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Publications (2)9.93 Total impact

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    ABSTRACT: The gravitational lens system MG 0414+0534 has an unexceptional four- image lensing geometry; however, the optical counterparts of the radio images are exceedingly red, with spectra unlike that of any previously observed active nucleus. New infrared spectra reveal broad Balmer lines at a redshift of 2.639+/-0.002. We use these spectra, in combination with infrared and HST images, IRAS flux densities, the radio images of Hewitt et al. [AJ, 104,968(1992)] and Katz & Hewitt (ApJL, 409, L9 (1993)], and the optical spectrum of Hewitt et al. (1992), to argue that the background source in MG 0414+0534 is a typical high-redshift quasar heavily reddened by dust in the lens. Inferred values of visual extinction (A_V_) along the path of the brightest image range up to 6 mag, depending on the assumed shape of the unreddened spectrum and the redshift of the lens. Extinction along one of the other image paths is somewhat larger, along the other two somewhat smaller. The image paths all lie roughly 5 kpc from the core of the lens. The presence of large quantities of dust in the lenses of both MG 0414+0534 and MG 1131+0456 (Larkin et al. ApJL, 420, L9 (1994)] suggests that a significant fraction of massive galaxies at high redshifts is dusty. This has important implications for our understanding of galaxies at high redshift, as well as for optical searches for gravitational lensing.
    The Astronomical Journal 11/1995; 110:2570. · 4.97 Impact Factor
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    ABSTRACT: We have observed the rest-frame optical and UV spectra of the luminous, high redshift Infrared Astronomy Satellite (IRAS) source FSC 10214+4724. We find the optical emission lines to be characterized by ratios similar to those found in Seyfert II galaxies. We support the conclusion of previous work that the UV emission lines are similar to those attributed to Active Galactic Nuclei (AGN) rather than to star formation. The ratio H alpha/H beta greater than or equal to 20 (2 sigma lower limit) implies substantial reddening of the narrow line region with A(sub V) greater than 5.5, sufficient to hide a broad line region in our H alpha observations. Given this large inferred reddening and the strength of the UV continuum and emission lines, we conclude (as have others) that simple screen models of reddening are not appropriate for this object. These properties are very similar to those of the infrared luminous galaxies at lower redshift, suggesting that FSC 10244+4724 is the luminous extreme of the same population. We also present H band (1.6 micrometer) imaging polarimetry observations and find that the rest-frame optical emission is unpolarized (P = 3.2% +/- 22.0%). This deep image of the field shows FSC 10214+4724 to possess an unresolved core, with several companions located within 10 sec of the point source. We find it unlikely that this group of objects is physically associated with FSC 10214+4724 at z = 2.3, and we argue that their magnitudes and colors are more consistant with those expected with those expected for galaxies in a foreground group. While galaxy number counts would suggest that such a projection has a low probability of being observed randomly, a foreground group might gravitational lens the z = 2.3 source, making such random statistics inappropriate, and contribute to the large observed luminosity of FSC 10214+4724. Comparison of H band images taken on two occasions one year apart show that FSC 10214+4724 had varied by 0.16 +/- 0.03 mag relative to a nearby star during that time. The UV-optical emission line spectra, the bright dereddened continuum magnitude (K less than 12) of the unresolved core, its extremely large bolometric luminosity, strong UV polarization, and possible variability all suggest that FSC 10214+4724 harbors an obscured AGN. Given that we observe no spectral features attributable to star formation, it appears either that star formation in FSC 10214+4724 is more highly obscured at optical and UV wavelengths than the narrow line region of the AGN, or that the AGN (rather than star formation) dominates the large luminosity of this object.
    The Astronomical Journal 04/1994; · 4.97 Impact Factor