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Articles 1 - 14 of 14
Full-Text Articles in Physical Sciences and Mathematics
The Relations Among 8, 24 And 160 Mu M Dust Emission Within Nearby Spiral Galaxies, Gj Bendo, Bt Draine, Cw Engelbracht, G Helou, Md Thornley, C Bot, Ba Buckalew, D Calzetti, Da Dale, J Hollenbach, A Li, J Moustakas
The Relations Among 8, 24 And 160 Mu M Dust Emission Within Nearby Spiral Galaxies, Gj Bendo, Bt Draine, Cw Engelbracht, G Helou, Md Thornley, C Bot, Ba Buckalew, D Calzetti, Da Dale, J Hollenbach, A Li, J Moustakas
Astronomy Department Faculty Publication Series
We investigate the relations among the stellar continuum-subtracted 8 μm polycyclic aromatic hydrocarbon (PAH 8 μ m) emission, 24 μm hot dust emission and 160 μm cold dust emission in 15 nearby face-on spiral galaxies in the Spitzer Infrared Nearby Galaxies Survey sample. The relation between PAH 8 and 24 μm emission measured in ∼2 kpc regions is found to exhibit a significant amount of scatter, and strong spatial variations are observed in the (PAH 8 μ m)/24 μm surface brightness ratio. In particular, the (PAH 8 μ m)/24 μm surface brightness ratio is observed to be high in the …
Self-Regulated Fueling Of Galaxy Centers: Evidence For Star Formation Feedback, E Schinnerer, T Boker, Ds Meier, D Calzetti
Self-Regulated Fueling Of Galaxy Centers: Evidence For Star Formation Feedback, E Schinnerer, T Boker, Ds Meier, D Calzetti
Astronomy Department Faculty Publication Series
Using new, high-resolution interferometric observations of the CO and HCN molecules, we directly compare the molecular and ionized components of the interstellar medium in the center of the nearby spiral galaxy IC 342, on spatial scales of 10 pc. The morphology of the tracers suggests that the molecular gas flow caused by a large-scale stellar bar has been strongly affected by the mechanical feedback from recent star formation activity within the central 100 pc in the nucleus of the galaxy. Possibly, stellar winds and/or supernova shocks originating in the nuclear star cluster have compressed, and likely pushed outward, the infalling …
Spitzer Observations Of Star Formation In The Extreme Outer Disk Of M83 (Ngc5236), H Dong, D Calzetti, M Regan, D Thilker, L Bianchi, Gr Meurer, F Walter
Spitzer Observations Of Star Formation In The Extreme Outer Disk Of M83 (Ngc5236), H Dong, D Calzetti, M Regan, D Thilker, L Bianchi, Gr Meurer, F Walter
Astronomy Department Faculty Publication Series
Spitzer Infrared Array Camera (IRAC) observations of two fields in the extended UV disk (XUV-disk) of M83 have been recently obtained, ~3 R HII away from the center of the galaxy (R HII = 6.6 kpc). Galaxy Evolution Explorer (GALEX) UV images have shown the two fields to host in situ recent star formation. The IRAC images are used in conjunction with GALEX data and new H I imaging from The H I Nearby Galaxy Survey (THINGS) to constrain stellar masses and ages of the UV clumps in the fields, and to relate the local recent star formation to the …
The Opacity Of Spiral Galaxy Disks. Viii. Structure Of The Cold Ism, Bw Holwerda, B Draine, Kd Gordon, Ra Gonzalez, D Calzetti, M Thornley, B Buckalew, Rj Allen, Pc Van Der Kruit
The Opacity Of Spiral Galaxy Disks. Viii. Structure Of The Cold Ism, Bw Holwerda, B Draine, Kd Gordon, Ra Gonzalez, D Calzetti, M Thornley, B Buckalew, Rj Allen, Pc Van Der Kruit
Astronomy Department Faculty Publication Series
The quantity of dust in a spiral disk can be estimated using the dust's typical emission or the extinction of a known source. In this paper we compare two techniques, one based on emission and one on absorption, applied to sections of 14 disk galaxies. The two measurements reflect, respectively, the average and apparent optical depth of a disk section. Hence, they depend differently on the average number and optical depth of ISM structures in the disk. The small-scale geometry of the cold ISM is critical for accurate models of the overall energy budget of spiral disks. ISM geometry, relative …
