UK involvement in LSST: Phase C (Herts component)
Lead Research Organisation:
University of Hertfordshire
Department Name: School of Physics, Eng & Computer Scienc
Abstract
Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.
Publications
Bichang'a B
(2024)
The properties of AGN in dwarf galaxies identified via SED fitting
Bichang'a B
(2024)
The properties of AGN in dwarf galaxies identified via SED fitting
in Monthly Notices of the Royal Astronomical Society
Jackson R
(2024)
The formation of cores in galaxies across cosmic time - the existence of cores is not in tension with the ?CDM paradigm
in Monthly Notices of the Royal Astronomical Society
Kraljic K
(2024)
Emergence and cosmic evolution of the Kennicutt-Schmidt relation driven by interstellar turbulence
in Astronomy & Astrophysics
Lazar I
(2024)
The morphological mix of dwarf galaxies in the nearby Universe
in Monthly Notices of the Royal Astronomical Society
Lazar I
(2024)
The structural properties of nearby dwarf galaxies in low-density environments - size, surface brightness, and colour gradients
in Monthly Notices of the Royal Astronomical Society
| Title | Prototype sky subtraction method for the LSST pipeline that is optimised for low-surface-brightness science |
| Description | This method is a modification to the LSST pipeline which avoids the over-subtraction of flux from real astronomical objects due to an over-estimate of the night sky brightness in each exposure. This will be particularly important for low-surface-brightness (LSB) objects which are most affected by sky over-subtraction. Since most of the extra-galactic discovery space of LSST is in the LSB regime, this altered pipeline setup will be important for enabling LSST to fulfil its full scientific potential. The method is currently in the prototype stage and, in the coming years, will be fine-tuned and tested on real data (e.g. from the LSST commissioning surveys in 2024/25). |
| Type Of Material | Improvements to research infrastructure |
| Year Produced | 2024 |
| Provided To Others? | Yes |
| Impact | The method will allow LSST to produce images which can be more broadly utilised by the astronomical community than the survey's original key science goals, without hampering the survey's ability to achieve said goals. Additionally, the paper we have published describing the method will help provide a path for similar surveys to similarly broaden their scientific scopes. The paper can be found here: https://ui.adsabs.harvard.edu/abs/2024MNRAS.528.4289W/abstract A prototype of this method is currently being tested in the LSST pipeline. Initial tests show that several metrics improve when this setup is used compared to the default version of the pipeline. |
| URL | https://ui.adsabs.harvard.edu/abs/2024MNRAS.528.4289W/abstract |
| Title | Strategies for optimal sky subtraction in the low surface brightness regime |
| Description | Synthetic source master images and associated source property catalogues used in the study "Strategies for optimal sky subtraction in the low surface brightness regime" (Watkins et al.). |
| Type Of Material | Database/Collection of data |
| Year Produced | 2023 |
| Provided To Others? | Yes |
| Impact | This paper discusses the merits and pitfalls of different kinds of sky subtraction techniques. It describes experiments using fully synthetic images to investigate three different techniques, two commonly used in low surface brightness surveys, another experimental. The study's results quantify the impact of undetected flux on sky models, which tends to bias estimated sky brightnesses high, risking over-subtraction of flux. If the sky is modelled with a complex function (for example, a high-order polynomial, or a spline interpolation), that over-subtraction can occur locally, leading to artificial divots surrounding extended objects like galaxies, or even objects which are simply located close together on the sky. However, the results demonstrate that when a simple model is used, and when proper care is taken to mask detected astronomical objects to low surface brightness levels, this bias can be reduced to negligible amounts. Even for a survey as deep as LSST, any sky subtraction technique traditionally used in low surface brightness surveys can still be applied safely, so long as empirical corrections are made for scattered light and undetected faint sources. The paper justifies the recommendations Watkins and collaborators have proposed to LSST's data management (DM) team regarding the survey's pipeline sky subtraction. Working alongside DM, Watkins et al. found that the existing algorithm suffers from two problems: insufficient masking of low surface brightness flux, and too complex a sky model. Following the paper's results, the team found that adjusting the algorithm to use a much simpler model, even without an improvement to the masking, proves very successful at minimising the impact of the sky subtraction on the flux of extended or clustered objects. In fact, a preliminary investigation suggests that the proposed revised algorithm might benefit more than just low surface brightness science: a number of DM's photometric quality metrics appear to improve slightly when the revised algorithm is used, compared to the default pipeline. However, the full impact of the proposed change is still being investigated. |
| URL | https://zenodo.org/record/8192051 |
| Description | Collaboration with LSST Data Management Team on low-surface-brightness science pipelines |
| Organisation | Princeton University |
| Country | United States |
| Sector | Academic/University |
| PI Contribution | We are collaborating with the LSST Data Management team (principally Lee Kelvin, Robert Lupton and Yusra Al-Sayyad at Princeton) to develop pipelines for low-surface-brightness (LSB) science for LSST. The default pipelines produced by the Data Management team are not optimised for low-surface-brightness science, which represents a significant discovery space for LSST. Probing this space therefore requires developing bespoke pipelines that preserve LSB structures in the LSST images. Our team will develop these pipelines in collaboration with the Data Management Team, who will help us with incorporating our code into the LSST software stack and performing tests of the software using the HSC and LSST commissioning surveys. |
| Collaborator Contribution | Robert Lupton and Yusra Al-Sayyad are acting as consultants on this project. Their team will help us incorporate the software we will produce into the LSST software stack. Since their team is also reducing the HSC survey (which is the precursor to LSST) they will provide assistance in testing our pipeline software using HSC data before the main LSST survey starts. |
| Impact | LSST:UK deliverables D3.7.1 30 Nov 2020 Report on optimal metrics for preserving low-surface-brightness flux at different spatial scales https://lsst-uk.atlassian.net/wiki/download/attachments/1146928/LUSC-B-10-D3.7.1-OptimalMetrics-LSB.pdf?api=v2 D3.7.2 28 Feb 2021 Report on mock testing results - quantification of depth improvements made over existing datasets https://lsst-uk.atlassian.net/wiki/download/attachments/1146928/LUSC-B-14-D3.7.2-MockTesting.pdf?api=v2 D3.7.3 31 Aug 2021 Software to output metrics that keep track of improvements to the pipeline sky subtraction https://lsst-uk.atlassian.net/wiki/download/attachments/1146928/LUSC-B19-D3.7.3-Improvement-Metrics-Software.pdf?api=v2 |
| Start Year | 2020 |
| Description | Modifying the HSC pipeline sky-subtraction algorithm low-surface-brightness science with LSST |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Professional Practitioners |
| Results and Impact | Invited talk at the LSST@Europe 5 conference. |
| Year(s) Of Engagement Activity | 2023 |
| URL | https://www.lssteu5.eu/ |
| Description | The merits and pitfalls of sky subtraction techniques |
| Form Of Engagement Activity | A magazine, newsletter or online publication |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Professional Practitioners |
| Results and Impact | Contribution to LSST:UK newsletter based on articles published in MNRAS by Aaron Watkins, Sugata Kaviraj and collaborators. It discusses the merits and pitfalls of different kinds of sky subtraction techniques. The paper describes experiments using fully synthetic images to investigate three different techniques, two commonly used in low surface brightness surveys, another experimental. |
| Year(s) Of Engagement Activity | 2024 |
| URL | https://lsst-uk.atlassian.net/wiki/spaces/HOME/pages/3385688065/LSST+UK+Newsletter+41+February+2024#... |