Wine and Cheese Fall 2019 - Revision history

Kdkuntz: /* Joseph Cleary (JHU) */

2019-11-25T19:46:24Z

Joseph Cleary (JHU)

← Older revision		Revision as of 19:46, 25 November 2019
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	= 2 December 2019 =		= 2 December 2019 =
	== Joseph Cleary (JHU) ==		== Joseph Cleary (JHU) ==
	''' '''<br>		'''Building the CLASS Telescope Array'''<br>
			The Cosmology Large Angular Scale Surveyor (CLASS) aims to measure the polarization of the CMB at the largest angular scales. To achieve this, CLASS uses an array of four telescopes observing at frequencies of 40, 90, 150, and 220 GHz. The 40 and 90 GHz telescopes were installed in Spring 2016 and Spring 2018, and a dichroic 150/220 GHz telescope was deployed during Summer 2019. Each of these telescope deployments is the culmination of years of work by the CLASS collaboration. In this talk, I will discuss the work that goes into getting a CLASS telescope operational in the field.

	== Alex de la Vega (JHU) ==		== Alex de la Vega (JHU) ==

Kdkuntz at 16:42, 25 November 2019

2019-11-25T16:42:00Z

← Older revision		Revision as of 16:42, 25 November 2019
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	'''Tidal Disruption Events in Active Galactic Nuclei'''<br>		'''Tidal Disruption Events in Active Galactic Nuclei'''<br>
	A fraction of tidal disruption events (TDEs) occur in active galactic nuclei (AGNs) whose black holes possess accretion disks; these TDEs can be confused with common AGN flares. The disruption itself is unaffected by the disk, but the evolution of the bound debris stream is modified by its collision with the disk when it returns to pericenter. The outcome of the collision is largely determined by the ratio of the stream mass current to the azimuthal mass current of the disk rotating underneath the stream footprint, which in turns depends on the mass and luminosity of the AGN. To characterize TDEs in AGNs, we simulated a suite of stream--disk collisions with various mass current ratios. The collision excites shocks in the disk, leading to inflow and energy dissipation orders of magnitude above Eddington. However, much of the radiation is trapped in the inflow and advected into the black hole, so the actual luminosity may be closer to Eddington. The rapid inflow causes the disk interior to the impact point to be depleted within a fraction of the mass return time. If the stream is heavy enough to penetrate the disk, part of the outgoing material eventually hits the disk at larger radii, dissipating its kinetic energy there; another part becomes unbound, emitting synchrotron radiation as it shocks with surrounding gas.		A fraction of tidal disruption events (TDEs) occur in active galactic nuclei (AGNs) whose black holes possess accretion disks; these TDEs can be confused with common AGN flares. The disruption itself is unaffected by the disk, but the evolution of the bound debris stream is modified by its collision with the disk when it returns to pericenter. The outcome of the collision is largely determined by the ratio of the stream mass current to the azimuthal mass current of the disk rotating underneath the stream footprint, which in turns depends on the mass and luminosity of the AGN. To characterize TDEs in AGNs, we simulated a suite of stream--disk collisions with various mass current ratios. The collision excites shocks in the disk, leading to inflow and energy dissipation orders of magnitude above Eddington. However, much of the radiation is trapped in the inflow and advected into the black hole, so the actual luminosity may be closer to Eddington. The rapid inflow causes the disk interior to the impact point to be depleted within a fraction of the mass return time. If the stream is heavy enough to penetrate the disk, part of the outgoing material eventually hits the disk at larger radii, dissipating its kinetic energy there; another part becomes unbound, emitting synchrotron radiation as it shocks with surrounding gas.

			= 2 December 2019 =
			== Joseph Cleary (JHU) ==
			''' '''<br>

			== Alex de la Vega (JHU) ==
			'''Dust Attenuation Assumptions and Spatially Resolved Quenching in CANDELS'''<br>
			Determining how galaxies stop forming stars remains an open issue in our understanding of galaxy evolution. The mechanisms behind the cessation of star formation can be identified by studying the radial profiles of the specific star formation rate (sSFR, SFR / stellar mass) for galaxies of different integrated masses, star formation properties, and at different redshifts. Estimating radial sSFR profiles, however, depends sensitively on assumptions of the nature of dust attenuation within galaxies. We examine the effects of assuming different attenuation curves in integrated and spatially resolved spectral energy distribution fitting of massive galaxies at redshift about 1 in the CANDELS survey. Surprisingly, the integrated SFRs for massive galaxies vary dramatically depending on the assumed attenuation curve, yet the nature of quenching within these galaxies is qualitatively the same, independent of dust attenuation assumptions. In this talk, I present preliminary results and hints of a varying slope of the attenuation curve within galaxies, provided other parameters degenerate with dust are accounted for adequately.

