Browsing by Author "Wilner, D."

Now showing 1 - 5 of 5
  • No Thumbnail Available
    Item
    DOES THE PRESENCE OF PLANETS AFFECT THE FREQUENCY AND PROPERTIES OF EXTRASOLAR KUIPER BELTS? RESULTS FROM THE HERSCHEL DEBRIS AND DUNES SURVEYS
    (2015) Moro-Martin, A.; Marshall, J. P.; Kennedy, G.; Sibthorpe, B.; Matthews, B. C.; Eiroa, C.; Wyatt, M. C.; Lestrade, J. -F.; Maldonado, J.; Rodriguez, D.; Greaves, J. S.; Montesinos, B.; Mora, A.; Booth, M.; Duchene, G.; Wilner, D.; Horner, J.
    The study of the planet-debris disk connection can shed light on the formation and evolution of planetary systems. and may help "predict" the presence of planets around stars with certain disk characteristics. In preliminary analyses of subsamples of the Herschel DEBRIS and DUNES surveys, Wyatt et al. and Marshall et al. identified a tentative correlation between debris and the presence of low-mass planets. Here we use the cleanest possible sample out of these Herschel surveys to assess the presence of such a correlation, discarding stars without known ages, with ages <1 Gyr, and with binary companions <100 AU. to rule out possible correlations due to effects other than planet presence. In our resulting subsample of 204 FGK stars, we do not find evidence that debris disks are more common or more dusty around stars harboring high-mass or low-mass planets compared to a control sample without identified planets. There is no evidence either that the characteristic dust temperature of the debris disks around planet-bearing stars is any different from that in debris disks without identified planets, nor that debris disks are more or less common (or more or less dusty) around stars harboring multiple planets compared to single-planet systems. Diverse dynamical histories may account for the lack of correlations. The data show a correlation between the presence of high-mass planets and stellar metallicity, but no correlation between the presence of low-mass planets or debris and stellar metallicity. Comparing the observed cumulative distribution of fractional luminosity to those expected from a Gaussian distribution in logarithmic scale, we find that a distribution centered on the solar system's value fits the data well, while one centered at 10 times this value can be rejected. This is of interest in the context of future terrestrial planet detection and characterization because it indicates that there are good prospects for finding a large number of debris disk systems (i.e., with evidence of harboring planetesimals, the building blocks of planets) with exozodiacal emission low enough to be appropriate targets for an ATLAST-type mission to search for biosignatures.
  • No Thumbnail Available
    Item
    GRAVITATIONAL LENS MODELS BASED ON SUBMILLIMETER ARRAY IMAGING OF HERSCHEL-SELECTED STRONGLY LENSED SUB-MILLIMETER GALAXIES AT z > 1.5
    (2013) Bussmann, R. S.; Perez-Fournon, I.; Amber, S.; Calanog, J.; Gurwell, M. A.; Dannerbauer, H.; De Bernardis, F.; Fu, Hai; Harris, A. I.; Krips, M.; Lapi, A.; Maiolino, R.; Omont, A.; Riechers, D.; Wardlow, J.; Baker, A. J.; Birkinshaw, M.; Bock, J.; Bourne, N.; Clements, D. L.; Cooray, A.; De Zotti, G.; Dunne, L.; Dye, S.; Eales, S.; Farrah, D.; Gavazzi, R.; Nuevo, J. Gonzalez; Hopwood, R.; Ibar, E.; Ivison, R. J.; Laporte, N.; Maddox, S.; Martinez-Navajas, P.; Michalowski, M.; Negrello, M.; Oliver, S. J.; Roseboom, I. G.; Scott, Douglas; Serjeant, S.; Smith, A. J.; Smith, Matthew; Streblyanska, A.; Valiante, E.; van der Werf, P.; Verma, A.; Vieira, J. D.; Wang, L.; Wilner, D.