Warm Molecular Hydrogen In The Spitzer Sings Galaxy Sample, H Roussel, G Helou, Dj Hollenbach, Bt Draine, Jd Smith, L Armus, E Schinnerer, F Walter, Cw Engelbracht, Md Thornley, Rc Kennicutt, D Calzetti, Da Dale, Ej Murphy, C Bot
Warm Molecular Hydrogen In The Spitzer Sings Galaxy Sample, H Roussel, G Helou, Dj Hollenbach, Bt Draine, Jd Smith, L Armus, E Schinnerer, F Walter, Cw Engelbracht, Md Thornley, Rc Kennicutt, D Calzetti, Da Dale, Ej Murphy, C Bot
Astronomy Department Faculty Publication Series
Results on the properties of warm molecular hydrogen in 57 normal galaxies are derived from measurements of H2 rotational transitions, obtained as part of SINGS. This study extends previous extragalactic surveys of emission lines of H2 to fainter and more common systems (LFIR = 107-6 × 1010 L). The 17 μm S(1) transition is securely detected in the nuclear regions of 86% of galaxies with stellar masses above 109.5 M. The derived column densities of warm H2 (T ≥ 100 K), although averaged over kiloparsec-scale areas, are commensurate with values observed in resolved photodissociation regions. They amount to between 1% …
The Incidence Of Highly Obscured Star-Forming Regions In Sings Galaxies, Mkm Prescott, Rc Kennicutt, Gj Bendo, Ba Buckalew, D Calzetti, Cw Engelbracht, Kd Gordon, Dj Hollenbach, Jc Lee, J Moustakas, Da Dale, G Helou, Th Jarrett, Ej Murphy, Jdt Smith, S Akiyama, Ml Sosey
The Incidence Of Highly Obscured Star-Forming Regions In Sings Galaxies, Mkm Prescott, Rc Kennicutt, Gj Bendo, Ba Buckalew, D Calzetti, Cw Engelbracht, Kd Gordon, Dj Hollenbach, Jc Lee, J Moustakas, Da Dale, G Helou, Th Jarrett, Ej Murphy, Jdt Smith, S Akiyama, Ml Sosey
Astronomy Department Faculty Publication Series
Using the new capabilities of Spitzer and extensive multiwavelength data from SINGS, it is now possible to study the infrared properties of star formation in nearby galaxies down to scales equivalent to large H II regions. We are therefore able to determine what fraction of large, infrared-selected star-forming regions in normal galaxies are highly obscured and address how much of the star formation we miss by relying solely on the optical portion of the spectrum. Employing a new empirical method for deriving attenuations of infrared-selected star-forming regions, we investigate the statistics of obscured star formation on 500 pc scales in …
Gaps In The Cloud Cover? Comparing Extinction Measures In Spiral Disks, Bw Holwerda, M Meyer, M Regan, D Calzetti, Kd Gordon, Jd Smith, D Dale, Cw Engelbracht, T Jarrett, M Thornley, C Bot, B Buckalew, Rc Kennicutt, Ra Gonzalez
Gaps In The Cloud Cover? Comparing Extinction Measures In Spiral Disks, Bw Holwerda, M Meyer, M Regan, D Calzetti, Kd Gordon, Jd Smith, D Dale, Cw Engelbracht, T Jarrett, M Thornley, C Bot, B Buckalew, Rc Kennicutt, Ra Gonzalez
Astronomy Department Faculty Publication Series
Dust in galaxies can be mapped either by the FIR/submillimeter emission, the optical or infrared reddening of starlight, or the extinction of a known background source. We compare two dust extinction measurements for a set of 15 sections in 13 nearby galaxies to determine the scale of the dusty interstellar medium (ISM) responsible for disk opacity: one using stellar reddening and the other a known background source. In our earlier papers, we presented extinction measurements of 29 galaxies, based on calibrated counts of distant background objects identified though foreground disks in Hubble Space Telescope WFPC2 images. For the 13 galaxies …
Accretion, Feedback And Galaxy Bimodality: A Comparison Of The Galics Semi-Analytic Model And Cosmological Sph Simulations, A Cattaneo, J Blaizot, Dh Weinberg, D Keres, S Colombi, R Dave, J Devriendt, B Guiderdoni, N Katz