			== Hsiang-Chih Hwang (JHU) ==
			'''Lifetime of Main-Sequence Contact Binaries'''<br>
			Binaries play a crucial role in stellar evolution, providing sources for gravitational-wave astronomy, type-Ia supernovae, and other stellar mergers. Binaries must evolve to close configuration while on the main sequence in order to result in these interesting phenomena. One key open question is how main-sequence binaries lose their angular momentum to shrink the orbits. Several mechanisms have been proposed, including pre-main-sequence interaction, three-body interactions (the Kozai-Lidov mechanism), and magnetic braking. These mechanisms are operating on different timescales. However, the age of binaries is notoriously difficult to measure and it is still unclear which is the dominant mechanism. Fortunately, because stars' motion becomes more randomized when they age, stellar kinematics provides a unique way to determine the binary age. In this talk, we will use the kinematics of main-sequence contact binaries to understand when and how they are formed, and when they merge.

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

2019-11-08T16:09:42Z

Chi-Ho Edwin Chan (Tel Aviv)

← Older revision		Revision as of 16:09, 8 November 2019
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	=<font color="red">19 November</font> =		=<font color="red">19 November</font> =
	== Chi-Ho Edwin Chan (Tel Aviv) ==		== Chi-Ho Edwin Chan (Tel Aviv) ==
	'''Tidal ~~disruption events~~ in Active Galactic Nuclei'''<br>		'''Tidal Disruption Events in Active Galactic Nuclei'''<br>
	A fraction of tidal disruption events (TDEs) occur in active galactic nuclei (AGNs) whose black holes possess accretion disks; these TDEs can be confused with common AGN flares. The disruption itself is unaffected by the disk, but the evolution of the bound debris stream is modified by its collision with the disk when it returns to pericenter. The outcome of the collision is largely determined by the ratio of the stream mass current to the azimuthal mass current of the disk rotating underneath the stream footprint, which in turns depends on the mass and luminosity of the AGN. To characterize TDEs in AGNs, we simulated a suite of stream--disk collisions with various mass current ratios. The collision excites shocks in the disk, leading to inflow and energy dissipation orders of magnitude above Eddington. However, much of the radiation is trapped in the inflow and advected into the black hole, so the actual luminosity may be closer to Eddington. The rapid inflow causes the disk interior to the impact point to be depleted within a fraction of the mass return time. If the stream is heavy enough to penetrate the disk, part of the outgoing material eventually hits the disk at larger radii, dissipating its kinetic energy there; another part becomes unbound, emitting synchrotron radiation as it shocks with surrounding gas.		A fraction of tidal disruption events (TDEs) occur in active galactic nuclei (AGNs) whose black holes possess accretion disks; these TDEs can be confused with common AGN flares. The disruption itself is unaffected by the disk, but the evolution of the bound debris stream is modified by its collision with the disk when it returns to pericenter. The outcome of the collision is largely determined by the ratio of the stream mass current to the azimuthal mass current of the disk rotating underneath the stream footprint, which in turns depends on the mass and luminosity of the AGN. To characterize TDEs in AGNs, we simulated a suite of stream--disk collisions with various mass current ratios. The collision excites shocks in the disk, leading to inflow and energy dissipation orders of magnitude above Eddington. However, much of the radiation is trapped in the inflow and advected into the black hole, so the actual luminosity may be closer to Eddington. The rapid inflow causes the disk interior to the impact point to be depleted within a fraction of the mass return time. If the stream is heavy enough to penetrate the disk, part of the outgoing material eventually hits the disk at larger radii, dissipating its kinetic energy there; another part becomes unbound, emitting synchrotron radiation as it shocks with surrounding gas.

