Wine and Cheese Fall 2025 - Revision history

Kdkuntz at 16:04, 3 December 2025

2025-12-03T16:04:31Z

← Older revision		Revision as of 16:04, 3 December 2025
Line 69:		Line 69:
	Dwarf galaxies and globular clusters probe chemical evolution on opposite sides of a critical boundary between dark-matter-dominated systems capable of retaining supernova ejecta, and primarily baryonic systems that cannot. The chemical compositions of individual members preserve direct records of these contrasting enrichment histories. Traditionally, such studies rely on high-resolution spectroscopy to derive detailed abundances from individual absorption lines. However, medium-resolution spectroscopy opens access to much larger and fainter samples, at the cost of more complex modeling of blended features.		Dwarf galaxies and globular clusters probe chemical evolution on opposite sides of a critical boundary between dark-matter-dominated systems capable of retaining supernova ejecta, and primarily baryonic systems that cannot. The chemical compositions of individual members preserve direct records of these contrasting enrichment histories. Traditionally, such studies rely on high-resolution spectroscopy to derive detailed abundances from individual absorption lines. However, medium-resolution spectroscopy opens access to much larger and fainter samples, at the cost of more complex modeling of blended features.
	In this talk, I will present my approach to medium-resolution chemical analysis, beginning with globular clusters. Recent surveys have uncovered new variations in r-process element abundances, shedding light on the timescales of star formation and enrichment in these systems. I will then turn to the next frontier: dwarf galaxies of the Local Group. The Subaru Prime Focus Spectrograph (PFS) will obtain medium-resolution spectra for ~100,000 extragalactic stars, opening the possibility of finding members whose compositions preserve the imprint of individual nucleosynthetic events, incorporating the spatial distribution of abundances into chemical evolution models, and identifying past mergers between dwarf galaxies.		In this talk, I will present my approach to medium-resolution chemical analysis, beginning with globular clusters. Recent surveys have uncovered new variations in r-process element abundances, shedding light on the timescales of star formation and enrichment in these systems. I will then turn to the next frontier: dwarf galaxies of the Local Group. The Subaru Prime Focus Spectrograph (PFS) will obtain medium-resolution spectra for ~100,000 extragalactic stars, opening the possibility of finding members whose compositions preserve the imprint of individual nucleosynthetic events, incorporating the spatial distribution of abundances into chemical evolution models, and identifying past mergers between dwarf galaxies.

			=08 December=
			==Ho Sang (Leon) Chan (Colorado)==
			'''Topics on Computational Modelling of Accreting Black Holes'''<br>
			Recent advances in computational technology have enabled astrophysicists to model accreting black holes with more detailed microphysics and over longer durations. In this seminar, I will present our work on simulating accreting black holes to examine several largely unexplored topics.
			In the first part of the talk, I will describe our attempt to include electron-positron pairs in global, general relativistic magnetohydrodynamic (GRMHD) simulations of accreting black holes. We found that in models with moderate to high accretion rates, pairs are close to equilibrium near the disk midplane, where the scattering optical depth is high and pair-equilibrium timescales are short, and could be comparable to the Coulomb collision timescale. This suggests the possibility of a pair-regulated coronal temperature. In contrast, the upper corona and jets, where the scattering optical depth is relatively low and pair- equilibrium timescales are long, are populated with pairs that may exceed their equilibrium value by orders of magnitude. These pairs are transported outward by advection from the disk, which dominates over local pair processes. This result highlights advection as a significant source of pair injection.
			In the second part of the talk, I will present our self-consistent simulation of a strongly relativistic tidal disruption event (TDE) with astrophysical relevant parameters. As expected, we find that GR-induced apsidal precession drives strong stream self-intersection shocks, which rapidly dissipate orbital energy, reduce the fluid eccentricity, and power the bolometric luminosity. However, these shocks also broaden the debris’ angular momentum distribution, widen the range of fluid orbital pericenters, and shift the self-intersection points to larger radii. The subsequent evolution then resembles that of a weakly relativistic TDE. These findings suggest that while GR effects strongly shape the early-time dynamics and emission, their influence on the long-term evolution of TDEs is limited.

