2021 Seminars

This page lists the Seminars that were given virtually on zoom in 2021. The EAO staff would like to thank all guest speakers and encourage new astronomers/instrument specialists to give virtual talks.

 

September 10th, 10:30am (HST)

Title: Hunting gamma-ray blazars and presenting Turin-SyCAT a Seyfert galaxies catalog

Harold Peña, EAO/JCMT

A significant fraction of all γ-ray sources detected by the Large Area Telescope aboard the Fermi satellite still lacks a low-energy counterpart. In addition, there is still a large population of γ-ray sources with associated low-energy counterparts that lack firm classifications. Here, I will present an ongoing optical spectroscopic campaign to address the problem of unassociated or unidentified γ-ray sources (UGSs) and Blazar Candidates of Uncertain type (BCUs), mainly devoted to observing blazars and blazar candidates because they are the largest population of γ-ray sources associated to date.

Additionally, I will present the 1st release of the Turin-SyCAT, a multifrequency catalog of Seyfert galaxies. We selected Seyfert galaxies considering criteria based on radio, infrared, and optical properties and from sources belonging to hard X-ray catalogs. We visually inspected the optical spectra available for all selected sources. We adopted homogeneous and stringent criteria in the source selection to reduce possible contamination from other source classes. Our final catalog includes 351 Seyfert galaxies distinguished in 233 type-1 and 118 type-2. Then, I will show the statistical analysis of the sample. Finally, I will present preliminary results on a study of the large-scale environment of Seyfert galaxies using the SyCAT sample.

July 26th, 3 pm (HST)

Title: Magnetic fields in early stages of star formation revealed by mm/submm observations of polarized dust emission
Junhao Liu, EAO/JCMT

The formation of stars plays a major role in the formation and evolution of galaxies. However, the detailed physics of star formation is still far from being understood. In particular, despite significant progress in recent years, the role of magnetic fields in star formation, especially in the early stage, is still under debate. Observing the polarized emission of dust grains has been proven to be a powerful way to investigate the plane-of-sky magnetic field structure in star-forming regions. In this talk, I will present results of the JCMT POL-2 dust polarization observations toward the low-mass starless core Ophiuchus C as part of the JCMT large program BISTRO, and present the results from ALMA dust polarization observations of three high-mass molecular clumps in the infrared dark cloud G28.34. The two studies begin to reveal the role of magnetic fields in the early stages of low-mass and high-mass star formation, which set the stage for future dust polarization surveys of larger samples of early-stage star-formation regions. I will also present the recent simulation results on the reliability of the Davis-Chandrasekhar-Fermi method to derive the magnetic field strength from dust polarization observations at dense clump and core scales.

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