2020 Fiscal Year Research-status Report
Effect of Local Environment on Galaxy Quenching and Morphology at z < 1
| Project/Area Number |
20K14514
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| Research Institution | The University of Tokyo |
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Principal Investigator |
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| Project Period (FY) |
2020-04-01 – 2024-03-31
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| Keywords | galaxy formation / galaxy evolution / galaxy morphology / structural parameters / size-mass relation |
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| Outline of Annual Research Achievements |
We utilised the Subaru Hyper Suprime- Cam (HSC) imaging, covering 100 deg^2, to measure structural properties of ~1.5 million galaxies at z < 1. We carefully calibrated our measurements using simulated galaxies to account for various systematic biases. Our test using the simulated galaxies showed that we obtain sizes for galaxies with i< 24.5 mag with 5% accuracy (or better).
As a demonstration of science, PI has utilised the size measurements to robustly determine the size-mass relation over the broad range in stellar mass and show that the relations for are better characterised a double-power function: the relation is steeper slope above the pivot mass. Our result from the HSC are in excellent agreements with those from thespaced-based observations, particularly for low-mass galaxies, strongly suggesting that our size measurements are robust and not driven by a systematic bias. In addition, the larger sample of massive galaxies (M* > 10^11 solar masses) than the previous deep surveys enable us to derive the tighter constraint on the size-mass relation for most massive galaxies. The results presented here bridge the gap between the local Universe (z~0) and the high redshift works. PI has submitted the publication with the title “Hyper Suprime-Cam Subaru Strategic Survey: A Mass-Dependent Slope of the Galaxy Size-Mass Relation at z<1” to Astrophysical Journal. It is in the progress of revising the manuscript, and we expected that the manuscript will be accepted for publication around July 2021. We have also made our catalog available to HSC Collaboration.
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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
Due to the large galaxy sample from HSC (over 7 million galaxies), the computational time used for measuring and calibrating the structural parameters for these galaxies are quite slow due to the limited resources of IPMU high performance computing clusters.
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| Strategy for Future Research Activity |
First, PI further utilise the HSC structural parameter measurement to quantify the size-mass relation of galaxies residing in X-ray selects clusters at z< 1 from the eROSITA Final Equatorial Depth Survey. The observable properties of galaxy clusters from the eFEDS, such as X-ray luminosity and temperature, serves as mass proxy for clusters and enable us to explore the environmental effects on galaxy structural parameters. PI is preparing the publication and expect to submit it to ApJ around September-October 2021.
Second, PI is using the IPMU high performance computing clusters to measure structural parameters galaxies in HSC S19A data release, covering ~510 deg^2. The large sample of galaxies with structural parameters will be a complement with the HSC weak lensing shape catalog, enabling PI to analyse the connection between the structural parameter of galaxies and their host dark matter halo mass for a larger sample of galaxies than previous analysis. Motivated by the results from Kawinwanichakij et al. submitted of the galaxy size-mass relations with a clear change of power-law slope at a pivot stellar mass, PI will further investigate the average dark matter halo mass derived by analysing stacking weak lensing signal for galaxies above, near, and below the pivot mass. Therefore, this will provide important observational constraint on the scatter in stellar mass and halo mass relation and the dependent on the scatter with galaxy structural parameters.
PI also plan to prepare the publication and submit it to the Astrophysical Journal around the beginning of 2022.
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| Causes of Carryover |
PI will plan to use research funding for the publication fees (at least three publications) based on the results from: 1) the HSC galaxy size-mass relation at z<1 (submitted), the eROSITA Final Equatorial-Depth Survey (eFEDS): Morphological Properties of Galaxies in X-ray Clusters at z < 1 with HSC, and 3) Mapping the halo mass across the galaxy size-stellar mass plane.
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