Kdkuntz: /* 10 November */

2025-11-03T20:24:57Z

10 November

← Older revision		Revision as of 20:24, 3 November 2025
Line 66:		Line 66:
	=10 November=		=10 November=
	==Roman Gerasimov (ND)==		==Roman Gerasimov (ND)==
	''' '''<br>		'''Medium-resolution Galactic Archaeology: Sharp Insights in Blurry Data'''<br>
			Dwarf galaxies and globular clusters probe chemical evolution on opposite sides of a critical boundary between dark-matter-dominated systems capable of retaining supernova ejecta, and primarily baryonic systems that cannot. The chemical compositions of individual members preserve direct records of these contrasting enrichment histories. Traditionally, such studies rely on high-resolution spectroscopy to derive detailed abundances from individual absorption lines. However, medium-resolution spectroscopy opens access to much larger and fainter samples, at the cost of more complex modeling of blended features.
			In this talk, I will present my approach to medium-resolution chemical analysis, beginning with globular clusters. Recent surveys have uncovered new variations in r-process element abundances, shedding light on the timescales of star formation and enrichment in these systems. I will then turn to the next frontier: dwarf galaxies of the Local Group. The Subaru Prime Focus Spectrograph (PFS) will obtain medium-resolution spectra for ~100,000 extragalactic stars, opening the possibility of finding members whose compositions preserve the imprint of individual nucleosynthetic events, incorporating the spatial distribution of abundances into chemical evolution models, and identifying past mergers between dwarf galaxies.

Kdkuntz at 13:24, 30 October 2025

2025-10-30T13:24:53Z

← Older revision		Revision as of 13:24, 30 October 2025
Line 58:		Line 58:
	'''Inflation as a Particle Factory'''<br>		'''Inflation as a Particle Factory'''<br>
	Cosmological gravitational particle production (GPP) is the process by which particles are created due to the expansion of spacetime during inflation. In this talk I will give an overview of GPP and discuss two scenarios in which it leads to highly efficient particle production. First, I will show how GPP of scalar fields in Higgs inflation models leads to a characteristic peaked spectrum and enhanced particle number. Then I will discuss GPP of dark photons with non-minimal couplings to gravity, which similarly leads to an enhancement of the particle number, but also instabilities. Finally, I will comment on phenomenological implications of these scenarios for dark matter.		Cosmological gravitational particle production (GPP) is the process by which particles are created due to the expansion of spacetime during inflation. In this talk I will give an overview of GPP and discuss two scenarios in which it leads to highly efficient particle production. First, I will show how GPP of scalar fields in Higgs inflation models leads to a characteristic peaked spectrum and enhanced particle number. Then I will discuss GPP of dark photons with non-minimal couplings to gravity, which similarly leads to an enhancement of the particle number, but also instabilities. Finally, I will comment on phenomenological implications of these scenarios for dark matter.

			=03 November=
			==Robert Coyne (URI)==
			'''Title: A Decade of Discovery: Gravitational Wave Astronomy and the Search for Elusive Multi-Messenger Signals'''<br>
			It has been 10 years since LIGO's first detection of gravitational waves, and the international LIGO-Virgo-KAGRA (LVK) collaboration continues to deliver new discoveries in this young field. Recent publications have more than doubled the number of detected gravitational wave signals through the fourth Gravitational Wave Transient Catalog. We have identified the most massive stellar-mass black hole merger observed to date. And we have used our loudest signal to conduct the most stringent tests of General Relativity yet – probing black hole structure and setting even tighter constraints on black hole thermodynamics. With more results still to come, the pace of discovery shows no signs of slowing. Yet despite these successes, a critical gap remains: we have detected only one multi-messenger event. Over 8 years ago, LIGO and Virgo observed GW170817, a binary neutron star merger that powered Gamma-Ray Burst 170817A. This joint observation demonstrated the potential of multi-messenger astronomy, but as the fourth observing run draws to a close, a second multi-messenger event has remained elusive. In this talk, I will summarize recent LVK discoveries and discuss how we search for gravitational wave emission associated with GRBs—before, during, and after the burst itself.

