Near-infrared Extragalactic Background Light Research Articles

Near-infrared Extragalactic Background Light Fluctuations on Nonlinear Scales

Several fluctuation studies on the near-infrared extragalactic background light (EBL) find an excess power at tens of arcminute scales (ℓ ∼ 103). Emission from the intra-halo light (IHL) has been proposed as a possible explanation for the excess signal. In this work, we investigate the emission from the integrated galaxy light (IGL) and IHL in the power spectrum of EBL fluctuations using the simulated galaxy catalog MICECAT. We find that at ℓ ∼ 103, the one-halo clustering from satellite galaxies has comparable power to the two-halo term in the IGL power spectrum. In some previous EBL analyses, the IGL model assumed a small one-halo clustering signal, which may result in overestimating the IHL contribution to the EBL. We also investigate the dependence of the IGL+IHL power spectrum on the IHL distribution as a function of redshift and halo mass, and the spatial profile within the halo. Our forecast suggests that the upcoming SPHEREx deep field survey can distinguish different IHL models considered in this work with high significance. Finally, we quantify the bias in the power spectrum from the correlation of the mask and the signal, which has not been accounted for in previous analyses.

Probing Intra-Halo Light with Galaxy Stacking in CIBER Images

Abstract We study the stellar halos of 0.2 ≲ z ≲ 0.5 galaxies with stellar masses spanning M * ∼ 1010.5 to 1012 M ⊙ (approximately L * galaxies at this redshift) using imaging data from the Cosmic Infrared Background Experiment (CIBER). A previous CIBER fluctuation analysis suggested that intra-halo light (IHL) contributes a significant portion of the near-infrared extragalactic background light (EBL), the integrated emission from all sources throughout cosmic history. In this work, we carry out a stacking analysis with a sample of ∼30,000 Sloan Digital Sky Survey (SDSS) photometric galaxies from CIBER images in two near-infrared bands (1.1 and 1.8 μm) to directly probe the IHL associated with these galaxies. We stack galaxies in five sub-samples split by brightness and detect an extended galaxy profile beyond the instrument point-spread function (PSF) derived by stacking stars. We jointly fit a model for the inherent galaxy light profile plus large-scale one- and two-halo clustering to measure the extended galaxy IHL. We detect nonlinear one-halo clustering in the 1.8 μm band at a level consistent with numerical simulations. By extrapolating the fraction of extended galaxy light we measure to all galaxy mass scales, we find ∼30%/15% of the total galaxy light budget from galaxies is at radius r > 10/20 kpc, respectively. These results are new at near-infrared wavelengths at the L * mass scale and suggest that the IHL emission and one-halo clustering could have appreciable contributions to the amplitude of large-scale EBL background fluctuations.

On the origin of the optical and near-infrared extragalactic background light.

In optical and near-infrared background light, excess brightness and fluctuation over the known backgrounds have been reported. To delineate their origin, a fluctuation analysis of the deepest optical images was performed, leading to the detection of a flat fluctuation down to 0.2 arcsec, which is much larger than that expected for galaxies. The sky brightness obtained from the detected fluctuation is a few-times brighter than the integrated light of the galaxies. These findings require some new objects. As a candidate, faint compact objects (FCOs) whose surface number density rapidly increases to the faint end were proposed. FCOs are very compact and show peculiar spectra with infrared excess. If FCOs cause the excess brightness and fluctuation, the surface number density reaches 2.6 × 103 arcsec−2. γ-ray observations require the redshift of FCOs to be less than 0.1 with FCOs consisting of missing baryons. A very low M/L indicates that FCOs are powered by gravitational energy associated with black holes.

