A comparison of secondary and postsecondary school teachers' and administrators' attitudes toward tech-prep programs

Huang, Liang-Chih

doi:10.31274/rtd-180813-9820

Cited by 1 publication

(1 citation statement)

References 26 publications

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“…Trying to determine if the IR-excess objects in our sample harbor Compton-thick AGN is beyond the scope of this paper. Some recent work suggests alternative explanations for mid-IR excess at z ∼ 2 involving PAH emission at 8 µm (Murphy et al 2008;Huang et al 2009). The AGN that we identify in Section 6 are mostly not IR-excess sources (only 12% of optical or X-ray AGN have IRX> 3.16), although they do represent somewhat higher fraction among IRexcess sources (10%) than among those which are not (4%).…”

Section: Ir Excess and Compton-thick Agnmentioning

confidence: 99%

MID-IR LUMINOSITIES AND UV/OPTICAL STAR FORMATION RATES ATz< 1.4

Salim

Dickinson

Rich

et al. 2009

ApJ

151

192

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Ultraviolet non-ionizing continuum and mid-IR emission constitute the basis of two widely used star formation indicators at intermediate and high redshifts. We study 2430 galaxies with z < 1.4 in the Extended Groth Strip with deep MIPS 24 µm observations from FIDEL, spectroscopy from DEEP2, and UV, optical, and near-IR photometry from AEGIS. The data are coupled with dust-reddened stellar population models and Bayesian SED fitting to estimate dust-corrected SFRs. In order to probe the dust heating from stellar populations of various ages, the derived SFRs were averaged over various timescales-from 100 Myr for "current" SFR (corresponding to young stars) to 1-3 Gyr for long-timescale SFRs (corresponding to the light-weighted age of the dominant stellar populations). These SED-based UV/optical SFRs are compared to total infrared luminosities extrapolated from 24 µm observations, corresponding to 10-18 µm rest frame. The total IR luminosities are in the range of normal star forming galaxies and LIRGs (10 10 -10 12 L ⊙ ). We show that the IR luminosity can be estimated from the UV and optical photometry to within a factor of two, implying that most z < 1.4 galaxies are not optically thick. We find that for the blue, actively star forming galaxies the correlation between the IR luminosity and the UV/optical SFR shows a decrease in scatter when going from shorter to longer SFR-averaging timescales. We interpret this as the greater role of intermediate age stellar populations in heating the dust than what is typically assumed. Equivalently, we observe that the IR luminosity is better correlated with dust-corrected optical luminosity than with dust-corrected UV light. We find that this holds over the entire redshift range. Many so-called green valley galaxies are simply dust-obscured actively star-forming galaxies. However, there exist 24 µm-detected galaxies, some with L IR > 10 11 L ⊙ , yet with little current star formation. For them a reasonable amount of dust absorption of stellar light (but presumably higher than in nearby early-type galaxies) is sufficient to produce the observed levels of IR, which includes a large contribution from intermediate and old stellar populations. In our sample, which contains very few ULIRGs, optical and X-ray AGNs do not contribute on average more than ∼ 50% to the mid-IR luminosity, and we see no evidence for a large population of "IR excess" galaxies.

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Section: Ir Excess and Compton-thick Agnmentioning

confidence: 99%