			=10 November=
			==Roman Gerasimov (ND)==
			''' '''<br>

Kdkuntz at 15:36, 24 October 2025

2025-10-24T15:36:33Z

← Older revision		Revision as of 15:36, 24 October 2025
Line 49:		Line 49:
	Guided by the recent discovery of the faint Milky Way satellite UMa3/UnionsI, in this talk I will present the results of our controlled high-resolution simulations to discuss how ”micro galaxies” could be distinguished observationally from self-gravitating star		Guided by the recent discovery of the faint Milky Way satellite UMa3/UnionsI, in this talk I will present the results of our controlled high-resolution simulations to discuss how ”micro galaxies” could be distinguished observationally from self-gravitating star
	clusters, and how such systems would help us to constrain both the properties of dark matter and the physical processes underlying the formation of the faintest of galaxies. Micro galaxies are a plausible prediction of Cold Dark Matter (CDM) cosmology: The centrally divergent density cusps of CDM subhaloes render them remarkably resilient to tides. Heavily stripped tidal remnants of the Milky Way accretion may survive even in the strong tidal field of the inner regions of our Galaxy. Some of these tidal remnants may have been sufficiently massive in the past to allow for star formation within their potential wells, giving rise to a population of micro galaxies: co-moving groups of stars, gravitationally supported by the dark matter subhalo which surrounds them.		clusters, and how such systems would help us to constrain both the properties of dark matter and the physical processes underlying the formation of the faintest of galaxies. Micro galaxies are a plausible prediction of Cold Dark Matter (CDM) cosmology: The centrally divergent density cusps of CDM subhaloes render them remarkably resilient to tides. Heavily stripped tidal remnants of the Milky Way accretion may survive even in the strong tidal field of the inner regions of our Galaxy. Some of these tidal remnants may have been sufficiently massive in the past to allow for star formation within their potential wells, giving rise to a population of micro galaxies: co-moving groups of stars, gravitationally supported by the dark matter subhalo which surrounds them.

			=27 October=
			==Emily Witt (JHU)==
			'''The Juniper CubeSat Concept: A Mission to Observe CGM Kinematics in Nearby Galaxies'''<br>
			The circumgalactic media (CGM) of galaxies play a key role in the baryon cycle of galactic feedback. Ultraviolet (UV) radiation from the CGM in particular is crucial to understanding the flow of gas and metals into and out of galaxies, probing warm/hot gas in the CGM that forms the transition between hot gas that remains in the galaxy's halo and cooler gas that recycles into the galaxy, feeding star formation and evolution. To characterize this process, the Juniper 16U CubeSat mission concept has been under development at Johns Hopkins University and the University of Colorado. Juniper will conduct observations of the CGM of nearby galaxies in multiple far ultraviolet (FUV) bandpasses that include key metal lines such as O VI (103.5 nm), C II (133.5 nm), and C IV (154.9 nm). The instrument is enabled by an innovative dual-grating optical design, Xenon-enhanced Lithium Fluoride (XeLiF) thin film coatings being considered for use on Habitable Worlds Observatory, and a FUV-sensitive photon-counting MCP detector. The use of these technologies results in Juniper's unprecedented spectral resolution, permitting for the first time the detailed study of the kinematics of the warm/hot gas in the CGM and how the material moves and cycles through the galaxy.

			==Leah Jenks (JHU)==
			'''Inflation as a Particle Factory'''<br>
			Cosmological gravitational particle production (GPP) is the process by which particles are created due to the expansion of spacetime during inflation. In this talk I will give an overview of GPP and discuss two scenarios in which it leads to highly efficient particle production. First, I will show how GPP of scalar fields in Higgs inflation models leads to a characteristic peaked spectrum and enhanced particle number. Then I will discuss GPP of dark photons with non-minimal couplings to gravity, which similarly leads to an enhancement of the particle number, but also instabilities. Finally, I will comment on phenomenological implications of these scenarios for dark matter.

