Measuring gas-phase metallicity gradients in star-forming galaxies at z=1.2~2.3 in the deepest field probed by HST spectroscopy----中国科学院紫金山天文台

Seminar Title	Measuring gas-phase metallicity gradients in star-forming galaxies at z=1.2~2.3 in the deepest field probed by HST spectroscopya

Speaker:	Dr. WANG Xin

Affiliation:	(University of California)

When	Friday morning , June 17, 10:00 a.m

Where:	Room 619, Office Block, 2 West Beijing Road (PMO, CAS)
	Welcome to Attend

	( PMO Academic Committee & Academic Circulating committee)

Abstract

How baryons and metals cycle in and out of galaxies has remained to be a crucial question in galaxy formation and evolution. A variety of physical processes, including gas inflows/outflows, galactic feedback, and major/minor mergers, manifest themselves as a complex interplay which regulates baryonic mass assembly and star formation. A key diagnostic of this complex system is the radial gradient of gas-phase oxygen abundance (i.e. metallicity). With the HST near-infared grism spectroscopy from the supernova Refsdal follow-up program and the Grism Lens-Amplified Survey from Space, we are able to observe the cycle of baryons to the lowest mass galaxies (~100 million solar masses), at the peak epoch of cosmic star formation. I will present the first results on the metallicity gradient measurements in a sample of 12 star-forming galaxies at z=1.2~2.3, with high spatial sampling (sub-kpc scales in the source plane), in the field of the Hubble Frontier Field cluster MACS1149.6+2223. The synergy of ultra deep diffraction-limited exposure and lensing magnification offers a great gain in source plane angular resolution and emission line limiting flux, which makes this study unique in all high-z metallicity gradient analyses so far. We obtain a number of flat metallicity gradients in isolated galaxies, suggesting strong radial mixing and disfavoring weak galactic feedback models.