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Astrophysics and Astronomy

2010

University of Massachusetts Amherst

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Articles 1 - 30 of 90

Full-Text Articles in Physical Sciences and Mathematics

Globe Walk, Rob Snyder Jan 2010

Globe Walk, Rob Snyder

IPY STEM Polar Connections

A “Globe Walk” can be used as a demonstration or classroom activity to guide students toward a better understanding of the affects that Earth’s axial tilt, rotation on Earth’s axis, and orbital motion have on the angles of incidence of sunlight, the lengths of daytimes, and solar insolation.

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On The Algorithms Of Radiative Cooling In Semi-Analytic Models, Yu Lu, Dusan Keres, N Katz, H.J. Mo, Mark Fardal, Martin D. Weinberg Jan 2010

On The Algorithms Of Radiative Cooling In Semi-Analytic Models, Yu Lu, Dusan Keres, N Katz, H.J. Mo, Mark Fardal, Martin D. Weinberg

Astronomy Department Faculty Publication Series

We study the behaviour of multiple radiative cooling algorithms implemented in six Semi-Analytic Models (SAMs) of galaxy formation, including a new model we propose in this paper. We use versions of the models without feedback and apply them to dark matter haloes growing in a cosmological context, which have final masses that range from 10^{11}Msun to 10^{14}Msun. First, using simplified smoothly-growing halo models, we demonstrate that the different algorithms predict cooling rates and final cold gas masses that differ by a factor of ~5 for massive haloes (>10^{12}Msun). The algorithms are in better agreement for less massive haloes because …

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Computing The Bayes Factor From A Markov Chain Monte Carlo Simulation Of The Posterior Distribution, Martin D. Weinberg Jan 2010

Computing The Bayes Factor From A Markov Chain Monte Carlo Simulation Of The Posterior Distribution, Martin D. Weinberg

Astronomy Department Faculty Publication Series

Computation of the marginal likelihood from a simulated posterior distribution is central to Bayesian model selection but is computationally difficult. I argue that the marginal likelihood can be reliably computed from a posterior sample by careful attention to the numerics of the probability integral. Posing the expression for the marginal likelihood as a Lebesgue integral, we may convert the harmonic mean approximation from a sample statistic to a quadrature rule. As a quadrature, the harmonic mean approximation suffers from enormous truncation error as consequence . In addition, I demonstrate that the integral expression for the harmonic-mean approximation converges slowly at …

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The Evolution Of Stellar Structures In Dwarf Galaxies, N. Bastian, D. R. Weisz, E. D. Skillman, K. B.W. Mc Quinn, A E. Dolphin, R. A. Gutermuth Jan 2010

The Evolution Of Stellar Structures In Dwarf Galaxies, N. Bastian, D. R. Weisz, E. D. Skillman, K. B.W. Mc Quinn, A E. Dolphin, R. A. Gutermuth

Astronomy Department Faculty Publication Series

We present a study of the variation of spatial structure of stellar populations within dwarf galaxies as a function of the population age. We use deep Hubble Space Telescope/Advanced Camera for Surveys imaging of nearby dwarf galaxies in order to resolve individual stars and create composite colour-magnitude diagrams (CMDs) for each galaxy. Using the obtained CMDs, we select Blue Helium Burning stars (BHeBs), which can be unambiguously age-dated by comparing the absolute magnitude of individual stars with stellar isochrones. Additionally, we select a very young (<10 >Myr) population of OB stars for a subset of the galaxies based on the …

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The Spatial Distribution Of Star Formation In The Solar Neighbourhood: Do All Stars Form In Dense Clusters?, E. Bressert, N. Bastian, R. Gutermuth Jan 2010

The Spatial Distribution Of Star Formation In The Solar Neighbourhood: Do All Stars Form In Dense Clusters?, E. Bressert, N. Bastian, R. Gutermuth

Astronomy Department Faculty Publication Series

We present a global study of low-mass, young stellar object (YSO) surface densities (Σ) in nearby (<500 >pc) star-forming regions based on a comprehensive collection of Spitzer Space Telescope surveys. We show that the distribution of YSO surface densities in the solar neighbourhood is a smooth distribution, being adequately described by a lognormal function from a few to 103 YSOs pc−2, with a peak at ∼22 stars pc−2 and a dispersion of inline image. We do not find evidence for multiple discrete modes of star formation (e.g. clustered and distributed). Comparing the observed surface density distribution to previously reported surface …

