Wine and Cheese Spring 2018 - Revision history

Kdkuntz at 18:38, 9 August 2018

2018-08-09T18:38:57Z

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	This page records the schedule, titles and abstracts of the [[CAS_Wine_and_Cheese_Seminars\|JHU/STScI CAS Astrophysics Wine & Cheese Series]] in ~~Fall 2017~~.		This page records the schedule, titles and abstracts of the [[CAS_Wine_and_Cheese_Seminars\|JHU/STScI CAS Astrophysics Wine & Cheese Series]] in Spring 2018.

	Wine and Cheese sessions with one talk will have a 50 minute talk with 10 minutes for questions. Sessions with two speakers will have two 25 minute talks, each with 5 minutes for questions. Sessions in the Graduate Student Series will have three 15 minute talks, each with 5 minutes for questions.		Wine and Cheese sessions with one talk will have a 50 minute talk with 10 minutes for questions. Sessions with two speakers will have two 25 minute talks, each with 5 minutes for questions. Sessions in the Graduate Student Series will have three 15 minute talks, each with 5 minutes for questions.

Kdkuntz: /* Alan Rhodes (ARC-PX) */

2018-05-03T15:05:41Z

Alan Rhodes (ARC-PX)

← Older revision		Revision as of 15:05, 3 May 2018
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	= May 8th =		= May 8th =
	== Alan Rhodes (ARC-PX) ==		== Alan Rhodes (ARC-PX) ==
	'''~~A Sofia Related Talk, Title TBA~~'''<br>		'''Come Explore With Us'''<br>
			SOFIA is entering a new era of research and capability with significant new opportunities! From funding of $10,000 per hour of award observation time, to a multi-million dollar call for new groundbreaking science programs that can require updates to existing instruments or the fabrication of new instruments, there are a number of new ways to explore with the SOFIA team. This is a chance to review those funded opportunities and to learn about the new ideas you have for SOFIA. Please join to discuss these opportunities!

Kdkuntz at 13:31, 27 April 2018

2018-04-27T13:31:12Z

← Older revision		Revision as of 13:31, 27 April 2018
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	'''Interstellar Dust and X-Ray Spectroscopy'''<br>		'''Interstellar Dust and X-Ray Spectroscopy'''<br>
	X-ray spectroscopy is a crucial tool in studies of the interstellar medium, and interstellar dust in particular, in that it can provide direct measurements of elemental abundances and grain compositions, thus allowing us to build more realistic grain models. Arcus, a high-resolution X-ray spectrometer mission currently in Phase A, will allow us to examine aspects of dust that have remained hidden until now. I will discuss Arcus's potential for shedding light on some of the more pressing questions in interstellar dust studies.		X-ray spectroscopy is a crucial tool in studies of the interstellar medium, and interstellar dust in particular, in that it can provide direct measurements of elemental abundances and grain compositions, thus allowing us to build more realistic grain models. Arcus, a high-resolution X-ray spectrometer mission currently in Phase A, will allow us to examine aspects of dust that have remained hidden until now. I will discuss Arcus's potential for shedding light on some of the more pressing questions in interstellar dust studies.

			= May 8th =
			== Alan Rhodes (ARC-PX) ==
			'''A Sofia Related Talk, Title TBA'''<br>

Kdkuntz: /* April 30th */

2018-04-27T13:28:39Z

April 30th

← Older revision		Revision as of 13:28, 27 April 2018
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	It is well known that stars observed in the local Universe form with something very close to a universal initial mass function (IMF) where the vast majority are of low mass. However, theory and simulations of the formation of the first stars in the Universe predict a top-heavy IMF with significant dependence on environment. How and when does this transition occur? I will report on the Pop2Prime simulations, which begin with cosmological initial conditions and end with the collapse and fragmentation of metal-enriched gas on scales of a few hundred AU. With these simulations, we are able to study the physical conditions in which the oldest stars observed formed as well as the means by which star-forming gas was first enriched with metals.		It is well known that stars observed in the local Universe form with something very close to a universal initial mass function (IMF) where the vast majority are of low mass. However, theory and simulations of the formation of the first stars in the Universe predict a top-heavy IMF with significant dependence on environment. How and when does this transition occur? I will report on the Pop2Prime simulations, which begin with cosmological initial conditions and end with the collapse and fragmentation of metal-enriched gas on scales of a few hundred AU. With these simulations, we are able to study the physical conditions in which the oldest stars observed formed as well as the means by which star-forming gas was first enriched with metals.

