Wine and Cheese Fall 2018 - Revision history

Kdkuntz: /* Claire Murray (JHU) */

2018-11-30T20:50:12Z

Claire Murray (JHU)

← Older revision		Revision as of 20:50, 30 November 2018
Line 117:		Line 117:
	The Atacama B-mode Search is an experiment designed to measure the cosmic microwave background polarization. It observed at 145 GHz from a site at 5,190 m elevation in northern Chile. The noise equivalent polarization temperature, or NEQ, is 41 uK*rt(s). One of the unique features of ABS is its use of a rapidly rotating ambient-temperature half-wave plate (HWP) as the first optical element. The HWP spun at 2.55 Hz to modulate the incident polarized signal at frequencies above where instrument white noise dominates over atmospheric fluctuations and other sources of low-frequency noise. I will present the analysis of data from a 2,400 sq. deg. region of sky. We perform a blind analysis to reduce potential bias. After unblinding, we find agreement with the Planck TE and EE measurements on the same region of sky, with a derived calibration factor of 0.89 +/- 0.10. We marginally detect polarized dust emission (at 3.2-sigma for EE and 2.2-sigma for BB) and give an upper limit on the tensor-to-scalar ratio of r < 2.3 (95% confidence level) with the equivalent of 100 on-sky days of observation. We also present a new measurement of the polarization of Tau A and introduce new methods for calibration and data analysis associated with HWP-based observations.		The Atacama B-mode Search is an experiment designed to measure the cosmic microwave background polarization. It observed at 145 GHz from a site at 5,190 m elevation in northern Chile. The noise equivalent polarization temperature, or NEQ, is 41 uK*rt(s). One of the unique features of ABS is its use of a rapidly rotating ambient-temperature half-wave plate (HWP) as the first optical element. The HWP spun at 2.55 Hz to modulate the incident polarized signal at frequencies above where instrument white noise dominates over atmospheric fluctuations and other sources of low-frequency noise. I will present the analysis of data from a 2,400 sq. deg. region of sky. We perform a blind analysis to reduce potential bias. After unblinding, we find agreement with the Planck TE and EE measurements on the same region of sky, with a derived calibration factor of 0.89 +/- 0.10. We marginally detect polarized dust emission (at 3.2-sigma for EE and 2.2-sigma for BB) and give an upper limit on the tensor-to-scalar ratio of r < 2.3 (95% confidence level) with the equivalent of 100 on-sky days of observation. We also present a new measurement of the polarization of Tau A and introduce new methods for calibration and data analysis associated with HWP-based observations.
	== Claire Murray (JHU)==		== Claire Murray (JHU)==
	'''~~Title~~'''<br>		'''Taking the Temperature of the Local Interstellar Medium'''<br>
	~~Abstract~~		A precise observational accounting for physical conditions of gas and dust in the Galactic interstellar medium (ISM) is vital both for correcting observations of extragalactic light and for resolving the bottleneck between mass reservoirs and star formation in galaxies. A key phase in the ISM lifecycle is occupied by neutral hydrogen (HI), whose temperature and density are crucial for understanding the formation of star-forming cloud complexes from the ambient neutral medium. However, multiphase HI properties remain mysterious due to limited direct measurements of HI optical depth and uncertainty in how and whether this material can be traced by dust. I will present results from the deepest-ever study of HI properties via 21cm absorption at the Karl G. Jansky Very Large Array, 21-SPONGE. We detect an
			unexpectedly ``warm" neutral medium and a significant fraction of thermally unstable gas,
			emphasizing the importance of dynamical processes for regulating the ISM and the need for new 21cm excitation models. Furthermore,
			although cold HI is ubiquitously detected in absorption, its optical depth is not sufficient to entirely account for ``dark gas". I will finally discuss applications of machine vision for characterizing 21cm spectra and making objective comparisons with numerical simulations, as well as future Galactic surveys with SKA pathfinder telescopes.

