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Stars, Interstellar Medium and the Galaxy Commons

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877 full-text articles. Page 4 of 25.

Where Is Oh And Does It Trace The Dark Molecular Gas (Dmg)?, Di Li, Ningyu Tang, Hiep Nguyen, J. R. Dawson, Carl Heiles, Duo Xu, Zhichen Pan, Paul F. Goldsmith, Steven J. Gibson, Claire E. Murray, Tim Robishaw, N. M. McClure-Griffiths, John Dickey, Jorge Pineda, Snežana Stanimirović, L. Bronfman, Thomas Troland 2018 Chinese Academy of Sciences, China

Where Is Oh And Does It Trace The Dark Molecular Gas (Dmg)?, Di Li, Ningyu Tang, Hiep Nguyen, J. R. Dawson, Carl Heiles, Duo Xu, Zhichen Pan, Paul F. Goldsmith, Steven J. Gibson, Claire E. Murray, Tim Robishaw, N. M. Mcclure-Griffiths, John Dickey, Jorge Pineda, Snežana Stanimirović, L. Bronfman, Thomas Troland

Physics and Astronomy Faculty Publications

Hydroxyl (OH) is expected to be abundant in diffuse interstellar molecular gas because it forms along with H2 under similar conditions and forms within a similar extinction range.

For the remainder of the abstract, please download this article or visit: https://doi.org/10.3847/1538-4365/aaa762


Frb 121102: A Repeatedly Combed Neutron Star By A Nearby Low-Luminosity Accreting Supermassive Black Hole, Bing Zhang 2018 University of Nevada, Las Vegas

Frb 121102: A Repeatedly Combed Neutron Star By A Nearby Low-Luminosity Accreting Supermassive Black Hole, Bing Zhang

Physics & Astronomy Faculty Publications

The origin of fast radio bursts (FRBs) remains mysterious. Recently, the only repeating FRB source, FRB 121102, was reported to possess an extremely large and variable rotation measure (RM). The inferred magnetic field strength in the burst environment is comparable to that in the vicinity of the supermassive black hole Sagittarius A* of our Galaxy. Here, we show that all of the observational properties of FRB 121102 (including the high RM and its evolution, the high linear polarization degree, an invariant polarization angle across each burst and other properties previously known) can be interpreted within the "cosmic comb" model, which ...


Direct Collapse To Supermassive Black Hole Seeds With Radiative Transfer: Isolated Halos, Yang Luo, Kazem Ardaneh, Isaac Shlosman, Kentaro Nagamine, John H. Wise, Mitchell C. Begelman 2018 University of Kentucky

Direct Collapse To Supermassive Black Hole Seeds With Radiative Transfer: Isolated Halos, Yang Luo, Kazem Ardaneh, Isaac Shlosman, Kentaro Nagamine, John H. Wise, Mitchell C. Begelman

Physics and Astronomy Faculty Publications

Direct collapse within dark matter haloes is a promising path to form supermassive black hole seeds at high redshifts. The outer part of this collapse remains optically thin. However, the innermost region of the collapse is expected to become optically thick and requires to follow the radiation field in order to understand its evolution. So far, the adiabatic approximation has been used exclusively for this purpose. We apply radiative transfer in the flux-limited diffusion (FLD) approximation to solve the evolution of coupled gas and radiation for isolated haloes. We find that (1) the photosphere forms at 10−6 pc and ...


A Young Solar Twin In The Rosette Cluster Ngc 2244 Line Of Sight, Jeremy M. Huber, John F. Kielkopf, Matthew Mengel, Bradley D. Carter, Gary J. Ferland, Frank O. Clark 2018 Thomas Moore College

A Young Solar Twin In The Rosette Cluster Ngc 2244 Line Of Sight, Jeremy M. Huber, John F. Kielkopf, Matthew Mengel, Bradley D. Carter, Gary J. Ferland, Frank O. Clark

Physics and Astronomy Faculty Publications

Based on prior precision photometry and cluster age analysis, the bright star GSC 00154−01819 is a possible young pre-main sequence member of the Rosette cluster, NGC 2244. As part of a comprehensive study of the large-scale structure of the Rosette and its excitation by the cluster stars, we noted this star as a potential backlight for a probe of the interstellar medium and extinction along the sight line towards a distinctive nebular feature projected on to the cluster centre. New high-resolution spectra of the star were taken with the University College London Echelle Spectrograph of the AAT. They reveal ...