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A Bayesian Approach To The Semi-Analytic Model Of Galaxy Formation: Methodology, Yu Lu, H.J. Mo, Martin D. Weinberg, N Katz Jan 2010

A Bayesian Approach To The Semi-Analytic Model Of Galaxy Formation: Methodology, Yu Lu, H.J. Mo, Martin D. Weinberg, N Katz

Astronomy Department Faculty Publication Series

We believe that a wide range of physical processes conspire to shape the observed galaxy population but we remain unsure of their detailed interactions. The semi-analytic model (SAM) of galaxy formation uses multi-dimensional parameterizations of the physical processes of galaxy formation and provides a tool to constrain these underlying physical interactions. Because of the high dimensionality, the parametric problem of galaxy formation may be profitably tackled with a Bayesian-inference based approach, which allows one to constrain theory with data in a statistically rigorous way. In this paper, we develop a generalized SAM using the framework of Bayesian inference. We show …

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The Properties Of X-Ray Luminous Young Stellar Objects In The Ngc 1333 And Serpens Embedded Clusters, E. Winston, S. T. Megeath, S. J. Wolk, B. Spitzbart, R. Gutermuth Jan 2010

The Properties Of X-Ray Luminous Young Stellar Objects In The Ngc 1333 And Serpens Embedded Clusters, E. Winston, S. T. Megeath, S. J. Wolk, B. Spitzbart, R. Gutermuth

Astronomy Department Faculty Publication Series

We present new Chandra X-ray data of the NGC 1333 embedded cluster and combine these data with existing Chandra data, Spitzer photometry, and ground-based spectroscopy of both the NGC 1333 and Serpens cloud core clusters to perform a detailed study of the X-ray properties of two of the nearest embedded clusters to the Sun. We first present new, deeper observations of NGC 1333 with Chandra ACIS-I and combine these with existing Spitzer observations of the region. In NGC 1333, a total of 95 cluster members are detected in X-rays of which 54 were previously identified in the Spitzer data. Of …

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Circumstellar Structure Around Evolved Stars In The Cygnus-X Star Formation Region, Kathleen E. Kraemer, Joseph L. Hora, Michael P. Egan, Joseph Adams, Lori E. Allen, Sylvain Bontemps, Sean J. Carey, Giovanni G. Fazio, Robert Gutermuth Jan 2010

Circumstellar Structure Around Evolved Stars In The Cygnus-X Star Formation Region, Kathleen E. Kraemer, Joseph L. Hora, Michael P. Egan, Joseph Adams, Lori E. Allen, Sylvain Bontemps, Sean J. Carey, Giovanni G. Fazio, Robert Gutermuth

Astronomy Department Faculty Publication Series

We present observations of newly discovered 24 micron circumstellar structures detected with the Multiband Imaging Photometer for Spitzer (MIPS) around three evolved stars in the Cygnus-X star forming region. One of the objects, BD+43 3710, has a bipolar nebula, possibly due to an outflow or a torus of material. A second, HBHA 4202-22, a Wolf-Rayet candidate, shows a circular shell of 24 micron emission suggestive of either a limb-brightened shell or disk seen face-on. No diffuse emission was detected around either of these two objects in the Spitzer 3.6-8 micron Infrared Array Camera (IRAC) bands. The third object is the …

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An Aromatic Inventory Of The Local Volume, Ar Marble, Cw Engelbracht, L Van Zee, Da Dale, Jdt Smith, Kd Gordon, Y Wu, Jc Lee, Rc Kennicutt, Ed Skillman, Lc Johnson, M Block, D Calzetti, Sa Cohen, H Lee, Md Schuster Jan 2010

An Aromatic Inventory Of The Local Volume, Ar Marble, Cw Engelbracht, L Van Zee, Da Dale, Jdt Smith, Kd Gordon, Y Wu, Jc Lee, Rc Kennicutt, Ed Skillman, Lc Johnson, M Block, D Calzetti, Sa Cohen, H Lee, Md Schuster

Astronomy Department Faculty Publication Series

Using infrared photometry from the Spitzer Space Telescope, we perform the first inventory of aromatic feature emission (also commonly referred to as polycyclic aromatic hydrocarbon emission) for a statistically complete sample of star-forming galaxies in the local volume. The photometric methodology involved is calibrated and demonstrated to recover the aromatic fraction of the Infrared Array Camera 8 μm flux with a standard deviation of 6% for a training set of 40 SINGS galaxies (ranging from stellar to dust dominated) with both suitable mid-infrared Spitzer Infrared Spectrograph spectra and equivalent photometry. A potential factor of 2 improvement could be realized with …

