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Astronomy: Faculty Publications

Articles 61 - 90 of 119

Full-Text Articles in Physical Sciences and Mathematics

Detection Of A Substantial Molecular Gas Reservoir In A Brightest Cluster Galaxy At Z = 1.7, Tracy M.A. Webb, James Lowenthal, Min Yun, Allison G. Nobel, Adam Muzzin, Gillian Wilson, H.K.C. Yee, Ryan Cybulski, D. H. Hughes Aug 2017

Detection Of A Substantial Molecular Gas Reservoir In A Brightest Cluster Galaxy At Z = 1.7, Tracy M.A. Webb, James Lowenthal, Min Yun, Allison G. Nobel, Adam Muzzin, Gillian Wilson, H.K.C. Yee, Ryan Cybulski, D. H. Hughes

Astronomy: Faculty Publications

We report the detection of CO(2–1) emission coincident with the brightest cluster galaxy (BCG) of the high- redshift galaxy cluster SpARCS1049+56, with the Redshift Search Receiver (RSR) on the Large Millimeter Telescope (LMT). We confirm a spectroscopic redshift for the gas of z = 1.7091 ± 0.0004, which is consistent with the systemic redshift of the cluster galaxies of z = 1.709. The line is well fit by a single-component Gaussian with an RSR-resolution-corrected FWHM of 569 ± 63kms−1. We see no evidence for multiple velocity components in the gas, as might be expected from the multiple image components seen …

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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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Tracing Slow Winds From T Tauri Stars Via Low-Velocity Forbidden Line Emission, M. N. Simon, I. Pascucci, Suzan Edwards, W. Feng, U. Gorti, D. Hollenbach, E. Rigliaco, J. T. Keane Nov 2016

Tracing Slow Winds From T Tauri Stars Via Low-Velocity Forbidden Line Emission, M. N. Simon, I. Pascucci, Suzan Edwards, W. Feng, U. Gorti, D. Hollenbach, E. Rigliaco, J. T. Keane

Astronomy: Faculty Publications

Using Keck/HIRES spectra (Δ v ∼ 7 km s−1) we analyze forbidden lines of [O I] 6300 Å, [O I] 5577 Å and [S II] 6731 Å from 33 T Tauri stars covering a range of disk evolutionary stages. After removing a high-velocity component (HVC) associated with microjets, we study the properties of the low-velocity component (LVC). The LVC can be attributed to slow disk winds that could be magnetically (magnetohydrodynamic) or thermally (photoevaporative) driven. Both of these winds play an important role in the evolution and dispersal of protoplanetary material. LVC emission is seen in all 30 stars with …

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Narrow Na And K Absorption Lines Toward T Tauri Stars: Tracing The Atomic Envelope Of Molecular Clouds, I. Pascucci, Suzan Edwards, M Heyer, E. Rigliaco, L. Hillenbrand, U. Gorti, D. Hollenbach, M. N. Simon Nov 2015

Narrow Na And K Absorption Lines Toward T Tauri Stars: Tracing The Atomic Envelope Of Molecular Clouds, I. Pascucci, Suzan Edwards, M Heyer, E. Rigliaco, L. Hillenbrand, U. Gorti, D. Hollenbach, M. N. Simon

Astronomy: Faculty Publications

We present a detailed analysis of narrow Na I and K I absorption resonance lines toward nearly 40 T Tauri stars in Taurus with the goal of clarifying their origin. The Na I λ5889.95 line is detected toward all but one source, while the weaker K I λ7698.96 line is detected in about two-thirds of the sample. The similarity in their peak centroids and the significant positive correlation between their equivalent widths demonstrate that these transitions trace the same atomic gas. The absorption lines are present toward both disk and diskless young stellar objects, which excludes cold gas within the …

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Probing Stellar Accretion With Mid-Infrared Hydrogen Lines, Elisabetta Rigliaco, Ilaria Pascucci, Gaspard Duchene, Suzan Edwards, D. R. Ardila, C. Grady, Ignacio Mendigutía, Benjamín Montesinos, Gijs D. Mulders, Joan R. Najita, J. Carpenter, Elise Furlan, Uma Gorti, Rowin Meijerink, M. R. Meyer Feb 2015

Probing Stellar Accretion With Mid-Infrared Hydrogen Lines, Elisabetta Rigliaco, Ilaria Pascucci, Gaspard Duchene, Suzan Edwards, D. R. Ardila, C. Grady, Ignacio Mendigutía, Benjamín Montesinos, Gijs D. Mulders, Joan R. Najita, J. Carpenter, Elise Furlan, Uma Gorti, Rowin Meijerink, M. R. Meyer

Astronomy: Faculty Publications

In this paper we investigate the origin of the mid-infrared (IR) hydrogen recombination lines for a sample of 114 disks in different evolutionary stages (full, transitional, and debris disks) collected from the Spitzer archive. We focus on the two brighter H I lines observed in the Spitzer spectra, the H I (7-6) at 12.37 μm and the H I (9-7) at 11.32 μm. We detect the H I (7-6) line in 46 objects, and the H I (9-7) in 11. We compare these lines with the other most common gas line detected in Spitzer spectra, the [Ne II] at 12.81 …