	== ==		== Lynne Valencic (GSFC) ==
	'''-'''<br>		'''Interstellar Dust and X-Ray Spectroscopy'''<br>
			X-ray spectroscopy is a crucial tool in studies of the interstellar medium, and interstellar dust in particular, in that it can provide direct measurements of elemental abundances and grain compositions, thus allowing us to build more realistic grain models. Arcus, a high-resolution X-ray spectrometer mission currently in Phase A, will allow us to examine aspects of dust that have remained hidden until now. I will discuss Arcus's potential for shedding light on some of the more pressing questions in interstellar dust studies.

Kdkuntz: /* April 23rd (Graduate Student Series) */

2018-04-20T07:00:42Z

April 23rd (Graduate Student Series)

← Older revision		Revision as of 07:00, 20 April 2018
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	'''Detectors for the CLASS Telescopes'''<br>		'''Detectors for the CLASS Telescopes'''<br>
	The Cosmology Large Angular Scale Surveyor (CLASS) aims to detect and characterize the primordial B-mode signal, and make a cosmic variance limited measurement of the optical depth to reionization. CLASS is a ground-based multi-frequency microwave polarimeter that will survey 70% of the cosmic microwave background sky from the Atacama Desert. It is designed to measure or place upper limits on the tensor-to-scalar ratio (r) at a level of r = 0.01. This requires high sensitivity measurement of the CMB polarization, which is achieved through a combination of highly efficient and reproducible polarization-sensitive detectors, high-efficiency optics, choice of W-band-centered frequency coverage, and transition-edge sensor (TES) bolometers cooled to ~ 50 mK by a dilution refrigerator. I will talk about the design and performance of the background-limited CLASS detectors, primarily focusing on the W-band detectors that are currently being deployed.		The Cosmology Large Angular Scale Surveyor (CLASS) aims to detect and characterize the primordial B-mode signal, and make a cosmic variance limited measurement of the optical depth to reionization. CLASS is a ground-based multi-frequency microwave polarimeter that will survey 70% of the cosmic microwave background sky from the Atacama Desert. It is designed to measure or place upper limits on the tensor-to-scalar ratio (r) at a level of r = 0.01. This requires high sensitivity measurement of the CMB polarization, which is achieved through a combination of highly efficient and reproducible polarization-sensitive detectors, high-efficiency optics, choice of W-band-centered frequency coverage, and transition-edge sensor (TES) bolometers cooled to ~ 50 mK by a dilution refrigerator. I will talk about the design and performance of the background-limited CLASS detectors, primarily focusing on the W-band detectors that are currently being deployed.
			==Mystery Speaker==
			'''To Be Announced'''<br>

	=April 30th=		=April 30th=

Kdkuntz: /* April 23rd (Graduate Student Series) */

2018-04-20T06:58:19Z

April 23rd (Graduate Student Series)

