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Astrophysics and Astronomy

Dust

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Articles 1 - 30 of 76

Full-Text Articles in Physical Sciences and Mathematics

Delving Deep: A Population Of Extremely Dusty Dwarfs Observed By Jwst, L. Bisigello, G. Gandolfi, A. Grazian, G. Rodighiero, L. Costantin, A. R. Cooray, A. Feltre, C. Gruppioni, N. P. Hathi, Benne W. Holwerda, A. M. Koekemoer, R. A. Lucas, J. A. Newman, P. G. Pérez-González, L. Y. A. Yung, A. De La Vega, P. Arrabal Haro, M. B. Bagley, M. Dickinson, S. L. Finkelstein, J. S. Kartaltepe, C. Papovich, N. Pirzkal, S. Wilkins Aug 2023

Delving Deep: A Population Of Extremely Dusty Dwarfs Observed By Jwst, L. Bisigello, G. Gandolfi, A. Grazian, G. Rodighiero, L. Costantin, A. R. Cooray, A. Feltre, C. Gruppioni, N. P. Hathi, Benne W. Holwerda, A. M. Koekemoer, R. A. Lucas, J. A. Newman, P. G. Pérez-González, L. Y. A. Yung, A. De La Vega, P. Arrabal Haro, M. B. Bagley, M. Dickinson, S. L. Finkelstein, J. S. Kartaltepe, C. Papovich, N. Pirzkal, S. Wilkins

Faculty Scholarship

Aims. We take advantage of the NIRCam photometric observations available as part of the Cosmic Evolution Early Release Science survey (CEERS) to identify and analyse very red sources in an effort to discover very dusty star forming galaxies. Methods. We select red galaxies as objects with a S / N > 3 at 4.4 μm and a S / N < 2 in all JWST and HST filters at λ ≤ 2 μm, which corresponds to [ F 200 W ]−[ F 444 W ]> 1.2 considering CEERS depths. This selection is ideal to identify very dusty ( A V > 1 mag) galaxies with stellar masses between 10 6 and 10 10 M ⊙ at z < 5, more massive dusty galaxies at z = 5 − 18 and galaxies at z > 18 due to the Lyman absorption, independently of their dust …

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Generating Synthetic Satellite Images Of Mars Dust Storms Based On Radiative Transfer Models, As A Follow-On Application Of Marswrf Dust Cycle Simulations, Fatima Ali Alkaabi Mar 2023

Generating Synthetic Satellite Images Of Mars Dust Storms Based On Radiative Transfer Models, As A Follow-On Application Of Marswrf Dust Cycle Simulations, Fatima Ali Alkaabi

Theses

Dust is a fundamental component of the Martian atmosphere; it plays a vital role in the planet's climate system and atmospheric variability. For these reasons, it is considered one of the essential keys to understanding the Martian atmosphere's behavior. The dust events on Mars range from local/regional dust storms that occur every Martian year to global dust storms that have only been observed, on average, once every 3-4 Martian years. The large regional and global dust storms have strong thermal and dynamic effects on the atmosphere. MarsWRF is a Mars version of the terrestrial numerical weather and climate model WRF …

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How Do Galaxies Form Their Stars Over Cosmic Time?, Jed H. Mckinney Oct 2022

How Do Galaxies Form Their Stars Over Cosmic Time?, Jed H. Mckinney

Doctoral Dissertations

Galaxies in the past were forming more stars than those today, but the driving force behind this increase in activity remains uncertain. In this thesis I explore the origin of high star-formation rates today and in the past by studying the properties of gas and dust in the cold interstellar medium (ISM) of dusty galaxies over cosmic time. Critically, we do not yet understand how these galaxies could form so many stars. This work began with my discovery of unusual infrared (IR) emission line ratios in the class of dusty galaxies where most of the Universe’s stars were formed. To …

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Comparing Dust In Other Galaxies To Dust In Our Galaxy, Fatima Elkhatib Apr 2021

Comparing Dust In Other Galaxies To Dust In Our Galaxy, Fatima Elkhatib

Senior Theses

Interstellar dust in galaxies has a profound effect on the galaxies’ light output and apparent properties as well as on the physical processes connected to star formation. Therefore, to understand the true properties of the galaxies around us, it is important to understand the dust in those galaxies and compare it to the dust in our galaxy. To do this, we study the effects of dust on background quasars by analyzing interstellar reddening and extinction. It has been shown that many quasars look redder and dimmer than the average quasar when observing them from Earth, due to the dust in …