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The Calibration Of Monochromatic Far-Infrared Star Formation Rate Indicators, D Calzetti, Sy Wu, S Hong, Rc Kennicutt, Jc Lee, Da Dale, Cw Engelbracht, L Van Zee, Bt Draine, Cn Hao, Kd Gordon, J Moustakas, Ej Murphy, M Regan, A Begum, M Block, J Dalcanton, J Funes, Ag De Paz, B Johnson, S Sakai, E Skillman, F Walter, D Weisz, B Williams, Y Wu Jan 2010

The Calibration Of Monochromatic Far-Infrared Star Formation Rate Indicators, D Calzetti, Sy Wu, S Hong, Rc Kennicutt, Jc Lee, Da Dale, Cw Engelbracht, L Van Zee, Bt Draine, Cn Hao, Kd Gordon, J Moustakas, Ej Murphy, M Regan, A Begum, M Block, J Dalcanton, J Funes, Ag De Paz, B Johnson, S Sakai, E Skillman, F Walter, D Weisz, B Williams, Y Wu

Astronomy Department Faculty Publication Series

Spitzer data at 24, 70, and 160 μm and ground-based Hα images are analyzed for a sample of 189 nearby star-forming and starburst galaxies to investigate whether reliable star formation rate (SFR) indicators can be defined using the monochromatic infrared dust emission centered at 70 and 160 μm. We compare recently published recipes for SFR measures using combinations of the 24 μm and observed Hα luminosities with those using 24 μm luminosity alone. From these comparisons, we derive a reference SFR indicator for use in our analysis. Linear correlations between SFR and the 70 μm and 160 μm luminosity are …

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Hst/Nicmos Paschen-Alpha Survey Of The Galactic Centre: Overview, Qd Wang, H Dong, A Cotera, S Stolovy, M Morris, Cc Lang, Mp Muno, G Schneider, D Calzetti Jan 2010

Hst/Nicmos Paschen-Alpha Survey Of The Galactic Centre: Overview, Qd Wang, H Dong, A Cotera, S Stolovy, M Morris, Cc Lang, Mp Muno, G Schneider, D Calzetti

Astronomy Department Faculty Publication Series

We have recently carried out the first wide-field hydrogen Paschen-α line imaging survey of the Galactic Centre using the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) instrument aboard the Hubble Space Telescope. The survey maps out a region of ) around the central supermassive black hole (Sgr A*) in the 1.87 and 1.90 μm narrow bands with a spatial resolution of ∼0.01 pc (0.2 arcsec full width at half-maximum) at a distance of 8 kpc. Here, we present an overview of the observations, data reduction, preliminary results and potential scientific implications, as well as a description of the rationale and …

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Supernova Remnants And The Interstellar Medium Of M83: Imaging And Photometry With The Wide Field Camera 3 On The Hubble Space Telescope, Ma Dopita, Wp Blair, Ks Long, M Mutchler, Bc Whitmore, Kd Kuntz, B Balick, He Bond, D Calzetti, M Carollo, M Disney, Ja Frogel, R O'Connell, D Hall, Ja Holtzman, Ra Kimble, J Mackenty, P Mccarthy, F Paresce, A Saha, J Silk, M Sirianni, J Trauger, Ar Walker, R Windhorst, E Young Jan 2010

Supernova Remnants And The Interstellar Medium Of M83: Imaging And Photometry With The Wide Field Camera 3 On The Hubble Space Telescope, Ma Dopita, Wp Blair, Ks Long, M Mutchler, Bc Whitmore, Kd Kuntz, B Balick, He Bond, D Calzetti, M Carollo, M Disney, Ja Frogel, R O'Connell, D Hall, Ja Holtzman, Ra Kimble, J Mackenty, P Mccarthy, F Paresce, A Saha, J Silk, M Sirianni, J Trauger, Ar Walker, R Windhorst, E Young