Kdkuntz: /* 3 December */

2018-11-26T16:18:00Z

3 December

← Older revision		Revision as of 16:18, 26 November 2018
Line 113:		Line 113:

	=3 December =		=3 December =
	== ~~Speaker~~ ==		== Thomas Essinger-Hileman (GSFC)==
			'''Results from the Atacama B-Mode Search (ABS)'''<br>
			The Atacama B-mode Search is an experiment designed to measure the cosmic microwave background polarization. It observed at 145 GHz from a site at 5,190 m elevation in northern Chile. The noise equivalent polarization temperature, or NEQ, is 41 uK*rt(s). One of the unique features of ABS is its use of a rapidly rotating ambient-temperature half-wave plate (HWP) as the first optical element. The HWP spun at 2.55 Hz to modulate the incident polarized signal at frequencies above where instrument white noise dominates over atmospheric fluctuations and other sources of low-frequency noise. I will present the analysis of data from a 2,400 sq. deg. region of sky. We perform a blind analysis to reduce potential bias. After unblinding, we find agreement with the Planck TE and EE measurements on the same region of sky, with a derived calibration factor of 0.89 +/- 0.10. We marginally detect polarized dust emission (at 3.2-sigma for EE and 2.2-sigma for BB) and give an upper limit on the tensor-to-scalar ratio of r < 2.3 (95% confidence level) with the equivalent of 100 on-sky days of observation. We also present a new measurement of the polarization of Tau A and introduce new methods for calibration and data analysis associated with HWP-based observations.
			== Claire Murray (JHU)==
	'''Title'''<br>		'''Title'''<br>
	Abstract		Abstract

Kdkuntz: /* 26 November (GSS) */

2018-11-26T14:03:38Z

26 November (GSS)

← Older revision		Revision as of 14:03, 26 November 2018
Line 104:		Line 104:

	=26 November (GSS)=		=26 November (GSS)=
	== Hiro Nishikawa ==		== Hiro Nishikawa (JHU) ==
	'''Core Formation and Collapse of Self-Interacting Dark Matter Halos and Subhalos'''<br>		'''Core Formation and Collapse of Self-Interacting Dark Matter Halos and Subhalos'''<br>
	Self-interacting dark matter (SIDM) has remained a viable candidate of dark matter, as it may overcome some of the challenges the standard collisionless cold dark matter paradigm faces in small-scale structures, such as the core-cusp problem. In this talk, I will explore the evolution of dark matter halos and subhalos in the presence of SIDMs through the use of gravothermal fluid approximation. In particular, I will talk about the evolution of SIDM subhalos that undergo tidal disruption and show that it subsequently leads to formation of denser cores or core collapses, which may provide a new mechanism in creating intermediate mass black holes at the centers of such halos.		Self-interacting dark matter (SIDM) has remained a viable candidate of dark matter, as it may overcome some of the challenges the standard collisionless cold dark matter paradigm faces in small-scale structures, such as the core-cusp problem. In this talk, I will explore the evolution of dark matter halos and subhalos in the presence of SIDMs through the use of gravothermal fluid approximation. In particular, I will talk about the evolution of SIDM subhalos that undergo tidal disruption and show that it subsequently leads to formation of denser cores or core collapses, which may provide a new mechanism in creating intermediate mass black holes at the centers of such halos.

	== ~~Speaker~~ ==		== Kaze Wong (JHU) ==
	'''~~Title~~'''<br>		'''The Potential of Multiband Gravitational Wave Astronomy'''<br>
	~~Abstract~~		Some recent developments in multiband data analysis have prompted us to explore the prospects of multiband gravitational wave science. A ground-based detector network has detected several stellar-mass black hole merger events, and many more detections are expected in the near future. A space-based detector such as LISA could observe the early inspiral of these systems. Multiband observations can improve our ability to determine source parameters by removing degeneracies, and possibly allow us to measure parameters (such as the orbital eccentricity) that may not be measurable on the ground. Space-based inspiral detections could allow us to forecast merger events observable from the ground; vice versa, by post-processing LISA data and exploiting coincidence with mergers observed on the ground we could be able to detect LISA inspirals that would otherwise be sub-threshold. We will quantify these possibilities and discuss some of their astrophysical implications.

	~~== Speaker ==~~
	~~'''Title'''<br>~~
	~~Abstract~~

	=3 December =		=3 December =

Kdkuntz: /* 26 November (GSS) */

2018-11-24T14:46:14Z

26 November (GSS)

← Older revision		Revision as of 14:46, 24 November 2018
Line 104:		Line 104:

	=26 November (GSS)=		=26 November (GSS)=
	== ~~Speaker~~ ==		== Hiro Nishikawa ==
	'''~~Title~~'''<br>		'''Core Formation and Collapse of Self-Interacting Dark Matter Halos and Subhalos'''<br>
	~~Abstract~~		Self-interacting dark matter (SIDM) has remained a viable candidate of dark matter, as it may overcome some of the challenges the standard collisionless cold dark matter paradigm faces in small-scale structures, such as the core-cusp problem. In this talk, I will explore the evolution of dark matter halos and subhalos in the presence of SIDMs through the use of gravothermal fluid approximation. In particular, I will talk about the evolution of SIDM subhalos that undergo tidal disruption and show that it subsequently leads to formation of denser cores or core collapses, which may provide a new mechanism in creating intermediate mass black holes at the centers of such halos.