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A Search For Optical Afterglow From Grb 970828, P. J. Groot, T. J. Galama, J. Van Paradijs, C. Kouveliotou, R. A. M. J. Wijers, J. Bloom, N. Tanvir, R. Vanderspek, J. Greiner, A. J. Castro-Tirado, J. Gorosabel, T. Von Hippel, M. Lehnert, K. Kuijken, H. Hoekstra, N. Metcalfe, C. Howk, C. Conselice, J. Telting, R. G. M. Rutten, J. Rhoads, A. Cole, D. J. Pisano, R. Naber, R. Schwarz Aug 2019

A Search For Optical Afterglow From Grb 970828, P. J. Groot, T. J. Galama, J. Van Paradijs, C. Kouveliotou, R. A. M. J. Wijers, J. Bloom, N. Tanvir, R. Vanderspek, J. Greiner, A. J. Castro-Tirado, J. Gorosabel, T. Von Hippel, M. Lehnert, K. Kuijken, H. Hoekstra, N. Metcalfe, C. Howk, C. Conselice, J. Telting, R. G. M. Rutten, J. Rhoads, A. Cole, D. J. Pisano, R. Naber, R. Schwarz

Ted von Hippel

We report on the results of R-band observations of the error box of the g-ray burst of 1997 August 28 made between 4 hr and 8 days after this burst occurred. No counterpart was found varying by more than 0.2 mag down to R 5 23.8. We discuss the consequences of this nondetection for relativistic blast wave models of g-ray bursts and the possible effect of redshift on the relation between optical absorption and the low-energy cutoff in the X-ray afterglow spectrum.

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Aztec Survey Of The Central Molecular Zone: Modeling Dust Seds With Hierarchical Bayesian Analysis, Yuping Tang Jul 2019

Aztec Survey Of The Central Molecular Zone: Modeling Dust Seds With Hierarchical Bayesian Analysis, Yuping Tang

Doctoral Dissertations

In this dissertation, we present a study based on the AzTEC/Large Millimeter Telescope (LMT) survey of dust continuum at 1.1mm on the central 200 parsecs (The Central Molecular Zone (CMZ)) of our Galaxy. Owing to its unusually high gas density and turbulence, strong magnetic field, and high cosmic ray flux, the CMZ represents an initial condition for star-formation typical of starburst galaxies in the distant universe. In order to understand dust properties in such an extreme environment. We perform a joint SED analysis of existing dust continuum surveys on the CMZ, from a wavelength of 160 μm to 1.1 mm. …

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Dust–Gas Scaling Relations And Oh Abundance In The Galactic Ism, Hiep Nguyen, J. R. Dawson, M. -A. Miville-Deschênes, Ningyu Tang, Di Li, Carl Heiles, Claire E. Murray, Snežana Stanimirović, Steven J. Gibson, N. M. Mcclure-Griffiths, Thomas Troland, L. Bronfman, R. Finger Jul 2018

Dust–Gas Scaling Relations And Oh Abundance In The Galactic Ism, Hiep Nguyen, J. R. Dawson, M. -A. Miville-Deschênes, Ningyu Tang, Di Li, Carl Heiles, Claire E. Murray, Snežana Stanimirović, Steven J. Gibson, N. M. Mcclure-Griffiths, Thomas Troland, L. Bronfman, R. Finger

Physics and Astronomy Faculty Publications

Observations of interstellar dust are often used as a proxy for total gas column density NH. By comparing Planck thermal dust data (Release 1.2) and new dust reddening maps from Pan-STARRS 1 and 2MASS, with accurate (opacity-corrected) H I column densities and newly published OH data from the Arecibo Millennium survey and 21-SPONGE, we confirm linear correlations between dust optical depth τ353, reddening E(B − V), and the total proton column density NH in the range (1–30) × 1020 cm−2, along sightlines with no molecular gas detections in emission. …

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Using An Astrophysical Model To Characterize Nuclear Dust, Anita N. Dunsmore Mar 2018

Using An Astrophysical Model To Characterize Nuclear Dust, Anita N. Dunsmore

Theses and Dissertations

Dust clouds resulting from nuclear explosions are complex phenomena, and knowledge on how they form is lacking. Noting the similarities between supernovae and nuclear explosions led to the concept of modeling a nuclear dust cloud using a supernova simulation. MOCASSIN uses a Monte Carlo approach to model photons traveling through a dust cloud, allowing the cloud's characteristics to be discovered by comparing an observed spectrum to a calculated one and then changing input values to make the spectra match. Data files describing two nuclear fireballs of varying yields were created and analyzed using MOCASSIN, but yielded zero energy spectra. After …

