The Experts below are selected from a list of 234 Experts worldwide ranked by ideXlab platform

Klaus J. Boller - One of the best experts on this subject based on the ideXlab platform.

I. D. Lindsay - One of the best experts on this subject based on the ideXlab platform.

Babu Adhimoolam - One of the best experts on this subject based on the ideXlab platform.

D Weedman - One of the best experts on this subject based on the ideXlab platform.

  • spitzer irs spectra of optically faint Infrared Sources with weak spectral features
    The Astrophysical Journal, 2006
    Co-Authors: D Weedman, Le E Floch, Sarah J U Higdon, J L Higdon, J R Houck, B T Soifer, M J I Brown, Buell T Jannuzi, Marcia J Rieke, V Desai
    Abstract:

    Spectra have been obtained with the low-resolution modules of the Infrared Spectrograph (IRS) on the Spitzer Space Telescope (Spitzer) for 58 Sources having f_ν(24 μm) > 0.75 mJy. Sources were chosen from a survey of 8.2 deg^2 within the NOAO Deep Wide-Field Survey region in Bootes (NDWFS) using the Multiband Imaging Photometer (MIPS) on Spitzer. Most Sources are optically very faint (I > 24 mag). Redshifts have previously been determined for 34 Sources, based primarily on the presence of a deep 9.7 μm silicate absorption feature, with a median z of 2.2. Spectra are presented for the remaining 24 Sources for which we were previously unable to determine a confident redshift because the IRS spectra show no strong features. Optical photometry from the NDWFS and Infrared photometry with MIPS and the Infrared Array Camera on Spitzer (IRAC) are given, with K photometry from the Keck I telescope for some objects. The Sources without strong spectral features have overall spectral energy distributions (SEDs) and distributions among optical and Infrared fluxes that are similar to those for the Sources with strong absorption features. Nine of the 24 Sources are found to have feasible redshift determinations based on fits of a weak silicate absorption feature. Results confirm that the "1 mJy" population of 24 μm Spitzer Sources that are optically faint is dominated by dusty Sources with spectroscopic indicators of an obscured AGN rather than a starburst. There remain 14 of the 58 Sources observed in Bootes for which no redshift could be estimated, and 5 of these Sources are invisible at all optical wavelengths.

  • redshifts from spitzer spectra for optically faint radio selected Infrared Sources
    The Astrophysical Journal, 2006
    Co-Authors: D Weedman, Le E Floch, Sarah J U Higdon, J L Higdon, J R Houck
    Abstract:

    Spectra have been obtained with the Infrared Spectrograph on the Spitzer Space Telescope for 18 optically faint Sources (R 23.9 mag) having fν(24 μm) > 1.0 mJy and having radio detections at 20 cm to a limit of 115 μJy. The Sources are within the Spitzer First Look Survey. Redshifts are determined for 14 Sources from strong silicate absorption features (12 Sources) or strong PAH emission features (two Sources), with median redshift of 2.1. Results confirm that optically faint Sources of ~1 mJy at 24 μm are typically at redshifts z ~ 2, verifying the high efficiency in selecting high-redshift Sources based on extreme Infrared-to-optical flux ratio, and indicate that 24 μm Sources that also have radio counterparts are not systematically different than samples chosen only by their Infrared-to-optical flux ratios. Using the parameter q = log[fν(24 μm)/fν(20 cm)], 17 of the 18 Sources observed have values of 0 < q < 1, in the range expected for starburst-powered Sources, but only a few of these show strong PAH emission as expected from starbursts, with the remainder showing absorbed or power-law spectra consistent with an AGN luminosity source. This confirms previous indications that optically faint Spitzer Sources with fν(24 μm) 1.0 mJy are predominately AGNs and represent the upper end of the luminosity function of dusty Sources at z ~ 2. Based on the characteristics of the Sources observed so far, we predict that the nature of Sources selected at 24 μm will change for fν(24 μm) 0.5 mJy to Sources dominated primarily by starbursts.

J R Houck - One of the best experts on this subject based on the ideXlab platform.

  • spitzer irs spectra of optically faint Infrared Sources with weak spectral features
    The Astrophysical Journal, 2006
    Co-Authors: D Weedman, Le E Floch, Sarah J U Higdon, J L Higdon, J R Houck, B T Soifer, M J I Brown, Buell T Jannuzi, Marcia J Rieke, V Desai
    Abstract:

    Spectra have been obtained with the low-resolution modules of the Infrared Spectrograph (IRS) on the Spitzer Space Telescope (Spitzer) for 58 Sources having f_ν(24 μm) > 0.75 mJy. Sources were chosen from a survey of 8.2 deg^2 within the NOAO Deep Wide-Field Survey region in Bootes (NDWFS) using the Multiband Imaging Photometer (MIPS) on Spitzer. Most Sources are optically very faint (I > 24 mag). Redshifts have previously been determined for 34 Sources, based primarily on the presence of a deep 9.7 μm silicate absorption feature, with a median z of 2.2. Spectra are presented for the remaining 24 Sources for which we were previously unable to determine a confident redshift because the IRS spectra show no strong features. Optical photometry from the NDWFS and Infrared photometry with MIPS and the Infrared Array Camera on Spitzer (IRAC) are given, with K photometry from the Keck I telescope for some objects. The Sources without strong spectral features have overall spectral energy distributions (SEDs) and distributions among optical and Infrared fluxes that are similar to those for the Sources with strong absorption features. Nine of the 24 Sources are found to have feasible redshift determinations based on fits of a weak silicate absorption feature. Results confirm that the "1 mJy" population of 24 μm Spitzer Sources that are optically faint is dominated by dusty Sources with spectroscopic indicators of an obscured AGN rather than a starburst. There remain 14 of the 58 Sources observed in Bootes for which no redshift could be estimated, and 5 of these Sources are invisible at all optical wavelengths.

  • redshifts from spitzer spectra for optically faint radio selected Infrared Sources
    The Astrophysical Journal, 2006
    Co-Authors: D Weedman, Le E Floch, Sarah J U Higdon, J L Higdon, J R Houck
    Abstract:

    Spectra have been obtained with the Infrared Spectrograph on the Spitzer Space Telescope for 18 optically faint Sources (R 23.9 mag) having fν(24 μm) > 1.0 mJy and having radio detections at 20 cm to a limit of 115 μJy. The Sources are within the Spitzer First Look Survey. Redshifts are determined for 14 Sources from strong silicate absorption features (12 Sources) or strong PAH emission features (two Sources), with median redshift of 2.1. Results confirm that optically faint Sources of ~1 mJy at 24 μm are typically at redshifts z ~ 2, verifying the high efficiency in selecting high-redshift Sources based on extreme Infrared-to-optical flux ratio, and indicate that 24 μm Sources that also have radio counterparts are not systematically different than samples chosen only by their Infrared-to-optical flux ratios. Using the parameter q = log[fν(24 μm)/fν(20 cm)], 17 of the 18 Sources observed have values of 0 < q < 1, in the range expected for starburst-powered Sources, but only a few of these show strong PAH emission as expected from starbursts, with the remainder showing absorbed or power-law spectra consistent with an AGN luminosity source. This confirms previous indications that optically faint Spitzer Sources with fν(24 μm) 1.0 mJy are predominately AGNs and represent the upper end of the luminosity function of dusty Sources at z ~ 2. Based on the characteristics of the Sources observed so far, we predict that the nature of Sources selected at 24 μm will change for fν(24 μm) 0.5 mJy to Sources dominated primarily by starbursts.