Wine and Cheese Spring 2017 - Revision history

Kdkuntz at 17:34, 1 May 2017

2017-05-01T17:34:41Z

← Older revision		Revision as of 17:34, 1 May 2017
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	'''Stars Re-Shaping Galaxies'''<br>		'''Stars Re-Shaping Galaxies'''<br>
	The most fundamental unsolved problems in galaxy formation revolve around "feedback" from massive stars and black holes. I'll present new results from the FIRE simulations which combine new numerical methods and physics in an attempt to realistically model the diverse physics of the interstellar medium, star formation, and feedback from stellar radiation pressure, supernovae, stellar winds, and photo-ionization. These mechanisms lead to 'self-regulated' galaxy and star formation, in which global correlations such as the Schmidt-Kennicutt law and the global inefficiency of star formation -- the stellar mass function -- emerge naturally. Within galaxies, feedback regulates the structure of the interstellar medium, but more radically drives outflows which can actually change the dynamics, morphologies, and sizes of galaxies, in addition to transforming cusps into cores and suppressing star formation. We are actually reaching the point where different stellar feedback and stellar types can produce observable differences on extra-galactic scales. Finally, I'll discuss where stellar feedback fails, and additional feedback, perhaps from AGN, is really needed to explain observations.		The most fundamental unsolved problems in galaxy formation revolve around "feedback" from massive stars and black holes. I'll present new results from the FIRE simulations which combine new numerical methods and physics in an attempt to realistically model the diverse physics of the interstellar medium, star formation, and feedback from stellar radiation pressure, supernovae, stellar winds, and photo-ionization. These mechanisms lead to 'self-regulated' galaxy and star formation, in which global correlations such as the Schmidt-Kennicutt law and the global inefficiency of star formation -- the stellar mass function -- emerge naturally. Within galaxies, feedback regulates the structure of the interstellar medium, but more radically drives outflows which can actually change the dynamics, morphologies, and sizes of galaxies, in addition to transforming cusps into cores and suppressing star formation. We are actually reaching the point where different stellar feedback and stellar types can produce observable differences on extra-galactic scales. Finally, I'll discuss where stellar feedback fails, and additional feedback, perhaps from AGN, is really needed to explain observations.

			=May 8th=
			== Lauren Corlies ==
			''' '''<br>

			== Patrick Breysse ==
			'''High-Redshift Astrophysics Using Every Photon'''<br>
			Large galaxy surveys have dramatically improved our understanding of the complex processes which govern gas dynamics and star formation in the nearby universe. However, we know far less about the most distant galaxies, as existing high-redshift observations can only detect the very brightest sources. Intensity mapping surveys provide a promising tool to access this poorly-studied population. By observing emission lines with low angular resolution, these surveys can make use of every photon in a target line to study faint emitters which are inaccessible using traditional techniques. With upcoming carbon monoxide experiments in mind, I will demonstrate how an intensity map can be used to measure the luminosity function of a galaxy population, and in turn how these measurements will allow us to place robust constraints on the cosmic star formation history. I will then show how cross-correlating CO isotopologue lines will make it possible to study gas dynamics within the earliest galaxies in unprecedented detail.

Kdkuntz: /* Philip Hopkins (Caltech) */

2017-04-27T01:39:13Z

Philip Hopkins (Caltech)

← Older revision		Revision as of 01:39, 27 April 2017
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	=May Day=		=May Day=
	== Philip Hopkins (Caltech) ==		== Philip Hopkins (Caltech) ==
	'''~~Title~~'''<br>		'''Stars Re-Shaping Galaxies'''<br>
	~~Abstract~~		The most fundamental unsolved problems in galaxy formation revolve around "feedback" from massive stars and black holes. I'll present new results from the FIRE simulations which combine new numerical methods and physics in an attempt to realistically model the diverse physics of the interstellar medium, star formation, and feedback from stellar radiation pressure, supernovae, stellar winds, and photo-ionization. These mechanisms lead to 'self-regulated' galaxy and star formation, in which global correlations such as the Schmidt-Kennicutt law and the global inefficiency of star formation -- the stellar mass function -- emerge naturally. Within galaxies, feedback regulates the structure of the interstellar medium, but more radically drives outflows which can actually change the dynamics, morphologies, and sizes of galaxies, in addition to transforming cusps into cores and suppressing star formation. We are actually reaching the point where different stellar feedback and stellar types can produce observable differences on extra-galactic scales. Finally, I'll discuss where stellar feedback fails, and additional feedback, perhaps from AGN, is really needed to explain observations.