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Herschel Observations Of Edge-On Spirals (Heroes) Iv. Dust Energy Balance Problem, Aleksandr V. Mosenkov, Flor Allaert, Maarten Baes, Simone Bianchi, Peter Camps, Christopher J.R. Clark, Marjorie Decleir, Gert De Geyter, Ilse De Looze, Jacopo Fritz, Gianfranco Gentile, Benne W. Holwerda, Thomas M. Hughes, Fraser Lewis, Matthew W.L. Smith, Joris Verstappen, Sam Verstocken, Sébastien Viaene Jan 2018

Herschel Observations Of Edge-On Spirals (Heroes) Iv. Dust Energy Balance Problem, Aleksandr V. Mosenkov, Flor Allaert, Maarten Baes, Simone Bianchi, Peter Camps, Christopher J.R. Clark, Marjorie Decleir, Gert De Geyter, Ilse De Looze, Jacopo Fritz, Gianfranco Gentile, Benne W. Holwerda, Thomas M. Hughes, Fraser Lewis, Matthew W.L. Smith, Joris Verstappen, Sam Verstocken, Sébastien Viaene

Faculty Scholarship

We present results of the detailed dust energy balance study for the seven large edge-on galaxies in the HEROES sample using three-dimensional (3D) radiative transfer (RT) modelling. Based on available optical and near-infrared (NIR) observations of the HEROES galaxies, we derive the 3D distribution of stars and dust in these galaxies. For the sake of uniformity, we apply the same technique to retrieve galaxy properties for the entire sample: we use a stellar model consisting of a Sérsic bulge and three double-exponential discs (a superthin disc for a young stellar population and thin and thick discs for old populations). For …

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On The Time Variation Of Dust Extinction And Gas Absorption For Type Ia Supernovae Observed Through A Nonuniform Interstellar Medium, Xiaosheng Huang, G Aldering, M. Biederman, B. Herger Nov 2017

On The Time Variation Of Dust Extinction And Gas Absorption For Type Ia Supernovae Observed Through A Nonuniform Interstellar Medium, Xiaosheng Huang, G Aldering, M. Biederman, B. Herger

Physics and Astronomy

For Type Ia supernovae (SNe Ia) observed through a nonuniform interstellar medium (ISM) in its host galaxy, we investigate whether the nonuniformity can cause observable time variations in dust extinction and in gas absorption due to the expansion of the SN photosphere with time. We show that, owing to the steep spectral index of the ISM density power spectrum, sizable density fluctuation amplitudes at the length scale of typical ISM structures () will translate to much smaller fluctuations on the scales of an SN photosphere. Therefore, the typical amplitude of time variation due to a nonuniform ISM, of absorption equivalent …

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A Direct Comparison Of Lyman-Alpha And Neutral Hydrogen Morphologies, Kathleen Fitzgibbon, John M. Cannon May 2017

A Direct Comparison Of Lyman-Alpha And Neutral Hydrogen Morphologies, Kathleen Fitzgibbon, John M. Cannon

Macalester Journal of Physics and Astronomy

The Lyman-Alpha Reference Sample (LARS) and its extension (eLARS) represent an exhaustive campaign to reverse-engineer galaxies. The main goal is to understand how \lya radiation is transported within galaxies: what fraction of it escapes, and what physical properties affect the \lya morphology and radiative transport (e.g., dust and gas content, metallicity, kinematics, properties of the producing and underlying stellar populations). Two galaxies from the sample, LARS02 and LARS09, were observed using the B and C configurations of the Very Large Array to examine the neutral hydrogen emission, which can be used to determine a galaxy's neutral hydrogen (HI) structure and …

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Early Science With The Large Millimeter Telescope: Detection Of Dust Emission In Multiple Images Of A Normal Galaxy At Z > 4 Lensed By A Frontier Fields Cluster, Alexandra Pope, Alfredo Montaña, Andrew Battisti, Marceau Limousin, Danilo Marchesini, Grant W. Wilson, Stacy Alberts, Itziar Aretxaga, Vladimir Avila-Reese, José Ramón Bermejo-Climent, Gabriel Brammer, Hector Bravo-Alfaro, Daniela Calzetti, Ranga-Ram Chary, Ryan Cybulski, Mauro Giavalisco, David Hughes, Erin Kado-Fong, Erica Keller, Allison Kirkpatrick, Ivo Labbe, Daniel Lange-Vagle, James Lowenthal, Eric Murphy, Pascal Oesch, Daniel Rosa Gonzalez, David Sánchez-Argüelles, Heath Shipley, Mauro Stefanon, Olga Vega, Katherine Whitaker, Christina C. Williams, Min Yun, Jorge A. Zavala, Milagros Zeballos Apr 2017