Accretion, Feedback And Galaxy Bimodality: A Comparison Of The Galics Semi-Analytic Model And Cosmological Sph Simulations, A Cattaneo, J Blaizot, Dh Weinberg, D Keres, S Colombi, R Dave, J Devriendt, B Guiderdoni, N Katz
Astronomy Department Faculty Publication Series
We compare the galaxy population of a smoothed particle hydrodynamics (SPH) simulation to those predicted by the GalICS (Galaxies In Cosmological Simulations) N-body + semi-analytic model and a stripped down version of GalICS that omits the effects of supernova and active galactic nucleus (AGN) feedback. The SPH simulation and the no-feedback GalICS model make similar predictions for the baryonic mass functions of galaxies and for the dependence of these mass functions on environment and redshift. The two methods also make similar predictions for the galaxy content of dark matter haloes as a function of halo mass and for the …
Variations In 24-Mu M Morphologies Among Galaxies In The Spitzer Infrared Nearby Galaxies Survey: New Insights Into The Hubble Sequence, Gj Bendo, D Calzetti, Cw Engelbracht, Rc Kennicutt, Mj Meyer, Md Thornley, F Walter, Da Dale, A Li, Ej Murphy
Variations In 24-Mu M Morphologies Among Galaxies In The Spitzer Infrared Nearby Galaxies Survey: New Insights Into The Hubble Sequence, Gj Bendo, D Calzetti, Cw Engelbracht, Rc Kennicutt, Mj Meyer, Md Thornley, F Walter, Da Dale, A Li, Ej Murphy
Astronomy Department Faculty Publication Series
To study the distribution of star formation and dust emission within nearby galaxies, we measured five morphological parameters in the 3.6- and 24-μm wavebands for 65 galaxies in the Spitzer Infrared Nearby Galaxies Survey (SINGS) and eight galaxies that were serendipitously observed by SINGS. The morphological parameters demonstrate strong variations along the Hubble sequence, including statistically significant differences between S0/a-Sab and Sc-Sd galaxies. Early-type galaxies are generally found to be compact, centralized, symmetric sources in the 24-μm band, while late-type galaxies are generally found to be extended, asymmetric sources. These results suggest that the processes that increase the real or …
The Calibration Of Mid-Infrared Star Formation Rate Indicators, D Calzetti, Rc Kennicutt, Cw Engelbracht, C Leitherer, Bt Draine, L Kewley, J Moustakas, M Sosey, Da Dale, Kd Gordon, Gx Helou, Dj Hollenbach, L Armus, G Bendo, C Bot, B Buckalew, T Jarrett, A Li, M Meyer, Ej Murphy, M Prescott, Mw Regan, Gh Rieke, H Roussel, K Sheth, Jdt Smith, Md Thornley, F Walter
The Calibration Of Mid-Infrared Star Formation Rate Indicators, D Calzetti, Rc Kennicutt, Cw Engelbracht, C Leitherer, Bt Draine, L Kewley, J Moustakas, M Sosey, Da Dale, Kd Gordon, Gx Helou, Dj Hollenbach, L Armus, G Bendo, C Bot, B Buckalew, T Jarrett, A Li, M Meyer, Ej Murphy, M Prescott, Mw Regan, Gh Rieke, H Roussel, K Sheth, Jdt Smith, Md Thornley, F Walter
Astronomy Department Faculty Publication Series
With the goal of investigating the degree to which the MIR emission traces the SFR, we analyze Spitzer 8 and 24 μm data of star-forming regions in a sample of 33 nearby galaxies with available HST NICMOS images in the Paα (1.8756 μm) emission line. The galaxies are drawn from the SINGS sample and cover a range of morphologies and a factor ~10 in oxygen abundance. Published data on local low-metallicity starburst galaxies and LIRGs are also included in the analysis. Both the stellar continuum-subtracted 8 μm emission and the 24 μm emission correlate with the extinction-corrected Paα line emission, …
Star Formation In Ngc 5194 (M51a). Ii. The Spatially Resolved Star Formation Law, Rc Kennicutt, D Calzetti, F Walter, G Helou, Dj Hollenbach, L Armus, G Bendo, Da Dale, Bt Draine, Cw Engelbracht, Kd Gordon, Mkm Prescott, Mw Regan, Md Thornley, C Bot, E Brinks, E De Blok, D De Mello, M Meyer, J Moustakas, Ej Murphy, K Sheth, Jdt Smith