The Isotropic Interplanetary Dust Cloud and Near-infrared Extragalactic Background Light Observed with COBE/DIRBE

Abstract We report observation of isotropic interplanetary dust (IPD) by analyzing the infrared (IR) maps of the Diffuse Infrared Background Experiment (DIRBE) on board the Cosmic Background Explorer (COBE) spacecraft. To search for the isotropic IPD, we perform new analysis in terms of the solar elongation angle (ϵ), because we expect the zodiacal light (ZL) intensity from the isotropic IPD to decrease as a function of ϵ. We use the DIRBE weekly averaged maps covering 64° ≲ ϵ ≲ 124° and inspect the ϵ dependence of residual intensity after subtracting conventional ZL components. We find the ϵ dependence of the residuals, indicating the presence of the isotropic IPD. However, the mid-IR ϵ dependence is different from that of the isotropic IPD model at ϵ ≳ 90°, where the residual intensity increases as a function of ϵ. To explain the observed ϵ dependence, we assume a spheroidal IPD cloud showing higher density farther away from the Sun. We estimate the intensity of the near-IR extragalactic background light (EBL) by subtracting the spheroidal component, assuming the spectral energy distribution from the residual brightness at 12 μm. The EBL intensity is derived as , , and at 1.25, 2.2, and 3.5 μm, respectively. The EBL is still a few times larger than the integrated light of normal galaxies, suggesting the existence of unaccounted-for extragalactic sources.

Large angular scale fluctuations of near-infrared extragalactic background light based on the IRTS observations

Abstract We measure the spatial fluctuations of the Near-Infrared Extragalactic Background Light (NIREBL) from 2° to 20° in angular scale at the 1.6 and $2.2\, \mu \mathrm{m}$ using data obtained with Near-Infrared Spectrometer (NIRS) on board the Infrared Telescope in Space (IRTS). The brightness of the NIREBL is estimated by subtracting foreground components such as zodiacal light, diffuse Galactic light, and integrated star light from the observed sky. The foreground components are estimated using well-established models and archive data. The NIREBL fluctuations for the 1.6 and $2.2\, \mu \mathrm{m}$ connect well toward the sub-degree scale measurements from previous studies. Overall, the fluctuations show a wide bump with a center at around 1° and the power decreases toward larger angular scales with nearly a single power-law spectrum (i.e., ${F[\sqrt{l(l+1)C_l/2\pi }]} \sim \theta ^{-1}]$, indicating that the large-scale power is dominated by the random spatial distribution of the sources. After examining several known sources, contributors such as normal galaxies, high-redshift objects, intra-halo light, and far-IR cosmic background, we conclude that the excess fluctuation at around the 1° scale cannot be explained by any of them.

New Spectral Evidence of an Unaccounted Component of the Near-infrared Extragalactic Background Light from the CIBER

Abstract The extragalactic background light (EBL) captures the total integrated emission from stars and galaxies throughout the cosmic history. The amplitude of the near-infrared EBL from space absolute photometry observations has been controversial and depends strongly on the modeling and subtraction of the zodiacal light (ZL) foreground. We report the first measurement of the diffuse background spectrum at 0.8–1.7 μm from the CIBER experiment. The observations were obtained with an absolute spectrometer over two flights in multiple sky fields to enable the subtraction of ZL, stars, terrestrial emission, and diffuse Galactic light. After subtracting foregrounds and accounting for systematic errors, we find the nominal EBL brightness, assuming the Kelsall ZL model, is nW m−2 sr−1 at 1.4 μm. We also analyzed the data using the Wright ZL model, which results in a worse statistical fit to the data and an unphysical EBL, falling below the known background light from galaxies at λ < 1.3 μm. Using a model-independent analysis based on the minimum EBL brightness, we find an EBL brightness of nWm−2 sr−1 at 1.4 μm. While the derived EBL amplitude strongly depends on the ZL model, we find that we cannot fit the spectral data to ZL, Galactic emission, and EBL from solely integrated galactic light from galaxy counts. The results require a new diffuse component, such as an additional foreground or an excess EBL with a redder spectrum than that of ZL.