Early Science With The Large Millimeter Telescope: Detection Of Dust Emission In Multiple Images Of A Normal Galaxy At Z > 4 Lensed By A Frontier Fields Cluster, Alexandra Pope, Alfredo Montaña, Andrew Battisti, Marceau Limousin, Danilo Marchesini, Grant W. Wilson, Stacy Alberts, Itziar Aretxaga, Vladimir Avila-Reese, José Ramón Bermejo-Climent, Gabriel Brammer, Hector Bravo-Alfaro, Daniela Calzetti, Ranga-Ram Chary, Ryan Cybulski, Mauro Giavalisco, David Hughes, Erin Kado-Fong, Erica Keller, Allison Kirkpatrick, Ivo Labbe, Daniel Lange-Vagle, James Lowenthal, Eric Murphy, Pascal Oesch, Daniel Rosa Gonzalez, David Sánchez-Argüelles, Heath Shipley, Mauro Stefanon, Olga Vega, Katherine Whitaker, Christina C. Williams, Min Yun, Jorge A. Zavala, Milagros Zeballos

Astronomy: Faculty Publications

We directly detect dust emission in an optically detected, multiply imaged galaxy lensed by the Frontier Fields cluster MACSJ0717.5+3745. We detect two images of the same galaxy at 1.1 mm with the AzTEC camera on the Large Millimeter Telescope leaving no ambiguity in the counterpart identification. This galaxy, MACS0717_Az9, is at z > 4 and the strong lensing model (μ=7.5) allows us to calculate an intrinsic IR luminosity of 9.7 × 1010 Le and an obscured star formation rate of 14.6 ± 4.5 Me yr−1. The unobscured star formation rate from the UV is only 4.1 ± 0.3 Me yr−1, which …

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An Extended Dust Disk In A Spiral Galaxy : An Occulting Galaxy Pair In The Acs Nearby Galaxy Survey Treasury., Benne W. Holwerda, W. C. Keel, B. Williams, J. J. Dalcanton, R. S. De Jong Mar 2017

An Extended Dust Disk In A Spiral Galaxy : An Occulting Galaxy Pair In The Acs Nearby Galaxy Survey Treasury., Benne W. Holwerda, W. C. Keel, B. Williams, J. J. Dalcanton, R. S. De Jong

Benne Holwerda

We present an analysis of an occulting galaxy pair, serendipitously discovered in the ACS Nearby Galaxy Survey Treasury observations of NGC 253 taken with the Hubble Space Telescope’s (HST) Advanced Camera for Surveys in F475W, F606W, and F814W (SDSS − g, broad V, and I). The foreground disk system (at z 0.06) shows a dusty disk much more extended than the starlight, with spiral lanes seen in extinction out to 1.5 R25, approximately 6 half-light radii. This pair is the first where extinction can be mapped reliably out to this distance from the center. The spiral arms of the extended …

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Galaxy Zoo : A Catalog Of Overlapping Galaxy Pairs For Dust Studies., William C. Keel, Anna M. Manning, Benne W. Holwerda, Massimo Mezzoprete, Chris J. Lintott, Kevin Schawinski, Pamela Gay, Karen L. Masters Mar 2017

Galaxy Zoo : A Catalog Of Overlapping Galaxy Pairs For Dust Studies., William C. Keel, Anna M. Manning, Benne W. Holwerda, Massimo Mezzoprete, Chris J. Lintott, Kevin Schawinski, Pamela Gay, Karen L. Masters

Benne Holwerda

Analysis of galaxies with overlapping images offers a direct way to probe the distribution of dust extinction and its effects on the background light. We present a catalog of 1990 such galaxy pairs selected from the Sloan Digital Sky Survey (SDSS) by volunteers of the Galaxy Zoo project. We highlight subsamples which are particularly useful for retrieving such properties of the dust distribution as UV extinction, the extent perpendicular to the disk plane, and extinction in the inner parts of disks. The sample spans wide ranges of morphology and surface brightness, opening up the possibility of using this technique to …

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The Extinction Properties Of And Distance To The Highly Reddened Type Ia Supernova Sn 2012cu, Xiaosheng Huang, Z. Raha, G. Aldering, P. Antilogus, S. Bailey, C. Baltay, K. Barbary, D. Baugh, K. Boone, S. Bongard, C. Buton, J. Chen, N. Chotard, Y. Copin, P. Fagrelius, H. K. Fakhouri, U. Feindt, D. Fouchez, E. Gangler, B. Hayden, W. Hillebrandt, A. G. Kim, M. Kowalski, P. F. Leget, S. Lombardo, J. Nordin, R. Pain, E. Pecontal, R. Pereira, S. Perlmutter, D. Rabinowitz, M. Rigault, D. Rubin, K. Runge, C. Saunders, G. Smadja, C. Sofiatti, A. Stocker, N. Suzuki, S. Taubenberger, C. Tao, R. C. Thomas Feb 2017

