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L. Y. Aaron Yung
Приєднався 3 лип 2020
[Galaxies SIG] Understanding Galaxy Formation and Growth Through Chemical Abundances - Ryan Sanders
Understanding Galaxy Formation and Growth Through Chemical Abundances
Ryan Sanders (Univ. of Kentucky)
The abundance of metals in gas and stars is a powerful probe of the baryon cycle and galaxy formation histories. There is particlar interest in using chemical abundances to probe the growth and formation of galaxies at high redshifts, when star-formation rates were higher and gas flows are thought to be stronger than in the local Universe. The majority of work in this area has focused on "one-dimensional" single-element analyses leveraging the oxygen abundance in the gas-phase ISM or the iron abundance in the stellar population as a tracer of bulk metallicity. Recently, the spectroscopic sensitivity of JWST's instrument suite has enabled the measurement of detailed chemical abundance patterns of several elements in individual high-redshift galaxies for the first time. I will discuss progress in understanding galaxy formation through the lens of chemical abundances both before and during the JWST era, and highlight some unexpected results that remain difficult to interpret. HWO's UV+optical spectrograph could provide key observations to solve JWST's mysteries of the high-redshift Universe.
Ryan Sanders (Univ. of Kentucky)
The abundance of metals in gas and stars is a powerful probe of the baryon cycle and galaxy formation histories. There is particlar interest in using chemical abundances to probe the growth and formation of galaxies at high redshifts, when star-formation rates were higher and gas flows are thought to be stronger than in the local Universe. The majority of work in this area has focused on "one-dimensional" single-element analyses leveraging the oxygen abundance in the gas-phase ISM or the iron abundance in the stellar population as a tracer of bulk metallicity. Recently, the spectroscopic sensitivity of JWST's instrument suite has enabled the measurement of detailed chemical abundance patterns of several elements in individual high-redshift galaxies for the first time. I will discuss progress in understanding galaxy formation through the lens of chemical abundances both before and during the JWST era, and highlight some unexpected results that remain difficult to interpret. HWO's UV+optical spectrograph could provide key observations to solve JWST's mysteries of the high-redshift Universe.
Переглядів: 172
Відео
[Galaxies SIG] Star Formation in the Diffuse Universe - Jason Young
Переглядів 14221 день тому
Star Formation in the Diffuse Universe Jason Young (Williams College) The modern view of galaxy evolution links gas availability to star formation, with the depletion / removal of gas seen as the end of a galaxy's active life. However, about 10% of local spirals are gas rich, yet host little star formation. The paradox presented by these "classical low surface brightness (LSB) spirals" tests th...
[Galaxies SIG] Mapping Dust Attenuation from Overlapping Galaxy Pairs - Clayton Robertson
Переглядів 292 місяці тому
Mapping Dust Attenuation from Overlapping Galaxy Pairs Clayton Robertson (University of Louisville) The combination of extinction and scattering combined (i.e., attenuation) due to dust grains remain a critical uncertainty; for nearly all astronomical measurements, one needs to account for the dust in space. A technique to obtain extra-galactic spatially resolved attenuation measurements is to ...
[Galaxies SIG] Galactic Paleontology in the Era of HWO - Mia Bovill
Переглядів 492 місяці тому
Galactic Paleontology in the Era of HWO. Feel free to make suggestions if you want me to change it Mia Bovill (University of Maryland) Upcoming telescopes, including HWO, will revolutionize our understanding of near field cosmology with unprecedented observations of dwarf galaxies into the Local Volume. However, we do not have a sufficient theoretical understanding of the scatter inherent in dw...
[Galaxies SIG] Uncovering the Drivers of Galaxies Growth WG - Marc Postman & Swara Ravindranath
Переглядів 972 місяці тому
Unveiling the Drivers of Galaxy Growth with the Habitable Worlds Observatory Swara Ravindranath & Marc Postman, on behalf of the HWO Galaxy Growth Working Group Habitable Worlds Observatory (HWO) is a large (6 meter) ultraviolet / optical /near-infrared ultra-stable space telescope recommended by the National Academies Decadal Survey "Pathways to Discovery in Astronomy and Astrophysics for the ...
[Galaxies SIG] Modelling the Interstellar Medium of Galaxies - Rahul Kannan
Переглядів 795 місяців тому
Modelling the Interstellar Medium of Galaxies Rahul Kannan (York University) The Habitable Worlds Observatory is set to provide groundbreaking imaging and spectroscopic observations of galaxies, which will greatly enhance our understanding of how galaxies form and evolve. To fully capitalize on these new observations, it is crucial to develop advanced numerical models that can accurately predic...