Astronomy Department Faculty Publication Series

We present Wide Field Camera 3 images taken with the Hubble Space Telescope within a single field in the southern grand design star-forming galaxy M83. Based on their size, morphology, and photometry in continuum-subtracted Hα, [S II], Hβ, [O III], and [O II] filters, we have identified 60 supernova remnant (SNR) candidates, as well as a handful of young ejecta-dominated candidates. A catalog of these remnants, their sizes and, where possible, their Hα fluxes are given. Radiative ages and pre-shock densities are derived from those SNRs that have good photometry. The ages lie in the range 2.62 < log (τrad/yr) < 5.0, and the pre-shock densities at the blast wave range over 0.56 < n 0/cm-3 < 1680. Two populations of SNRs have been discovered. These divide into a nuclear and spiral arm group and an inter-arm population. We infer an arm to inter-arm density contrast of 4. The surface flux in diffuse X-rays is correlated with the inferred pre-shock density, indicating that the warm interstellar medium (ISM) is pressurized by the hot X-ray plasma. We also find that the ISM in the nuclear region of M83 is characterized by a very high porosity and pressure, and infer an SNR rate of 1 per 70-150 yr for the nuclear (R < 300 pc) region. On the basis of the number of SNRs detected and their radiative ages, we infer that the lower mass of Type II SNe in M83 is M min = 16+7 –5 M . Finally, we give evidence for the likely detection of the remnant of the historical supernova, SN1968L.

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An Investigation Of The Dust Content In The Galaxy Pair Ngc 1512/1510 From Near-Infrared To Millimeter Wavelengths, Gl Liu, D Calzetti, Min Yun, Gw Wilson, Bt Draine, K Scott, J Austermann, T Perera, D Hughes, I Aretxaga, K Kohno, R Kawabe, H Ezawa Jan 2010

An Investigation Of The Dust Content In The Galaxy Pair Ngc 1512/1510 From Near-Infrared To Millimeter Wavelengths, Gl Liu, D Calzetti, Min Yun, Gw Wilson, Bt Draine, K Scott, J Austermann, T Perera, D Hughes, I Aretxaga, K Kohno, R Kawabe, H Ezawa

Astronomy Department Faculty Publication Series

We combine new ASTE/AzTEC 1.1 mm maps of the galaxy pair NGC 1512/1510 with archival Spitzer IRAC and MIPS images covering the wavelength range 3.6-160 μm from the SINGS project. The availability of the 1.1 mm map enables us to measure the long-wavelength tail of the dust emission in each galaxy, and in sub-galactic regions in NGC 1512, and to derive accurate dust masses. The two galaxies form a pair consisting of a large, high-metallicity spiral (NGC 1512) and a low-metallicity, blue compact dwarf (NGC 1510), which we use to compare similarities and contrast differences. Using the models of Draine …

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A Z=1.82 Analog Of Local Ultra-Massive Elliptical Galaxies, M Onodera, E Daddi, R Gobat, M Cappellari, N Arimoto, A Renzini, Y Yamada, Hj Mccracken, C Mancini, P Capak, M Carollo, A Cimatti, M Giavalisco, O Ilbert, X Kong, S Lilly, K Motohara, K Ohta, Db Sanders, N Scoville, N Tamura, Y Taniguchi Jan 2010

A Z=1.82 Analog Of Local Ultra-Massive Elliptical Galaxies, M Onodera, E Daddi, R Gobat, M Cappellari, N Arimoto, A Renzini, Y Yamada, Hj Mccracken, C Mancini, P Capak, M Carollo, A Cimatti, M Giavalisco, O Ilbert, X Kong, S Lilly, K Motohara, K Ohta, Db Sanders, N Scoville, N Tamura, Y Taniguchi

Astronomy Department Faculty Publication Series

We present observations of a very massive galaxy at z = 1.82 that show that its morphology, size, velocity dispersion, and stellar population properties are fully consistent with those expected for passively evolving progenitors of today's giant ellipticals. These findings are based on a deep optical rest-frame spectrum obtained with the Multi-Object InfraRed Camera and Spectrograph on the Subaru Telescope of a high-z passive galaxy candidate (pBzK) from the COSMOS field, for which we accurately measure its redshift of z = 1.8230 and obtain an upper limit on its velocity dispersion σ⋆ < 326  km s−1. By detailed stellar population modeling of both the galaxy broadband spectral energy distribution and the rest-frame optical spectrum, we derive a star formation-weighted age and formation redshift of tsf ≃ 1–2 Gyr and z …

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The Nature Of Submillimetre Galaxies In Cosmological Hydrodynamic Simulations, R Dave, K Finlator, Bd Oppenheimer, M Fardal, N Katz, D Keres, Dh Weinberg Jan 2010

The Nature Of Submillimetre Galaxies In Cosmological Hydrodynamic Simulations, R Dave, K Finlator, Bd Oppenheimer, M Fardal, N Katz, D Keres, Dh Weinberg