Kdkuntz at 16:04, 8 November 2019

2019-11-08T16:04:22Z

← Older revision		Revision as of 16:04, 8 November 2019
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	'''Lensing and Delensing: Results and Updates from BICEP/Keck and the South Pole Telescope'''<br>		'''Lensing and Delensing: Results and Updates from BICEP/Keck and the South Pole Telescope'''<br>
	Gravitational lensing of the cosmic microwave background (CMB) encodes information from the low-redshift universe. Therefore, its measurement is useful for constraining cosmological parameters that describe structure formation, e.g. Omega_m, sigma_8, and the sum of neutrino masses. In this talk, I will present a measurement of and the cosmological constraints from the CMB lensing potential and its power spectrum using data from the SPTpol 500 deg^2 survey. From the minimum-variance combination of the lensing estimators from all combinations of SPTpol temperature and polarization data, we measure the lensing amplitude A_MV = 0.944 \pm 0.058 (Stat.) \pm 0.025 (Sys.), which constitutes the tightest lensing amplitude measurement using ground-based CMB data alone. Using this lensing spectrum measurement, we constrain sigma_8*Omega_m^0.25 to 4%, compared to Planck lensing’s 3% measurement. In combination with galaxy BAO and a BBN prior, SPTpol lensing measures H0 to be ~2 sigma higher than the Planck measurement. Looking to the future, high signal-to-noise measurements of lensing enabled by deep polarization maps is crucial for constraining the sum of neutrino masses and the amplitude of inflationary gravitational waves through delensing. If time permits, I will give an update on the current effort of delensing the BICEP/Keck telescope data.		Gravitational lensing of the cosmic microwave background (CMB) encodes information from the low-redshift universe. Therefore, its measurement is useful for constraining cosmological parameters that describe structure formation, e.g. Omega_m, sigma_8, and the sum of neutrino masses. In this talk, I will present a measurement of and the cosmological constraints from the CMB lensing potential and its power spectrum using data from the SPTpol 500 deg^2 survey. From the minimum-variance combination of the lensing estimators from all combinations of SPTpol temperature and polarization data, we measure the lensing amplitude A_MV = 0.944 \pm 0.058 (Stat.) \pm 0.025 (Sys.), which constitutes the tightest lensing amplitude measurement using ground-based CMB data alone. Using this lensing spectrum measurement, we constrain sigma_8*Omega_m^0.25 to 4%, compared to Planck lensing’s 3% measurement. In combination with galaxy BAO and a BBN prior, SPTpol lensing measures H0 to be ~2 sigma higher than the Planck measurement. Looking to the future, high signal-to-noise measurements of lensing enabled by deep polarization maps is crucial for constraining the sum of neutrino masses and the amplitude of inflationary gravitational waves through delensing. If time permits, I will give an update on the current effort of delensing the BICEP/Keck telescope data.

			=<font color="red">19 November</font> =
			== Chi-Ho Edwin Chan (Tel Aviv) ==
			'''Tidal disruption events in Active Galactic Nuclei'''<br>
			A fraction of tidal disruption events (TDEs) occur in active galactic nuclei (AGNs) whose black holes possess accretion disks; these TDEs can be confused with common AGN flares. The disruption itself is unaffected by the disk, but the evolution of the bound debris stream is modified by its collision with the disk when it returns to pericenter. The outcome of the collision is largely determined by the ratio of the stream mass current to the azimuthal mass current of the disk rotating underneath the stream footprint, which in turns depends on the mass and luminosity of the AGN. To characterize TDEs in AGNs, we simulated a suite of stream--disk collisions with various mass current ratios. The collision excites shocks in the disk, leading to inflow and energy dissipation orders of magnitude above Eddington. However, much of the radiation is trapped in the inflow and advected into the black hole, so the actual luminosity may be closer to Eddington. The rapid inflow causes the disk interior to the impact point to be depleted within a fraction of the mass return time. If the stream is heavy enough to penetrate the disk, part of the outgoing material eventually hits the disk at larger radii, dissipating its kinetic energy there; another part becomes unbound, emitting synchrotron radiation as it shocks with surrounding gas.

Kdkuntz at 18:01, 5 November 2019

2019-11-05T18:01:27Z

← Older revision		Revision as of 18:01, 5 November 2019
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	driven by star formation and black holes that probe their extent and		driven by star formation and black holes that probe their extent and
	illuminate the connection between galaxies and their surroundings.		illuminate the connection between galaxies and their surroundings.