	== Speaker ==		== Speaker ==

Kdkuntz: /* Chi-Ho (Edwin) Chan */

2018-11-14T16:10:04Z

Chi-Ho (Edwin) Chan

← Older revision		Revision as of 16:10, 14 November 2018
Line 99:		Line 99:

	=19 November =		=19 November =
	== Chi-Ho (Edwin) Chan ==		== Chi-Ho (Edwin) Chan (Racah Institute) ==
	'''Magnetorotational Instability in Eccentric Disks'''<br>		'''Magnetorotational Instability in Eccentric Disks'''<br>
	Eccentric disks arise in such astrophysical contexts as tidal disruption events, but it is unknown whether the magnetorotational instability (MRI), which powers accretion in circular disks, operates in eccentric disks as well. We examine the linear evolution of unstratified, incompressible MRI in an eccentric disk orbiting a point mass and threaded with a vertical background magnetic field. Much like in circular disks, MRI grows when the field is weak, but the growth per orbit declines slightly with increasing eccentricity; unlike in circular disks, MRI grows in highly eccentric disks even when the field is extremely strong. Eccentric MRI can be understood either as the competition between orbital shear and magnetic tension; or as the parametric destabilization of magnetic modes by eccentric orbital motion, which is resonant at small eccentricities.		Eccentric disks arise in such astrophysical contexts as tidal disruption events, but it is unknown whether the magnetorotational instability (MRI), which powers accretion in circular disks, operates in eccentric disks as well. We examine the linear evolution of unstratified, incompressible MRI in an eccentric disk orbiting a point mass and threaded with a vertical background magnetic field. Much like in circular disks, MRI grows when the field is weak, but the growth per orbit declines slightly with increasing eccentricity; unlike in circular disks, MRI grows in highly eccentric disks even when the field is extremely strong. Eccentric MRI can be understood either as the competition between orbital shear and magnetic tension; or as the parametric destabilization of magnetic modes by eccentric orbital motion, which is resonant at small eccentricities.

Kdkuntz at 16:08, 14 November 2018

2018-11-14T16:08:27Z

← Older revision		Revision as of 16:08, 14 November 2018
Line 97:		Line 97:
	'''Ex Luna Scientia! The Lunar Occultation Explorer (LOX) and Transformational Astrophysics Enabled by the Moon'''<br>		'''Ex Luna Scientia! The Lunar Occultation Explorer (LOX) and Transformational Astrophysics Enabled by the Moon'''<br>
	Astronomical investigations from the Moon afford new opportunities to advance our understanding of the cosmos. The Lunar Occultation Explorer (LOX) will leverage the power of a new observational paradigm to transform our understanding of the nuclear cosmos (0.1–10 MeV) and establish the Moon as a platform for astrophysics. LOX directly challenges traditional paradigms to circumvent the mission complexity, technology development lifecycles, and cost constraints that have limited the tremendous potential of nuclear gamma-ray (MeV) astrophysics to date. Temporal modulation is the foundation of our approach. Operating from lunar orbit, LOX will use the Moon as a natural occulting disk to generate the required modulation via repeated eclipses of astronomical sources. The resulting occultation signatures contain all the information necessary for source characterization and localization. Simplicity is a hallmark of this efficient and validated approach. LOX’s lone instrument, the Big Array for Gamma-ray Energy Logging (BAGEL) is highly scalable, limited only by available mission mass and power resources. Nuclear astrophysics is ripe for new discoveries and cracking open this critical window will reveal the details of essential astrophysical phenomena in one of the least explored cosmic domains. I will review ongoing development of the LOX mission including in-situ validation of the technique from lunar orbit, discuss the benefits of the lunar environment, and highlight several high-priority science goals uniquely enabled by LOX that will provide new insights into the lifecycle of matter and energy in our galaxy and beyond.		Astronomical investigations from the Moon afford new opportunities to advance our understanding of the cosmos. The Lunar Occultation Explorer (LOX) will leverage the power of a new observational paradigm to transform our understanding of the nuclear cosmos (0.1–10 MeV) and establish the Moon as a platform for astrophysics. LOX directly challenges traditional paradigms to circumvent the mission complexity, technology development lifecycles, and cost constraints that have limited the tremendous potential of nuclear gamma-ray (MeV) astrophysics to date. Temporal modulation is the foundation of our approach. Operating from lunar orbit, LOX will use the Moon as a natural occulting disk to generate the required modulation via repeated eclipses of astronomical sources. The resulting occultation signatures contain all the information necessary for source characterization and localization. Simplicity is a hallmark of this efficient and validated approach. LOX’s lone instrument, the Big Array for Gamma-ray Energy Logging (BAGEL) is highly scalable, limited only by available mission mass and power resources. Nuclear astrophysics is ripe for new discoveries and cracking open this critical window will reveal the details of essential astrophysical phenomena in one of the least explored cosmic domains. I will review ongoing development of the LOX mission including in-situ validation of the technique from lunar orbit, discuss the benefits of the lunar environment, and highlight several high-priority science goals uniquely enabled by LOX that will provide new insights into the lifecycle of matter and energy in our galaxy and beyond.