Luminous And Obscured Quasars And Their Host Galaxies, Agnese Del Moro, David M. Alexander, Franz E. Bauer, Emanuele Daddi, Dale D. Kocevski, Flora Stanley, Daniel H. McIntosh 2018 Max-Planck-Institut für Extraterrestrische Physik, Germany

Luminous And Obscured Quasars And Their Host Galaxies, Agnese Del Moro, David M. Alexander, Franz E. Bauer, Emanuele Daddi, Dale D. Kocevski, Flora Stanley, Daniel H. Mcintosh

Physics and Astronomy Faculty Publications

The most heavily-obscured, luminous quasars might represent a specific phase of the evolution of the actively accreting supermassive black holes and their host galaxies, possibly related to mergers. We investigated a sample of the most luminous quasars at z ≈ 1 − 3 in the GOODS fields, selected in the mid-infrared band through detailed spectral energy distribution (SED) decomposition. The vast majority of these quasars (~80%) are obscured in the X-ray band and ~30% of them to such an extent, that they are undetected in some of the deepest (2 and 4 Ms) Chandra X-ray data. Although no clear relation is found ...


On The Formation Mechanisms Of Compact Elliptical Galaxies, Anna Ferré-Mateu, Duncan Forbes, Aaron Romanowsky, Joachim Janz, Christopher Dixon 2018 Swinburne University of Technology

On The Formation Mechanisms Of Compact Elliptical Galaxies, Anna Ferré-Mateu, Duncan Forbes, Aaron Romanowsky, Joachim Janz, Christopher Dixon

Faculty Publications

In order to investigate the formation mechanisms of the rare compact elliptical (cE) galaxies, we have compiled a sample of 25 cEs with good SDSS spectra, covering a range of stellar masses, sizes and environments. They have been visually classified according to the interaction with their host, representing different evolutionary stages. We have included clearly disrupted galaxies, galaxies that despite not showing signs of interaction are located close to a massive neighbour (thus are good candidates for a stripping process), and cEs with no host nearby. For the latter, tidal stripping is less likely to have happened and instead they ...


On The Formation Mechanisms Of Compact Elliptical Galaxies, Anna Ferré-Mateu, Duncan A. Forbes, Aaron J. Romanowsky, Joachim Janz, Christopher Dixon 2018 Swinburne University of Technology

On The Formation Mechanisms Of Compact Elliptical Galaxies, Anna Ferré-Mateu, Duncan A. Forbes, Aaron J. Romanowsky, Joachim Janz, Christopher Dixon

Aaron J. Romanowsky

In order to investigate the formation mechanisms of the rare compact elliptical (cE) galaxies, we have compiled a sample of 25 cEs with good SDSS spectra, covering a range of stellar masses, sizes and environments. They have been visually classified according to the interaction with their host, representing different evolutionary stages. We have included clearly disrupted galaxies, galaxies that despite not showing signs of interaction are located close to a massive neighbour (thus are good candidates for a stripping process), and cEs with no host nearby. For the latter, tidal stripping is less likely to have happened and instead they ...