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Interpreting Near Infrared Hydrogen Line Ratios In T Tauri Stars, Suzan Edwards Dec 2013

Interpreting Near Infrared Hydrogen Line Ratios In T Tauri Stars, Suzan Edwards

Astronomy: Faculty Publications

In accreting young stars, one of the prominent spectral features in the near-infrared is the Paschen and Brackett series in emission. We examine hydrogen line ratios for 16 classical T Tauri stars from SpeX spectra and assess the trends with veiling and accretion. The observed line ratios are compared with two theoretical models for line formation: (1) Baker & Menzel’s Case B for radiative ionization and recombination and (2) a set of local line excitation calculations designed to replicate the conditions in T Tauri winds and magnetic accretion columns (KF). While the comparison between Case B and observed line ratios …

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Understanding The Origin Of The [Oi] Low-Velocity Component From T Tauri Stars, Elisabetta Rigliaco, Ilaria Pascucci, Uma Gorti, Suzan Edwards, D. Hollenbach Jul 2013

Understanding The Origin Of The [Oi] Low-Velocity Component From T Tauri Stars, Elisabetta Rigliaco, Ilaria Pascucci, Uma Gorti, Suzan Edwards, D. Hollenbach

Astronomy: Faculty Publications

The formation time, masses, and location of planets are strongly impacted by the physical mechanisms that disperse protoplanetary disks and the timescale over which protoplanetary material is cleared out. Accretion of matter onto the central star, protostellar winds/jets, magnetic disk winds, and photoevaporative winds operate concurrently. Hence, disentangling their relative contribution to disk dispersal requires identifying diagnostics that trace different star–disk environments. Here, we analyze the low-velocity component (LVC) of the oxygen optical forbidden lines, which is found to be blueshifted by a few km s−1 with respect to the stellar velocity. We find that the [O i] LVC …

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Hot Gas Lines In T Tauri Stars, David R. Ardila, Gregory J. Herczeg, Scott G. Gregory, Laura Ingleby, Kevin France, Alexander Brown, Suzan Edwards, Christopher Johns-Krull, Jeffrey L. Linsky, Hao Yang, Jeff A. Valenti, Hervé Abgrall, Richard D. Alexander, Edwin Bergin, Thomas Bethell, Joanna M. Brown, Nuria Calvet, Catherine Espaillat, Lynne A. Hillenbrand, Gaitee Hussain, Evelyne Roueff, Eric R. Schindhelm, Frederick M. Walter Jul 2013

Hot Gas Lines In T Tauri Stars, David R. Ardila, Gregory J. Herczeg, Scott G. Gregory, Laura Ingleby, Kevin France, Alexander Brown, Suzan Edwards, Christopher Johns-Krull, Jeffrey L. Linsky, Hao Yang, Jeff A. Valenti, Hervé Abgrall, Richard D. Alexander, Edwin Bergin, Thomas Bethell, Joanna M. Brown, Nuria Calvet, Catherine Espaillat, Lynne A. Hillenbrand, Gaitee Hussain, Evelyne Roueff, Eric R. Schindhelm, Frederick M. Walter

Astronomy: Faculty Publications

For Classical T Tauri Stars (CTTSs), the resonance doublets of N v, Si iv, and Civ, as well as the He ii 1640 Å line, trace hot gas flows and act as diagnostics of the accretion process. In this paper we assemble a large high-resolution, high-sensitivity data set of these lines in CTTSs and Weak T Tauri Stars (WTTSs). The sample comprises 35 stars: 1 Herbig Ae star, 28 CTTSs, and 6 WTTSs. We find that the Civ, Si iv, and N v lines in CTTSs all have similar shapes. We decompose the Civ and He ii lines into broad …

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The Source Counts Of Submillimetre Galaxies Detected At Λ= 1.1 Mm, K. S. Scott, G. W. Wilson, I. Aretxaga, J. E. Austermann, E. L. Chapin, J. S. Dunlop, H. Ezawa, M. Halpern, B. Hatsukade, D. H. Hughes, R. Kawabe, S. Kim, K. Kohno, James D. Lowenthal, A. Montaña, K. Nakanishi, T. Oshima, D. Sanders, D. Scott, N. Scoville, Y. Tamura, D. Welch, M. S. Yun, M. Zeballos Jun 2012

The Source Counts Of Submillimetre Galaxies Detected At Λ= 1.1 Mm, K. S. Scott, G. W. Wilson, I. Aretxaga, J. E. Austermann, E. L. Chapin, J. S. Dunlop, H. Ezawa, M. Halpern, B. Hatsukade, D. H. Hughes, R. Kawabe, S. Kim, K. Kohno, James D. Lowenthal, A. Montaña, K. Nakanishi, T. Oshima, D. Sanders, D. Scott, N. Scoville, Y. Tamura, D. Welch, M. S. Yun, M. Zeballos

Astronomy: Faculty Publications

The source counts of galaxies discovered at submillimetre and millimetre wavelengths provide important information on the evolution of infrared-bright galaxies. We combine the data from six blank-field surveys carried out at 1.1mm with AzTEC, totalling 1.6deg in area with root-mean-square depths ranging from 0.4 to 1.7mJy, and derive the strongest constraints to date on the 1.1 mm source counts at flux densities S = 1-12mJy. Using additional data from the AzTEC Cluster Environment Survey to extend the counts to S ∼ 20mJy, we see tentative evidence for an enhancement relative to the exponential drop in the counts at S ∼ …

