STScI Research | STScI Discovery Seminar Series - Matilde Mingozzi (STScI) and Ramona Augustin (STScI) @stsciresearch6722 | Uploaded 2 years ago | Updated 1 hour ago
This Discovery Seminar features talks by Ramona Augustin on Characterising the Small-scale Structure in the Circumgalactic Medium and Matilde Mingozzi on UV Diagnostics in Local High-z Analogs with the CLASSY Survey.
Tuesday, June 21 2022.
Speaker: Ramona Augustin
Title: Characterising the Small-scale Structure in the Circumgalactic Medium
Abstract: Gas flows in and out of galaxies are typically probed by quasar absorption lines which are usually limited to a single sightline through the halo, giving no information on the structure of the gas probed in absorption. First studies using lensed, multiple or extended background objects have shown that there can be significant variation of absorber strengths on relatively small (~kpc and less) scales, hinting at an inhomogeneous clumpy circum-galactic medium. I am going to present our ongoing efforts of combining observational IFU data of lensed quasars with high spatial resolution cosmological simulations in order to study the small-scale structure of the CGM. I will show the results of our non-targeted "blind" search for intermediate absorbers and their metal line variations over kpc scales using MUSE data of a lensed quasar field. To learn more about the underlying physical structure of the gas probed in the CGM, I am using FOGGIE's highly resolved cosmological simulations to extract and analyse the clumps and filaments in galactic halos and I will report on the current state of our efforts to mock and interpret observables from these simulations.
Speaker: Matilde Mingozzi
Title: UV Diagnostics in Local High-z Analogs with the CLASSY Survey
Abstract: Rest-frame UV spectra play a key role in the understanding of massive stellar populations, chemical evolution, feedback processes, and reionization. Indeed, in the upcoming JWST era, the UV spectroscopic frontier will be pushed to higher redshifts than ever before, to finally reveal and explore the first galaxies in the distant Universe. In this context, the COS Legacy Archive Spectroscopic SurveY (CLASSY) provides the first high-quality, high-resolution and broad-wavelength range catalogue of 45 local star-forming high-z analogues in the rest-frame UV (1150 −2000 Å) to investigate their stellar and gas properties. As such, CLASSY provides the ideal FUV atlas with which we can tailor a complete UV diagnostic toolkit to investigate the interstellar medium (ISM) properties. In this talk I will present such a toolkit, obtained from the analysis of the main emission lines of CLASSY spectra excluding Lya (i.e., N IV] λλ1483,87, C IV λλ1548,51, He IIλ1640, O III]λλ1661,6, Si III] λλ1882,93, C III] λλ1907,9). Specifically, here we focus our investigation on dust attenuation, density, temperature, gas-phase metallicity, ionization parameter diagnostics and source of ionization, taking into account the different ionization zones of the ISM. Finally, I will discuss how our UV tool-kit compares to well-known optical diagnostics, analyzing archival optical spectra for all the CLASSY targets. Overall, this set of rest-FUV diagnostics will be crucial to interpret the earliest galaxies that JWST will reveal.
This Discovery Seminar features talks by Ramona Augustin on Characterising the Small-scale Structure in the Circumgalactic Medium and Matilde Mingozzi on UV Diagnostics in Local High-z Analogs with the CLASSY Survey.
Tuesday, June 21 2022.
Speaker: Ramona Augustin
Title: Characterising the Small-scale Structure in the Circumgalactic Medium
Abstract: Gas flows in and out of galaxies are typically probed by quasar absorption lines which are usually limited to a single sightline through the halo, giving no information on the structure of the gas probed in absorption. First studies using lensed, multiple or extended background objects have shown that there can be significant variation of absorber strengths on relatively small (~kpc and less) scales, hinting at an inhomogeneous clumpy circum-galactic medium. I am going to present our ongoing efforts of combining observational IFU data of lensed quasars with high spatial resolution cosmological simulations in order to study the small-scale structure of the CGM. I will show the results of our non-targeted "blind" search for intermediate absorbers and their metal line variations over kpc scales using MUSE data of a lensed quasar field. To learn more about the underlying physical structure of the gas probed in the CGM, I am using FOGGIE's highly resolved cosmological simulations to extract and analyse the clumps and filaments in galactic halos and I will report on the current state of our efforts to mock and interpret observables from these simulations.
Speaker: Matilde Mingozzi
Title: UV Diagnostics in Local High-z Analogs with the CLASSY Survey
Abstract: Rest-frame UV spectra play a key role in the understanding of massive stellar populations, chemical evolution, feedback processes, and reionization. Indeed, in the upcoming JWST era, the UV spectroscopic frontier will be pushed to higher redshifts than ever before, to finally reveal and explore the first galaxies in the distant Universe. In this context, the COS Legacy Archive Spectroscopic SurveY (CLASSY) provides the first high-quality, high-resolution and broad-wavelength range catalogue of 45 local star-forming high-z analogues in the rest-frame UV (1150 −2000 Å) to investigate their stellar and gas properties. As such, CLASSY provides the ideal FUV atlas with which we can tailor a complete UV diagnostic toolkit to investigate the interstellar medium (ISM) properties. In this talk I will present such a toolkit, obtained from the analysis of the main emission lines of CLASSY spectra excluding Lya (i.e., N IV] λλ1483,87, C IV λλ1548,51, He IIλ1640, O III]λλ1661,6, Si III] λλ1882,93, C III] λλ1907,9). Specifically, here we focus our investigation on dust attenuation, density, temperature, gas-phase metallicity, ionization parameter diagnostics and source of ionization, taking into account the different ionization zones of the ISM. Finally, I will discuss how our UV tool-kit compares to well-known optical diagnostics, analyzing archival optical spectra for all the CLASSY targets. Overall, this set of rest-FUV diagnostics will be crucial to interpret the earliest galaxies that JWST will reveal.