			=19 November =
			== Chi-Ho (Edwin) Chan ==
			'''Magnetorotational Instability in Eccentric Disks'''<br>
			Eccentric disks arise in such astrophysical contexts as tidal disruption events, but it is unknown whether the magnetorotational instability (MRI), which powers accretion in circular disks, operates in eccentric disks as well. We examine the linear evolution of unstratified, incompressible MRI in an eccentric disk orbiting a point mass and threaded with a vertical background magnetic field. Much like in circular disks, MRI grows when the field is weak, but the growth per orbit declines slightly with increasing eccentricity; unlike in circular disks, MRI grows in highly eccentric disks even when the field is extremely strong. Eccentric MRI can be understood either as the competition between orbital shear and magnetic tension; or as the parametric destabilization of magnetic modes by eccentric orbital motion, which is resonant at small eccentricities.

	=26 November (GSS)=		=26 November (GSS)=

Kdkuntz: /* 12 November */

2018-11-07T03:26:04Z

12 November

← Older revision		Revision as of 03:26, 7 November 2018
Line 94:		Line 94:

	= 12 November =		= 12 November =
	== ~~Speaker~~ ==		== Richard Miller (APL) ==
	'''~~Title~~'''<br>		'''Ex Luna Scientia! The Lunar Occultation Explorer (LOX) and Transformational Astrophysics Enabled by the Moon'''<br>
	~~Abstract~~		Astronomical investigations from the Moon afford new opportunities to advance our understanding of the cosmos. The Lunar Occultation Explorer (LOX) will leverage the power of a new observational paradigm to transform our understanding of the nuclear cosmos (0.1–10 MeV) and establish the Moon as a platform for astrophysics. LOX directly challenges traditional paradigms to circumvent the mission complexity, technology development lifecycles, and cost constraints that have limited the tremendous potential of nuclear gamma-ray (MeV) astrophysics to date. Temporal modulation is the foundation of our approach. Operating from lunar orbit, LOX will use the Moon as a natural occulting disk to generate the required modulation via repeated eclipses of astronomical sources. The resulting occultation signatures contain all the information necessary for source characterization and localization. Simplicity is a hallmark of this efficient and validated approach. LOX’s lone instrument, the Big Array for Gamma-ray Energy Logging (BAGEL) is highly scalable, limited only by available mission mass and power resources. Nuclear astrophysics is ripe for new discoveries and cracking open this critical window will reveal the details of essential astrophysical phenomena in one of the least explored cosmic domains. I will review ongoing development of the LOX mission including in-situ validation of the technique from lunar orbit, discuss the benefits of the lunar environment, and highlight several high-priority science goals uniquely enabled by LOX that will provide new insights into the lifecycle of matter and energy in our galaxy and beyond.