[Galaxies SIG] Dwarf Galaxies: Yesterday, Now, and Tomorrow - Burçin Mutlu-Pakdil
Переглядів 567 місяців тому
Dwarf Galaxies: Yesterday, Now, and Tomorrow Burçin Mutlu-Pakdil (Dartmouth College) I will review the revolution that has unfolded over the last 20 years in the search for the satellites in the Local Group and beyond thanks to a flurry of large photometric surveys with which we can unveil dwarf galaxies of incredibly low luminosity. The discovery and characterization of these smallest galaxies...
[Galaxies SIG] Understanding the Production and Escape of Ionizing Photons with HWO - Anne Jaskot
Переглядів 897 місяців тому
Understanding the Production and Escape of Ionizing Photons - Far-UV Science with HWO Anne Jaskot (Williams College) JWST is transforming our knowledge of galaxy properties at z greater than 6, but one property it cannot observe is the emission of ionizing, Lyman Continuum (LyC) photons from these galaxies. At high redshifts, these LyC photons are absorbed by the IGM en route to Earth. Yet stud...
[Galaxies SIG] Cosmo Hyper-Refinement Sims to Leverage Future Observatories - Daniel Anglés-Alcázar
Переглядів 588 місяців тому
Galaxies SIG Seminar on Wednesday, 3 April 2024 Cosmological Hyper-Refinement Simulations to Leverage Future Great Observatories Daniel Anglés-Alcázar (UConn) The Habitable Worlds Observatory and other Future Great Observatories will provide an unprecedented window into the physical mechanisms driving active galactic nuclei (AGN) fueling and feedback, which play a key role in galaxy evolution b...
[Galaxies SIG] The Role of UV Spectroscopy to Interpret the First Galaxies - Matilde Mingozzi
Переглядів 648 місяців тому
Galaxies SIG Seminar on Wednesday, 6 March 2024 The Role of UV Spectroscopy to Interpret the Properties of the First Galaxies Rest-frame UV spectra play a key role in the understanding of massive stellar populations, chemical evolution, feedback processes, and reionization. In particular, in the current JWST era, the UV spectroscopic frontier has been pushed to higher redshifts than ever before...
[Galaxies SIG] Using Empirical Models to Explore Science Uncertainties for HWO - Peter Behroozi
Переглядів 1159 місяців тому
Galaxies SIG Seminar on Wednesday, 7 February 2024 Using Empirical Models to Explore Science Uncertainties for HWO We review recent progress in empirical modeling, including a new empirical model, Trinity, that observationally constrains the joint relationship between supermassive black holes (SMBHs), galaxies, and dark matter halos from z=0 to z=7. Trinity can recover the average growth and me...
[Galaxies SIG] How HWO Can Constrain the Geometry of High-Redshift MW Progenitors - Viraj Pandya
Переглядів 13310 місяців тому
Galaxies SIG Seminar on Wednesday, 24 January 2024 How Habitable Worlds Observatory Can Definitively Constrain the 3D Geometry of High-Redshift Milky Way Progenitors There is now strong evidence from both NASA's HST and JWST that the majority of high-redshift dwarf galaxies (including Milky Way progenitors) cannot be axisymmetric (circular) disks or spheroids as commonly assumed. Instead, galax...
[Galaxies SIG] The Case for a FUV Spectrograph: From Molecular ISM to Hot IGM - Blakesley Burkhart
Переглядів 22511 місяців тому
Galaxies SIG Seminar on Tuesday, 5 December 2023 The Case for a High-resolution FUV Spectrograph: From the Molecular Galactic ISM to the Hot IGM In this talk, I will highlight two areas in gaseous astrophysics where exciting mysteries could be addressed with a high-resolution (R greater than 10, 000) FUV spectrograph. First, I will discuss how the low redshift (z ~0.1) Lyman-α forest observatio...
[Galaxies SIG] Near, far, wherever you are: Connecting local and high-z galaxy - Mia de los Reyes
Переглядів 57Рік тому
Near, far, wherever you are: Connecting local and high-z dwarf galaxy populations with HWO 7 November 2023, 1:00pm ET Mia de los Reyes (Amherst College) Although we are entering a new era of high-redshift science, we still don’t fully understand the systematic effects that impact our observations of high-redshift galaxies. At the same time, although we have begun mapping our own galaxy and its ...