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Deep 1.1mm-Wavelength Imaging Of The Goods-S Field By Aztec/Aste - Ii. Redshift Distribution And Nature Of The Submillimetre Galaxy Population, Min S. Yun, K. S. Scott, Yicheng Guo, I. Aretxaga, M. Giavalisco, J. E. Austermann, P. Capak, Yuxi Chen, H. Ezawa, B. Hatsukade, D. H. Hughes, D. Iono, S. Johnson, R. Kawabe, K. Kohno, James D. Lowenthal, N. Miller, G. Morrison, T. Oshima, T. A. Perera, M. Salvato, J. Silverman, Y. Tamura, C. C. Williams, G. W. Wilson Feb 2012

Deep 1.1mm-Wavelength Imaging Of The Goods-S Field By Aztec/Aste - Ii. Redshift Distribution And Nature Of The Submillimetre Galaxy Population, Min S. Yun, K. S. Scott, Yicheng Guo, I. Aretxaga, M. Giavalisco, J. E. Austermann, P. Capak, Yuxi Chen, H. Ezawa, B. Hatsukade, D. H. Hughes, D. Iono, S. Johnson, R. Kawabe, K. Kohno, James D. Lowenthal, N. Miller, G. Morrison, T. Oshima, T. A. Perera, M. Salvato, J. Silverman, Y. Tamura, C. C. Williams, G. W. Wilson

Astronomy: Faculty Publications

We report the results of the counterpart identification and a detailed analysis of the physical properties of the 48 sources discovered in our deep 1.1-mm wavelength imaging survey of the Great Observatories Origins Deep Survey-South (GOODS-S) field using the AzTEC instrument on the Atacama Submillimeter Telescope Experiment. One or more robust or tentative counterpart candidate is found for 27 and 14 AzTEC sources, respectively, by employing deep radio continuum, Spitzer/Multiband Imaging Photometer for Spitzer and Infrared Array Camera, and Large APEX Bolometer Camera 870μm data. Five of the sources (10 per cent) have two robust counterparts each, supporting the idea …

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The Vlt Lbg Redshift Survey I: Clustering And Dynamics Of ≈ 1000 Galaxies At Z ≈ 3⋆, R. M. Bielby, T. Shanks, P. M. Weilbacher, L. Infante, N. H.M. Crighton, C. Bornancini, N. Bouché, P. Héraudeau, D. G. Lambas, James D. Lowenthal, D. Minniti, N. Padilla, P. Petitjean, T. Theuns Jun 2011

The Vlt Lbg Redshift Survey I: Clustering And Dynamics Of ≈ 1000 Galaxies At Z ≈ 3⋆, R. M. Bielby, T. Shanks, P. M. Weilbacher, L. Infante, N. H.M. Crighton, C. Bornancini, N. Bouché, P. Héraudeau, D. G. Lambas, James D. Lowenthal, D. Minniti, N. Padilla, P. Petitjean, T. Theuns

Astronomy: Faculty Publications

We present the initial imaging and spectroscopic data acquired as part of the Very Large Telescope (VLT) VIMOS Lyman-break galaxy Survey. UBR (or UBVI) imaging covers five ≈36 × 36 arcmin fields centred on bright z > 3 quasi-stellar objects (QSOs), allowing ≈210002 < z < 3.5 galaxy candidates to be selected using the Lyman-break technique. We performed spectroscopic follow-up using VLT VIMOS, measuring redshifts for 1020 z > 2 Lyman-break galaxies and 10 z > 2 QSOs from a total of 19 VIMOS pointings. From the galaxy spectra, we observe a 625 ± 510kms velocity offset between the interstellar absorption and Lyman α emission-line redshifts, consistent with previous results. Using the photometric and spectroscopic catalogues, we have analysed the galaxy clustering at z≈ 3. The angular correlation …

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Characterizing The Iyj Excess Continuum Emission In T Tauri Stars, William J. Fischer, Suzan Edwards, Lynne A. Hillenbrand, John Kwan Apr 2011

Characterizing The Iyj Excess Continuum Emission In T Tauri Stars, William J. Fischer, Suzan Edwards, Lynne A. Hillenbrand, John Kwan

Astronomy: Faculty Publications

We present the first characterization of the excess continuum emission of accreting T Tauri stars between optical and near-infrared wavelengths. With nearly simultaneous spectra from 0.48 to 2.4μm acquired with HIRES and NIRSPEC on Keck and SpeX on the Infrared Telescope Facility, we find significant excess continuum emission throughout this region, including the I, Y, and J bands, which are usually thought to diagnose primarily photospheric emission. The IYJ excess correlates with the excess in the V band, attributed to accretion shocks in the photosphere, and the excess in the K band, attributed to dust in the inner …

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The Vlt Lbg Redshift Survey- Ii. Interactions Between Galaxies And The Igm At Z ~ 3, N. H.M. Crighton, R. Bielby, T. Shanks, L. Infante, C. G. Bornancini, N. Bouché, D. G. Lambas, James D. Lowenthal, D. Minniti, S. L. Morris, N. Padilla, C. Péroux, P. Petitjean, T. Theuns, P. Tummuangpak, P. M. Weilbacher, L. Wisotzki, G. Worseck Jan 2011