Astronomy Department Faculty Publication Series

We study the nature of rapidly star-forming galaxies at z= 2 in cosmological hydrodynamic simulations, and compare their properties to observations of submillimetre galaxies (SMGs). We identify simulated SMGs as the most rapidly star-forming systems that match the observed number density of SMGs. In our models, SMGs are massive galaxies sitting at the centres of large potential wells, being fed by smooth infall and gas-rich satellites at rates comparable to their star formation rates (SFRs). They are not typically undergoing major mergers that significantly boost their quiescent SFR, but they still often show complex gas morphologies and kinematics. Our …

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Ly Alpha Emission From Cosmic Structure. I. Fluorescence, Ja Kollmeier, Z Zheng, R Dave, A Gould, N Katz, J Miralda-Escude, Dh Weinberg Jan 2010

Ly Alpha Emission From Cosmic Structure. I. Fluorescence, Ja Kollmeier, Z Zheng, R Dave, A Gould, N Katz, J Miralda-Escude, Dh Weinberg

Astronomy Department Faculty Publication Series

We present predictions for the fluorescent Lyα emission signature arising from photoionized, optically thick structures in smoothed particle hydrodynamic cosmological simulations of a ΛCDM universe using a Monte Carlo Lyα radiative transfer code. We calculate the expected Lyα image and two-dimensional spectra for gas exposed to a uniform ultraviolet ionizing background as well as gas exposed additionally to the photoionizing radiation from a local quasar, after correcting for the self-shielding of hydrogen. As a test of our numerical methods and for application to current observations, we examine simplified analytic structures that are uniformly or anisotropically illuminated. We compare these results …

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Mid-Infrared Spectroscopy Of Candidate Active Galactic Nuclei-Dominated Submillimeter Galaxies, K Coppin, A Pope, K Menendez-Delmestre, Dm Alexander, Js Dunlop, E Egami, J Gabor, E Ibar, Rj Ivison, Je Austermann, Aw Blain, Sc Chapman, Dl Clements, L Dunne, S Dye, D Farrah, Dh Hughes, Amj Mortier, Mj Page, M Rowan-Robinson, D Scott, C Simpson, I Smail, Am Swinbank, M Vaccari, Min Yun Jan 2010

Mid-Infrared Spectroscopy Of Candidate Active Galactic Nuclei-Dominated Submillimeter Galaxies, K Coppin, A Pope, K Menendez-Delmestre, Dm Alexander, Js Dunlop, E Egami, J Gabor, E Ibar, Rj Ivison, Je Austermann, Aw Blain, Sc Chapman, Dl Clements, L Dunne, S Dye, D Farrah, Dh Hughes, Amj Mortier, Mj Page, M Rowan-Robinson, D Scott, C Simpson, I Smail, Am Swinbank, M Vaccari, Min Yun

Astronomy Department Faculty Publication Series

Spitzer spectroscopy has revealed that 80% of submm galaxies (SMGs) are starburst (SB)-dominated in the mid-infrared. Here we focus on the remaining 20% that show signs of harboring powerful active galactic nuclei (AGNs). We have obtained Spitzer-InfraRed Spectrograph spectroscopy of a sample of eight SMGs that are candidates for harboring powerful AGNs on the basis of IRAC color selection (S 8 μm/S 4.5 μm>2, i.e., likely power-law mid-infrared spectral energy distributions). SMGs with an AGN dominating (50%) their mid-infrared emission could represent the "missing link" sources in an evolutionary sequence involving a major merger. First …

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The Dearth Of Chemically Enriched Warm-Hot Circumgalactic Gas, Y Yao, Qd Wang, Sv Penton, Tm Tripp, Jm Shull, Jt Stocke Jan 2010

The Dearth Of Chemically Enriched Warm-Hot Circumgalactic Gas, Y Yao, Qd Wang, Sv Penton, Tm Tripp, Jm Shull, Jt Stocke

Astronomy Department Faculty Publication Series

The circumgalactic medium (CGM) around galaxies is believed to record various forms of galaxy feedback and contain a significant portion of the "missing baryons" of individual dark matter halos. However, clear observational evidence for the existence of the hot CGM is still absent. We use intervening galaxies along 12 background active galactic nuclei (AGNs) as tracers to search for X-ray absorption lines produced in the corresponding CGM. Stacking Chandra grating observations with respect to galaxy groups and different luminosities of these intervening galaxies, we obtain spectra with signal-to-noise ratios of 46-72 per 20 mÅ spectral bin at the expected O …