Energy Density Driven Galactic Formation and Evolution

© La Fortune This article is distributed under the terms of the Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and redistribution in any medium, provided that the original author and source are credited. This letter is inspired by the findings of M. Rabinowitz in his recent publication, “Why Observable Space Is Solely Three Dimensional” (Rabinowitz 2014). His paper provides coherent reasoning why our physical universe can only have one time and three spatial dimensions. He also states that “flux,” i.e., electrostatics and by analogy, gravitation, must remain consistent with threedimensional space with forces obeying the inverse-square law.

On the origin of near-infrared extragalactic background light anisotropy.

Extragalactic background light (EBL) anisotropy traces variations in the total production of photons over cosmic history and may contain faint, extended components missed in galaxy point-source surveys. Infrared EBL fluctuations have been attributed to primordial galaxies and black holes at the epoch of reionization (EOR) or, alternately, intrahalo light (IHL) from stars tidally stripped from their parent galaxies at low redshift. We report new EBL anisotropy measurements from a specialized sounding rocket experiment at 1.1 and 1.6 micrometers. The observed fluctuations exceed the amplitude from known galaxy populations, are inconsistent with EOR galaxies and black holes, and are largely explained by IHL emission. The measured fluctuations are associated with an EBL intensity that is comparable to the background from known galaxies measured through number counts and therefore a substantial contribution to the energy contained in photons in the cosmos.

THE COSMIC INFRARED BACKGROUND EXPERIMENT ( CIBER ): THE WIDE-FIELD IMAGERS

We have developed and characterized an imaging instrument to measure the spatial properties of the diffuse near-infrared extragalactic background light in a search for fluctuations from z > 6 galaxies during the epoch of reionization. The instrument is part of the Cosmic Infrared Background Experiment (CIBER), designed to observe the extragalactic background light above the Earth's atmosphere during a suborbital sounding rocket flight. The imaging instrument incorporates a 2x2 degree field of view, to measure fluctuations over the predicted peak of the spatial power spectrum at 10 arcminutes, and 7"x7" pixels, to remove lower redshift galaxies to a depth sufficient to reduce the low-redshift galaxy clustering foreground below instrumental sensitivity. The imaging instrument employs two cameras with \Delta \lambda / \lambda ~0.5 bandpasses centered at 1.1 and 1.6 microns to spectrally discriminate reionization extragalactic background fluctuations from local foreground fluctuations. CIBER operates at wavelengths where the electromagnetic spectrum of the reionization extragalactic background is thought to peak, and complements fluctuations measurements by AKARI and Spitzer at longer wavelengths. We have characterized the instrument in the laboratory, including measurements of the sensitivity, flat-field response, stray light performance, and noise properties. Several modifications were made to the instrument following a first flight in 2009 February. The instrument performed to specifications in subsequent flights in 2010 July and 2012 March, and the scientific data are now being analyzed.

THE COSMIC INFRARED BACKGROUND EXPERIMENT ( CIBER ): THE LOW RESOLUTION SPECTROMETER

Absolute spectrophotometric measurements of diffuse radiation at 1 \mu m to 2 \mu m are crucial to our understanding of the radiative content of the Universe from nucleosynthesis since the epoch of reionization, the composition and structure of the Zodiacal dust cloud in our solar system, and the diffuse galactic light arising from starlight scattered by interstellar dust. The Low Resolution Spectrometer (LRS) on the rocket-borne Cosmic Infrared Background Experiment (CIBER) is a \lambda / \Delta \lambda \sim 15-30 absolute spectrophotometer designed to make precision measurements of the absolute near-infrared sky brightness between 0.75 \mu m < \lambda < 2.1 \mu m. This paper presents the optical, mechanical and electronic design of the LRS, as well as the ground testing, characterization and calibration measurements undertaken before flight to verify its performance. The LRS is shown to work to specifications, achieving the necessary optical and sensitivity performance. We describe our understanding and control of sources of systematic error for absolute photometry of the near-infrared extragalactic background light.