The Vlt Lbg Redshift Survey- Ii. Interactions Between Galaxies And The Igm At Z ~ 3, N. H.M. Crighton, R. Bielby, T. Shanks, L. Infante, C. G. Bornancini, N. Bouché, D. G. Lambas, James D. Lowenthal, D. Minniti, S. L. Morris, N. Padilla, C. Péroux, P. Petitjean, T. Theuns, P. Tummuangpak, P. M. Weilbacher, L. Wisotzki, G. Worseck

Astronomy: Faculty Publications

We have measured redshifts for 243 z≈ 3 quasars in nine Very Large Telescope (VLT) Visible Imaging and Multi-Object Spectrograph (VIMOS) Lyman-break galaxy (LBG) redshift survey areas, each of which is centred on a known bright quasar. Using the spectra of these quasars, we measure the cross-correlation between neutral hydrogen gas causing the Lyα forest and 1020 LBGs at z≈ 3. We find an increase in neutral hydrogen absorption within ≈5h Mpc of a galaxy in agreement with the results of Adelberger et al. The Lyα-LBG cross-correlation can be described by a power law on scales larger than 3h Mpc. …

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Color-Magnitude Relation And Morphology Of Low-Redshift Ulirgs In Sloan Digital Sky Survey, Yuxi Chen, James D. Lowenthal, Min S. Yun Jan 2010

Color-Magnitude Relation And Morphology Of Low-Redshift Ulirgs In Sloan Digital Sky Survey, Yuxi Chen, James D. Lowenthal, Min S. Yun

Astronomy: Faculty Publications

We present color-magnitude and morphological analysis of 54 low-redshift ultraluminous infrared galaxies (ULIRGs; 0.018 < z < 0.265 with z = 0.151), a subset of the Infrared Astronomical Satellite 1Jy sample, in the Sloan Digital Sky Survey (SDSS). The ULIRGs are both bright and blue: they are on average 1mag brighter in than the SDSS galaxies within the same redshift range, and 0.2mag bluer in g - r. They form a group in the color-magnitude diagram distinct from both the red sequence and the blue cloud formed by the SDSS galaxies: 24 out of the 52 unsaturated objects (46%) lie outside the 90% level number density contour of the SDSS galaxies. The majority (47, or 87%) have the colors typical of the blue cloud, and only four (7%) sources are located in the red sequence. While ULIRGs are popularly thought to be precursors to a QSO phase, we find few (three, or 6%) in the "green valley" where the majority of the X-ray- and IR-selected active galactic nuclei (AGNs) are found. Moreover, none of the AGN-host ULIRGs are found in the green valley. For the 14 previously spectroscopic identified AGNs (28%), we perform point-spread function subtractions and find that on average the central point sources contribute less than one-third to the total luminosity, and that their high optical luminosities and overall blue colors are apparently the result of star formation activity of the host galaxies. Visual inspection of the SDSS images reveals a wide range of morphologies including many close pairs, tidal tails, and otherwise disturbed profiles, in strong support of previous studies and the general view of ULIRGs as major mergers of gas-rich disk galaxies. A detailed morphology analysis using Gini and M coefficients shows that slightly less than one-half (42% in g band) of the ULIRGs are located in the merger region defined by morphology studies of local galaxies, while the remaining sources are located in the region of late-type and irregular galaxies. The heterogeneous distribution of ULIRGs in the G-M space is qualitatively consistent with the results found by numerical simulations of disk-disk mergers, and our study also shows that the measured morphological parameters are systematically affected by the signal-to-noise ratio and thus the merging galaxies can appear in various regions of the G-M parameter space. We briefly discuss the origins of the uncertainties and note that the morphology measurements should be implemented with caution for low physical resolution images. In general, our results reinforce the view that ULIRGs contain young stellar populations and are mergers in progress, but we do not observe the concentration of ULIRGs/AGN in the green valley as found by other studies. Our study provides a uniform comparison sample for studying dusty starbursts at higher redshifts such as Spitzer MIPS 24 μm-selected ULIRGs at z = 1-2 or submillimeter galaxies.

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Aztec Half Square Degree Survey Of The Shades Fields - I. Maps, Catalogues And Source Counts, J. E. Austermann, J. S. Dunlop, T. A. Perera, K. S. Scott, G. W. Wilson, I. Aretxaga, D. H. Hughes, O. Almaini, E. L. Chapin, S. C. Chapman, M. Cirasuolo, D. L. Clements, K. E.K. Coppin, L. Dunne, S. Dye, S. A. Eales, E. Egami, D. Farrah, D. Ferrusca, S. Flynn, D. Haig, M. Halpern, E. Ibar, R. J. Ivison, E. Van Kampen, Y. Kang, S. Kim, C. Lacey, James D. Lowenthal, P. D. Mauskopf, R. J. Mclure, A. M.J. Mortier Jan 2010