			= 18 November =
			== Kimmy Wu (Chicago) ==
			'''Lensing and Delensing: Results and Updates from BICEP/Keck and the South Pole Telescope'''<br>
			Gravitational lensing of the cosmic microwave background (CMB) encodes information from the low-redshift universe. Therefore, its measurement is useful for constraining cosmological parameters that describe structure formation, e.g. Omega_m, sigma_8, and the sum of neutrino masses. In this talk, I will present a measurement of and the cosmological constraints from the CMB lensing potential and its power spectrum using data from the SPTpol 500 deg^2 survey. From the minimum-variance combination of the lensing estimators from all combinations of SPTpol temperature and polarization data, we measure the lensing amplitude A_MV = 0.944 \pm 0.058 (Stat.) \pm 0.025 (Sys.), which constitutes the tightest lensing amplitude measurement using ground-based CMB data alone. Using this lensing spectrum measurement, we constrain sigma_8*Omega_m^0.25 to 4%, compared to Planck lensing’s 3% measurement. In combination with galaxy BAO and a BBN prior, SPTpol lensing measures H0 to be ~2 sigma higher than the Planck measurement. Looking to the future, high signal-to-noise measurements of lensing enabled by deep polarization maps is crucial for constraining the sum of neutrino masses and the amplitude of inflationary gravitational waves through delensing. If time permits, I will give an update on the current effort of delensing the BICEP/Keck telescope data.

Kdkuntz: /* 4 November */

2019-11-01T21:14:12Z

4 November

← Older revision		Revision as of 21:14, 1 November 2019
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	= 4 November =		= 4 November =
	== Erini Lambrides (JHU) ==		== Erini Lambrides (JHU) ==
	'''~~Something~~ AGN ~~This Way Comes~~'''<br>		'''A Large Population of Obscured AGN in Disguise as Low Luminosity AGN in Chandra Deep Field South'''<br>
	~~Abstract TBD~~		Population synthesis models of actively accreting super-massive black holes (or active galactic nuclei -- AGN) predict a large fraction that must grow behind dense, obscuring screens of gas and dust. Deep X-ray surveys are thought to have provided the most complete and unbiased samples of AGN, but there is strong observational evidence that a portion of the population of obscured AGN is being missed. In this paper we use a sample of AGN derived from the deepest X-ray survey to date, the Chandra 7Ms GOODS-South Survey, to investigate the nature of low flux X-ray sources. We maximize the diverse wavelength coverage of the GOODS-South field, and cross-match our objects with wavelengths from the Radio to the IR. We find the low X-ray flux AGN in our sample have X-ray luminosities that indicate low-luminosity AGN classification, while their radio, infrared and optical counterparts indicate moderate to powerful AGN classification. We find the predicted column densities is on average an order of magnitude higher than the calculated column densities via X-ray detections for X-ray faint sources. We interpret our results as evidence of obscured AGN disguising as low-luminosity AGN via their X-ray luminosities. When we compare the estimation of the obscured AGN space density with and without these objects, we find a difference of 40\% in the lowest X-ray luminosity regime probed by our sample.

	== Keisuke Osumi(JHU) ==		== Keisuke Osumi(JHU) ==

Kdkuntz: /* Erini Lambrides (JHU) */

2019-11-01T19:30:00Z

Erini Lambrides (JHU)

← Older revision		Revision as of 19:30, 1 November 2019
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	== Erini Lambrides (JHU) ==		== Erini Lambrides (JHU) ==
	'''Something AGN This Way Comes'''<br>		'''Something AGN This Way Comes'''<br>
			Abstract TBD

	== Keisuke Osumi(JHU) ==		== Keisuke Osumi(JHU) ==

Kdkuntz: /* Erini Lambrides (JHU) */

2019-11-01T19:28:14Z

Erini Lambrides (JHU)

← Older revision		Revision as of 19:28, 1 November 2019
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	= 4 November =		= 4 November =
	== Erini Lambrides (JHU) ==		== Erini Lambrides (JHU) ==
	'''~~___~~'''<br>		'''Something AGN This Way Comes'''<br>

	== Keisuke Osumi(JHU) ==		== Keisuke Osumi(JHU) ==

Kdkuntz: /* 4 November */

2019-11-01T19:25:22Z

4 November

← Older revision		Revision as of 19:25, 1 November 2019
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	'''___'''<br>		'''___'''<br>