The Extinction Properties Of And Distance To The Highly Reddened Type Ia Supernova Sn 2012cu, Xiaosheng Huang, Z. Raha, G. Aldering, P. Antilogus, S. Bailey, C. Baltay, K. Barbary, D. Baugh, K. Boone, S. Bongard, C. Buton, J. Chen, N. Chotard, Y. Copin, P. Fagrelius, H. K. Fakhouri, U. Feindt, D. Fouchez, E. Gangler, B. Hayden, W. Hillebrandt, A. G. Kim, M. Kowalski, P. F. Leget, S. Lombardo, J. Nordin, R. Pain, E. Pecontal, R. Pereira, S. Perlmutter, D. Rabinowitz, M. Rigault, D. Rubin, K. Runge, C. Saunders, G. Smadja, C. Sofiatti, A. Stocker, N. Suzuki, S. Taubenberger, C. Tao, R. C. Thomas

Physics and Astronomy

Correcting Type Ia Supernova brightnesses for extinction by dust has proven to be a vexing problem. Here we study the dust foreground to the highly reddened SN 2012cu, which is projected onto a dust lane in the galaxy NGC 4772. The analysis is based on multi-epoch, spectrophotometric observations spanning from 3300–9200 Å, obtained by the Nearby Supernova Factory. Phase-matched comparison of the spectroscopically twinned SN 2012cu and SN 2011fe across 10 epochs results in the best-fit color excess of (, RMS) = (1.00, 0.03) and total-to-selective extinction ratio of (R V , RMS) = (2.95, 0.08) toward SN 2012cu …

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Sn Ia Host Galaxy Properties And The Dust Extinction Distribution., Benne W. Holwerda, A. Reynolds, M. Smith, R. C. Kraan-Korteweg Feb 2017

Sn Ia Host Galaxy Properties And The Dust Extinction Distribution., Benne W. Holwerda, A. Reynolds, M. Smith, R. C. Kraan-Korteweg

Benne Holwerda

Type Ia supernovae (SNeIa) display a complex relation with their host galaxies. An important prior to the fit of the supernovae's light curve is the distribution of host galaxy extinction values that can be encountered. The Sloan Digital Sky Survey SuperNova survey project has published light-curve fits using both mlcs2k2 and salt2. We use the former fits extinction parameter (AV) to map this distribution of extinction values. We explore the dependence of this distribution on four observables; the inclination of the host galaxy disc, radial position of the supernova, redshift of the supernova and host, and the level of star …

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Origin Of The Diffuse, Far Ultraviolet Emission In The Interarm Regions Of M101., Alison F. Crocker, Rupali Chandar, Daniela Calzetti, Benne W. Holwerda, Claus Leitherer, Cristina C. Popescu, R. J. Tuffs Feb 2017

Origin Of The Diffuse, Far Ultraviolet Emission In The Interarm Regions Of M101., Alison F. Crocker, Rupali Chandar, Daniela Calzetti, Benne W. Holwerda, Claus Leitherer, Cristina C. Popescu, R. J. Tuffs

Benne Holwerda

We present images from the Solar Blind Channel on the Hubble Space Telescope that resolve hundreds of farultraviolet (FUV) emitting stars in two ∼1 kpc2 interarm regions of the grand-design spiral M101. The luminosity functions of these stars are compared with predicted distributions from simple star formation histories, and are best reproduced when the star formation rate has recently declined (past 10–50 Myr). This pattern is consistent with stars forming within spiral arms and then streaming into the interarm regions. We measure the diffuse FUV surface brightness after subtracting all of the detected stars, clusters, and background galaxies. A residual …

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Galaxy And Mass Assembly (Gama) Blended Spectra Catalogue : Strong Galaxy–Galaxy Lens And Occulting Galaxy Pair Candidates., Benne W. Holwerda, I. K. Baldry, M. Alpaslan, A. E. Bauer, J. Bland-Hawthorn, S. Brough, M. J. I. Brown, M. E. Cluver, C. J. Conselice, S. P. Driver, A. M. Hopkins, D. H. Jones, Angel R. Lopez-Sanchez, J. Loveday, M. J. Meyer, A. Moffett Feb 2017