Aztec Half Square Degree Survey Of The Shades Fields - I. Maps, Catalogues And Source Counts, J. E. Austermann, J. S. Dunlop, T. A. Perera, K. S. Scott, G. W. Wilson, I. Aretxaga, D. H. Hughes, O. Almaini, E. L. Chapin, S. C. Chapman, M. Cirasuolo, D. L. Clements, K. E.K. Coppin, L. Dunne, S. Dye, S. A. Eales, E. Egami, D. Farrah, D. Ferrusca, S. Flynn, D. Haig, M. Halpern, E. Ibar, R. J. Ivison, E. Van Kampen, Y. Kang, S. Kim, C. Lacey, James D. Lowenthal, P. D. Mauskopf, R. J. Mclure, A. M.J. Mortier

Astronomy: Faculty Publications

We present the first results from the largest deep extragalactic mm-wavelength survey undertaken to date. These results are derived from maps covering over 0.7 deg , made at λ = 1.1 mm, using the AzTEC continuum camera mounted on the James Clerk Maxwell Telescope. The maps were made in the two fields originally targeted at λ = 850 μm with the Submillimetre Common-User Bolometer Array (SCUBA) in the SCUBA Half-Degree Extragalactic Survey (SHADES) project, namely the Lockman Hole East (mapped to a depth of 0.9-1.3 mJy rms) and the Subaru/XMM-Newton Deep Field (mapped to a depth of 1.0-1.7 mJy rms). …

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An Aztec 1.1 Mm Survey Of The Goods-N Field - Ii. Multiwavelength Identifications And Redshift Distribution, Edward L. Chapin, Alexandra Pope, Douglas Scott, Itziar Aretxaga, Jason E. Austermann, Ranga Ram Chary, Kristen Coppin, Mark Halpern, David H. Hughes, James D. Lowenthal, Glenn E. Morrison, Thushara A. Perera, Kimberly S. Scott, Grant W. Wilson, Min S. Yun Oct 2009

An Aztec 1.1 Mm Survey Of The Goods-N Field - Ii. Multiwavelength Identifications And Redshift Distribution, Edward L. Chapin, Alexandra Pope, Douglas Scott, Itziar Aretxaga, Jason E. Austermann, Ranga Ram Chary, Kristen Coppin, Mark Halpern, David H. Hughes, James D. Lowenthal, Glenn E. Morrison, Thushara A. Perera, Kimberly S. Scott, Grant W. Wilson, Min S. Yun

Astronomy: Faculty Publications

We present results from a multiwavelength study of 29 sources (false detection probabilities cent) from a survey of the Great Observatories Origins Deep Survey-North (GOODS-N) field at 1.1 mm using the Astronomical Thermal Emission Camera (AzTEC). Comparing with existing 850 μm Submillimetre Common-User Bolometer Array (SCUBA) studies in the field, we examine differences in the source populations selected at the two wavelengths. The AzTEC observations uniformly cover the entire survey field to a 1σ depth of ∼1 mJy. Searching deep 1.4 GHz Very Large Array (VLA) and Spitzer 3-24 μm catalogues, we identify robust counterparts for 21 1.1 mm sources, …

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Dynamics Of Lyman Break Galaxies And Their Host Halos, James D. Lowenthal, David C. Koo, Luc Simard, Eelco Van Kampen Sep 2009

Dynamics Of Lyman Break Galaxies And Their Host Halos, James D. Lowenthal, David C. Koo, Luc Simard, Eelco Van Kampen

Astronomy: Faculty Publications

We present deep two-dimensional spectra of 22 candidate and confirmed Lyman break galaxies (LBGs) at redshifts 2 < z < 4 in the Hubble Deep Field (HDF) obtained at the Keck II telescope. The targets were preferentially selected with spatial extent and/or multiple knot morphologies, and we used slitmasks and individual slits tilted to optimize measurement of any spatially resolved kinematics. Our sample is more than 1 mag fainter and is at higher redshift than the kinematic LBG targets previously studied by others. The median target magnitude was I814 = 25.3, and total exposure times ranged from 10 to 50 ks. We measure redshifts, some new, ranging from z = 0.2072 to z = 4.056, including two interlopers at z < 1, and resulting in a sample of 14 LBGs with a median redshift z = 2.424. The morphologies and kinematics of the close pairs and multiple knot sources in our sample are generally inconsistent with galaxy formation scenarios postulating that LBGs occur only at the bottom of the potential wells of massive host halos; rather, they support "collisional starburst" models with significant …

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Aztec Millimetre Survey Of The Cosmos Field - Ii. Source Count Overdensity And Correlations With Large-Scale Structure, J. E. Austermann, I. Aretxaga, D. H. Hughes, Y. Kang, S. Kim, James D. Lowenthal, T. A. Perera, D. B. Sanders, K. S. Scott, N. Scoville, G. W. Wilson, M. S. Yun Mar 2009

Aztec Millimetre Survey Of The Cosmos Field - Ii. Source Count Overdensity And Correlations With Large-Scale Structure, J. E. Austermann, I. Aretxaga, D. H. Hughes, Y. Kang, S. Kim, James D. Lowenthal, T. A. Perera, D. B. Sanders, K. S. Scott, N. Scoville, G. W. Wilson, M. S. Yun

