ON THE EFFECT OF THE COSMIC MICROWAVE BACKGROUND IN HIGH-REDSHIFT (SUB-)MILLIMETER OBSERVATIONS

By E. D. Cunha, B. Groves, F. Walter, R. Decarli, A. Weiss, C. Carilli, E. Daddi, D. Elbaz, R. Ivison, R. Maiolino and 4 more. Astrophysical Journal, 2013

222 citations recorded by the source corpus.

Modern (sub-)millimeter interferometers enable the measurement of the cool gas and dust emission of high-redshift galaxies (z > 5). However, at these redshifts the cosmic microwave background (CMB) temperature is higher, approaching, and even exceeding, the temperature of cold dust and molecular gas observed in the local universe. In this paper, we discuss the impact of the warmer CMB on (sub-)millimeter observations of high-redshift galaxies. The CMB affects the observed (sub-)millimeter dust continuum and the line emission (e.g., carbon monoxide, CO) in two ways: (1) it provides an additional source of (both dust and gas) heating and (2) it is a non-negligible background against which the line and continuum emission are measured. We show that these two competing processes affect the way we interpret the dust and gas properties of high-redshift galaxies using spectral energy distribution models. We quantify these effects and provide correction factors to compute what fraction of the intrinsic dust (and line) emission can be detected against the CMB as a function of frequency, redshift, and temperature. We discuss implications on the derived properties of high-redshift galaxies from (sub-)millimeter data. Specifically, the inferred dust and molecular gas masses can be severely underestimated for cold systems if the impact of the CMB is not properly taken into account.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/d0031d2a8f258ae676bb6bb9b021d1b989fdd538

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Citations in the corpus

GRAVITATIONAL LENS MODELS BASED ON SUBMILLIMETER ARRAY IMAGING OF HERSCHEL-SELECTED STRONGLY LENSED SUB-MILLIMETER GALAXIES AT z > 1.5 (2013, methodology): “However, for the dust temperatures and redshifts of the SMA subsample, this effect is insignificant (da Cunha et al. 2013) and we therefore do not incorporate it into our model fitting process.”
Pōniuā‘ena: A Luminous z = 7.5 Quasar Hosting a 1.5 Billion Solar Mass Black Hole (2020, background): “…LFIR = (3.3±0.1)×1012 L and LTIR = (4.7±0.1)×1012 L , assuming an optically thin grey body with dust temperature Td = 47 K and emissivity index β = 1.6 (Beelen et al. 2006) and taking the effect of the cosmic microwave background (CMB) on the dust emission into account (e.g., da Cunha et al. 2013).”
Dusty Star Forming Galaxies at High Redshift (2014, background): “An important sidenote is that very high redshift galaxies’ dust temperatures are also partially heated from Cosmic Microwave Background (CMB) radiation, which can be easily accounted for at a known redshift (da Cunha et al., 2013).”
The assembly of ‘normal’ galaxies at z ∼ 7 probed by ALMA (2015, methodology): “Other transitions are generally much fainter. da Cunha et al. (2013b) have inferred the cumulative space density of CO transitions as a function of flux detection threshold.”
Cool Gas in High-Redshift Galaxies (2013, background): “The molecular gas is affected in two ways by the CMB: First, the higher temperature of the CMB will lead to an increase of the line excitation, and thus the line luminosities (e.g., Obreschkow et al. 2009a, da Cunha et al. 2013).”
An Extreme Protocluster of Luminous Dusty Starbursts in the Early Universe (2017, background): “Equation (1) does not take into account the effect of the cosmic microwave background (CMB) on the [C I](1–0) line strength (da Cunha et al. 2013; Zhang et al. 2016).”
ALMA SPECTROSCOPIC SURVEY IN THE HUBBLE ULTRA DEEP FIELD: THE INFRARED EXCESS OF UV-SELECTED z = 2–10 GALAXIES AS A FUNCTION OF UV-CONTINUUM SLOPE AND STELLAR MASS (2016, background): “Dust-continuum emission shows a clear connection with the apparent stellar mass in galaxies – which is similar to a few prominent earlier predictions for the expected findings from a deep far-IR continuum survey over the HUDF with ALMA (da Cunha et al. 2013).”
Evolution of the dust emission of massive galaxies up to z=4 and constraints on their dominant mode of star formation (2014, methodology): “The dust temperature that our high-redshift galaxies would have for a virtually z = 0 CMB temperature, T z=0dust, is estimated following da Cunha et al. (2013) T z=0dust = ( (T measdust ) 4+β − (T z=0CMB)4+β [ (1 + z)4+β − 1 ]) 1 4+β , (4) 6 We could have used the mean stellar masses in each…”
ALMA IMAGING OF GAS AND DUST IN A GALAXY PROTOCLUSTER AT REDSHIFT 5.3: [C ii] EMISSION IN “TYPICAL” GALAXIES AND DUSTY STARBURSTS ≈1 BILLION YEARS AFTER THE BIG BANG (2014, background): “Any corrections to the LFIR limits required are small compared to other sources of uncertainty unless the dust temperature approaches Tz,CMB (see, e.g., da Cunha et al. 2013).”
Big Three Dragons: A z = 7.15 Lyman-break galaxy detected in [O iii] 88 μm, [C ii] 158 μm, and dust continuum with ALMA (2018, methodology): “For the whole system, correcting for the cosmic microwave background (CMB) effects (da Cunha et al. 2013; Ota et al. 2014), we obtain the best-fit Td values of 61 K, 54 K, and 48 K for βd = 1.5, 1.75, and 2.0, respectively, where the 1σ temperature uncertainty is about 10 K for each case.”
AN INTENSELY STAR-FORMING GALAXY AT z ∼ 7 WITH LOW DUST AND METAL CONTENT REVEALED BY DEEP ALMA AND HST OBSERVATIONS (2013, background): “…microwave background (CMB) whose blackbody temperature scales as T z=0CMB(1 + z), where T z=0 CMB is the temperature of present-day CMB, T z=0CMB = 2.73 K. Assuming local thermal equilibrium between ISM of Himiko and CMB at z = 6.595 (da Cunha et al. 2013), this yields a lower limit of Td = 21 K.”
ALMA SPECTROSCOPIC SURVEY IN THE HUBBLE ULTRA DEEP FIELD: SURVEY DESCRIPTION (2016, methodology): “J CO detections of ASPECS 1mm.1/2, a galaxy that was not included in the UDF catalog on which the predictions by da Cunha et al. (2013) were based.”