Solar Eclipse, 2017 (Sc 3152), Manuscripts & Folklife Archives 2018 Western Kentucky University

Solar Eclipse, 2017 (Sc 3152), Manuscripts & Folklife Archives

MSS Finding Aids

Finding aid only for Manuscripts Small Collection 3152. Materials relating to the 2017 solar eclipse as experienced primarily in Bowling Green and Hopkinsville, Kentucky and vicinity. Includes viewing glasses, first day stamped covers, stickers, art work, photographs (in digital format), promotional materials, and impressions of the eclipse contributed as part of WKU’s Department of Library Special Collections’ “Tell Us About Your Eclipse Day” project. Also includes wristbands, handouts and volunteer information relating to an eclipse viewing event for schoolchildren held at WKU’s Smith-Houchens Stadium. Digital photographs are stored in the Photo Archives.


Effects Of Mass And Distance Uncertainties On Calculations Of Flux From Giant Molecular Clouds, Matt Coel 2018 Michigan Technological University

Effects Of Mass And Distance Uncertainties On Calculations Of Flux From Giant Molecular Clouds, Matt Coel

Dissertations, Master's Theses and Master's Reports

It is assumed that the distribution of the Milky Way cosmic rays, the cosmic ray ‘sea,’ is even throughout the Galaxy. This assumption can be tested by measuring gamma rays produced from cosmic ray interactions with Giant Molecular Clouds. The gamma ray flux depends on the mass and distance of a given molecular cloud as well as the cosmic ray flux in its vicinity. Thus a predicted gamma ray flux can be compared to actual flux data from a detector. Uncertainties from measuring the mass of and distance to the clouds are taken into account for this prediction. This report ...


Fuel For The Star Formation Engine: Dense Molecular Cloud Clumps In The Northern Galactic Plane, Erika Henning Zetterlund 2018 University of Colorado at Boulder

Fuel For The Star Formation Engine: Dense Molecular Cloud Clumps In The Northern Galactic Plane, Erika Henning Zetterlund

Astrophysical & Planetary Sciences Graduate Theses & Dissertations

The interstellar medium (ISM) is a confusing, muddled place. It provides the fuel for star formation, but before that can occur, the ISM must cool and condense into molecular clouds. Even this is not enough, however. It is only the cores, contained within the clumps, contained within the clouds, which form stars. With all these nested structures, it takes an optically thin, yet still bright, tracer to uncover the processes which convert the molecular clouds into stars. Luckily, the ISM is dusty.

I use the Herschel infrared GALactic plane survey (Hi-GAL) to study molecular cloud clumps through their thermal dust ...


The Cosmic Twilight Polarimeter: A Model-Independent Approach To Constrain The Synchrotron Foreground Spectrum For Global 21-Cm Cosmology, Bang Dinh Nhan 2018 University of Colorado at Boulder

The Cosmic Twilight Polarimeter: A Model-Independent Approach To Constrain The Synchrotron Foreground Spectrum For Global 21-Cm Cosmology, Bang Dinh Nhan

Astrophysical & Planetary Sciences Graduate Theses & Dissertations

Detecting the cosmological sky-averaged (global) 21-cm spectrum as a function of observed frequency will provide a powerful tool to study the ionization and thermal history of intergalactic medium (IGM) in the high-redshift Universe (∼ 400 million years after the Big Bang). The biggest challenge in conventional ground-based total-power global 21-cm experiments is the removal of the Galactic and extragalactic synchrotron foreground (~ 10,000-100,000 K) to uncover the weak cosmological signal (∼ 10-100 mK) due to corruption on the spectral smoothness of foreground spectrum by instrumental effects. Although an absorption profile has been reported recently at 78 MHz in the sky-averaged spectrum ...


Multi-Telescope Radio Observations For Low Frequency Gravitational Wave Astrophysics, Megan L. Jones 2018 West Virginia University

Multi-Telescope Radio Observations For Low Frequency Gravitational Wave Astrophysics, Megan L. Jones

Graduate Theses, Dissertations, and Problem Reports

The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has the principal goal of detecting gravitational waves (GWs) in the nanohertz part of the spectrum using pulsar timing. This thesis presents results from radio campaigns at frequencies from 322 MHz to 10 GHz aimed at both multi-messenger constraints on GW sources and improving the timing sensitivity. The primary expected source of GWs at the nanohertz frequencies to which pulsar timing is sensitive are supermassive black hole (SMBH) binaries. We investigate a purported SMBH displaced from the galactic photocenter in NGC 3115. We explore the possibilities that the source is a ...