← Older revision		Revision as of 06:58, 20 April 2018
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	=April 23rd (Graduate Student Series)=		=April 23rd (Graduate Student Series)=
	== ==		==Keisuke Osumi==
	'''-'''<br>		'''Template Uncertainties and the Reionization Optical Depth'''<br>
			The reionization optical depth is the most poorly determined of the six ΛCDM parameters fit to CMB anisotropy data. Instrumental noise and systematics have prevented uncertainties from reaching their cosmic variance limit. At present, the datasets providing the most statistical constraining power are the WMAP, Planck LFI, and Planck HFI full-sky polarization maps. We examine determinations of τ using the latest publicly available data from each experiment, the 9-year WMAP and 2015 Planck LFI data, with emphasis on characterizing potential systematic bias resulting from foreground template choices. We find evidence for a low-level systematic in the LFI polarization data with a roughly common-mode morphology across the LFI frequencies and a spectrum consistent with leakage of intensity signal into the polarization channels. We demonstrate significant bias in the optical depth derived when using the LFI 30 GHz map as a template to clean synchrotron from WMAP data, and recommend against use of the 2015 LFI 30 GHz polarization data as a foreground template for non-LFI datasets. The spread in τ values over the ensemble of data combinations we study suggests that systematic uncertainties still contribute significantly to the current uncertainty in τ, but all values are consistent with the range τ = 0.07 +/- 0.02.
			==Sumit Dahal==
			'''Detectors for the CLASS Telescopes'''<br>
			The Cosmology Large Angular Scale Surveyor (CLASS) aims to detect and characterize the primordial B-mode signal, and make a cosmic variance limited measurement of the optical depth to reionization. CLASS is a ground-based multi-frequency microwave polarimeter that will survey 70% of the cosmic microwave background sky from the Atacama Desert. It is designed to measure or place upper limits on the tensor-to-scalar ratio (r) at a level of r = 0.01. This requires high sensitivity measurement of the CMB polarization, which is achieved through a combination of highly efficient and reproducible polarization-sensitive detectors, high-efficiency optics, choice of W-band-centered frequency coverage, and transition-edge sensor (TES) bolometers cooled to ~ 50 mK by a dilution refrigerator. I will talk about the design and performance of the background-limited CLASS detectors, primarily focusing on the W-band detectors that are currently being deployed.

	=April 30th=		=April 30th=

Kdkuntz: /* April 16th */

2018-04-04T22:16:35Z

April 16th

← Older revision		Revision as of 22:16, 4 April 2018
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	=April 16th=		=April 16th=
	== ==		== Abigail Vieregg (Chicago) ==
	'''-'''<br>		'''Discovering the Highest Energy Neutrinos Using a Radio Phased Array'''<br>
			Ultra-high energy neutrino astronomy sits at the boundary between particle physics and astrophysics. The detection of the highest energy neutrinos would be an important step toward understanding the most energetic cosmic accelerators and would enable tests of fundamental physics at energy scales that cannot easily be achieved on Earth. IceCube has detected astrophysical neutrinos at lower energies, and at higher energies the best limits to date on the flux comes from IceCube and the ANITA experiment, a NASA balloon-borne radio telescope designed to detect coherent radio Cherenkov emission from cosmogenic ultra-high energy neutrinos. The future of high energy neutrino detection lies with ground-based radio arrays like ARA, which would represent an large leap in sensitivity. I will discuss a new radio phased array design that will improve sensitivity enormously and could push the energy threshold for radio detection down to overlap with the energy range probed by IceCube.

	=April 23rd (Graduate Student Series)=		=April 23rd (Graduate Student Series)=

Kdkuntz: /* April 9th */

2018-04-03T18:04:52Z

April 9th

← Older revision		Revision as of 18:04, 3 April 2018
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	=April 9th=		=April 9th=
	== ==		== Chris Howk (Notre Dame) ==
	'''-'''<br>		'''The Positive Side of the Galactic Baryon Ledger: the Evidence for Cold Inflow '''<br>
			The flow of gas through galactic halos is crucial to the evolution of galaxies, as the nature of such flows can dictate the star formation properties of galaxies and regulate their metallicity. Outflows through the circumgalactic medium (CGM) carry metals away from galaxies (although many may return), while infalling metal-poor gas from the intergalactic medium dilutes the metals in galaxies and provides new fuel for star formation. The nature of the infalling baryons, in particular, is of great interest, but such gas has historically been difficult to identify. I'll review our work on galaxies both near and far that suggests the inflow of new matter is robust even in today's massive galaxies, both at the halo scale and the disk scale.

