Diane Cormier

Publications (2)6.02 Total impact

• Source

  Available from: arxiv.org

  Article: Infrared Luminosities and Aromatic Features in the 24 μm Flux-limited Sample of 5MUSES

  Yanling Wu, George Helou, Lee Armus, Diane Cormier, Yong Shi, Daniel Dale, Kalliopi Dasyra, J. D. Smith, Casey Papovich, Bruce Draine, Nurur Rahman, Sabrina Stierwalt, Dario Fadda, G. Lagache, and Edward L. Wright
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  ABSTRACT: We study a 24 μm selected sample of 330 galaxies observed with the infrared spectrograph for the 5 mJy Unbiased Spitzer Extragalactic Survey. We estimate accurate total infrared luminosities by combining mid-IR spectroscopy and mid-to-far infrared photometry, and by utilizing new empirical spectral templates from Spitzer data. The infrared luminosities of this sample range mostly from 109 L ☉ to 1013.5 L ☉, with 83% in the range 1010 L ☉ < L IR < 1012 L ☉. The redshifts range from 0.008 to 4.27, with a median of 0.144. The equivalent widths of the 6.2 μm aromatic feature have a bimodal distribution, probably related to selection effects. We use the 6.2 μm polycyclic aromatic hydrocarbon equivalent width (PAH EW) to classify our objects as starburst (SB)-dominated (44%), SB-AGN composite (22%), and active galactic nucleus (AGN)-dominated (34%). The high EW objects (SB-dominated) tend to have steeper mid-IR to far-IR spectral slopes and lower L IR and redshifts. The low EW objects (AGN-dominated) tend to have less steep spectral slopes and higher L IR and redshifts. This dichotomy leads to a gross correlation between EW and slope, which does not hold within either group. AGN-dominated sources tend to have lower log(L PAH7.7 μm/L PAH11.3 μm) ratios than star-forming galaxies, possibly due to preferential destruction of the smaller aromatics by the AGN. The log(L PAH7.7 μm/L PAH11.3 μm) ratios for star-forming galaxies are lower in our sample than the ratios measured from the nuclear spectra of nearby normal galaxies, most probably indicating a difference in the ionization state or grain size distribution between the nuclear regions and the entire galaxy. Finally, we provide a calibration relating the monochromatic continuum or aromatic feature luminosity to L IR for different types of objects.
  The Astrophysical Journal 10/2010; 723(1):895. · 6.02 Impact Factor
• Source

  Available from: Kalliopi Dasyra

  Article: Infrared Luminosities and Aromatic Features in the 24um Flux Limited Sample of 5MUSES

  Yanling Wu, George Helou, Lee Armus, Diane Cormier, Yong Shi, Daniel Dale, Kalliopi Dasyra, J. D. Smith, Casey Papovich, Bruce Draine, Nurur Rahman, Sabrina Stierwalt, Dario Fadda, G. Lagache, Edward L. Wright
  [show abstract] [hide abstract]
  ABSTRACT: We study a 24\,$\mu$m selected sample of 330 galaxies observed with the Infrared Spectrograph for the 5\,mJy Unbiased Spitzer Extragalactic Survey. We estimate accurate total infrared luminosities by combining mid-IR spectroscopy and mid-to-far infrared photometry, and by utilizing new empirical spectral templates from {\em Spitzer} data. The infrared luminosities of this sample range mostly from 10$^9$L$_\odot$ to $10^{13.5}$L$_\odot$, with 83% in the range 10$^{10}$L$_\odot$$<$L$_{\rm IR}$$<10^{12}$L$_\odot$. The redshifts range from 0.008 to 4.27, with a median of 0.144. The equivalent widths of the 6.2\,$\mu$m aromatic feature have a bimodal distribution. We use the 6.2\,$\mu$m PAH EW to classify our objects as SB-dominated (44%), SB-AGN composite (22%), and AGN-dominated (34%). The high EW objects (SB-dominated) tend to have steeper mid-IR to far-IR spectral slopes and lower L$_{\rm IR}$ and redshifts. The low EW objects (AGN-dominated) tend to have less steep spectral slopes and higher L$_{\rm IR}$ and redshifts. This dichotomy leads to a gross correlation between EW and slope, which does not hold within either group. AGN dominated sources tend to have lower log(L$_{\rm PAH 7.7\mu m}$/L$_{\rm PAH 11.3\mu m}$) ratios than star-forming galaxies, possibly due to preferential destruction of the smaller aromatics by the AGN. The log(L$_{\rm PAH 7.7\mu m}$/L$_{\rm PAH 11.3\mu m}$) ratios for star-forming galaxies are lower in our sample than the ratios measured from the nuclear spectra of nearby normal galaxies, most probably indicating a difference in the ionization state or grain size distribution between the nuclear regions and the entire galaxy. Finally, we provide a calibration relating the monochromatic 5.8, 8, 14 and 24um continuum or Aromatic Feature luminosity to L$_{\rm IR}$ for different types of objects. Comment: accepted for publication in ApJ
  09/2010;