Study Of The Cygnus Region With Fermi And Hawc, Andrew Robare 2018 Michigan Technological University

Study Of The Cygnus Region With Fermi And Hawc, Andrew Robare

Dissertations, Master's Theses and Master's Reports

The Cygnus Cocoon is an extended source of high-energy gamma-ray emission in the Cygnus region. The gamma-ray emission has been attributed to a volume 50pc in diameter of freshly-accelerated particles near the Supernova Remnant γ Cygni which is located 1.4kpc from the solar system [Ackermann et al., 2011], [Tibaldo et al., 2013]. Since its discovery in 2011, Fermi LAT has improved their event reconstruction to allow analysis at higher energies, and recorded six additional years of data. An analysis was performed on the entire dataset to reproduce the previous results, then expand on them with higher energies and larger ...


Collective Gravity Of Minor Planets In The Outer Solar System, Jacob Fleisig 2018 University of Colorado, Boulder

Collective Gravity Of Minor Planets In The Outer Solar System, Jacob Fleisig

Undergraduate Honors Theses

Our Solar System contains a large population of icy bodies beyond the orbit of Neptune. This group of objects, known as the Kuiper Belt, are remnants from early in the formation of the Solar System. However, these bodies exhibit strange orbital characteristics, hinting at the possibility of a missing chapter in the Solar System's formation history. To find an explanation to these phenomena, we investigate the effects that the KBOs' collective gravity has on the Solar System using computer simulations. In doing so, we find a new mechanism capable of changing objects' distances of closest approach to the Sun ...


Rr Lyrae Calibration Using Sdss, Single-Epoch Spectroscopy, Stacy Long 2018 University of Kentucky

Rr Lyrae Calibration Using Sdss, Single-Epoch Spectroscopy, Stacy Long

Theses and Dissertations--Physics and Astronomy

I use single-epoch, SDSS spectroscopy of RR Lyraes identified in the Catalina survey to separate the spectra into same-temperature groups. Then I draw temperature-phase diagrams of the groups. I find shocked stars, improperly phased stars, low amplitude stars, and a few that are more likely eclipsing binaries. The RR Lyraes are then given precise metallicities by measurements of the CaII K and H-β, H-γ, and H-δ lines. This leads to better distance measurements, which allow me to confirm a distinction between the inner and outer galactic halo.


An Additional Pulsating Mode (7.35 Mhz) And Pulsations Timing Variations Of Pg 1613+426, Tomomi Otani, Terry D. Oswalt, Patrice Majewski, Riley Jordan, Marc Amaral, Adam Moss 2017 Embry-Riddle Aeronautical University

An Additional Pulsating Mode (7.35 Mhz) And Pulsations Timing Variations Of Pg 1613+426, Tomomi Otani, Terry D. Oswalt, Patrice Majewski, Riley Jordan, Marc Amaral, Adam Moss

Publications

We present the detection of an additional pulsation mode (7.35 mHz) of a subdwarf B star, PG 1613+426, and periodic Observed minus Calculated (O-C) variations for two existing pulsations. PG 1613+426 is near the hot end of the sdB instability strip. One pulsation mode (6.94 mHz) was detected so far by Bonanno et al. (2002) and another pulsation mode candidate (7.05 mHz) was proposed with a confidence level above 90% by Kuassivi and Ferlet (2005). To constrain sdB star evolutional scenarios, this star was monitored in 2010, 2011, 2015, and 2017 as a part of ...