Kdkuntz at 13:19, 17 October 2025

2025-10-17T13:19:28Z

← Older revision		Revision as of 13:19, 17 October 2025
Line 43:		Line 43:
	'''Where the Hot Universe Meets the Energetic Universe'''<br>		'''Where the Hot Universe Meets the Energetic Universe'''<br>
	The hot circumgalactic medium (CGM), a reservoir of missing baryons, metals, and energy, plays a key role in our understanding of galaxy evolution. However, extraordinary observational challenges make the hot CGM one of the least understood components of galaxies. Studying the hot CGM was not the objective of current X-ray or mm facilities during the design phase. However, as an excellent byproduct, observing the hot CGM has emerged as a promising field over the last two decades, coming at the forefront of priority science goals for the current and upcoming decades. I will discuss three snippets of our recent efforts to detect and characterize the hot CGM: 1) X-raying the Milky Way: Investigating thermal and chemical anomalies; 2) Is CGM detectable? Conducting deep searches in individual external galaxies using X-ray, and 3) Test for self-similarity: stacking thousands of galaxies in mm (Sunyaev-Zeldovich Effect). I will highlight how our findings provide insights into the impact of galactic feedback on the hot CGM, establish our confidence in leveraging current telescopes to inform theoretical simulations, and set a benchmark for designing experiments with next-generation X-ray and mm facilities.		The hot circumgalactic medium (CGM), a reservoir of missing baryons, metals, and energy, plays a key role in our understanding of galaxy evolution. However, extraordinary observational challenges make the hot CGM one of the least understood components of galaxies. Studying the hot CGM was not the objective of current X-ray or mm facilities during the design phase. However, as an excellent byproduct, observing the hot CGM has emerged as a promising field over the last two decades, coming at the forefront of priority science goals for the current and upcoming decades. I will discuss three snippets of our recent efforts to detect and characterize the hot CGM: 1) X-raying the Milky Way: Investigating thermal and chemical anomalies; 2) Is CGM detectable? Conducting deep searches in individual external galaxies using X-ray, and 3) Test for self-similarity: stacking thousands of galaxies in mm (Sunyaev-Zeldovich Effect). I will highlight how our findings provide insights into the impact of galactic feedback on the hot CGM, establish our confidence in leveraging current telescopes to inform theoretical simulations, and set a benchmark for designing experiments with next-generation X-ray and mm facilities.

			=20 October=
			==Raphael Errani (CMU)==
			'''How Micro Galaxies Could Help Constrain the Properties of Dark Matter'''<br>
			Guided by the recent discovery of the faint Milky Way satellite UMa3/UnionsI, in this talk I will present the results of our controlled high-resolution simulations to discuss how ”micro galaxies” could be distinguished observationally from self-gravitating star
			clusters, and how such systems would help us to constrain both the properties of dark matter and the physical processes underlying the formation of the faintest of galaxies. Micro galaxies are a plausible prediction of Cold Dark Matter (CDM) cosmology: The centrally divergent density cusps of CDM subhaloes render them remarkably resilient to tides. Heavily stripped tidal remnants of the Milky Way accretion may survive even in the strong tidal field of the inner regions of our Galaxy. Some of these tidal remnants may have been sufficiently massive in the past to allow for star formation within their potential wells, giving rise to a population of micro galaxies: co-moving groups of stars, gravitationally supported by the dark matter subhalo which surrounds them.