Astronomy: Faculty Publications

We report an overdensity of bright submillimetre galaxies (SMGs) in the 0.15 deg AzTEC/COSMOS survey and a spatial correlation between the SMGs and the optical-IR galaxy density at z ≲ 1.1. This portion of the COSMOS field shows a ∼3σ overdensity of robust SMG detections when compared to a background, or 'blank-field', population model that is consistent with SMG surveys of fields with no extragalactic bias. The SMG overdensity is most significant in the number of very bright detections (14 sources with measured fluxes S > 6 mJy), which is entirely incompatible with sample variance within our adopted blank-field number densities …

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Winds And Accretion In Young Stars, Suzan Edwards Jan 2009

Winds And Accretion In Young Stars, Suzan Edwards

Astronomy: Faculty Publications

Establishing the origin of accretion powered winds from forming stars is critical for understanding angular momentum evolution in the star‐disk interaction region. Here, the high velocity component of accretion powered winds is launched and accreting stars are spun down, in defiance of the expected spin‐up during magnetospheric accretion. T Tauri stars in the final stage of disk accretion offer a unique opportunity to study the connection between accretion and winds and their relation to stellar spindown. Although spectroscopic indicators of high velocity T Tauri winds have been known for decades, the line of He I 10830 offers a promising new …

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The Aztec/Sma Interferometric Imaging Survey Of Submillimeter-Selected High-Redshift Galaxies, Joshua D. Younger, Giovanni G. Fazio, Jia Sheng Huang, Min S. Yun, Grant W. Wilson, Matthew L.N. Ashby, Mark A. Gurwell, Alison B. Peck, Glen R. Petitpas, David J. Wilner, David H. Hughes, Itziar Aretxaga, Sungeun Kim, Kimberly S. Scott, Jason Austermann, Thushara Perera, James D. Lowenthal Jan 2009

The Aztec/Sma Interferometric Imaging Survey Of Submillimeter-Selected High-Redshift Galaxies, Joshua D. Younger, Giovanni G. Fazio, Jia Sheng Huang, Min S. Yun, Grant W. Wilson, Matthew L.N. Ashby, Mark A. Gurwell, Alison B. Peck, Glen R. Petitpas, David J. Wilner, David H. Hughes, Itziar Aretxaga, Sungeun Kim, Kimberly S. Scott, Jason Austermann, Thushara Perera, James D. Lowenthal

Astronomy: Faculty Publications

We present results from a continuing interferometric survey of high-redshift submillimeter galaxies (SMGs) with the Submillimeter Array, including high-resolution (beam size ∼ 2 arcsec) imaging of eight additional AzTEC 1.1 mm selected sources in the COSMOS field, for which we obtain six reliable (peak signal-to-noise ratio (S/N) >5 or peak S/N >4 with multiwavelength counterparts within the beam) and two moderate significance (peak S/N >4) detections. When combined with previous detections, this yields an unbiased sample of millimeter-selected SMGs with complete interferometric follow up. With this sample in hand, we (1) empirically confirm the radio-submillimeter association, (2) examine the submillimeter …

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An Aztec 1.1 Mm Survey Of The Goods-N Field - I. Maps, Catalogue And Source Statistics, T. A. Perera, E. L. Chapin, J. E. Austermann, K. S. Scott, G. W. Wilson, M. Halpern, A. Pope, D. Scott, M. S. Yun, James D. Lowenthal, G. Morrison, I. Aretxaga, J. J. Bock, K. Coppin, M. Crowe, L. Frey, D. H. Hughes, Y. Kang, S. Kim, P. D. Mauskopf Dec 2008

An Aztec 1.1 Mm Survey Of The Goods-N Field - I. Maps, Catalogue And Source Statistics, T. A. Perera, E. L. Chapin, J. E. Austermann, K. S. Scott, G. W. Wilson, M. Halpern, A. Pope, D. Scott, M. S. Yun, James D. Lowenthal, G. Morrison, I. Aretxaga, J. J. Bock, K. Coppin, M. Crowe, L. Frey, D. H. Hughes, Y. Kang, S. Kim, P. D. Mauskopf

Astronomy: Faculty Publications

We have conducted a deep and uniform 1.1 mm survey of the Great Observatories Origins Deep Survey-North (GOODS-N) field with AzTEC on the James Clerk Maxwell Telescope. Here, we present the first results from this survey including maps, the source catalogue and 1.1 mm number counts. The results presented here were obtained from a 245 arcmin region with a near uniform coverage to a depth of 0.96-1.16 mJy beam . Our robust catalogue contains 28 source candidates detected with S/N ≥ 3.75, only ∼1- 2 of which are expected to be spurious detections. Of these source candidates, eight are also …

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Redshifted Absorption At He I Λ10830 As A Probe Of The Accretion Geometry Of T Tauri Stars, William Fischer, John Kwan, Suzan Edwards, Lynne A. Hillenbrand Nov 2008

Redshifted Absorption At He I Λ10830 As A Probe Of The Accretion Geometry Of T Tauri Stars, William Fischer, John Kwan, Suzan Edwards, Lynne A. Hillenbrand

Astronomy: Faculty Publications

We probe the geometry of magnetospheric accretion in classical T Tauri stars (CTTSs) by modeling red absorption at He I λ10830 via scattering of the stellar and veiling continua. Under the assumptions that the accretion flow is an azimuthally symmetric dipole and helium is sufficiently optically thick that all incident 1 μm radiation is scattered, we illustrate the sensitivity of He I λ10830 red absorption to both the size of the magnetosphere and the filling factor of the hot accretion shock. We compare model profiles to those observed in 21 CTTSs with subcontinuum redshifted absorption at He I λ10830 and …

