2021 Fiscal Year Research-status Report
An Independent Test of the Hubble Constant Tension with Time-Delay Cosmography
| Project/Area Number |
20K14511
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| Research Institution | National Astronomical Observatory of Japan |
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Principal Investigator |
Wong Kenneth 国立天文台, ハワイ観測所, 特任研究員 (00794207)
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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Keywords | gravitational lensing / cosmology / extragalactic astronomy |
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| Outline of Annual Research Achievements |
In FY2020, I have submitted one refereed journal paper as the corresponding author (Wong et al. 2022, PASJ, submitted; arXiv:2203.12805), which is currently undergoing review. I also have an additional submitted paper (Shajib et al. 2022, A&A, submitted; arXiv:2202.11101) where I was one of the two primary authors.
I primarily worked on the TDCOSMO project to measure the Hubble Constant (H0) using strong gravitational lensing time delays. I modeled of the lensed quasar system WGD 2038-4008 as the leader of one of two independent teams to predict the time delay of this lens (which has not yet been measured but is currently being monitored) using both a power-law and composite (stars+dark matter) model. The purpose of having two independent teams model this system was to evaluate systematic uncertainties associated with the choice of lens modeling codes and assumptions. At the moment, statistical uncertainties in the time-delay cosmography method are at a level where we are able to constrain H0 to a few percent, but systematic uncertainties are the primary limitation. Our results (Shajib et al. 2022) show that the predicted time delays between the two teams agree to within ~1-sigma.
I am also co-chair of the Hyper Suprime Cam SSP Strong Lensing Working Group. We have published several papers with hundreds of newly-discovered strong lens candidates from the survey, and intend to obtain redshifts for the most promising systems. I led a lens search through the latest HSC SSP data release (Wong et al. 2022) and discovered tens of new galaxy-scale lens candidates.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
My research has been progressing at about the rate expected. Since I am working in international collaborations, the projects as a whole have
been moving forward thanks to the efforts of both myself and other researchers, and we are continuously publishing new results and obtaining
observing time on large telescopes. There have been minor delays in certain aspects of the various projects, but overall, the research is
progressing at a reasonable pace.
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| Strategy for Future Research Activity |
As part of TDCOSMO, I am doing a detailed model of the gravitational lens J0029-3814. A collaborator of mine has developed an automated pipeline for preliminary modeling, and I will conduct a more refined analysis of this lens in order to make them usable for precision cosmology. This will probably be finished by the end of FY2022. I will also apply for observing time on the Subaru telescope in FY2022, to determine redshifts of several lensed quasars. These redshifts can then be used to analyze these systems in more detail for cosmological inference.
The HSC SSP Strong Lensing Working Group is continuing to develop new search methods for lenses in the survey data. I am starting to learn about and develop machine learning algorithms to supplement our current search methods. I will also work with a student who is modeling the double source plane lens "Eye of Horus" using HST data that I had previously obtained. I will help her to publish a preliminary lens model on this unique system.
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| Causes of Carryover |
I intend to use the remaining funds to pay for journal page charges for my submitted publication to PASJ, as well as any other publications I may submit this year. I will also travel to several upcoming conferences in France and South Korea to present my work. There may be additional conferences later in the academic year that I will attend, and I may spend the remaining amount on equipment for my research. My expenditure was low in FY2021 because travel restrictions due to the COVID pandemic resulted in a lack of opportunities to travel to conferences and collaboration meetings.
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[Journal Article] TDCOSMO. IX. Systematic comparison between lens modelling software programs: time delay prediction for WGD 2038-40082022
Author(s)
Shajib, Anowar J.; Wong, Kenneth. C.; Birrer, Simon; Suyu, Sherry. H.; Treu, Tommaso; Buckley-Geer, Elizabeth; Lin, Huam; Rusu, Cristian. E.; Poh, Jason; Palmese, Antonella; Agnello, Adriano; Auger, Matthew W.; Galan, Aymeric.; Schuldt, Stefan; Sluse, Dominique; Courbin, Frederic; Frieman, Josh; Millon, Martin
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Journal Title
Astronomy & Astrophysics
Volume: -
Pages: -
Peer Reviewed / Int'l Joint Research
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