Star Formation In Ngc 5194 (M51a). Ii. The Spatially Resolved Star Formation Law, Rc Kennicutt, D Calzetti, F Walter, G Helou, Dj Hollenbach, L Armus, G Bendo, Da Dale, Bt Draine, Cw Engelbracht, Kd Gordon, Mkm Prescott, Mw Regan, Md Thornley, C Bot, E Brinks, E De Blok, D De Mello, M Meyer, J Moustakas, Ej Murphy, K Sheth, Jdt Smith
Astronomy Department Faculty Publication Series
We have studied the relationship between the star formation rate (SFR), surface density, and gas surface density in the spiral galaxy M51a (NGC 5194), using multiwavelength data obtained as part of the Spitzer Infrared Nearby Galaxies Survey (SINGS). We introduce a new SFR index based on a linear combination of Hα emission-line and 24 μm continuum luminosities, which provides reliable extinction-corrected ionizing fluxes and SFR densities over a wide range of dust attenuations. The combination of these extinction-corrected SFR densities with aperture synthesis H I and CO maps has allowed us to probe the form of the spatially resolved star …
The Cosmological Significance Of High-Velocity Cloud Complex H, Jd Simon, L Blitz, Aa Cole, Md Weinberg, M Cohen
The Cosmological Significance Of High-Velocity Cloud Complex H, Jd Simon, L Blitz, Aa Cole, Md Weinberg, M Cohen
Astronomy Department Faculty Publication Series
We have used new and archival infrared and radio observations to search for a dwarf galaxy associated with the high-velocity cloud (HVC) known as `complex H.' Complex H is a large (Ω gtrsim 400 deg2) and probably nearby (d = 27 kpc) HVC whose location in the Galactic plane has hampered previous investigations of its stellar content. The H I mass of the cloud is 2.0 × 107(d/27 kpc)2 Msun, making complex H one of the most massive HVCs if its distance is more than ~20 kpc. Virtually all similar H I clouds in other galaxy groups are associated with …
A First Estimate Of The Baryonic Mass Function Of Galaxies, Ef Bell, Dh Mcintosh, N Katz, Md Weinberg
A First Estimate Of The Baryonic Mass Function Of Galaxies, Ef Bell, Dh Mcintosh, N Katz, Md Weinberg
Astronomy Department Faculty Publication Series
We estimate the baryonic (stellar+cold gas) mass function of galaxies in the local universe by assigning a complete sample of Two Micron All Sky Survey and Sloan Digital Sky Survey galaxies a gas fraction based on a statistical sample of the entire population, under the assumption of a universally applicable stellar initial mass function. The baryonic mass function is similar to the stellar mass function at the high-mass end and has a reasonably steep faint-end slope owing to the typically high cold gas fractions and low stellar mass-to-light ratios characteristic of low-mass galaxies. The Schechter function fit parameters are phi*h-3 …
Cooling Radiation And The Ly Alpha Luminosity Of Forming Galaxies, Ma Fardal, N Katz, Jp Gardner, L Hernquist, Dh Weinberg, R Dave
Cooling Radiation And The Ly Alpha Luminosity Of Forming Galaxies, Ma Fardal, N Katz, Jp Gardner, L Hernquist, Dh Weinberg, R Dave
Astronomy Department Faculty Publication Series
We examine the cooling radiation from forming galaxies in hydrodynamic simulations of the LCDM model (cold dark matter with a cosmological constant), focusing on the Lyα line luminosities of high-redshift systems. Primordial composition gas condenses within dark matter potential wells, forming objects with masses and sizes comparable to the luminous regions of observed galaxies. As expected, the energy radiated in this process is comparable to the gravitational binding energy of the baryons, and the total cooling luminosity of the galaxy population peaks at z 2. However, in contrast to the classical picture of gas cooling from the ~106 K …