Kdkuntz: /* Special Graduate Seminar: Philip Engelke */

2017-04-17T21:32:00Z

Special Graduate Seminar: Philip Engelke

← Older revision		Revision as of 21:32, 17 April 2017
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	=April 24th=		=April 24th=
	== Special Graduate Seminar: Philip Engelke ==		== Special Graduate Seminar: Philip Engelke ==
	'''The Structure of "Dark" Gas in Star-Forming Regions: OH as an Alternate Molecular Tracer'''</br>		'''The Structure of "Dark" Gas in Star-Forming Regions: OH as an Alternate Molecular Tracer'''<br>
	Despite its near-universal acceptance, use of the CO(1-0) transition as a molecular gas tracer has been drawn into controversy for molecular gas for low densities, and evidence from gamma-ray and IR surveys suggest the presence of undetected gas in the Galaxy, which is likely molecular and which likely contains a mass similar to the mass of known molecular gas (Grenier et al. 2005, Tibaldo et al. 2015). I have worked with Drs. Ron Allen (STScI / JHU) and David Hogg (NRAO) to study the OH 18 cm transitions as an alternate tracer for molecular gas, using the Green Bank telescope for blind surveys towards the Outer Galaxy. These observations indicate that OH can be a viable alternative tracer for molecular gas and appears to trace a larger component of the molecular ISM than does CO, being widely detected in places many of which have no CO(1-0) detections in the literature. My thesis project applies the use of OH as an alternate molecular gas tracer to the W5 star-forming region. In order to do this, I have performed an OH survey with the Green Bank telescope over W5, which contains a free-free continuum background and a mixture of emission and absorption features. I will report findings regarding the OH line excitation temperatures in the region which are needed before column densities can be calculated, as well as describe a second method for determining excitation temperatures using the VLA. I will also show preliminary results on molecular gas column densities in W5 as derived from OH, and compare them to the column densities derived from the corresponding CO data from the literature.		Despite its near-universal acceptance, use of the CO(1-0) transition as a molecular gas tracer has been drawn into controversy for molecular gas for low densities, and evidence from gamma-ray and IR surveys suggest the presence of undetected gas in the Galaxy, which is likely molecular and which likely contains a mass similar to the mass of known molecular gas (Grenier et al. 2005, Tibaldo et al. 2015). I have worked with Drs. Ron Allen (STScI / JHU) and David Hogg (NRAO) to study the OH 18 cm transitions as an alternate tracer for molecular gas, using the Green Bank telescope for blind surveys towards the Outer Galaxy. These observations indicate that OH can be a viable alternative tracer for molecular gas and appears to trace a larger component of the molecular ISM than does CO, being widely detected in places many of which have no CO(1-0) detections in the literature. My thesis project applies the use of OH as an alternate molecular gas tracer to the W5 star-forming region. In order to do this, I have performed an OH survey with the Green Bank telescope over W5, which contains a free-free continuum background and a mixture of emission and absorption features. I will report findings regarding the OH line excitation temperatures in the region which are needed before column densities can be calculated, as well as describe a second method for determining excitation temperatures using the VLA. I will also show preliminary results on molecular gas column densities in W5 as derived from OH, and compare them to the column densities derived from the corresponding CO data from the literature.