	=26 November (GSS)=		=26 November (GSS)=

Kdkuntz: /* 5 November */

2018-10-29T15:34:15Z

5 November

← Older revision		Revision as of 15:34, 29 October 2018
Line 84:		Line 84:

	=5 November =		=5 November =
	== ~~Speaker~~ ==		== Paz Beniamini ==
	'''~~Title~~'''<br>		'''Observational constraints on the structure of gamma-ray burst jets and lessons from GW170817'''<br>
	~~Abstract~~		Motivated by GW170817 we examine three independent constraints on the angular structure of gamma-ray burst (GRB) jets that are required by observations of cosmological long GRBs. We find that efficient gamma-ray emission has to be restricted to material with Gamma>50 and is most likely confined to a narrow region around the core. Comparing GRB170817 with the regular population of short GRBs (sGRBs), we show that an order unity fraction of NS mergers result in sGRB jets that breakout of the surrounding ejecta, that their luminosity function must be intrinsically peaked and that sGRB jets are typically narrow with opening angles ~ 0.1 rad. Finally, we perform Monte Carlo simulations to examine models for the structure and efficiency of the prompt emission in off-axis sGRBs. We find that only a small fraction, 0.01-0.1, of NS mergers detectable by LIGO/VIRGO in GWs is expected to be also detected in prompt gamma-rays, and GW170817-like events are very rare.

	== ~~Speaker~~ ==		== Melanie Habouzit ==
	'''~~Title~~'''<br>		'''Black Hole Formation and Feedback'''<br>
	~~Abstract~~		Over the last decade, we have come to appreciate that supermassive black hole of millions of solar masses and above are commonly hosted by massive galaxies, but are also present in local dwarf galaxies. Black holes are a fundamental component of galaxies, but their origin and their ability to impact their host galaxies are still far from being understood. I will present recent results of the new IllustrisTNG simulations, particularly the time evolution of the BH and galaxy populations. There has been much debate in the literature to understand the physical mechanisms responsible for quenching massive galaxies, i.e., suppressing star formation in time. I will discuss how this is done in IllustrisTNG, and to what extent it agrees with observational constraints.

	12 November =
			= 12 November =
	== Speaker ==		== Speaker ==
	'''Title'''<br>		'''Title'''<br>

Kdkuntz: /* Kevin France (Colorado) */

2018-10-19T16:54:22Z

Kevin France (Colorado)

← Older revision		Revision as of 16:54, 19 October 2018
Line 76:		Line 76:
	Abstract		Abstract

			= 29 October=
	== Kevin France (Colorado) ==		== Kevin France (Colorado) ==
	'''Ultraviolet Spectroscopy from Suborbital and SmallSat Platforms: Little NASA Missions Supporting Big NASA Observatories and Bigger Science'''<br>		'''Ultraviolet Spectroscopy from Suborbital and SmallSat Platforms: Little NASA Missions Supporting Big NASA Observatories and Bigger Science'''<br>

Kdkuntz: /* 29 Kevin France (Colorado) */

2018-10-19T16:54:02Z

29 Kevin France (Colorado)

← Older revision		Revision as of 16:54, 19 October 2018
Line 76:		Line 76:
	Abstract		Abstract

	=29 Kevin France (Colorado) =		== Kevin France (Colorado) ==
	~~== Speaker~~ ==		'''Ultraviolet Spectroscopy from Suborbital and SmallSat Platforms: Little NASA Missions Supporting Big NASA Observatories and Bigger Science'''<br>
	'''~~Title~~'''<br>		Ultraviolet spectroscopy is a powerful tool for quantifying the physical state of molecular, neutral, and ionized gas in the universe. From the circumgalactic gas reservoirs around distant galaxies to the circumstellar disks out of which planets are born, ultraviolet (90 – 320nm) emission and absorption lines provide unique diagnostics of the composition, temperature, kinematics, and excitation conditions of these regions. As we look to the science capabilities of future large missions (e.g., the Large/Ultraviolet/Optical/InfraRed (LUVOIR) Surveyor), we require UV instruments that are both more efficient and more capable than our flagship instruments of today (HST/STIS and COS). Future UV spectrographs will rely on advanced components: UV mirror coatings, diffraction gratings, large format photon-counting detectors, and multi-object field selectors. These components are currently being developed and flight-tested through NASA’s suborbital research program.
	~~Abstract~~
			In this talk, I will present an overview of NASA’s sounding rocket + cubesat science and technology program. I will focus on the development of hardware required to realize the LUVOIR Ultraviolet Multi-Object Spectrograph (LUMOS), an ambitious UV spectroscopy and imaging instrument for LUVOIR. I will discuss two University of Colorado sounding rocket payloads (CHESS and SISTINE) that are demonstrating detector, coating, grating, and optical designs currently baselined for LUVOIR. I will also describe two cubesat missions in development (CUTE and SPRITE), highlighting the power of small UV spectrographs to provide unique data on topics as diverse as atmospheric escape from exoplanets to ionizing radiation escape from star-forming galaxies.

	=5 November =		=5 November =