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Using 21 Cm Absorption In Small Impact Parameter Galaxy-Quasar Pairs To Probe Low-Redshift Damped And Sub-Damped Ly Alpha Systems, S Borthakur, Tm Tripp, Min Yun, E Momjian, Jd Meiring, Dv Bowen, Dg York Jan 2010

Using 21 Cm Absorption In Small Impact Parameter Galaxy-Quasar Pairs To Probe Low-Redshift Damped And Sub-Damped Ly Alpha Systems, S Borthakur, Tm Tripp, Min Yun, E Momjian, Jd Meiring, Dv Bowen, Dg York

Astronomy Department Faculty Publication Series

To search for low-redshift damped Lyα (DLA) and sub-DLA quasar absorbers, we have conducted a 21 cm absorption survey of radio-loud quasars at small impact parameters to foreground galaxies selected from the Sloan Digital Sky Survey (SDSS). Here we present the first results from this survey based on observations of SDSS J104257.58+074850.5 (z QSO = 2.66521), a quasar at an angular separation from a foreground galaxy (z gal = 0.03321) of 25 (1.7 kpc in projection). The foreground galaxy is a low-luminosity spiral with on-going star formation (0.004 M yr–1 kpc–2) and a metallicity of …

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Uv-Dropout Galaxies In The Goods-South Field From Wfc3 Early Release Science Observations, N Hathi, R Ryan, S Cohen, H Yan, R Windhorst, P Mccarthy, R O'Connell, A Koekemoer, M Rutkowsk, B Balick, H Bond, D Calzetti Jan 2010

Uv-Dropout Galaxies In The Goods-South Field From Wfc3 Early Release Science Observations, N Hathi, R Ryan, S Cohen, H Yan, R Windhorst, P Mccarthy, R O'Connell, A Koekemoer, M Rutkowsk, B Balick, H Bond, D Calzetti

Astronomy Department Faculty Publication Series

We combine new high sensitivity ultraviolet (UV) imaging from the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) with existing deep HST/Advanced Camera for Surveys optical images from the Great Observatories Origins Deep Survey (GOODS) program to identify UV-dropouts, which are Lyman break galaxy (LBG) candidates at z sime 1-3. These new HST/WFC3 observations were taken over 50 arcmin2 in the GOODS-South field as a part of the Early Release Science program. The uniqueness of these new UV data is that they are observed in three UV/optical (WFC3 UVIS) channel filters (F225W, F275W, and F336W), which allows …

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The Lthe Luminosity, Mass, And Age Distributions Of Compact Star Clusters In M83 Based On Hubble Space Telescope/Wide Field Camera 3 Observations, R Chandar, B Whitmore, H Kim, C Kaleida, M Mutchler, D Calzetti Jan 2010

The Lthe Luminosity, Mass, And Age Distributions Of Compact Star Clusters In M83 Based On Hubble Space Telescope/Wide Field Camera 3 Observations, R Chandar, B Whitmore, H Kim, C Kaleida, M Mutchler, D Calzetti

Astronomy Department Faculty Publication Series

The newly installed Wide Field Camera 3 (WFC3) on the Hubble Space Telescope has been used to obtain multi-band images of the nearby spiral galaxy M83. These new observations are the deepest and highest resolution images ever taken of a grand-design spiral, particularly in the near-ultraviolet, and allow us to better differentiate compact star clusters from individual stars and to measure the luminosities of even faint clusters in the U band. We find that the luminosity function (LF) for clusters outside of the very crowded starburst nucleus can be approximated by a power law, dN/dL vprop L α, with α …

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The Star Formation Camera, P Scowen, R Jansen, M Beasley, D Calzetti Jan 2010

The Star Formation Camera, P Scowen, R Jansen, M Beasley, D Calzetti

Astronomy Department Faculty Publication Series

The Star Formation Camera (SFC) is a wide-field (~15f~19f, >280 arcmin2), highresolution (18~18 mas pixels) UV/optical dichroic camera designed for the Theia 4-m space-borne space telescope concept. SFC will deliver diffraction-limited images at ƒÉ > 300 nm in both a blue (190-517nm) and a red (517-1075nm) channel simultaneously. Our aim is to conduct a comprehensive and systematic study of the astrophysical processes and environments relevant for the births and life cycles of stars and their planetary systems, and to investigate and understand the range of environments, feedback mechanisms, and other factors that most affect the outcome of the star and planet …

