Starts With A Bang podcast

If you look out at the Universe and measure all the matter out there, including stars, gas, dust, plasma, black holes, etc., it simply doesn't add up. You can't explain the gravitational effects you see with the known particles of the Standard Model alone. But even if you add in the one extra ingredient of cold, collisionless dark matter, it only fixes everything to a certain extent. In particular, the small-scale structures of the Universe, on the scales of individual galaxies and below, have a large mismatch between what's observed and what's predicted. While there are many approaches we can take, and a few different possible explanations, perhaps the most compelling approach is to try and infer what particle properties might dark matter have to bring our observations in line with what our theories and simulations would predict? Here to talk to us about the latest progress on that front is PhD candidate and budding science communicator Sophia Gad-Nasr (a.k.a. @astropartigirl), who joins us for a fascinating ~90 minute discussion on this edition of the Starts With A Bang podcast! Follow Sophia: -on Twitter, https://twitter.com/Astropartigirl -on her Website, https://astropartigirl.com/ -or on Instagram, https://www.instagram.com/astropartigirl/?hl=en -or TikTok, https://www.tiktok.com/@astropartigirl (Image credit: Cathrin Machin; NASA, ESA, the Hubble Heritage (STScIAURA)-ESA/Hubble Collaboration, and A. Evans.)

Have you ever wondered what it's like to work as a small (but vital) part of a large collaboration, where hundreds or even thousands of experimental scientists get together to produce an experiment far larger or more complex than any one person could oversee on their own? Have you ever wondered where the line is between physics and astronomy, and whether it even makes sense to have a line at all in the case of astroparticle physics? And have you ever wished that people would be more honest about the recent toxic experiences that they had when they were starting out that are still relevant to young people in those shoes today? I'm so pleased to have such a remarkable discussion with astrophysicist Niko Sarcevic (pronounced "SHAR-chev-itch" when comes out of my mouth) that's was not only far ranging but incredibly enjoyable for me. I hope you like listening, and if you want to listen to me absolutely botch describing the XENON experiment (which doesn't use the lead shielding I described; that was a different detector: SuperCDMS!), it's well-documented for everyone to hear! (Image credit: M. van der Wild, using Niko's phone, of the then-under-construction electric field cage that Niko Sarcevic designed and built for the Time Projection Chamber (TPC) for the XENON collaboration.)

You might have thought that if we were going to find life anywhere in the Universe, our best bet would be to look at stars like our Sun, on account of the tremendous success of Earth. It's a good bet, for sure, but did you know that the Sun is brighter and more massive than 95% of stars in the Universe? And that down at the low-mass end of the spectrum, the most common type of objects out there are ultracool dwarfs: low-mass red dwarfs and even brown dwarfs? They have rocky planets around them and could be our first candidate Earth-sized worlds for direct imaging, and are incredible scientific objects of study all on their own. What do you want to know about them? I'm so pleased to welcome PhD candidate Anna Hughes onto the Starts With A Bang! podcast, and to share her knowledge and wisdom and enthusiasm with all of you. Here's how we start 2021 with a bang, and I hope you enjoy it!

Over the past 2 years, an exciting development has finally arisen: scientists have measured a large number of small, diffuse galaxies exquisitely well, and have finally found their first candidate galaxies that appear to have no dark matter at all. Whereas large cosmic structures typically have dark matter-to-normal matter ratios of 5-to-1, smaller structures typically have higher ratios, as star formation will kick some of the normal matter out but leave the dark matter intact. However, there should be a second type of galaxy: stars without dark matter, as tidal interactions can rip the normal matter out and keep it out. But these structures are easy to destroy, and so shouldn't persist for very long. How, then, did we find a galaxy that both appears to have no dark matter and also appears to have not formed any new stars in ~7 billion years or more? While the science is still ongoing, I'm so pleased to welcome Dr. Mireia Montes onto the program, whose recent paper may have just solved the mystery. Have a listen and enjoy the show; there's a lot of astronomy in here for you to enjoy! (Image credit: Montes et al., 2020, ApJ.)

Over the past 30 years, we've gone from zero exoplanets to thousands. With each new generation of telescopes, observatories, and scientists, we build upon our previous finds to make enormous advances that go beyond what any one person could ever produce. The ESA's Gaia mission has surveyed more than a billion stars, identifying the closest ones that would make potentially great targets for NASA's James Webb Space Telescope, if they had potentially habitable planets around them. NASA's TESS is doing the preliminary work of observing these stars, most of which are red dwarf (M-class) stars, to find which ones actually have interesting planets that transit across their parent star's face. So far, we've found some fascinating candidates, some of which just might be humanity's first discovery of biosignatures beyond our Solar System if we get lucky. This month, we're so fortunate to be joined by astronomer and TESS scientist Emily Gilbert, a Ph.D. candidate who specializes in exoplanets. (And who has the delightful Twitter handle: @EmDwarf.) Come learn where we are, what we know, and where this rapidly evolving scientific field is headed today! (Image credit: ENGELMANN-SUISSA ET AL.NASA'S GODDARD SPACE FLIGHT CENTER)

