Calendar

Sep
6
Fri
Colloquium: Brian Svoboda (Host: Moire Prescott)
Sep 6 @ 3:15 pm – 4:15 pm
Colloquium: Brian Svoboda (Host: Moire Prescott) @ BX102

Starless clumps and the earliest phases of high-mass star formation in the Milky Way

Brian Svoboda, NRAO Jansky Fellow

High-mass stars are key to regulating the interstellar medium, star formation activity, and overall evolution of galaxies, but their formation remains an open problem in astrophysics. In order to understand the physical conditions during the earliest phases of high-mass star formation, I will present observational studies we have carried out on dense starless clump candidates (SCCs) that show no signatures of star formation activity. We identify 2223 SCCs from the 1.1 mm Bolocam Galactic Plane Survey, systematically analyse their physical properties, and show that the starless phase is not represented by a single timescale, but evolves more rapidly with increasing clump mass. To investigate the sub-structure in SCCs at high spatial resolution, we investigate the 12 most high-mass SCCs within 5 kpc using ALMA. We find previously undetected low-luminosity protostars in 11 out of 12 SCCs, fragmentation equal to the thermal Jeans length of the clump, and no starless cores exceeding 30 solar masses. While uncertainties remain concerning the star formation efficiency in this sample, these observational facts are consistent with models where high-mass stars form from initially low- to intermediate-mass protostars that accrete most of their mass from the surrounding clump. I will also present on-going research studying gas inflow signatures with GBT/Argus and ALMA, and the dense core mass function with the JVLA.

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Dec
6
Fri
Colloquium: Elise Boera (Host: Kristian Finlator)
Dec 6 @ 3:15 pm – 4:15 pm
Colloquium: Elise Boera (Host: Kristian Finlator) @ BX102

Revealing reionization with the thermal history of the intergalactic medium

Elisa Boera, SISSA Trieste

During hydrogen reionization the UV radiation from the first luminous sources injected vast amount of energy into the intergalactic medium, photo-heating the gas to tens of thousands of degree Kelvin. This increase in temperature has left measurable `imprints’ in the thermal history of the cosmic gas: a peak in the temperature evolution at the mean density and a smoothing out of the gas in the physical space by the increased gas pressure following reionization (i.e. Jeans smoothing effect). The structures of the HI Lyman-alpha forest at high redshift are sensitive to both these effects and therefore represent a powerful tool to understand when and how reionization happened. I will present the most recent constraints on the thermal history of the intergalactic medium obtained using the Lyman-alpha forest flux power spectrum at z>5. I will show how these results can be used to obtain information on the timing and the sources of the reionization process and I will discuss their consistency with different possible reionization scenarios.
Jan
29
Fri
Colloquium: OPEN
Jan 29 @ 3:00 pm – 4:00 pm
Colloquium: OPEN @ BX102

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Feb
5
Fri
Colloquium: OPEN
Feb 5 @ 3:00 pm – 4:00 pm
Colloquium: OPEN @ BX102

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Feb
12
Fri
Colloquium: Durgesh Tripathi (host Juie Shetye)
Feb 12 @ 9:00 am – 10:00 am
Colloquium: Durgesh Tripathi (host Juie Shetye) @ BX102

The Aditya-L1 mission: ISRO’s first solar observatory in space

Durgesh Tripathi, Inter-University Centre for Astronomy and Astrophysics

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Feb
19
Fri
Colloquium: Alyson Brooks (host: Kristian Finlator)
Feb 19 @ 9:00 am – 10:00 am
Colloquium: Alyson Brooks (host: Kristian Finlator) @ BX102

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Alyson Brooks, Rutgers

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Feb
26
Fri
Colloquium: OPEN
Feb 26 @ 3:00 pm – 4:00 pm
Colloquium: OPEN @ BX102

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Mar
5
Fri
Colloquium (Ph. D. dissertation defense): Jodi Berdis
Mar 5 @ 3:00 pm – 4:00 pm
Colloquium (Ph. D. dissertation defense): Jodi Berdis @ BX102

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Jodi Berdis, NMSU

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Mar
12
Fri
Colloquium: OPEN
Mar 12 @ 3:00 pm – 4:00 pm
Colloquium: OPEN @ BX102

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Mar
19
Fri
Colloquium: OPEN
Mar 19 @ 3:00 pm – 4:00 pm
Colloquium: OPEN @ BX102

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