Kdkuntz: /* Special Graduate Seminar: Philip Engelke */

2017-04-17T21:31:36Z

Special Graduate Seminar: Philip Engelke

← Older revision		Revision as of 21:31, 17 April 2017
Line 97:		Line 97:
	=April 24th=		=April 24th=
	== Special Graduate Seminar: Philip Engelke ==		== Special Graduate Seminar: Philip Engelke ==
	The Structure of "Dark" Gas in Star-Forming Regions: OH as an Alternate Molecular Tracer</br>		'''The Structure of "Dark" Gas in Star-Forming Regions: OH as an Alternate Molecular Tracer'''</br>
	Despite its near-universal acceptance, use of the CO(1-0) transition as a molecular gas tracer has been drawn into controversy for molecular gas for low densities, and evidence from gamma-ray and IR surveys suggest the presence of undetected gas in the Galaxy, which is likely molecular and which likely contains a mass similar to the mass of known molecular gas (Grenier et al. 2005, Tibaldo et al. 2015). I have worked with Drs. Ron Allen (STScI / JHU) and David Hogg (NRAO) to study the OH 18 cm transitions as an alternate tracer for molecular gas, using the Green Bank telescope for blind surveys towards the Outer Galaxy. These observations indicate that OH can be a viable alternative tracer for molecular gas and appears to trace a larger component of the molecular ISM than does CO, being widely detected in places many of which have no CO(1-0) detections in the literature. My thesis project applies the use of OH as an alternate molecular gas tracer to the W5 star-forming region. In order to do this, I have performed an OH survey with the Green Bank telescope over W5, which contains a free-free continuum background and a mixture of emission and absorption features. I will report findings regarding the OH line excitation temperatures in the region which are needed before column densities can be calculated, as well as describe a second method for determining excitation temperatures using the VLA. I will also show preliminary results on molecular gas column densities in W5 as derived from OH, and compare them to the column densities derived from the corresponding CO data from the literature.		Despite its near-universal acceptance, use of the CO(1-0) transition as a molecular gas tracer has been drawn into controversy for molecular gas for low densities, and evidence from gamma-ray and IR surveys suggest the presence of undetected gas in the Galaxy, which is likely molecular and which likely contains a mass similar to the mass of known molecular gas (Grenier et al. 2005, Tibaldo et al. 2015). I have worked with Drs. Ron Allen (STScI / JHU) and David Hogg (NRAO) to study the OH 18 cm transitions as an alternate tracer for molecular gas, using the Green Bank telescope for blind surveys towards the Outer Galaxy. These observations indicate that OH can be a viable alternative tracer for molecular gas and appears to trace a larger component of the molecular ISM than does CO, being widely detected in places many of which have no CO(1-0) detections in the literature. My thesis project applies the use of OH as an alternate molecular gas tracer to the W5 star-forming region. In order to do this, I have performed an OH survey with the Green Bank telescope over W5, which contains a free-free continuum background and a mixture of emission and absorption features. I will report findings regarding the OH line excitation temperatures in the region which are needed before column densities can be calculated, as well as describe a second method for determining excitation temperatures using the VLA. I will also show preliminary results on molecular gas column densities in W5 as derived from OH, and compare them to the column densities derived from the corresponding CO data from the literature.

Kdkuntz: /* Special Graduate Seminar */

2017-04-17T21:31:04Z

Special Graduate Seminar

← Older revision		Revision as of 21:31, 17 April 2017
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	=April 24th=		=April 24th=
	== Special Graduate Seminar ==		== Special Graduate Seminar: Philip Engelke ==
			The Structure of "Dark" Gas in Star-Forming Regions: OH as an Alternate Molecular Tracer</br>
			Despite its near-universal acceptance, use of the CO(1-0) transition as a molecular gas tracer has been drawn into controversy for molecular gas for low densities, and evidence from gamma-ray and IR surveys suggest the presence of undetected gas in the Galaxy, which is likely molecular and which likely contains a mass similar to the mass of known molecular gas (Grenier et al. 2005, Tibaldo et al. 2015). I have worked with Drs. Ron Allen (STScI / JHU) and David Hogg (NRAO) to study the OH 18 cm transitions as an alternate tracer for molecular gas, using the Green Bank telescope for blind surveys towards the Outer Galaxy. These observations indicate that OH can be a viable alternative tracer for molecular gas and appears to trace a larger component of the molecular ISM than does CO, being widely detected in places many of which have no CO(1-0) detections in the literature. My thesis project applies the use of OH as an alternate molecular gas tracer to the W5 star-forming region. In order to do this, I have performed an OH survey with the Green Bank telescope over W5, which contains a free-free continuum background and a mixture of emission and absorption features. I will report findings regarding the OH line excitation temperatures in the region which are needed before column densities can be calculated, as well as describe a second method for determining excitation temperatures using the VLA. I will also show preliminary results on molecular gas column densities in W5 as derived from OH, and compare them to the column densities derived from the corresponding CO data from the literature.

