaries, curves, dips, and wrinkles. In order to accommodate changes in these high-level facial characteristics, this work introduces a shape and appearance-aware 3D reconstruction system (named SARS by us), a c modular pipeline that extracts body and face information from a single image to properly rebuild the 3D model of the human full body.

  • Open Access

    Galaxy and Mass Assembly (GAMA). The Properties of Quasar Host Galaxies: Star Formation Histories and Stellar Populations

    by Maria B. Stone, Roberto De Propris, Clare Wethers, Jari Kotilainen, Nischal Acharya, Benne Holwerda, Andrew M. Hopkins, Kevin Pimbblet

    We investigated the star formation history and stellar populations of a sample of 205 Type I quasar host galaxies (0.1 < z < 0.35) and compared them with normal (nonactive) galaxies of the same mass and redshift within the volume of the Galaxy and Mass Assembly redshift survey. We find that quasar host galaxies tend to be star-forming galaxies (∼80%) lying on the star-forming main sequence; the fraction of quasar host galaxies that are quiescent (∼20%) is lower than the fraction of quiescent galaxies in the comparison sample of normal galaxies (54%). We find that the mean star formation rate (SFR) of quasar host galaxies has increased over the past 100 Myr by a factor of 2–3, but these galaxies were star-forming at all times previously. Our data are more consistent with quasar activity originating together with an increase in the SFR of otherwise normal galaxies, similar to episodic star formation in normal spirals. We argue that this indicates that secular processes and minor mergers may be the favored triggers of nuclear activity in the local Universe.