Seminars

The UHH Research Park includes the headquarters for the East Asian Observatory, the Caltech Submillimeter Observatory, Subaru, Gemini, UKIRT, the Smithsonian Submillimeter Array and the Institute for Astronomy, plus the astronomers at the University of Hawaii at Hilo. We are one of the major centres for astronomy in the world and encourage all visitors to the JCMT to take advantage of the proximity of these institutes, and give a seminar while in Hilo. Your talk will be advertised at each of the above institutes.


Upcoming Seminar: November 21st, 2017, 2pm (HST)

Investigating the magnetic fields from diffuse to denser parts of the star forming regions

Location: EAO Office, Hilo

Archana Soam, KASI, South Korea

Star formation is a long-standing and most exciting fundamental problem to be understood by astrophysicists. Studying star formation in different environments using different astronomical techniques helps in understanding the various important aspects of the process. I mostly worked towards nearby low mass star forming regions which provide fascinating laboratories for studying this process. The two standard theories of star formation investigate the importance of magnetic fields (B-fields) and turbulence in star formation. In my work, I mostly focused on mapping the B-fields towards various star forming regions in different environments viz. molecular clouds in isolation and in HII regions at their different evolutionary stages. This was done using optical, near-IR and sub-mm polarization techniques to map B-fields at parsec to sub-parsec spatial scales (mostly at the distances of Taurus and Orion).

In the B-field-dominated scenario, the cores are envisaged to gradually condense out of a magnetically sub-critical background cloud, through ambipolar diffusion. B-fields are found to be in the star forming regions sitting on the peripheries of HII regions (a.k.a. bright-rimmed clouds) influenced by neighboring high energy sources. B-fields mapped at different wavelength in these clouds have helped in investigating their continuation from diffused to dense regions. I have sampled a number of isolated cores, including those containing very low luminosity objects (VeLLOs) and various BRCs in nearby HII regions. I will present my results based on the observations towards these regions, and will present this work in the context of the JCMT Large Program called BISTRO. Specifically, I am working on SCUBA-2/POL-2 data towards the Oph-B region as a part of this survey. I will present the results obtained and analysis done toward Oph-B. Along with this, I shall briefly introduce the importance of my accepted PI projects on JCMT for SCUBA-2/POL-2 observations towards cores with VeLLOs and some proto-brown dwarf candidates. I will also introduce my accepted Cycle 5 proposal for ALMA Band 6 polarization observations towards these sources.

Upcoming Seminar: November 27th, 2017, 11am (HST)

SPT unlensed protoclusters: a window into the early universe

Location: EAO Office, Hilo

Emily Pass, University of Waterloo, Canada

The South Pole Telescope’s SPT-SZ 2500 deg2 survey was originally designed to detect overdensities at z ~ 1 using the Sunyaev Zel’dovich effect. However, this data has also been able to be used to create a catalogue of high-redshift dusty star-forming galaxies (DSFGs) that have since received ALMA follow-up. While the majority of these sources are strongly lensed, a subset are unlensed, multi-component sources. These likely z > 4 overdensities may provide views into the early universe, allowing constraints to be placed on structure formation. In this talk, we will discuss the properties of SPT 2349-56, the most thoroughly-investigated member of the SPT unlensed sample and the densest protocluster discovered to date, summarizing our current understanding of protoclusters and highlighting the implications of this discovery. We will also describe our ongoing efforts to characterize the other z > 4 overdensity candidates in the SPT unlensed sample, as well as the future goals of the SPT protocluster project.

Upcoming Seminar: December 18th, 2017, 1pm (HST)

Demonstrating A New Census of INfrared Galaxies with ALMA (DANCING-ALMA). I. FIR Size and Luminosity Relation at z = 0 – 6 Revealed with 1034 ALMA Sources

Location: EAO Office, Hilo

Seiji Fujimoto, University of Tokyo, Japan

We present the large statistics of the galaxy effective radius in the rest-frame far-infrared (FIR) wavelength Re(FIR) obtained from 1627 deep ALMA 1-mm band maps that become public by 2017 July. Our ALMA sample consists of 1034 sources at z = 0 – 6 that typically have the star-formation rate of ~100-1000 M/yr and the stellar mass of ~1010 – 1011.5 M. We homogeneously derive Re(FIR) and FIR luminosity LFIR of our ALMA sources via the same uv-visibility method with the exponential disk fitting, carefully evaluating the selection and measurement incompletenesses by realistic Monte-Carlo simulations. We find that there is a positive correlation between Re(FIR) and LFIR at the > 99% significance level. The best-fit power-law function, Re(FIR)LFIRα, provides α = 0.28 ± 0.07, and shows that the average Re(FIR) at a fixed LFIR decreases toward high redshifts. The best-fit α and the redshift evolution of Re(FIR) are similar to those of the galaxy effective radius in the rest-frame UV (optical) wavelength Re(UV) (Re(Opt.)) revealed by Hubble Space Telescope (HST) studies. We identify that our ALMA sources have significant trends of Re(FIR)Re(UV) and Re(Opt.), suggesting that dusty starbursts take place in a compact region. Moreover, Re(FIR) of our ALMA sources is comparable to Re(Opt.) of quiescent galaxies at z ~1 – 3 as a function of stellar mass, supporting the evolutionary connection between these two galaxy populations. We also investigate rest-frame UV and optical morphologies of our ALMA sources with deep HST images, and find that ~ 30 – 40% of our ALMA sources are classified as major mergers. This indicates that dusty starbursts are triggered not only by the major mergers but also the other mechanism(s).


Where and How:

EAO seminars are (usually) held in the second floor conference room at the East Asia Observatory, 660 N. A’ohoku Place, Hilo, Hawaii. Please note that access to EAO is possible only through the main entrance (through the side doors facing Subaru).

If you would like to view the seminar via Polycom, please contact the helpdesk well in advance of the talk and we will make sure it’s switched on!

Our Polycom contact details are available on request.

The EAO phone number is: (808) 961-3756. A full list of past seminar speakers can be found here for 2017, here for 2016 and here for 2015. These pages also contain links to PDF copies of the seminar slides, where available.

To join the Seminar e-mail list:

EAO Seminars are sent out via eao_seminar@eao.hawaii.edu. If you wish to join this seminar list please send an e-mail to eao_seminar-join@eao.hawaii.edu.

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