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The Magellanic Clouds Survey: A Bridge To Nearby Galaxies, P Scowen, R Jansen, M Beasley, D Calzetti Jan 2010

The Magellanic Clouds Survey: A Bridge To Nearby Galaxies, P Scowen, R Jansen, M Beasley, D Calzetti

Astronomy Department Faculty Publication Series

We outline to the community the value of a Magellanic Clouds Survey that consists of three components: I) a complete-area, high resolution, multi-band UV-near-IR broadband survey; II) a narrowband survey in 7 key nebular filters to cover a statistically significant sample of representative HII regions and a large-area, contiguous survey of the diffuse, warm ISM; and III) a comprehensive FUV spectroscopic survey of 1300 early-type stars. The science areas enabled by such a dataset are as follows: A) assessment of massive star feedback in both HII regions and the diffuse, warm ISM; B) completion of a comprehensive study of the …

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Pacs And Spire Photometer Maps Of M 33: First Results Of The Herschel M 33 Extended Survey (Herm33es), C Kramer, C Buchbender, E Xilouris, M Boquien, J Braine, D Calzetti Jan 2010

Pacs And Spire Photometer Maps Of M 33: First Results Of The Herschel M 33 Extended Survey (Herm33es), C Kramer, C Buchbender, E Xilouris, M Boquien, J Braine, D Calzetti

Astronomy Department Faculty Publication Series

Context. Within the framework of the HERM33ES key program, we are studying the star forming interstellar medium in the nearby, metal-poor spiral galaxy M 33, exploiting the high resolution and sensitivity of Herschel. Aims. We use PACS and SPIRE maps at 100, 160, 250, 350, and 500 μm wavelength, to study the variation of the spectral energy distributions (SEDs) with galacto-centric distance. Methods. Detailed SED modeling is performed using azimuthally averaged fluxes in elliptical rings of 2 kpc width, out to 8 kpc galacto-centric distance. Simple isothermal and two-component grey body models, with fixed dust emissivity index, are fitted to …

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Molecular And Atomic Gas In The Local Group Galaxy M 33, Gratier, Braine, Rodriguez-Fernandez, Schuster, Kramer, Xilouris, Tabatabaei, Henkel, Corbelli, Israel, Van Der Werf, D Calzetti Jan 2010

Molecular And Atomic Gas In The Local Group Galaxy M 33, Gratier, Braine, Rodriguez-Fernandez, Schuster, Kramer, Xilouris, Tabatabaei, Henkel, Corbelli, Israel, Van Der Werf, D Calzetti

Astronomy Department Faculty Publication Series

We present high-resolution large-scale observations of the molecular and atomic gas in the Local Group galaxy M 33. The observations were carried out using the HEterodyne Receiver Array (HERA) at the 30 m IRAM telescope in the CO(2–1) line, achieving a resolution of 12″ × 2.6 km s-1, enabling individual giant molecular clouds (GMCs) to be resolved. The observed region is 650 square arcminutes mainly along the major axis and out to a radius of 8.5 kpc, and covers entirely the 2′ × 40′ radial strip observed with the HIFI and PACS Spectrometers as part of the HERM33ES Herschel key …

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Optical Spectroscopy And Nebular Oxygen Abundances Of The Spitzer/Sings Galaxies, J Moustakas, R Kennicutt, C Tremontt, D Dale5, J Smith, D Calzetti Jan 2010

Optical Spectroscopy And Nebular Oxygen Abundances Of The Spitzer/Sings Galaxies, J Moustakas, R Kennicutt, C Tremontt, D Dale5, J Smith, D Calzetti

Astronomy Department Faculty Publication Series

We present intermediate-resolution optical spectrophotometry of 65 galaxies obtained in support of the Spitzer Infrared Nearby Galaxies Survey (SINGS). For each galaxy we obtain a nuclear, circumnuclear, and semi-integrated optical spectrum designed to coincide spatially with mid- and far-infrared spectroscopy from the Spitzer Space Telescope. We make the reduced, spectrophotometrically calibrated one-dimensional spectra, as well as measurements of the fluxes and equivalent widths of the strong nebular emission lines, publically available. We use optical emission-line ratios measured on all three spatial scales to classify the sample into star-forming, active galactic nuclei (AGN), and galaxies with a mixture of star formation …

