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The COS Legacy Archive Spectroscopic SurveY Atlas

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About Me

My research focuses on bridging our deepest understanding of galaxies, which comes from connecting the local galaxies in our backyard with the first seeds of galaxies in the very distant and early universe. I am especially interested in how star-forming galaxies formed, reionized the universe, and evolved to the diverse population we see today. Using ground- and space-based multiwavlength observations (mostly X-ray, UV, optical, and IR spectra), I study the chemical and stellar evolution of star-forming galaxies, near and far. These observations probe the feedback between the ionizing stellar populations and their surroundings, revealing the properties of massive stars, high-mass X-ray binaries, resonantly scattered emission, galactic-scale feedback, interstellar medium absorption, and nebular emission.

I am an assistant professor in the Department of Astronomy at the University of Texas at Austin. Prior to that, I held postdoctoral research positions at the Ohio State University and the University of Wisconsin-Milwaukee. Currently my main research projects focus on the evolution of galaxies, both near and far, including:

                                            The COS Legacy Archive Spectroscopic SurveY (CLASSY), of which I am the PI:

                                            In Berg et al. 2022 I present CLASSY I: the COS Legacy Spectroscopic SurveY treasury

                                            and its first high level science product (HLSP), the CLASSY atlas. CLASSY builds on the

                                            Hubble Space Telescope (HST) far ultraviolet (FUV) archive to construct the first high-

                                            quality (S/N1500Å ≳ 5/resel), high-resolution (R~15,000) FUV spectral database of 45 

                                            nearby (0.002 << 0.182) star-forming galaxies. The CLASSY atlas is a the result of

                                            combining 94 archival spectra from 177 orbits with 76 new spectra from 135 orbits

                                            (170 spectra total from 312 orbits) of HST observations, or more than 600 total Cosmic

                                            Origins Spectrograph (COS) spectral images. The CLASSY spectra have been optimally

                                            extracted and coadded, and the final atlas is available to the public via the CLASSY HLSP


                                            Extreme emission line galaxies:

                                            Many of the best observations of UV emission-line spectra come from nearby, metal-

                                           poor, high ionization dwarf galaxies. This has lead me to discover galaxies with extreme

                                            emission line properties, including the largest equivalent width detections of nebular

                                            HeII and CIV emission amongst z~0 galaxies. Owing to the very hard ionizing radiation

                                            fields that necessarily accompany these galaxies, I suggested in Berg et al. 2021 these

                                            targets as a new class of high-z analogues that can help us study the sources

                                            responsible for cosmic reionization (e.g., extremely massive stars, stripped stars, high-

                                            mass X-ray binaries, etc.). 


                                            The evolution of C/O abundances in star-forming galaxies:                                                    

                                            The study of UV emission lines, especially carbon and oxygen lines, has become a

                                            niche of mine, as I continue to build a sample of galaxies with C, N, and O

                                            measurements and models in order to understand the nucleosynthetic production

                                            methods and stellar feedback that produces the observed abundance trends. See, e.g.,

                                            Berg et al. 2016 and Berg et al. 2019.

                                            Characterizing the stellar and nebular properties of lensed galaxies:

                                            I study, in detail, the rest-frame UV and optical emission and absorption line properties                                             of the most extreme distant lensed galaxies, e.g., Berg et al. 2018.

                                            The CHemical Abundances of Spirals (CHAOS) project, of which I am a main contributor:

                                            CHAOS studies the chemical abundance patters across the faces of spiral galaxies using

                                            UV, optical, and infrared (IR) spectra of nebular gas (e.g., Berg et al. 2015, Berg et al. 2020).

                                            Using comparisons to abundances from UV nebular lines and optical blue supergiant

                                            spectra, CHAOS is helping test the abundance discrepancy problem and determine an

                                            absolute abundance anchor for the local universe.

I am also a part of the following collaborations:

                                            The DUVET Survey - PI: Deanne Fisher (Swinburne)

                                            The NGDEEP Survey - PIs: Steven Finkelstein (UT), Casey Papovich (Texas A&M), and

                                                                                                  Norbert Pirzkal (STScI)


When I am not pondering profound astronomical questions, or soaking up the beauties of the night sky, I love to travel and play. I have a general goal to visit one new country a year and to keep exploring places that challenge me physically or emotionally. Whether on the trail or on a spin bike, I am always up for a good sweat. You can occasionally find me leading the pack at TruFusion​ in South Austin, TX.



Dwarf Galaxies

Metal-poor, star-forming dwarf galaxies (M★ < 10^9 M⊙) provide unique chemically-unevolved laboratories to study the evolution pathways of galaxies similar to the conditions of galaxies in the early universe. 


life beyond astronomy || instagram: @danielle.cycle614


Danielle A. Berg

The University of Texas at Austin
2515 Speedway, Stop C1400
Austin, TX 78712

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