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Cross-correlation of cosmic far-infrared background anisotropies with large scale structures
摘要： We measure the cross-power spectra between luminous red galaxies (LRGs) from the Sloan Digital Sky Survey (SDSS)-III data release 8 (DR8) and cosmic infrared background (CIB) anisotropies from Planck and data from the Improved Reprocessing (IRIS) of the Infrared Astronomical Satellite (IRAS) at 353, 545, 857, and 3000 GHz, corresponding to 850, 550, 350 and 100 μm, respectively, in the multipole range 100 < l < 1000. Using approximately 6.5 × 10^5 photometrically determined LRGs in 7760 deg^2 of the northern hemisphere in the redshift range 0.45 < z < 0.65, we model the far-infrared background (FIRB) anisotropies with an extended version of the halo model. With these methods, we confirm the basic picture obtained from recent analyses of FIRB anisotropies with Herschel and Planck that the most efficient halo mass at hosting star forming galaxies is log(Meff/M☉) = 12.84 ± 0.15. We estimate the percentage of FIRB anisotropies correlated with LRGs as approximately 11.8%, 3.9%, 1.8%, and 1.0% of the total at 3000, 857, 545, and 353 GHz, respectively. At redshift z ～ 0.55, the bias of FIRB galaxies with respect to the dark matter density field has the value bFIRB ～ 1.45, and the mean dust temperature of FIRB galaxies is Td = 26 K. Finally, we discuss the impact of present and upcoming cross-correlations with far-infrared background anisotropies on the determination of the global star formation history and the link between galaxies and dark matter.
关键词： galaxies: statistics,large-scale structure of Universe,galaxies: evolution,cosmic background radiation,infrared: diffuse background
更新于2025-09-23 15:22:29
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The extragalactic background light revisited and the cosmic photon–photon opacity ( <i>Corrigendum</i> )
摘要： For some unexplained reasons, all tables in the Franceschini & Rodighiero (2017) paper have been mixed up. Tables 1–3 reported there were identical to those published in Franceschini et al. (2008). We report here in Tables 1, 2, and 4 the corresponding correct values in terms of photon proper number densities and photon–photon optical depths as a function of photon energy. We also took this occasion to add a new table (Table 3) including the predicted extragalactic background light values at redshifts between 2 and 3.5, as requested by some readers of the Franceschini & Rodighiero (2017) paper. Both photon number densities and photon–photon optical depths are calculated including the contributions of the cosmic microwave background assumed as a black-body with T = 2.728 K. Except for the numerical values in the tables, all the rest of the Franceschini & Rodighiero (2017) paper is unaffected by the problem.
关键词： addenda,gamma rays: galaxies,diffuse radiation,errata,cosmic background radiation,BL Lacertae objects: general
更新于2025-09-23 15:22:29
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The EBEX Balloon-borne Experiment—Optics, Receiver, and Polarimetry
摘要： The E and B Experiment (EBEX) was a long-duration balloon-borne cosmic microwave background (CMB) polarimeter that flew over Antarctica in 2012. We describe the experiment’s optical system, receiver, and polarimetric approach and report on their in-flight performance. EBEX had three frequency bands centered on 150, 250, and 410 GHz. To make efficient use of limited mass and space, we designed a 115 cm2 sr high-throughput optical system that had two ambient temperature mirrors and four antireflection-coated polyethylene lenses per focal plane. All frequency bands shared the same optical train. Polarimetry was achieved with a continuously rotating achromatic half-wave plate (AHWP) that was levitated with a superconducting magnetic bearing (SMB). This is the first use of an SMB in astrophysics. Rotation stability was 0.45% over a period of 10 hr, and angular position accuracy was 0°.01. The measured modulation efficiency was above 90% for all bands. To our knowledge the 109% fractional bandwidth of the AHWP was the broadest implemented to date. The receiver, composed of one lens and the AHWP at a temperature of 4 K, the polarizing grid and other lenses at 1 K, and the two focal planes at 0.25 K, performed according to specifications, giving focal plane temperature stability with a fluctuation power spectrum that had a 1/f knee at 2 mHz. EBEX was the first balloon-borne instrument to implement technologies characteristic of modern CMB polarimeters, including high-throughput optical systems, and large arrays of transition edge sensor bolometric detectors with multiplexed readouts.
关键词： cosmology: observations,instrumentation: polarimeters,cosmic background radiation,polarization,balloons
更新于2025-09-23 15:21:01
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The EBEX Balloon-borne Experiment—Detectors and Readout
摘要： EBEX was a long-duration balloon-borne experiment to measure the polarization of the cosmic microwave background. The experiment had three frequency bands centered at 150, 250, and 410 GHz and was the first to use a kilopixel array of transition edge sensor bolometers aboard a balloon platform. We describe the design and characterization of the array and the readout system. From the lowest to highest frequency, the median measured detectors' average thermal conductances were 39, 53, and 63 pW/K, the medians of transition temperatures were 0.45, 0.48, and 0.47 K, and the medians of normal resistances were 1.9, 1.5, and 1.4 Ω; we also give the measured distributions. With the exception of the thermal conductance at 150 GHz, all measured values are within 30% of their design. We measure median low-loop-gain time constants τ0 = 88, 46, and 57 ms. Two measurements of bolometer absorption efficiency gave results consistent within 10% and showing high (～0.9) efficiency at 150 GHz and medium (～0.35 and ～0.25) efficiency at the two higher bands. We measure a median total optical power absorbed of 3.6, 5.3, and 5.0 pW. EBEX pioneered the use of the digital version of the frequency domain multiplexing system. We multiplexed the bias and readout of 16 bolometers onto two wires. The median per-detector noise-equivalent temperatures are 400, 920, and 14,500 mK. We compare these values to our preflight predictions and to a previous balloon payload. We discuss the sources of excess noise and the path for a future payload to make full use of the balloon environment.
关键词： cosmology: observations,instrumentation: polarimeters,cosmic background radiation,balloons,instrumentation: detectors
更新于2025-09-23 15:21:01
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QUANTIFYING DISTRIBUTIONS OF THE LYMAN CONTINUUM ESCAPE FRACTION
摘要： Simulations have indicated that most of the escaped Lyman continuum (LyC) photons escape through a minority of solid angles with near complete transparency, with the remaining majority of the solid angles largely opaque, resulting in a very broad and skewed probability distribution function (PDF) of the escape fraction when viewed at different angles. Thus, the escape fraction of LyC photons of a galaxy observed along a line of sight merely represents the properties of the interstellar medium along that line of sight, which may be an ill-representation of the true escape fraction of the galaxy averaged over its full sky. Here we study how LyC photons escape from galaxies at z = 4–6, utilizing high-resolution large-scale cosmological radiation-hydrodynamic simulations. We compute the PDF of the mean escape fraction (?f_esc?) averaged over mock observational samples, as a function of the sample size, compared to the true mean (if an infinite sample size is used). We find that, when the sample size is small, the apparent mean skews to the low end. For example, for a true mean of 6.7%, an observational sample of (2,10,50) galaxies at z = 4 would have a 2.5% probability of obtaining the sample mean lower than (0.007%, 1.8%, 4.1%) and a 2.5% probability of obtaining the sample mean greater than (43%, 18%, 11%). Our simulations suggest that at least ～100 galaxies should be stacked in order to constrain the true escape fraction within 20% uncertainty.
关键词： dark ages, reionization, first stars,cosmic background radiation,galaxies: high-redshift,ultraviolet: galaxies,radiative transfer,large-scale structure of universe
更新于2025-09-19 17:15:36