	== Keisuke Osumi(JHU)		== Keisuke Osumi(JHU) ==
	'''Mapping the CMB with the Cosmology Large Angular Scale Surveyor (CLASS)'''<br>		'''Mapping the CMB with the Cosmology Large Angular Scale Surveyor (CLASS)'''<br>
	The Cosmology Large Angular Scale Surveyor (CLASS) is an array of telescopes in the Atacama Desert, Chile that observes 75% of the sky at 4 bands: 40, 90, 150, and 220 GHz. The primary objective is to measure the cosmic microwave background (CMB) polarization at the largest angular scales to constrain the tensor-to-scalar ratio at the r = 0.01 level and make a sample variance limited measurement of the optical depth to reionization, τ. This will be achieved through the use of rapid front-end polarization modulation along with multi-frequency observations to distinguish the CMB from galactic foregrounds. CLASS will be releasing its first set of results from the initial 40 GHz survey in the near future. In this talk, I will present part of my contributions to the data analysis pipeline. Namely, the destriping mapmaker which plays a critical role in the data reduction and analysis of our dataset.		The Cosmology Large Angular Scale Surveyor (CLASS) is an array of telescopes in the Atacama Desert, Chile that observes 75% of the sky at 4 bands: 40, 90, 150, and 220 GHz. The primary objective is to measure the cosmic microwave background (CMB) polarization at the largest angular scales to constrain the tensor-to-scalar ratio at the r = 0.01 level and make a sample variance limited measurement of the optical depth to reionization, τ. This will be achieved through the use of rapid front-end polarization modulation along with multi-frequency observations to distinguish the CMB from galactic foregrounds. CLASS will be releasing its first set of results from the initial 40 GHz survey in the near future. In this talk, I will present part of my contributions to the data analysis pipeline. Namely, the destriping mapmaker which plays a critical role in the data reduction and analysis of our dataset.
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	'''The Structure and Environment of "CO-Dark" Molecular Gas in the Perseus Arm'''		'''The Structure and Environment of "CO-Dark" Molecular Gas in the Perseus Arm'''
	We report the results from a new, highly sensitive (∆Tmb ∼ 3mK) survey for thermal OH emission at 1665 and 1667 MHz over a dense, 9 x 9-pixel grid covering a 1 square degree patch of sky in the direction of L = 105.00, B = +2.50 towards the Perseus spiral arm of our Galaxy. We compare our Green Bank Telescope (GBT) 1667 MHz OH results with archival CO(1-0) observations from the Five College Radio Astronomy Observatory (FCRAO) Outer Galaxy Survey within the velocity range of the Perseus arm at these galactic coordinates. Of the 81 statistically-independent pointings in our survey area, 86% show detectable OH emission at 1667 MHz, and 19% of them show detectable CO emission. We explore the possible physical conditions of the observed features using a set of diffuse molecular cloud models. In the context of these models, both OH and CO disappear at current sensitivity limits, CO emission does not appear until the volume density exceeds 100-200 cm−3 . These results demonstrate that a combination of low column density and low volume density can explain the lack of CO emission at sightlines exhibiting OH emission.		We report the results from a new, highly sensitive (∆Tmb ∼ 3mK) survey for thermal OH emission at 1665 and 1667 MHz over a dense, 9 x 9-pixel grid covering a 1 square degree patch of sky in the direction of L = 105.00, B = +2.50 towards the Perseus spiral arm of our Galaxy. We compare our Green Bank Telescope (GBT) 1667 MHz OH results with archival CO(1-0) observations from the Five College Radio Astronomy Observatory (FCRAO) Outer Galaxy Survey within the velocity range of the Perseus arm at these galactic coordinates. Of the 81 statistically-independent pointings in our survey area, 86% show detectable OH emission at 1667 MHz, and 19% of them show detectable CO emission. We explore the possible physical conditions of the observed features using a set of diffuse molecular cloud models. In the context of these models, both OH and CO disappear at current sensitivity limits, CO emission does not appear until the volume density exceeds 100-200 cm−3 . These results demonstrate that a combination of low column density and low volume density can explain the lack of CO emission at sightlines exhibiting OH emission.

	= 11 November =		= 11 November =
	== David Rupke (Rhodes College) ==		== David Rupke (Rhodes College) ==

Kdkuntz at 19:25, 1 November 2019

2019-11-01T19:25:02Z

@@ Line 101: / Line 101: @@
 the (small-scale) structure of neutral hydrogen.
 = 11 November =
 == David Rupke (Rhodes College) ==