Kdkuntz: /* Sanskriti Das () */

2025-10-06T13:35:56Z

Sanskriti Das ()

← Older revision		Revision as of 13:35, 6 October 2025
Line 40:		Line 40:

	=13 October=		=13 October=
	==Sanskriti Das ()==		==Sanskriti Das (Stanford)==
	'''Where the Hot Universe Meets the Energetic Universe'''<br>		'''Where the Hot Universe Meets the Energetic Universe'''<br>
	The hot circumgalactic medium (CGM), a reservoir of missing baryons, metals, and energy, plays a key role in our understanding of galaxy evolution. However, extraordinary observational challenges make the hot CGM one of the least understood components of galaxies. Studying the hot CGM was not the objective of current X-ray or mm facilities during the design phase. However, as an excellent byproduct, observing the hot CGM has emerged as a promising field over the last two decades, coming at the forefront of priority science goals for the current and upcoming decades. I will discuss three snippets of our recent efforts to detect and characterize the hot CGM: 1) X-raying the Milky Way: Investigating thermal and chemical anomalies; 2) Is CGM detectable? Conducting deep searches in individual external galaxies using X-ray, and 3) Test for self-similarity: stacking thousands of galaxies in mm (Sunyaev-Zeldovich Effect). I will highlight how our findings provide insights into the impact of galactic feedback on the hot CGM, establish our confidence in leveraging current telescopes to inform theoretical simulations, and set a benchmark for designing experiments with next-generation X-ray and mm facilities.		The hot circumgalactic medium (CGM), a reservoir of missing baryons, metals, and energy, plays a key role in our understanding of galaxy evolution. However, extraordinary observational challenges make the hot CGM one of the least understood components of galaxies. Studying the hot CGM was not the objective of current X-ray or mm facilities during the design phase. However, as an excellent byproduct, observing the hot CGM has emerged as a promising field over the last two decades, coming at the forefront of priority science goals for the current and upcoming decades. I will discuss three snippets of our recent efforts to detect and characterize the hot CGM: 1) X-raying the Milky Way: Investigating thermal and chemical anomalies; 2) Is CGM detectable? Conducting deep searches in individual external galaxies using X-ray, and 3) Test for self-similarity: stacking thousands of galaxies in mm (Sunyaev-Zeldovich Effect). I will highlight how our findings provide insights into the impact of galactic feedback on the hot CGM, establish our confidence in leveraging current telescopes to inform theoretical simulations, and set a benchmark for designing experiments with next-generation X-ray and mm facilities.

Kdkuntz at 13:35, 6 October 2025

2025-10-06T13:35:12Z

← Older revision		Revision as of 13:35, 6 October 2025
Line 38:		Line 38:
	'''Forward to the Moon: Lunar radio telescopes and 21-cm Cosmology'''<br>		'''Forward to the Moon: Lunar radio telescopes and 21-cm Cosmology'''<br>
	The lunar farside provides an exceptionally radio-quiet environment for next-generation low-frequency cosmology, particularly measurements of the redshifted 21-cm line from the Cosmic Dawn and Dark Ages. This signal encodes the thermal and ionization history of the intergalactic medium, constrains the timing of the first luminous sources, and probes small-scale density fluctuations sensitive to dark matter and dark energy. Ground-based detection is precluded by anthropogenic interference, ionospheric opacity below ~40 MHz, and environmental variability. A radio telescope on the farside of the Moon, however, overcomes these difficulties. NASA’s first surface radio instrument, ROLSES, flew on the Odysseus CLPS lander in 2024, and despite a rocky landing, measured spectra from 2 kHz–30 MHz and detected terrestrial techno-signatures and placed soft constraints on the galactic background. Successor missions include LuSEE-Night (launch 2026), the first dedicated farside low-frequency telescope designed to access the unexplored Dark Ages band (1–50 MHz) with active EMI mitigation and orbital calibration, and ROLSES-2 (2028), an enhanced instrument with improved thermal tolerance, shielding, and full Stokes capability. These pathfinders will establish the technological and scientific foundation for future interferometric arrays capable of tomographic mapping of the early Universe, such as the NIAC-concept lunar interferometer arrays called Farview, or other large telescope concepts such as the Lunar Crater Radio Telescope.		The lunar farside provides an exceptionally radio-quiet environment for next-generation low-frequency cosmology, particularly measurements of the redshifted 21-cm line from the Cosmic Dawn and Dark Ages. This signal encodes the thermal and ionization history of the intergalactic medium, constrains the timing of the first luminous sources, and probes small-scale density fluctuations sensitive to dark matter and dark energy. Ground-based detection is precluded by anthropogenic interference, ionospheric opacity below ~40 MHz, and environmental variability. A radio telescope on the farside of the Moon, however, overcomes these difficulties. NASA’s first surface radio instrument, ROLSES, flew on the Odysseus CLPS lander in 2024, and despite a rocky landing, measured spectra from 2 kHz–30 MHz and detected terrestrial techno-signatures and placed soft constraints on the galactic background. Successor missions include LuSEE-Night (launch 2026), the first dedicated farside low-frequency telescope designed to access the unexplored Dark Ages band (1–50 MHz) with active EMI mitigation and orbital calibration, and ROLSES-2 (2028), an enhanced instrument with improved thermal tolerance, shielding, and full Stokes capability. These pathfinders will establish the technological and scientific foundation for future interferometric arrays capable of tomographic mapping of the early Universe, such as the NIAC-concept lunar interferometer arrays called Farview, or other large telescope concepts such as the Lunar Crater Radio Telescope.