Galaxy And Mass Assembly (Gama) Blended Spectra Catalogue : Strong Galaxy–Galaxy Lens And Occulting Galaxy Pair Candidates., Benne W. Holwerda, I. K. Baldry, M. Alpaslan, A. E. Bauer, J. Bland-Hawthorn, S. Brough, M. J. I. Brown, M. E. Cluver, C. J. Conselice, S. P. Driver, A. M. Hopkins, D. H. Jones, Angel R. Lopez-Sanchez, J. Loveday, M. J. Meyer, A. Moffett

Benne Holwerda

We present the catalogue of blended galaxy spectra from the Galaxy And Mass Assembly (GAMA) survey. These are cases where light from two galaxies are significantly detected in a single GAMA fibre. Galaxy pairs identified from their blended spectrum fall into two principal classes: they are either strong lenses, a passive galaxy lensing an emission-line galaxy; or occulting galaxies, serendipitous overlaps of two galaxies, of any type. Blended spectra can thus be used to reliably identify strong lenses for follow-up observations (high-resolution imaging) and occulting pairs, especially those that are a late-type partly obscuring an early-type galaxy which are of …

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The Dependence Of The Av Prior For Sn Ia On Host Mass And Disc Inclination., Benne W. Holwerda, W. C. Keel, M. A. Kenworthy, K. J. Mack Feb 2017

The Dependence Of The Av Prior For Sn Ia On Host Mass And Disc Inclination., Benne W. Holwerda, W. C. Keel, M. A. Kenworthy, K. J. Mack

Benne Holwerda

Type Ia supernovae (SNe Ia) are used as ‘standard candles’ for cosmological distance scales. To fit their light-curve shape–absolute luminosity relation, one needs to assume an intrinsic colour and a likelihood of host galaxy extinction or a convolution of these, a colour distribution prior. The host galaxy extinction prior is typically assumed to be an exponential drop-off for the current supernova programmes ( P(AV)∝e−AV/τ0" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; font-variant: inherit; font-stretch: inherit; line-height: normal; font-family: inherit; vertical-align: baseline; display: inline-table; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: …

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Structure And Physical Conditions In The Huygens Region Of The Orion Nebula, C. R. O'Dell, Gary J. Ferland, M. Peimbert Oct 2016

Structure And Physical Conditions In The Huygens Region Of The Orion Nebula, C. R. O'Dell, Gary J. Ferland, M. Peimbert

Physics and Astronomy Faculty Publications

Hubble Space Telescope images, MUSE maps of emission lines, and an atlas of high velocity resolution emission-line spectra have been used to establish for the first time correlations of the electron temperature, electron density, radial velocity, turbulence, and orientation within the main ionization front of the nebula. From the study of the combined properties of multiple features, it is established that variations in the radial velocity are primarily caused by the photoevaporating ionization front being viewed at different angles. There is a progressive increase of the electron temperature and density with decreasing distance from the dominant ionizing star θ1 …

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The Spectral Variability Of Astronomical Pahs, Matthew Shannon Aug 2016

The Spectral Variability Of Astronomical Pahs, Matthew Shannon

Electronic Thesis and Dissertation Repository

Polycyclic aromatic hydrocarbons (PAHs) are highly abundant molecules found throughout the universe. Illuminated by ultraviolet photons, they can emit up to 10% of the total power output of star-forming galaxies and are involved in many important physical and chemical processes (e.g., gas heating). They produce prominent emission bands between 3-20 μm which vary strongly in intensity and spectral profile. The origins of these variations are not fully understood, which limits the use of PAHs as (ubiquitous) diagnostic tracers of physical conditions. To characterize their variability, we studied the relative intensities and profiles of the 10-20 μm PAH bands in a …

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Peering Through The Dust: Nustar Observations Of Two First-2mass Red Quasars, Stephanie M. Lamassa, Angelo Ricarte, Eilat Glikman, C. Megan Urry, Daniel Stern, Tahir Yaqoob, George B. Lansbury, Francesca Civano Mar 2016

Peering Through The Dust: Nustar Observations Of Two First-2mass Red Quasars, Stephanie M. Lamassa, Angelo Ricarte, Eilat Glikman, C. Megan Urry, Daniel Stern, Tahir Yaqoob, George B. Lansbury, Francesca Civano