	=April 16th=		=April 16th=

Kdkuntz: /* April 2nd */

2018-03-30T17:03:37Z

April 2nd

← Older revision		Revision as of 17:03, 30 March 2018
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	=April 2nd=		=April 2nd=
	== ==		== Jennifer Wojno (JHU) ==
	'''-'''<br>		'''Correlations between age, kinematics, and chemistry as seen by the RAVE survey'''<br>
			We explore the connections between stellar age, chemistry, and kinematics across a Galactocentric distance of 7.5 < R(kpc) < 9.0, using a sample of ∼ 12000 intermediate-mass (FGK) turnoff stars observed with the RAdial Velocity Experiment (RAVE) survey. The kinematics of this sample are determined using radial velocity measurements from RAVE, and parallax and proper motion measurements from the Tycho-Gaia Astrometric Solution (TGAS). In addition, ages for RAVE stars are de- termined using a Bayesian method, taking TGAS parallaxes as a prior. We divide our sample into young (0 < τ < 3 Gyr) and old (8 < τ < 13 Gyr) populations, and then consider different metallicity bins for each of these age groups. We find signif- icant differences in kinematic trends of young and old, metal-poor and metal-rich, stellar populations. In particular, we find a strong metallicity dependence in the mean Galactocentric radial velocity as a function of radius (∂VR/∂R) for young stars, with metal-rich stars having a much steeper gradient than metal-poor stars. For ∂Vφ/∂R, young, metal-rich stars significantly lag the LSR with a slightly positive gradient, while metal-poor stars show a negative gradient above the LSR.
			== Wenlong Yuan (JHU) ==
			'''Period-Luminosity Relations of Mira Variables and Their Application to the Extragalactic Distance Scale'''<br>
			The Mira Period-Luminosity relations (PLRs) at near- and mid-infrared wavelengths are promising distance indicators, with brighter absolute magnitudes than Cepheids, comparable PLR dispersion and ubiquitous presence in all galaxy types. We developed a semi-parametric Gaussian process periodogram method for sparsely-sampled Mira light curves and discovered more than 1800 Miras in M33 using machine-learning techniques. We derived tight near-infrared PLRs for the LMC Miras, which was used to derive a Mira-based distance to M33. I will present an overview of the Gaussian process model, the Random Forest classifiers, and the resulting PLRs.

	=April 9th=		=April 9th=

Kdkuntz: /* March 26th */

2018-03-23T16:10:05Z

March 26th

← Older revision		Revision as of 16:10, 23 March 2018
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	=March 26th=		=March 26th=
	== ==		== Michael Busch (JHU) ==
	'''-'''<br>		'''Tracing Dark Molecular Gas with OH 18-cm Emission using the Green Bank Telescope'''<br>
			The formation of molecules out of hydrogen and other atoms in the interstellar medium (ISM) is one of the most important steps in star formation: that is, stars form exclusively in molecular clouds. The largest component of this gas, cold molecular hydrogen, is practically invisible due to the lack of a dipole moment and no easily excited rotational and vibrational states. Most astronomers attempt to trace molecular hydrogen using emission from other molecules, and specifically the CO molecule. In this talk I'll present the results of a highly sensitive, dense one-square-degree Green Bank Telescope survey of the ground-state 18cm OH lines which appear to trace molecular hydrogen in areas that are largely devoid of CO emission. I'll also present diffuse cloud models to explore the physical conditions of the gas in the survey area and present arguments for why the OH molecule can effectively trace the diffuse molecular gas where CO is unable to.
			== Tanvi Karwal (JHU) ==
			'''Generalised Dark Matter'''<br>
			My talk will introduce the generalised dark matter model, a powerful phenomenological model that can emulate the effects of various dark matter and dark energy candidates. I will motivate the need for such a model, discuss its effects on the cosmic microwave background (CMB) and how it can help diminish the low multipole tension in the CMB temperature spectrum.
			== Daniel Pfeffer (JHU) ==
			'''Probing The Effects of Interacting Dark Matter'''<br>
			In this talk I will discuss the impact of millicharged dark matter on the CMB. Various interactions between dark matter and standard model particles will modify the CMB in different ways and I will describe these effects. Previous works on interacting dark matter have mainly included individual interactions at a time, such as scattering with either photons or baryons. These different interactions dominate the constraints at different times in cosmic history. My work will include the effects of all these interactions and therefore lead to more realistic constraints.

	=April 2nd=		=April 2nd=