	=May Day=		=May Day=

Kdkuntz at 22:24, 11 April 2017

2017-04-11T22:24:17Z

← Older revision		Revision as of 22:24, 11 April 2017
Line 94:		Line 94:
	'''The Life Cycle of Dust in the Magellanic Clouds: Insights from Spitzer and Herschel'''<br>		'''The Life Cycle of Dust in the Magellanic Clouds: Insights from Spitzer and Herschel'''<br>
	The life cycle of dust in a galaxy involves the exchange of material between the interstellar medium (ISM) and stars. Dust is formed in the winds of dying stars, such as asymptotic giant branch (AGB) and red supergiant (RSG) stars, and the explosion of supernovae. In the ISM, the dust may be shattered and vaporized by supernova blast waves or accreted onto seed grains in the denser ISM. Dust is consumed in the star formation process and appears in the circumstellar environments of newly forming stars. By tracing the lifecycle of dust, we gain insights into the dust evolution processes and the origin of galactic dust. The Spitzer Space Telescope and Herschel Space Observatory provide a sensitive probe of circumstellar and interstellar dust. The Spitzer Surveying the Agents of Galaxy Evolution (SAGE; the ISM and stars) and the Herschel Inventory of the Agents of Galaxy Evolution (HERITAGE) surveys of the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) focus on the lifecycle of dust. The LMC and SMC are ideal astrophysical laboratories for this study because their proximity to us permits detailed studies of the stars and their relation to the ISM from local to galaxy wide scales. For example, the masses of the circumstellar dust shells of stars and ISM dust clouds can be determined producing a more precise dust budget than possible for our own Milky Way galaxy. I will present key results from the SAGE and HERITAGE projects that quantify the stellar origin of dust, its evolution in the ISM and its consumption by star formation. Our measurements of dust mass-loss rates from entire populations of AGB and RSG stars and the discovery of ~0.5 solar masses of dust in the ejecta of supernova, SN1987A, provide the dust production rates by the stars. The maps of dust masses and gas-to-dust ratios of the ISM reveal how dust is destroyed and possibly created in the ISM. Our discovery of thousands of young stellar object candidates shows us locations of active star formation and enables us to quantify the star formation rate. I will end with a brief summary of the potential of a large cryogenically cooled telescope, such as the Origins Space Telescope to extend this research.		The life cycle of dust in a galaxy involves the exchange of material between the interstellar medium (ISM) and stars. Dust is formed in the winds of dying stars, such as asymptotic giant branch (AGB) and red supergiant (RSG) stars, and the explosion of supernovae. In the ISM, the dust may be shattered and vaporized by supernova blast waves or accreted onto seed grains in the denser ISM. Dust is consumed in the star formation process and appears in the circumstellar environments of newly forming stars. By tracing the lifecycle of dust, we gain insights into the dust evolution processes and the origin of galactic dust. The Spitzer Space Telescope and Herschel Space Observatory provide a sensitive probe of circumstellar and interstellar dust. The Spitzer Surveying the Agents of Galaxy Evolution (SAGE; the ISM and stars) and the Herschel Inventory of the Agents of Galaxy Evolution (HERITAGE) surveys of the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) focus on the lifecycle of dust. The LMC and SMC are ideal astrophysical laboratories for this study because their proximity to us permits detailed studies of the stars and their relation to the ISM from local to galaxy wide scales. For example, the masses of the circumstellar dust shells of stars and ISM dust clouds can be determined producing a more precise dust budget than possible for our own Milky Way galaxy. I will present key results from the SAGE and HERITAGE projects that quantify the stellar origin of dust, its evolution in the ISM and its consumption by star formation. Our measurements of dust mass-loss rates from entire populations of AGB and RSG stars and the discovery of ~0.5 solar masses of dust in the ejecta of supernova, SN1987A, provide the dust production rates by the stars. The maps of dust masses and gas-to-dust ratios of the ISM reveal how dust is destroyed and possibly created in the ISM. Our discovery of thousands of young stellar object candidates shows us locations of active star formation and enables us to quantify the star formation rate. I will end with a brief summary of the potential of a large cryogenically cooled telescope, such as the Origins Space Telescope to extend this research.

			=April 24th=
			== Special Graduate Seminar ==

	=May Day=		=May Day=

Kdkuntz: /* Margaret Meixner (StScI) */

2017-04-11T22:22:24Z

Margaret Meixner (StScI)