Dartmouth Scholarship

Some reddened quasars appear to be transitional objects in the merger-induced black hole growth/galaxy evolution paradigm, where a heavily obscured nucleus starts to be unveiled by powerful quasar winds evacuating the surrounding cocoon of dust and gas. Hard X-ray observations are able to peer through this gas and dust, revealing the properties of circumnuclear obscuration. Here, we present NuSTAR and XMM-Newton/Chandra observations of FIRST-2MASS selected red quasars F2M 0830+3759 and F2M 1227+3214. We find that though F2M 0830+3759 is moderately obscured (NH,Z=2.1±0.2×1022 cm−2) and F2M 1227+3214 is mildly absorbed (NH,Z=3.4+0.8−0.7×1021 cm−2 …

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Herschel Dust Emission As A Probe Of Starless Cores Mass: Mcld 123.5+24.9 Of The Polaris Flare, Gururaj Anil Wagle, Thomas H. Troland, Gary J. Ferland, Nicholas P. Abel Aug 2015

Herschel Dust Emission As A Probe Of Starless Cores Mass: Mcld 123.5+24.9 Of The Polaris Flare, Gururaj Anil Wagle, Thomas H. Troland, Gary J. Ferland, Nicholas P. Abel

Physics and Astronomy Faculty Publications

We present newly processed archival Herschel images of molecular cloud MCLD 123.5+24.9 in the Polaris Flare. This cloud contains five starless cores. Using the spectral synthesis code Cloudy, we explore uncertainties in the derivation of column densities, and hence masses of molecular cores from Herschel data. We first consider several detailed grain models that predict far-infrared grain opacities. Opacities predicted by the models differ by more than a factor of two, leading to uncertainties in derived column densities by the same factor. Then we consider uncertainties associated with the modified blackbody fitting process used by observers to estimate column densities. …

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The Dependence Of The Av Prior For Sn Ia On Host Mass And Disc Inclination., Benne W. Holwerda, W. C. Keel, M. A. Kenworthy, K. J. Mack Aug 2015

The Dependence Of The Av Prior For Sn Ia On Host Mass And Disc Inclination., Benne W. Holwerda, W. C. Keel, M. A. Kenworthy, K. J. Mack

Faculty Scholarship

Type Ia supernovae (SNe Ia) are used as ‘standard candles’ for cosmological distance scales. To fit their light-curve shape–absolute luminosity relation, one needs to assume an intrinsic colour and a likelihood of host galaxy extinction or a convolution of these, a colour distribution prior. The host galaxy extinction prior is typically assumed to be an exponential drop-off for the current supernova programmes ( P(AV)∝e−AV/τ0" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; font-variant: inherit; font-stretch: inherit; line-height: normal; font-family: inherit; vertical-align: baseline; display: inline-table; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: …

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Observational Properties Of Simulated Galaxies In Overdense And Average Regions At Redshifts Z ≃ 6–12, Hidenobu Yajima, Isaac Shlosman, Emilio Romano-Díaz, Kentaro Nagamine Jul 2015

Observational Properties Of Simulated Galaxies In Overdense And Average Regions At Redshifts Z ≃ 6–12, Hidenobu Yajima, Isaac Shlosman, Emilio Romano-Díaz, Kentaro Nagamine

Physics and Astronomy Faculty Publications

We use high-resolution zoom-in cosmological simulations of galaxies of Romano-Díaz et al., post-processing them with a panchromatic three-dimensional radiation transfer code to obtain the galaxy UV luminosity function (LF) at z ≃ 6–12. The galaxies are followed in a rare, heavily overdense region within a ∼5σ density peak, which can host high-z quasars, and in an average density region, down to the stellar mass of Mstar ∼ 4 × 107 M⊙. We find that the overdense regions evolve at a substantially accelerated pace – the most massive galaxy has grown to Mstar ∼ 8.4 …

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Origin Of The Diffuse, Far Ultraviolet Emission In The Interarm Regions Of M101., Alison F. Crocker, Rupali Chandar, Daniela Calzetti, Benne W. Holwerda, Claus Leitherer, Cristina C. Popescu, R. J. Tuffs Jul 2015

Origin Of The Diffuse, Far Ultraviolet Emission In The Interarm Regions Of M101., Alison F. Crocker, Rupali Chandar, Daniela Calzetti, Benne W. Holwerda, Claus Leitherer, Cristina C. Popescu, R. J. Tuffs

Faculty Scholarship

We present images from the Solar Blind Channel on the Hubble Space Telescope that resolve hundreds of farultraviolet (FUV) emitting stars in two ∼1 kpc2 interarm regions of the grand-design spiral M101. The luminosity functions of these stars are compared with predicted distributions from simple star formation histories, and are best reproduced when the star formation rate has recently declined (past 10–50 Myr). This pattern is consistent with stars forming within spiral arms and then streaming into the interarm regions. We measure the diffuse FUV surface brightness after subtracting all of the detected stars, clusters, and background galaxies. A residual …

