Tahani, Kianoosh - Kwantlen Polytechnic University


How Characterizing Star Forming Clumps in the Galaxy Crossovers into Big Data Handling: A Comparison of JCMT and Herschel Observations


We present the first comparison between the Herschel Infrared Galactic plane survey (Hi-GAL) at 500µm and the James Clerk Maxwell Telescope (JCMT) Plane Survey (JPS) using SCUBA-2 at 450µm. The JCMT data were taken as a part of a follow up project for the JPS - circular regions with a radius of ~ 0.8o at l=10o & l=30o. Given the higher resolution of the JPS 450µm observations we were able to determine the number of clumps identified in the Hi-GAL 500µm data (PLW), that are actually composed of multiple, smaller clumps (i.e. the fragmentation). At l=10o, we find that 35% of the PLW clumps fragment into smaller pieces and at l=30o this multiplicity number is 23%. The result of which can be applied to the rest of the Hi-GAL data – in a statistical sense - where no higher resolution is available. Moreover, we present the results of our SED fitting to the combined datasets by extracting the clumps from five Hi-GAL bands, two JPS bands, and counterpart data at ~ 20µm. We determine the current physical conditions (i.e. temperature, luminosity, mass, density, etc.) of the star forming clumps in these Galactic coordinates. We investigate how Star Formation Efficiency (SFE) calculated for the monolithic Hi-GAL clumps changes when the multiplicity fraction is incorporated. The average SFE is observed to increase from 8% to 13% once the clump multiplicity was taken into account. Our simulations suggest that the low SFE in the most massive clumps is most likely due to the formation of massive stars. We then determine the SFE and investigate differences/similarities in these two galactic longitudes. The average SFE at l = 10o is 16% while at l = 30o the average SFE is 9%. We propose that the turbulence at l =30o is supporting this region against gravitational collapse, which potentially results in formation of more massive cores/stars and therefore lower SFE.

Short bio

I have been a Physics & Astronomy instructor at Kwantlen Polytechnic University since Sep 2018. While holding this position at KPU, I also collaborate with the James Clerk Maxwell Telescope (JCMT)  on the CHIMPS2 project focusing on the star formation in the Central Molecular Zone of our Galaxy.  I have earned my Ph.D of Physics in Aug 2018 from the University of Calgary with the specialization in the Astrophysics, Star Formation. I have worked on variety of astronomical data such as data collected by the James Clerk Maxwell Telescope Plane Survey (JPS), PACS & SPIRE abroad Herschel Space Observatory, and the Heterodyne Instrument for the Far Infrared. The experience of working with the large astronomical datasets allowed me to also work with the industry as a data scientist while finishing my PhD. I have earned my M.Sc from University of Calgary and my bachelor is done at the University of Tehran, both in Physics.

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