			=13 October=
			==Sanskriti Das ()==
			'''Where the Hot Universe Meets the Energetic Universe'''<br>
			The hot circumgalactic medium (CGM), a reservoir of missing baryons, metals, and energy, plays a key role in our understanding of galaxy evolution. However, extraordinary observational challenges make the hot CGM one of the least understood components of galaxies. Studying the hot CGM was not the objective of current X-ray or mm facilities during the design phase. However, as an excellent byproduct, observing the hot CGM has emerged as a promising field over the last two decades, coming at the forefront of priority science goals for the current and upcoming decades. I will discuss three snippets of our recent efforts to detect and characterize the hot CGM: 1) X-raying the Milky Way: Investigating thermal and chemical anomalies; 2) Is CGM detectable? Conducting deep searches in individual external galaxies using X-ray, and 3) Test for self-similarity: stacking thousands of galaxies in mm (Sunyaev-Zeldovich Effect). I will highlight how our findings provide insights into the impact of galactic feedback on the hot CGM, establish our confidence in leveraging current telescopes to inform theoretical simulations, and set a benchmark for designing experiments with next-generation X-ray and mm facilities.

Kdkuntz: /* Jashua Hibbard (Colorado) */

2025-10-03T13:13:41Z

Jashua Hibbard (Colorado)

← Older revision		Revision as of 13:13, 3 October 2025
Line 35:		Line 35:

	=06 October=		=06 October=
	==~~Jashua~~ Hibbard (Colorado)==		==Joshua Hibbard (Colorado)==
	'''Forward to the Moon: Lunar radio telescopes and 21-cm Cosmology'''<br>		'''Forward to the Moon: Lunar radio telescopes and 21-cm Cosmology'''<br>
	The lunar farside provides an exceptionally radio-quiet environment for next-generation low-frequency cosmology, particularly measurements of the redshifted 21-cm line from the Cosmic Dawn and Dark Ages. This signal encodes the thermal and ionization history of the intergalactic medium, constrains the timing of the first luminous sources, and probes small-scale density fluctuations sensitive to dark matter and dark energy. Ground-based detection is precluded by anthropogenic interference, ionospheric opacity below ~40 MHz, and environmental variability. A radio telescope on the farside of the Moon, however, overcomes these difficulties. NASA’s first surface radio instrument, ROLSES, flew on the Odysseus CLPS lander in 2024, and despite a rocky landing, measured spectra from 2 kHz–30 MHz and detected terrestrial techno-signatures and placed soft constraints on the galactic background. Successor missions include LuSEE-Night (launch 2026), the first dedicated farside low-frequency telescope designed to access the unexplored Dark Ages band (1–50 MHz) with active EMI mitigation and orbital calibration, and ROLSES-2 (2028), an enhanced instrument with improved thermal tolerance, shielding, and full Stokes capability. These pathfinders will establish the technological and scientific foundation for future interferometric arrays capable of tomographic mapping of the early Universe, such as the NIAC-concept lunar interferometer arrays called Farview, or other large telescope concepts such as the Lunar Crater Radio Telescope.		The lunar farside provides an exceptionally radio-quiet environment for next-generation low-frequency cosmology, particularly measurements of the redshifted 21-cm line from the Cosmic Dawn and Dark Ages. This signal encodes the thermal and ionization history of the intergalactic medium, constrains the timing of the first luminous sources, and probes small-scale density fluctuations sensitive to dark matter and dark energy. Ground-based detection is precluded by anthropogenic interference, ionospheric opacity below ~40 MHz, and environmental variability. A radio telescope on the farside of the Moon, however, overcomes these difficulties. NASA’s first surface radio instrument, ROLSES, flew on the Odysseus CLPS lander in 2024, and despite a rocky landing, measured spectra from 2 kHz–30 MHz and detected terrestrial techno-signatures and placed soft constraints on the galactic background. Successor missions include LuSEE-Night (launch 2026), the first dedicated farside low-frequency telescope designed to access the unexplored Dark Ages band (1–50 MHz) with active EMI mitigation and orbital calibration, and ROLSES-2 (2028), an enhanced instrument with improved thermal tolerance, shielding, and full Stokes capability. These pathfinders will establish the technological and scientific foundation for future interferometric arrays capable of tomographic mapping of the early Universe, such as the NIAC-concept lunar interferometer arrays called Farview, or other large telescope concepts such as the Lunar Crater Radio Telescope.

Kdkuntz at 13:13, 3 October 2025

2025-10-03T13:13:26Z

← Older revision		Revision as of 13:13, 3 October 2025
Line 33:		Line 33:
	'''Cosmic Dawn: Gaps in Our Understanding'''<br>		'''Cosmic Dawn: Gaps in Our Understanding'''<br>
	Wide area surveys from the ground going up to redshift 7, and sensitive JWST observations over smaller fields, both indicate that the reionization history of the universe is more complex than expected. I will discuss the gaps in our understanding of the reionization epoch, and what is needed from future missions such as Roman and HWO to understand our origins.		Wide area surveys from the ground going up to redshift 7, and sensitive JWST observations over smaller fields, both indicate that the reionization history of the universe is more complex than expected. I will discuss the gaps in our understanding of the reionization epoch, and what is needed from future missions such as Roman and HWO to understand our origins.

			=06 October=
			==Jashua Hibbard (Colorado)==
			'''Forward to the Moon: Lunar radio telescopes and 21-cm Cosmology'''<br>
			The lunar farside provides an exceptionally radio-quiet environment for next-generation low-frequency cosmology, particularly measurements of the redshifted 21-cm line from the Cosmic Dawn and Dark Ages. This signal encodes the thermal and ionization history of the intergalactic medium, constrains the timing of the first luminous sources, and probes small-scale density fluctuations sensitive to dark matter and dark energy. Ground-based detection is precluded by anthropogenic interference, ionospheric opacity below ~40 MHz, and environmental variability. A radio telescope on the farside of the Moon, however, overcomes these difficulties. NASA’s first surface radio instrument, ROLSES, flew on the Odysseus CLPS lander in 2024, and despite a rocky landing, measured spectra from 2 kHz–30 MHz and detected terrestrial techno-signatures and placed soft constraints on the galactic background. Successor missions include LuSEE-Night (launch 2026), the first dedicated farside low-frequency telescope designed to access the unexplored Dark Ages band (1–50 MHz) with active EMI mitigation and orbital calibration, and ROLSES-2 (2028), an enhanced instrument with improved thermal tolerance, shielding, and full Stokes capability. These pathfinders will establish the technological and scientific foundation for future interferometric arrays capable of tomographic mapping of the early Universe, such as the NIAC-concept lunar interferometer arrays called Farview, or other large telescope concepts such as the Lunar Crater Radio Telescope.