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Galaxy And Mass Assembly (Gama) Blended Spectra Catalogue : Strong Galaxy–Galaxy Lens And Occulting Galaxy Pair Candidates., Benne W. Holwerda, I. K. Baldry, M. Alpaslan, A. E. Bauer, J. Bland-Hawthorn, S. Brough, M. J. I. Brown, M. E. Cluver, C. J. Conselice, S. P. Driver, A. M. Hopkins, D. H. Jones, Angel R. Lopez-Sanchez, J. Loveday, M. J. Meyer, A. Moffett Jun 2015

Galaxy And Mass Assembly (Gama) Blended Spectra Catalogue : Strong Galaxy–Galaxy Lens And Occulting Galaxy Pair Candidates., Benne W. Holwerda, I. K. Baldry, M. Alpaslan, A. E. Bauer, J. Bland-Hawthorn, S. Brough, M. J. I. Brown, M. E. Cluver, C. J. Conselice, S. P. Driver, A. M. Hopkins, D. H. Jones, Angel R. Lopez-Sanchez, J. Loveday, M. J. Meyer, A. Moffett

Faculty Scholarship

We present the catalogue of blended galaxy spectra from the Galaxy And Mass Assembly (GAMA) survey. These are cases where light from two galaxies are significantly detected in a single GAMA fibre. Galaxy pairs identified from their blended spectrum fall into two principal classes: they are either strong lenses, a passive galaxy lensing an emission-line galaxy; or occulting galaxies, serendipitous overlaps of two galaxies, of any type. Blended spectra can thus be used to reliably identify strong lenses for follow-up observations (high-resolution imaging) and occulting pairs, especially those that are a late-type partly obscuring an early-type galaxy which are of …

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The Dust Geometric Distribution In Seyfert 1 And Seyfert 2 Galaxies, Isolated And In Interaction, S. Mendoza-Castrejón, D. Dultzin, Y. Krongold, J. J. González, Moshe Elitzur Mar 2015

The Dust Geometric Distribution In Seyfert 1 And Seyfert 2 Galaxies, Isolated And In Interaction, S. Mendoza-Castrejón, D. Dultzin, Y. Krongold, J. J. González, Moshe Elitzur

Physics and Astronomy Faculty Publications

We analyse the mid-infrared (MIR) spectra of 39 Seyfert galaxies observed with the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope. Our sample consists of 19 Seyfert type 1 (Sy1) galaxies, three intermediate Seyfert galaxies and 17 type 2 Seyfert (Sy2) galaxies in the nearby Universe. This sample was extracted from a larger sample, the circumgalactic environment of which was studied in a previous work by Dultzin-Hacyan et al., who found that Sy2 objects are in interaction more frequently than normal galaxies, while Sy1s are not. In this article, we study the silicate dust distribution that dominates the …

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Sn Ia Host Galaxy Properties And The Dust Extinction Distribution., Benne W. Holwerda, A. Reynolds, M. Smith, R. C. Kraan-Korteweg Feb 2015

Sn Ia Host Galaxy Properties And The Dust Extinction Distribution., Benne W. Holwerda, A. Reynolds, M. Smith, R. C. Kraan-Korteweg

Faculty Scholarship

Type Ia supernovae (SNeIa) display a complex relation with their host galaxies. An important prior to the fit of the supernovae's light curve is the distribution of host galaxy extinction values that can be encountered. The Sloan Digital Sky Survey SuperNova survey project has published light-curve fits using both mlcs2k2 and salt2. We use the former fits extinction parameter (AV) to map this distribution of extinction values. We explore the dependence of this distribution on four observables; the inclination of the host galaxy disc, radial position of the supernova, redshift of the supernova and host, and the level …

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Sic Particles From Asymptotic Giant Branch Stars: Mg Burning And The S-Process, Lawrence E. Brown, Donald D. Clayton Aug 2014

Sic Particles From Asymptotic Giant Branch Stars: Mg Burning And The S-Process, Lawrence E. Brown, Donald D. Clayton

Donald D Clayton

The question of whether isotopically anomalous SiC particles found in meteorites originate in AGB stars is addressed. It is shown that if the peak helium shell flash temperatures of massive (6-9 solar masses) stars are about 10 percent larger than they are normally assumed to be, alpha particle reactions with the magnesium will become significant. Then the (Mg-29)(alpha, n)Si-29 reaction produces a large excess of Si-29. With a light element nuclear reaction network, the evolution of the silicon isotopic composition during AGB evolution is calculated. It is found that the experimentally determined correlation between excess Si-29 and excess Si-30 in …

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