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SPitzer Irac Infrared Colours Of Submillimetre-Bright Galaxies, Min S. Yun, Itziar Aretxaga, Matthew L.N. Ashby, Jason Austermann, Giovanni G. Fazio, Mauro Giavalisco, Jia Sheng Huang, David H. Hughes, Sungeun Kim, James D. Lowenthal, Thushara Perera, Kim Scott, Grant Wilson, Joshua D. Younger Sep 2008

SPitzer Irac Infrared Colours Of Submillimetre-Bright Galaxies, Min S. Yun, Itziar Aretxaga, Matthew L.N. Ashby, Jason Austermann, Giovanni G. Fazio, Mauro Giavalisco, Jia Sheng Huang, David H. Hughes, Sungeun Kim, James D. Lowenthal, Thushara Perera, Kim Scott, Grant Wilson, Joshua D. Younger

Astronomy: Faculty Publications

High-redshift submillimetre-bright galaxies identified by blank field surveys at millimetre and submillimetre wavelengths appear in the region of the Infra Red Array Camera (IRAC) colour-colour diagrams previously identified as the domain of luminous active galactic nuclei (AGNs). Our analysis using a set of empirical and theoretical dusty starburst spectral energy distribution (SED) models shows that power-law continuum sources associated with hot dust heated by young (≲100 Myr old), extreme starbursts at z > 2 also occupy the same general area as AGNs in the IRAC colour-colour plots. A detailed comparison of the IRAC colours and SEDs demonstrates that the two populations …

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Evidence For A Population Of High-Redshift Submillimeter Galaxies From Interferometric Imaging, Joshua D. Younger, Giovanni G. Fazio, Jia Sheng Huang, Min S. Yun, Grant W. Wilson, Matthew L.N. Ashby, Mark A. Gurwell, Kamson Lai, Alison B. Peck, Glen R. Petitpas, David J. Wilner, Daisuke Iono, Kotaro Kohno, Ryohei Kawabe, David H. Hughes, Itziar Aretxaga, Tracy Webb, Alejo Martínez-Sansigre, Sungeun Kim, Kimberly S. Scott, Jason Austermann, Thushara Perera, James Lowenthal, Eva Schinnerer, Vernesa Smolčić Dec 2007

Evidence For A Population Of High-Redshift Submillimeter Galaxies From Interferometric Imaging, Joshua D. Younger, Giovanni G. Fazio, Jia Sheng Huang, Min S. Yun, Grant W. Wilson, Matthew L.N. Ashby, Mark A. Gurwell, Kamson Lai, Alison B. Peck, Glen R. Petitpas, David J. Wilner, Daisuke Iono, Kotaro Kohno, Ryohei Kawabe, David H. Hughes, Itziar Aretxaga, Tracy Webb, Alejo Martínez-Sansigre, Sungeun Kim, Kimberly S. Scott, Jason Austermann, Thushara Perera, James Lowenthal, Eva Schinnerer, Vernesa Smolčić

Astronomy: Faculty Publications

We have used the Submillimeter Array to image a flux-limited sample of seven submillimeter galaxies, selected by the AzTEC camera on the JCMT at 1.1 mm, in the COSMOS field at 890 μm with ∼2″ resolution. All of the sources - two radio-bright and five radio-dim - are detected as single point sources at high significance (>6 σ), with positions accurate to ∼0.2″ that enable counterpart identification at other wavelengths observed with similarly high angular resolution. All seven have IRAC counterparts, but only two have secure counterparts in deep HST ACS imaging. As compared to the two radio-bright sources …

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Modeling T Tauri Winds From He I Λ10830 Profiles, John Kwan, Suzan Edwards, William Fischer Nov 2007

Modeling T Tauri Winds From He I Λ10830 Profiles, John Kwan, Suzan Edwards, William Fischer

Astronomy: Faculty Publications

The high opacity of He I λ10830 makes it an exceptionally sensitive probe of the inner wind geometry of accreting T Tauri stars. In this line, blueshifted absorption below the continuum results from simple scattering of stellar photons, a situation that is readily modeled without definite knowledge of the physical conditions and recourse to multilevel radiative transfer. We present theoretical line profiles for scattering in two possible wind geometries, a disk wind and a wind emerging radially from the star, and compare them to observed He I λ10830 profiles from a survey of classical T Tauri stars. The comparison indicates …

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Measuring The Halo Mass Of Z ∼ 3 Damped Lyα Absorbers From The Absorber-Galaxy Cross-Correlation, Nicolas Bouché, Jeffrey P. Gardner, Neal Katz, David H. Weinberg, Romeel Davé, James D. Lowenthal Jul 2005

Measuring The Halo Mass Of Z ∼ 3 Damped Lyα Absorbers From The Absorber-Galaxy Cross-Correlation, Nicolas Bouché, Jeffrey P. Gardner, Neal Katz, David H. Weinberg, Romeel Davé, James D. Lowenthal

