Starts With A Bang podcast

If you want to understand the origin of life in the Universe, you have three basic ways to do it. One is to search for intelligent aliens directly: through a program such as SETI. Another is to search for life in Solar Systems beyond our own: looking for bio-signatures, or perhaps bio-hints, on extraterrestrial worlds many light-years away. But within our own Solar System, there are a plethora of worlds, including the ice-and-liquid-rich bodies we have, that are fascinating candidates for life of non-Earth origin. There's so much to explore and so many different aspects of what's out there that I went into an incredibly far-ranging conversation with our podcast guest, planetary scientists and NExSS postdoc Dr. Jessica Noviello, that we wound up talking for nearly two full hours, and still couldn't cover everything we wanted to! Still, it was an amazing conversation for me and I hope it is for you, too. Enjoy it! (Image credit: NASA/JPL/Ted Stryk, of Europa with its uniquely curved stripes, for the Galileo mission.)

Practically every galaxy in the Universe has a supermassive black hole at their core. Ranging from millions to many billions of solar masses, these cosmic behemoths are capable of behaving as engines: accreting and accelerating matter to tremendous speeds and temperatures, where they emit enormous amounts of radiation. Galaxies can remain in this active state for hundreds of millions of years, where they appear to us as active galactic nuclei or quasars, depending on their specific properties. But why are some galaxies active while others aren't? How long will the active ones we see remain active, and will some of the inactive ones turn on? What about flares? As it turns out, there's a powerful connection between the surrounding galaxy, the processes occurring at the core, and the activity levels of the central black hole. Here to help us put it all together is Dr. Yashashree Jadhav, who takes us on a fascinating and far-ranging discussion about black holes, gas, stars, and much, much more! Enjoy it all on this edition of the Starts With A Bang podcast! (The image here is a multiwavelength view of the galaxy Centaurus A: the closest active galaxy to the Milky Way. Image credit: X-ray: NASA/CXC/SAO; Optical: Rolf Olsen; Infrared: NASA/JPL-Caltech.)

Like everything in the Universe, stars are born, they live a little while, and then they die. But despite their similarities in terms of where they come from and what they're made of, these objects can have an enormous variety of fates that they experience, and there are some fascinating intermediate and near-final states along the way. Beyond that, the unique stories of the people who made those key discoveries that have brought us to where we are can help us understand exactly how we pieced together the stellar picture of our Universe's history together. I'm so pleased to welcome Emily Levesque, professor at the University of Washington, author of The Last Stargazers, and enthusiastic lover of the Universe beyond planet Earth to the podcast. This ~80 minute episode was one of my favorites, and showcases Emily's knack for combining her vast knowledge of astronomy with her passion for sharing those stories with the entire world. Have a listen on the latest installment of the Starts With A Bang podcast! (Image credit: Emily Levesque / Perimeter Institute.)

When we think about the Universe as a whole, the accelerations that objects experience from our perspective are overwhelmingly due to the expansion of the Universe. Nearby, however, it's the local gravitational effects of nearby masses that dominate. Within our own Local Group, we've been able to discover that the Milky Way is not some quiet, massive spiral just going about its own business, but rather that it's being tugged in a variety of ways from the large masses around it, including a nearby galaxy that was only discovered in very recent years: Antlia 2. This is one of the most exciting detective stories we've gotten to uncover in recent years, as the resolution of this mystery showcases how improved, high-resolution data taken over long periods of time can enable us to witness galactic changes, directly, on the timescale of a single human lifetime. Here to walk us through what we know, how we know it, and what comes next is Prof. Sukanya Chakrabarti of the Rochester Institute of Technology, and I think you'll really enjoy what turned out to be a deep and far-ranging conversation about astronomy right in our own cosmic neighborhood! (Image credit: V. Belokurov and A. Smith; acknowledgement: Markus and Gail Davies; Robert Gendler)

When you think about how astronomy works, you probably think about observers pointing telescopes at objects, collecting data about their properties, and then analyzing that data to determine what those objects are truly like, and to infer what they can teach or show us about the Universe. But that's a rather old-fashioned way of doing things: one that's contingent on there being enough astronomers to examine all of that data manually. What do we do in this new era of big data in astronomy, where there aren't enough astronomers on Earth to even look at all of the data by hand? The way we deal with it is fascinating, and involves a mix of statistics, classical analysis and categorization, and novel techniques like machine learning and simulating mock catalogues to "train" an artificial intelligence. Perhaps the most exciting aspect is how thoroughly the best of these applications continuously outperform, in both quality and speed, any of the manual techniques we've used previously. Here to walk us through this exciting and emerging field of machine learning in astronomy is Sankalp Gilda, PhD candidate and astronomer from the University of Florida. We've got a great 90 minutes here for you, so buckle up and enjoy the ride! (Image credit: VLT Survey Image / ESO; Acknowledgement: Aniello Grado & Luca Limatola)

Swarming through our own galaxy, we've detected quite a few bizarre objects: pulsars. These rapidly spinning neutron stars are only a few kilometers across, yet contain more mass than our entire Sun. They're denser than a uranium atom's nucleus, and some of them possess the strongest magnetic fields in the known Universe. The fastest-spinning one known rotates about its axis 766 times per second, and they can travel at up to ~65% the speed of light. And outside of the ones we've found, we fully expect there might hundreds of millions or even as many as a billion such neutron stars hanging out simply in our Milky Way galaxy. But they also emit their own light, and a good chunk of that light is polarized, giving us an incredible set of information. In addition, by coordinating the pulse times of many different pulsars, we can not only detect gravitational waves, but can detect the types of waves generated by objects that LIGO and even LISA will never see. I'm so pleased to welcome Haley Wahl, pulsar specialist and PhD candidate, onto the show, and I hope you enjoy what turned out to be a fantastic conversation! (Image credit: NanoGRAV Collaboration.)

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.)