It was only back in the early 2000s that scientists were struggling to identify and weigh the small number of supermassive black holes that we'd been able to identify in the known Universe, but the past 15-20 years have led to a revolution in what we know about them. We've identified tens of thousands of active galaxies, pinned down the masses of some of the closest ones to us through a variety of techniques, and even observed the event horizon of our first black hole directly. These powerful advances were mainly enabled by superior observatories and instruments, and the spectacular Atacama Large Millimetre/Submillimetre Array (ALMA) of telescopes, which was indispensible to measuring the mass and imaging the event horizon at the core of the largest massive galaxy in our neighborhood: M87. I'm so pleased to welcome astronomer and Ph.D. Candidate Kyle Kabasares onto the show, where we talk about black holes, mass measurements, ALMA, and the future of black hole-related astronomy! Kyle is also passionate about science outreach, and you can check out his YouTube channel here. (Image credit: EHT Collaboration; acknowledgement: ESO)

When most of us think of astronomy, we think about two types of scientists: the observers who point their telescopes at the sky and collect data, and the theorists who put together the physical rules of the Universe to both make critical predictions for what those observational results ought to yield and to interpret the data that comes in. But in reality, there are other important types of astronomers that we don't talk about frequently: analysts who focus on dealing with these literally astronomical data sets and the people who work on (and with) the instrumentation itself. This includes telescope and instrument builders, telescope operators and system specialists, and many other vital roles. Additionally, the science of astronomy isn't just about the science itself, but also questions important for the interplay of science and society. Whose land are these telescopes on? What does responsible stewardship look like? Who has access to these facilities, and who has equal (and unequal) access to the career paths of becoming a scientist? I'm so pleased to have astronomer Jess Schonhut-Stasik on the show, for a wide-ranging discussion about astronomy, from instruments to injustices and how the big questions about science and society are creating not only incredible dilemmas for astronomy, but an incredible opportunity to get things right. Have a listen today, and check out the fabulous Mauna Kea Scholars program that she's involved with here: https://maunakeascholars.com (With permission, her email address associated with inquiries about the program is here: j.stasik@ukirt.hawaii.edu) [Image credit: UKIRT / University of Hawaii Institute for Astronomy]

When we look out at the Universe today, we see that it's full of stars and galaxies. And yet, we can only see those stars and galaxies because the space between those galaxies and ourselves doesn't block that starlight before it gets to our instruments, observatories, telescopes, and eyes. But early on, that's an enormous problem: there is light-blocking gas and dust, and the record-holder for most distant galaxy ever discovered is still not a pristine, first-generation galaxy at all. But there are new observatories and cutting-edge techniques that will reveal them, teaching us how the Universe grew up: from a collection of neutral atoms with no stars and galaxies at all to the structure-rich Universe we see today. Joining me on this special, bonus edition of the Starts With A Bang podcast (because don't we all need a bonus?) is extragalactic astronomer and PhD candidate Rebecca Larson from the University of Texas - Austin, in a rich conversation that takes us all the way back to the edge of the Universe as we can observe it. Find out what lies at, and perhaps beyond, our current cosmic frontiers! (Image credit: NASA, ESA, and J. Kang (STScI))

When we look out at the galaxies in the Universe, almost all of them have supermassive black holes at their centers: millions or even many billions of times more massive than our Sun is. Most of the time, these black holes are relatively quiet, but every so often, a black hole can be spotted emitting enormous amounts of radiation over a large range of the electromagnetic spectrum. These "active galaxies" come in many different flavors, from blazars to AGNs to quasars and many others, but they're very closely tied to both the age of the Universe and how rapidly a galaxy forms stars. There's an awful lot that we've learned about these objects, and yet, still so many more mysteries to solve and uncover. This month, as the first of two podcasts, I'm so pleased to bring PhD candidate Alyssa Sokol, from the University of Massachusetts - Amherst, onto the program, as we enjoy a far-reaching conversation that takes us beyond the limits of what we know. (Image credit: X-ray - NASA, CXC, R.Kraft (CfA), et al.; Radio - NSF, VLA, M.Hardcastle (U Hertfordshire) et al.; Optical - ESO, M.Rejkuba (ESO-Garching) et al.)

When it comes to gravitational waves, our terrestrial laser interferometers have provided us with unparalleled success in terms of direct detection. But they have some strong fundamental limits: their laser arms are short; their sensitivity is limited to low-mass, small-radius objects; the signals they detect last for mere seconds, at most. Most importantly, seismic noise, and even the fact that we live on a planet with tectonic plates, place restrictions on how sensitive we'll ever be able to get. But in space, all of these stories change dramatically, and the upcoming European Space Agency mission LISA is aiming to open up our eyes to a realm of gravitational wave astronomy like we've never experienced before. On this edition of the Starts With A Bang podcast, we're joined by Dr. Ira Thorpe of NASA as we explore the future of gravitational wave astronomy in an entirely new realm: in space! (Image credit: EADS ASTRIUM)