Universiteit Leiden

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This Week's Discoveries | 5 November 2019

Tuesday 5 November 2019
This Week's Discoveries
Niels Bohrweg 2
2333 CA Leiden
De Sitterzaal

First lecture

Sarah Leslie (Leiden Observatory)
Sarah is a Postdoctoral Oort Fellow at the Leiden Observatory. She obtained her PhD from the Max Planck Institute for Astronomy (MPIA) in Heidelberg, Germany. Sarah works with multiwavelength surveys, with a particular interest in radio and optical synergies, to understand how galaxies form and change over cosmic time.

The Cosmic Evolution Survey (COSMOS) is a 2 square degree astronomical survey designed to probe the formation and evolution of galaxies as a function of both cosmic time (redshift) and the local galaxy environment. The COSMOS field has been observed by nearly all ground and space-based facilities and over 2 million galaxies are detected, spanning 75% of the age of the Universe. 

The Atacama Large Millimeter/submillimeter Array (ALMA) is a powerful new instrument for probing molecular gas in galaxies, the fuel for star formation. Observations in the public ALMA archive have been accumulating rapidly and are becoming more and more powerful for the study of galaxy scaling relations and evolution. To exploit these data, we have performed Monte Carlo simulations to understand the underlying biases and true uncertainties of various ALMA photometry methods.

Here, we present our Automated Mining of the ALMA Archive in COSMOS (A3COSMOS) pipelines that include machine-learning-based quality assurance steps. With our A3COSMOS pipelines, we have processed over 2500 ALMA continuum images and data, leading to more than 1000 robust (S/N>5.4) ALMA detections. A large fraction of these sources is totally obscured in optical wavelengths indicating a population of high-redshift (z>3-5) dusty galaxies. We also present results using the A3COSMOS catalogues and the literature to study the gas, stellar, and star formation rate scaling relations of star-forming galaxies across cosmic time. This large dataset supports the idea that galaxies are eco-systems whose properties can be well described by prescriptions that hint at the physical laws governing galaxy evolution.

Second lecture

Is it real? The role of authentic objects in science museums.

Anne Land-Zandstra (IBL, Science Communication and Society)
Anne is an assistant professor in science communication at the department of Science Communication & Society. Her research focuses on authenticity in informal science education, including the role of real objects in science museums. In collaboration with Naturalis, Museon and other science museums she studies how visitors value authentic objects as well as how they interact with these objects. Another part of her research includes citizen science as a way to get people in touch with real science.

Authenticity is often supposed to play an important role in natural history museums; visitors expect to see “the real thing”. Yet we know very little about how it affects the perception and appreciation of museum objects. In Naturalis, we examined children’s perceptions of real fossils and replicas. They were asked to rate two real dinosaur fossils and two replicas on how much they thought these objects belonged in a museum. They also explained their ratings. We found that children look beyond just the physical appearance of an object and take into account the object’s history in the value they attach to it. This has implications for the presentation of objects and the design of exhibitions.

Read more about the lecture series This Week's Discoveries

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