Unseen Science: Modern Discoveries Too Far Away Or Tiny For Human Eyes, Lucy Huang 2017 Cuny Graduate School of Journalism

Unseen Science: Modern Discoveries Too Far Away Or Tiny For Human Eyes, Lucy Huang

Capstones

As science has progressed, scientists have realized that evidence goes beyond the realms of physical sight. Whether it is too small or difficult to find, scientists have developed different ways to get around this problem. We see this in cancer genomics and in extrasolar planetary research. Scientists use what they know and what they measure to validate their work.

https://lucy-huang-9tge.squarespace.com/


Deep Subaru Hyper Suprime-Cam Observations Of Milky Way Satellites Columba I And Triangulum Ii*, Jeffrey Carlin, David Sand, Ricardo Muñoz, Kristine Spekkens, Beth Willman, Denija Crnojević, Duncan Forbes, Jonathan Hargis, Evan Kirby, Annika Peter, Aaron Romanowsky, Jay Strader 2017 LSST and Steward Observatory

Deep Subaru Hyper Suprime-Cam Observations Of Milky Way Satellites Columba I And Triangulum Ii*, Jeffrey Carlin, David Sand, Ricardo Muñoz, Kristine Spekkens, Beth Willman, Denija Crnojević, Duncan Forbes, Jonathan Hargis, Evan Kirby, Annika Peter, Aaron Romanowsky, Jay Strader

Faculty Publications

We present deep, wide-field Subaru Hyper Suprime-Cam photometry of two recently discovered satellites of the Milky Way (MW): Columba I (Col I) and Triangulum II (Tri II). The color–magnitude diagrams of both objects point to exclusively old and metal-poor stellar populations. We re-derive structural parameters and luminosities of these satellites, and find for Col I and for Tri II, with corresponding half-light radii of pc and pc. The properties of both systems are consistent with observed scaling relations for MW dwarf galaxies. Based on archival data, we derive upper limits on the neutral gas content of these dwarfs, and ...


Energy From Active Galactic Nuclei And The Effects On Host Spiral Galaxies, Amanda Schilling 2017 University of Arkansas, Fayetteville

Energy From Active Galactic Nuclei And The Effects On Host Spiral Galaxies, Amanda Schilling

Theses and Dissertations

I have investigated the energy output of active galactic nuclei (AGN) in order to understand how these objects evolve and the impact they may have on host galaxies. First, I looked at a sample of 96 AGN at redshifts $z \sim 2, 3,$ and $4$ which have imaging and thus luminosity measurements in the $griz$ and $JHK$ observed wavebands. For these galaxies, I have co-epochal data across those bands which accounted for variability in AGN luminosity. I used the luminosity measurements in the five bands to construct spectral energy distributions (SED) in the emitted optical-UV bands for each AGN. I ...


Deep Subaru Hyper Suprime-Cam Observations Of Milky Way Satellites Columba I And Triangulum Ii*, Jeffrey L. Carlin, David J. Sand, Ricardo R. Muñoz, Kristine Spekkens, Beth Willman, Denija Crnojević, Duncan A. Forbes, Jonathan Hargis, Evan Kirby, Annika H.G. Peter, Aaron J. Romanowsky, Jay Strader 2017 LSST and Steward Observatory

Deep Subaru Hyper Suprime-Cam Observations Of Milky Way Satellites Columba I And Triangulum Ii*, Jeffrey L. Carlin, David J. Sand, Ricardo R. Muñoz, Kristine Spekkens, Beth Willman, Denija Crnojević, Duncan A. Forbes, Jonathan Hargis, Evan Kirby, Annika H.G. Peter, Aaron J. Romanowsky, Jay Strader

Aaron J. Romanowsky

We present deep, wide-field Subaru Hyper Suprime-Cam photometry of two recently discovered satellites of the Milky Way (MW): Columba I (Col I) and Triangulum II (Tri II). The color–magnitude diagrams of both objects point to exclusively old and metal-poor stellar populations. We re-derive structural parameters and luminosities of these satellites, and find  for Col I and  for Tri II, with corresponding half-light radii of  pc and  pc. The properties of both systems are consistent with observed scaling relations for MW dwarf galaxies. Based on archival data, we derive upper limits on the neutral gas content of these dwarfs, and ...


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