Astronomy: Faculty Publications

We test the reliability of a method to measure the mean halo mass of absorption-line systems such as damped Lyα absorbers (DLAs). The method is based on measuring the ratio of the cross-correlation between DLAs and galaxies to the autocorrelation of the galaxies themselves, which is (in linear theory) the ratio of their bias factor b. We show that the ratio of the projected cross- and autocorrelation functions [W (r )/w (r )] is also the ratio of their bias factor, irrespective of the galaxy distribution, provided that one uses the same galaxies for w (r ) and w (r …

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The Star Formation Rate-Density Relationship At Redshift 3, Nicolas Bouché, James D. Lowenthal Apr 2005

The Star Formation Rate-Density Relationship At Redshift 3, Nicolas Bouché, James D. Lowenthal

Astronomy: Faculty Publications

We study the star formation rate (SFR) as a function of environment for UV-selected Lyman break galaxies (LBGs) at redshift 3. From deep [μ (sky) ≃ 27.6] UBVI MOSAIC images, covering a total of 0.90 deg , we select 334 LBGs in slices 100 h Mpc (comoving) deep spanning the redshift range 2.9 < z < 3.4 based on Bayesian photometric redshifts that include the I magnitude as a prior. The slice width (100 h Mpc) corresponds to the photometric redshift accuracy (Δ ∼ 0.15). We used mock catalogs from the GIF2 cosmological simulations to show that this redshift resolution is sufficient to statistically differentiate the high-density regions from the low-density regions using ∑ , the projected density to the fifth nearest neighbor. These mock catalogs have a redshift depth of 110 h Mpc, similar to our slice width. The large area of the MOSAIC images, ∼40 × 40 Mpc (comoving) per field, allows us to measure the SFR from the dust-corrected UV continuum as a function of ∑ . In contrast to low-redshift galaxies, we find that the SFR (or UV luminosity) of LBGs at z = 3 shows no detectable dependence on environment over 2 orders of magnitude in densities. To test the significance of our result, we use Monte Carlo simulations (from the mock catalogs) and the same projected density estimators that we applied to our data. We find that we can reject the steep z = 0 SFR-density relation at the 5 σ level. We conclude that the SFR-density relation at z = 3 must be at least 3.6 times flatter than it is locally; i.e., the SFR of LBGs is significantly less dependent on environment than the SFR of local star-forming galaxies. We find that the rest-frame UV colors are also independent of environment.

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The Clustering Of Galaxies Around Three Z ∼ 3 Damped Lyα Absorbers, Nicolas Bouché, James D. Lowenthal Jul 2004

The Clustering Of Galaxies Around Three Z ∼ 3 Damped Lyα Absorbers, Nicolas Bouché, James D. Lowenthal

Astronomy: Faculty Publications

We present our results on the cross-correlation of Lyman break galaxies (LBGs) around three damped Lyα absorbers (DLAs) at z ≃ 3 from deep [μ (sky) ≃ 27.6 mag arcsec ] UBVI KPNO 4 m/MOSAIC images. The large area of the MOSAIC images, 0.31 deg or ∼65 × 65 h Mpc comoving at redshift z = 3, allows us to probe the clustering of LBGs on scales up to 20 Mpc comoving. Our survey covers a total of 1 deg and contains ∼3000 LBGs with photometric redshifts between 2.8 and 3.5. Using the redshift likelihood distributions with m as a …

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Going Slitless: Images Of Forbidden Line Emission Regions Of Classical T Tauri Stars Observed With The Hubble Space Telescope, Patrick Hartigan, Suzan Edwards, Rachel Pierson Jul 2004

Going Slitless: Images Of Forbidden Line Emission Regions Of Classical T Tauri Stars Observed With The Hubble Space Telescope, Patrick Hartigan, Suzan Edwards, Rachel Pierson

Astronomy: Faculty Publications

We have observed five classical T Tauri stars known to have strong forbidden-line emission with STIS in slitless mode on the Hubble Space Telescope. This technique makes it possible to image jets within a few tens of AU of their exciting sources, a region of great interest for models of accretion disks and jets. Slitless images generate emission-line images at all wavelengths, including those where no narrowband filters exist. Images of the forbidden-line regions around each object, constructed by subtracting the stellar continuum and combining observations taken at different orientations, show [O I] jets from CW Tau, HN Tau, …

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He I Λ10830 As A Probe Of Winds In Accreting Young Stars, Suzan Edwards, William Fischer, John Kwan, L. Hillenbrand, Andrea K. Dupree Dec 2003

He I Λ10830 As A Probe Of Winds In Accreting Young Stars, Suzan Edwards, William Fischer, John Kwan, L. Hillenbrand, Andrea K. Dupree

Astronomy: Faculty Publications

He I 10830 profiles acquired with Keck's NIRSPEC for six young low-mass stars with high disk accretion rates (AS 353A, DG Tau, DL Tau, DR Tau, HL Tau, and SVS 13) provide new insight into accretion-driven winds. In four of the stars, the profiles have the signature of resonance scattering, and they possess a deep and broad blueshifted absorption that penetrates more than 50% into the 1 m continuum over a continuous range of velocities from near the stellar rest velocity to the terminal velocity of the wind, unlike inner wind signatures seen in other spectral features. This deep and …

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