Kdkuntz at 10:35, 26 September 2025

2025-09-26T10:35:17Z

← Older revision		Revision as of 10:35, 26 September 2025
Line 28:		Line 28:
	'''Tracing the Chemical Enrichment of the Milky Way using Star Clusters: Measurement and Analysis of Neutron Capture Elemental Abundances'''<br>		'''Tracing the Chemical Enrichment of the Milky Way using Star Clusters: Measurement and Analysis of Neutron Capture Elemental Abundances'''<br>
	The chemistry of stars in the Milky Way is a powerful tool for exploring the enrichment history of the Galaxy. With the all-sky spectroscopic surveys that are currently available to us, using chemistry as a means to study the evolution and history of the Milky Way and potentially characterize the ages of different stellar populations therein has flourished. Open clusters have long been used to determine ages of stars, helping to calibrate stellar evolution models and other methods of age dating stellar groups (e.g., gyrochronology and asteroseismology). In this work, we utilize the Open Cluster Chemical Abundances and Mapping (OCCAM) survey, which uses SDSS-IV/APOGEE to establish cluster membership and has already been used to study the chemical evolution of the Milky Way (Myers et al. 2022, Spoo et al. 2022). Using this infrared-based dataset as a foundation, we target stars with the Keck I and Magellan Baade telescopes to collect high-resolution (R > 50,000), high-S/N (>75 at 5500A), optical spectra for 56 stars in 18 open clusters. With these data, we derive abundances for 23 elements using BACCHUS, including 7 neutron capture abundances not measurable by APOGEE. Finally, we use these neutron capture abundances to characterize the distribution of these elements radially and chronologically in the Milky Way. We find that elements in the neutron-capture families exhibit significantly flatter gradients as compared to the lighter alpha and iron-peak elements. In addition, we find the abundance each of the elements exhibits large scatter and little mean variation through time. These results could indicate that the enrichers for the heavier elements are well-distributed throughout the Milky Way's thin disk, and that the ISM has stayed relatively well-mixed through time.		The chemistry of stars in the Milky Way is a powerful tool for exploring the enrichment history of the Galaxy. With the all-sky spectroscopic surveys that are currently available to us, using chemistry as a means to study the evolution and history of the Milky Way and potentially characterize the ages of different stellar populations therein has flourished. Open clusters have long been used to determine ages of stars, helping to calibrate stellar evolution models and other methods of age dating stellar groups (e.g., gyrochronology and asteroseismology). In this work, we utilize the Open Cluster Chemical Abundances and Mapping (OCCAM) survey, which uses SDSS-IV/APOGEE to establish cluster membership and has already been used to study the chemical evolution of the Milky Way (Myers et al. 2022, Spoo et al. 2022). Using this infrared-based dataset as a foundation, we target stars with the Keck I and Magellan Baade telescopes to collect high-resolution (R > 50,000), high-S/N (>75 at 5500A), optical spectra for 56 stars in 18 open clusters. With these data, we derive abundances for 23 elements using BACCHUS, including 7 neutron capture abundances not measurable by APOGEE. Finally, we use these neutron capture abundances to characterize the distribution of these elements radially and chronologically in the Milky Way. We find that elements in the neutron-capture families exhibit significantly flatter gradients as compared to the lighter alpha and iron-peak elements. In addition, we find the abundance each of the elements exhibits large scatter and little mean variation through time. These results could indicate that the enrichers for the heavier elements are well-distributed throughout the Milky Way's thin disk, and that the ISM has stayed relatively well-mixed through time.

			=29 September=
			==Sangeeta Malhotra (GSFC)==
			'''Cosmic Dawn: Gaps in Our Understanding'''<br>
			Wide area surveys from the ground going up to redshift 7, and sensitive JWST observations over smaller fields, both indicate that the reionization history of the universe is more complex than expected. I will discuss the gaps in our understanding of the reionization epoch, and what is needed from future missions such as Roman and HWO to understand our origins.