[Galaxies SIG] HabWorlds and What YOU Can Do About It - Jason Tumlinson
Переглядів 124Рік тому
Galaxies SIG Seminar on Tuesday, 5 September 2023 HabWorlds and What YOU Can Do About It NASA’s Cosmic Origins Program has established a Science Interest Group (SIG) specifically for galaxies science. Our goals are to map out the galaxies’ science priorities for the Habitable Worlds Observatory (HWO, the 6m UV-Optical-IR space telescope that is the top recommendation from the Astro2020 Decadal ...
[Galaxies SIG] Emission and Absorption Line Modeling from Hydrodynamical Simulations - Aaron Smith
Переглядів 75Рік тому
[Galaxies SIG] Emission and Absorption Line Modeling from Hydrodynamical Simulations - Aaron Smith
2016 UV Luminosity Functions Predicted by SAM
Переглядів 344 роки тому
2016 UV Luminosity Functions Predicted by SAM
Thank you both so much!
I found that this lecture focuses enough on visuals that i’ll be revisiting it later, excited to watch it when I’m able. I’m always happy to find channels like yours, and I hope you have a good day! Thank you for your work
Black holes are based on a mathematical misconception. G.R predicts dilation not singularities. In the 1939 journal "Annals of Mathematics" Einstein wrote - "The essential result of this investigation is a clear understanding as to why the Schwarzchild singularities (Schwarzchild was the first to raise the issue of G.R. predicting singularities) do not exist in physical reality. Although the theory given here treats only clusters (star clusters) whose particles move along circular paths it does seem to be subject to reasonable doubt that more general cases will have analogous results. The Schwarzchild singularities do not appear for the reason that matter cannot be concentrated arbitrarily. And this is due to the fact that otherwise the constituting particles would reach the velocity of light." He was referring to the phenomenon of dilation (sometimes called gamma or y) mass that is dilated is smeared through spacetime relative to an outside observer. It's the phenomenon behind the phrase "mass becomes infinite at the speed of light". A graph illustrates its squared nature, dilation increases at an exponential rate the closer you get to the speed of light. A "time dilation" graph illustrates the same phenomenon, it's not just time that gets dilated. Dilation will occur wherever there is an astronomical quantity of mass because high mass means high momentum. There is no singularity/black hole at the center of our galaxy. It can be inferred mathematically that dilation is occurring there. In other words that mass is all around us. This is the explanation for galaxy rotation curves. The "missing mass" is dilated mass. Dilation does not occur in galaxies with low mass centers because they do not have enough mass to achieve relativistic velocities. To date, 6 very low mass galaxies including NGC 1052-DF2 and DF4 have been confirmed to show no signs of dark matter. This also explains why all planets and all binary stars have normal rotation rates, not 3 times normal. The concept of singularities is preventing clarity in astronomy. Einstein is known to have repeatedly said that they cannot exist. Nobody believed in them when he was alive including Plank, Bohr, Schrodinger, Dirac, Heisenberg, Feynman etc.
So many imaginary problems from not understanding the observations. It’s the observations that are real and it’s gravity that is not being understood. We don’t need another law of gravity. Gravity is constant locally the same as the earth is flat locally. On a larger scale gravity is not constant and the earth is not flat. Gravity drops off considerably outside of the galaxy which changes considerably the measures of time and and distance which together make everything to appear to move faster including light. Things appear to be moving faster because they are moving faster as seen by us in our slower rate of time and our shorter measure of distance. This eliminates entirely the need for dark matter. The changes in time and distance compound the changes in the speed of light. Do a thought experiment. Hold your hands a foot apart representing 186,000 miles saying “one thousand and one” representing one second while pretending to see an imaginary photon going from one hand to the other. Now expand the distance saying “one thousand and one” as fast as you can. You should notice that the speed of the imaginary photon increases the more distance expands and the more time speeds up the farther away from the center of the galaxy it is. The energy source of the vacuum energy is all of the supermassive black holes that are growing by drawing in spacetime. This means that the universe is not expanding into oblivion for no reason. It means there is no need for imaginary inflatons. Redshift occurs when light leaves the gravity of a galaxy and then the light is blue shifted when it enters another galaxy. Obviously galaxies aren’t all equal that way and distant galaxies are much more redshifted because of all of the mass of the surrounding galaxies that distance light has to pass by.