    Strong gravitational lenses are now being routinely discovered in wide-field surveys at (sub-)millimeter wavelengths. We present Submillimeter Array (SMA) high-spatial resolution imaging and Gemini-South and Multiple Mirror Telescope optical spectroscopy of strong lens candidates discovered in the two widest extragalactic surveys conducted by the Herschel Space Observatory: the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS) and the Herschel Multi-tiered Extragalactic Survey (HerMES). From a sample of 30 Herschel sources with S-500 > 100 mJy, 21 are strongly lensed (i.e., multiply imaged), 4 are moderately lensed (i.e., singly imaged), and the remainder require additional data to determine their lensing status. We apply a visibility-plane lens modeling technique to the SMA data to recover information about the masses of the lenses as well as the intrinsic (i.e., unlensed) sizes (r(half)) and far-infrared luminosities (L-FIR) of the lensed submillimeter galaxies (SMGs). The sample of lenses comprises primarily isolated massive galaxies, but includes some groups and clusters as well. Several of the lenses are located at z(lens) > 0.7, a redshift regime that is inaccessible to lens searches based on Sloan Digital Sky Survey spectroscopy. The lensed SMGs are amplified by factors that are significantly below statistical model predictions given the 500 mu m flux densities of our sample. We speculate that this may reflect a deficiency in our understanding of the intrinsic sizes and luminosities of the brightest SMGs. The lensed SMGs span nearly one decade in L-FIR (median L-FIR = 7.9 x 10(12) L-circle dot) and two decades in FIR luminosity surface density (median Sigma(FIR) = 6.0 x 10(11) L-circle dot kpc(-2)). The strong lenses in this sample and others identified via (sub-) mm surveys will provide a wealth of information regarding the astrophysics of galaxy formation and evolution over a wide range in redshift.
  • Thumbnail Image
    Item
    High-resolution ALMA observations of compact discs in the wide-binary system Sz 65 and Sz 66
    (2024) Miley, J. M.; Carpenter, J.; Booth, R.; Jennings, J.; Haworth, T. J.; Vioque, M.; Andrews, S.; Wilner, D.; Benisty, M.; Huang, J.; Perez, L.; Guzman, V.; Ricci, L.; Isella, A.
    Context. Substructures in disc density are ubiquitous in the bright extended discs that are observed with high resolution. These substructures are intimately linked to the physical mechanisms driving planet formation and disc evolution. Surveys of star-forming regions find that most discs are in fact compact, less luminous, and do not exhibit these same substructures. It remains unclear whether compact discs also have similar substructures or if they are featureless. This suggests that different planet formation and disc evolution mechanisms operate in these discs. Aims. We investigated evidence of substructure within two compact discs around the stars Sz 65 and Sz 66 using high angular resolution observations with ALMA at 1.3 mm. The two stars form a wide-binary system with 6 ''.36 separation. The continuum observations achieve a synthesised beam size of 0 ''.026 x 0 ''.018, equivalent to about 4.0 x 2.8 au, enabling a search for substructure on these spatial scales and a characterisation of the gas and dust disc sizes with high precision. Methods. We analysed the data in the image plane through an analysis of reconstructed images, as well as in the uv plane by non-parametrically modelling the visibilities and by an analysis of the (CO)-C-12 (2-1) emission line. Comparisons were made with highresolution observations of compact discs and radially extended discs. Results. We find evidence of substructure in the dust distribution of Sz 65, namely a shallow gap centred at approximate to 20 au, with an emission ring exterior to it at the outer edge of the disc. Ninety percent of the measured continuum flux is found within 27 au, and the distance for (CO)-C-12 is 161 au. The observations show that Sz 66 is very compact: 90% of the flux is contained within 16 au, and 90% of the molecular gas flux lies within 64 au. Conclusions. While the overall prevalence and diversity of substructure in compact discs relative to larger discs is yet to be determined, we find evidence that substructures can exist in compact discs.
  • Thumbnail Image
    Item
    The AU Mic Debris Disk: far-infrared and submillimeter resolved imaging
    (2015) Matthews, B.; Kennedy, G.; Sibthorpe, B.; Holland, W.; Haworth-Booth, Mark; Kalas, P.; Macgregor, M.; Wilner, D.; Vandenbussche, B.; Olofsson, G.; Blommaert, J.; Brandeker, A.; Dent, W.; De, Vries, B.; Di, Francesco, J.; Fridlund, M.
  • Thumbnail Image
    Item
    The debris disc of solar analogue tau Ceti: Herschel observations and dynamical simulations of the proposed multiplanet system
    (2014) Lawler, S.; Di Francesco, J.; Kennedy, G.; Sibthorpe, B.; Haworth-Booth, Mark; Vandenbussche, B.; Matthews, B.; Holland, W.; Greaves, J.; Wilner, D.