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Mapping Far-Ir Emission From The Central Kiloparsec Of Ngc 1097, K Sandstrom, O Krause, H Linz, E Schinnerer, G Dumas, S Meidt, H Rix, M Sauvage, F Walter, R Kennicutt, D Calzetti Jan 2010

Mapping Far-Ir Emission From The Central Kiloparsec Of Ngc 1097, K Sandstrom, O Krause, H Linz, E Schinnerer, G Dumas, S Meidt, H Rix, M Sauvage, F Walter, R Kennicutt, D Calzetti

Astronomy Department Faculty Publication Series

Using photometry of NGC 1097 from the Herschel PACS (Photodetector Array Camera and Spectrometer) instrument, we study the resolved properties of thermal dust continuum emission from a circumnuclear starburst ring with a radius ~900 pc. These observations are the first to resolve the structure of a circumnuclear ring at wavelengths that probe the peak (i.e. λ ~ 100 μm) of the dust spectral energy distribution. The ring dominates the far-infrared (far-IR) emission from the galaxy – the high angular resolution of PACS allows us to isolate the ring's contribution and we find it is responsible for 75, 60 and 55% …

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Nearby Galaxies With Spitzer, D Calzetti Jan 2010

Nearby Galaxies With Spitzer, D Calzetti

Astronomy Department Faculty Publication Series

We review the main advances brought by the Spitzer Space Telescope in the field of nearby galaxies studies, concentrating on a few subject areas, including: (1) the physics of the Polycyclic Aromatic Hydrocarbons that generate the mid-infrared features between ~3.5 micron and ~20 micron; (2) the use of the mid- and far-infrared emission from galaxies as star formation rate indicators; and (3) the improvement of mid-infrared diagnostics to discriminate between thermal (star-formation) and non-thermal (AGN) emission in galaxies and galaxy centers.

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Hubble Space Telescope Imaging Of Lyman Alpha Emission At Z = 4.41, S Finkelstein, S Cohen, R Windhorst, R Ryan, N Hathi, K Finkelstein, J Anderson, N Grogin, A Koekemoer, S Malhotra, M Mutchler, J Rhoads, P Mccarthy, R O’Connell, B Balick, H Bond, D Calzetti Jan 2010

Hubble Space Telescope Imaging Of Lyman Alpha Emission At Z = 4.41, S Finkelstein, S Cohen, R Windhorst, R Ryan, N Hathi, K Finkelstein, J Anderson, N Grogin, A Koekemoer, S Malhotra, M Mutchler, J Rhoads, P Mccarthy, R O’Connell, B Balick, H Bond, D Calzetti

Astronomy Department Faculty Publication Series

We present the highest redshift detections of resolved Lyman alpha emission, using Hubble Space Telescope/ACS F658N narrowband-imaging data taken in parallel with the Wide Field Camera 3 Early Release Science program in the GOODS CDF-S. We detect Lyman alpha emission from three spectroscopically confirmed z = 4.4 Lyman alpha emitting galaxies (LAEs), more than doubling the sample of LAEs with resolved Lyman alpha emission. Comparing the light distribution between the rest-frame ultraviolet continuum and narrowband images, we investigate the escape of Lyman alpha photons at high redshift. While our data do not support a positional offset between the Lyman alpha …

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Far-Infrared Line Imaging Of The Starburst Ring In Ngc 1097 With The Herschel/Pacs Spectrometer, P Beirão, L Armus, P Appleton, J Smith, K Croxall, E Murphy, D Dale, G Helou, R Kennicutt, D Calzetti Jan 2010

Far-Infrared Line Imaging Of The Starburst Ring In Ngc 1097 With The Herschel/Pacs Spectrometer, P Beirão, L Armus, P Appleton, J Smith, K Croxall, E Murphy, D Dale, G Helou, R Kennicutt, D Calzetti

Astronomy Department Faculty Publication Series

NGC 1097 is a nearby SBb galaxy with a Seyfert nucleus and a bright starburst ring. We study the physical properties of the interstellar medium (ISM) in the ring using spatially resolved far-infrared spectral maps of the circumnuclear starburst ring of NGC 1097, obtained with the PACS spectrometer on board the Herschel Space Observatory. In particular, we map the important ISM cooling and diagnostic emission lines of [OI] 63 μm, [OIII] 88 μm, [NII] 122 μm, [CII] 158 μm and [NII] 205 μm. We observe that in the [OI] 63 μm, [OIII] 88 μm, and [NII] 122 μm line maps, …

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