← Older revision		Revision as of 22:22, 11 April 2017
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	=April 17th=		=April 17th=
	== Margaret Meixner (StScI) ==		== Margaret Meixner (StScI) ==
	'''~~Title~~'''<br>		'''The Life Cycle of Dust in the Magellanic Clouds: Insights from Spitzer and Herschel'''<br>
	~~Abstract~~		The life cycle of dust in a galaxy involves the exchange of material between the interstellar medium (ISM) and stars. Dust is formed in the winds of dying stars, such as asymptotic giant branch (AGB) and red supergiant (RSG) stars, and the explosion of supernovae. In the ISM, the dust may be shattered and vaporized by supernova blast waves or accreted onto seed grains in the denser ISM. Dust is consumed in the star formation process and appears in the circumstellar environments of newly forming stars. By tracing the lifecycle of dust, we gain insights into the dust evolution processes and the origin of galactic dust. The Spitzer Space Telescope and Herschel Space Observatory provide a sensitive probe of circumstellar and interstellar dust. The Spitzer Surveying the Agents of Galaxy Evolution (SAGE; the ISM and stars) and the Herschel Inventory of the Agents of Galaxy Evolution (HERITAGE) surveys of the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) focus on the lifecycle of dust. The LMC and SMC are ideal astrophysical laboratories for this study because their proximity to us permits detailed studies of the stars and their relation to the ISM from local to galaxy wide scales. For example, the masses of the circumstellar dust shells of stars and ISM dust clouds can be determined producing a more precise dust budget than possible for our own Milky Way galaxy. I will present key results from the SAGE and HERITAGE projects that quantify the stellar origin of dust, its evolution in the ISM and its consumption by star formation. Our measurements of dust mass-loss rates from entire populations of AGB and RSG stars and the discovery of ~0.5 solar masses of dust in the ejecta of supernova, SN1987A, provide the dust production rates by the stars. The maps of dust masses and gas-to-dust ratios of the ISM reveal how dust is destroyed and possibly created in the ISM. Our discovery of thousands of young stellar object candidates shows us locations of active star formation and enables us to quantify the star formation rate. I will end with a brief summary of the potential of a large cryogenically cooled telescope, such as the Origins Space Telescope to extend this research.

	=May Day=		=May Day=

Kdkuntz: /* April 10th */

2017-04-03T13:42:12Z

April 10th

← Older revision		Revision as of 13:42, 3 April 2017
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	=April 10th=		=April 10th=
	== Jay Felix Lockman (NRAO) ==		== Jay Felix Lockman (NRAO) ==
	'''~~Title~~'''<br>		'''Neutral Gas Outside the Disks of Local Group Galaxies'''<br>
	~~Abstract~~		Most of the neutral Hydrogen in the Local Group resides in the disks
			of the large spirals, but there are important exceptions, some of which
			are tied to basic processes in galaxy evolution. After giving a brief
			survey of recent science with the Green Bank Telescope, I'll discuss the
			different populations of neutral hydrogen that are found outside the disks
			of galaxies in the Local Group. The most puzzling are the clouds found
			between M31 and M33, which have the mass of dwarf galaxies but do not appear
			to contain any stars.

	=April 17th=		=April 17th=

Kdkuntz: /* April 3rd */

2017-03-24T23:29:05Z

April 3rd

← Older revision		Revision as of 23:29, 24 March 2017
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	=April 3rd=		=April 3rd=
	== Massimo Ricotti (UMd) ==		== Massimo Ricotti (UMd) ==
	'''~~Title~~'''<br>		'''X-ray Twinkles and Pop III Stars'''<br>
	~~Abstract~~		I will present new calculations on the optimal level of X-ray emission in the early universe that can promote the formation of the first stars (Pop~III). This is important in determining the number of dwarf galaxies formed before reionization and their fossils in present day universe.

			X-ray emissivity above the optimal level reduces the number of Pop~III stars because it increases the Jeans mass of the intergalactic medium (IGM), while a lower emissivity suppresses the formation rate of molecular hydrogen, preventing or delaying star formation in minihalos above the Jeans mass. The build up of the H_2 dissociating background is slower than the X-ray background due to the shielding effect of resonant Lyman lines. Hence, the nearly unavoidable X-ray emission from SN remnants of the first stars is sufficient to boost their number to few tens per comoving Mpc^3 at redshift z~5. High-mass X-ray binaries instead have a negligible effect with respect to SNe.

			Moreover, if a non-negligible fraction of Pop~III stars end their lives as hypernovae, their soft X-ray emission is sufficient promote the formation of Pop~III stars to about 400 per comoving Mpc^3, that is near the theoretically-allowed maximum number of Pop~III stars with typical masses 10-40~M_sun. A higher X-ray flux, for instance produced by accretion onto intermediate mass black holes and miniquasars, would suppress the number of first stars because of the excessive heating of the IGM. In these models the increased ionization fraction of the IGM from X-rays contributes negligibly to the optical depth to Thompson scattering, but the bursty ionization from UV emission by Pop~III stars can have a significant effect on tau_e .

	=April 10th=		=April 10th=

Kdkuntz: /* TBD */

2017-03-07T19:47:44Z

TBD

← Older revision		Revision as of 19:47, 7 March 2017
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	=April 17th=		=April 17th=
	== ~~TBD~~ ==		== Margaret Meixner (StScI) ==
	'''Title'''<br>		'''Title'''<br>
	Abstract		Abstract