THE RESOLVED NEAR-INFRARED EXTRAGALACTIC BACKGROUND

We present a current best estimate of the integrated near-infrared (NIR) extragalactic background light (EBL) attributable to resolved galaxies in J, H, and Ks. Our results in units of nW m-2 sr-1 are 11.7+5.6 -2.6 in J, 11.5+4.5 -1.5 in H and 10.0+2.8 -0.8 in Ks. We derive these new limits by combining our deep wide-field NIR photometry from five widely separated fields with other studies from the literature to create a galaxy counts sample that is highly complete and has good counting statistics out to JHKs ~ 27-28. As part of this effort we present new ultradeep Ks-band galaxy counts from 22 hours of observations with the Multi Object Infrared Camera and Spectrograph (MOIRCS) instrument on the Subaru Telescope. We use this MOIRCS Ks-band mosaic to estimate the total missing flux from sources beyond our detection limits. Our new limits to the NIR EBL are in basic agreement with, but 10 - 20% higher than previous estimates, bringing them into better agreement with estimates of the total NIR EBL (resolved + unresolved sources) obtained from TeV gamma-ray opacity measurements and recent direct measurements of the total NIR EBL. We examine field to field variations in our photometry to show that the integrated light from galaxies is isotropic to within uncertainties, consistent with the expected large-scale isotropy of the EBL. Our data also allow for a robust estimate of the NIR light from Galactic stars, which we find to be 14.7 +/- 2.4 in J, 10.1 +/- 1.9 in H and 7.6 +/- 1.8 in Ks in units of nW m-2 sr-1.

The 1- m discontinuity in the extragalactic background light spectrum: an artefact of foreground subtraction

Several recent papers claim the detection of a near-infrared (NIR) extragalactic background light (EBL) intensity at 1.25-4 μm that exceeds the integrated light of galaxies by factors of >3. When combined with a claimed optical detection of the EBL at 0.80 μm the EBL excess emission spectrum has a discontinuity at ∼1 μm. This discontinuity has given rise to an interpretation in terms of ultraviolet radiation emanating from the first generation of massive stars at redshifts of 7-20 (so-called Population III stars). The interpretation of the NIR excess emission as being of extragalactic origin depends crucially on the model used in the subtraction of the zodiacal light (ZL), the dominant foreground contaminant. We estimate the ZL at 0.80 μm using on the one hand the measurement by Bernstein et al., with corrections for some omitted effects of atmospheric scattering and calibration, and on the other hand the model of Kelsall et al. There is in neither case any evidence for a step in the EBL at ∼1 μm. We emphasize that in order to avoid systematic effects it is essential to use the same ZL model for both the NIR (1.25-4 μm) and optical (0.80 μm) data. We emphasize, however, that our analysis does not allow a statement on the overall level of the NIR EBL. The contribution of the diffuse galactic light to the 'EBL excess' emission is estimated. It is found to be significant at 3-4 μm and should be carefully evaluated in future measurements which aim at detecting an EBL signal at the level of ∼10 nW m -2 sr -1 , that is, at the level of the integrated light of (known) galaxies.

Subaru Super Deep Field with Adaptive Optics. I. Observations and First Implications

We present a deep K'-band (2.12 μm) imaging of the 1' × 1' Subaru Super Deep Field (SSDF) taken with the Subaru adaptive optics (AO) system. Total integration time of 26.8 hr results in the limiting magnitude of K' ~ 24.7 (5 σ, 02 aperture) for point sources and K' ~ 23.5 (5 σ, 06 aperture) for galaxies, which is the deepest limit ever achieved in the K' band. The average stellar full width at half-maximum (FWHM) of the co-added image is 018. Based on the photometric measurements of detected galaxies, we obtained the differential galaxy number counts, for the first time, down to K' ~ 25, which is more than 0.5 mag deeper than the previous data. We found that the number count slope d log N/dm is about 0.15 at 22 < K' < 25, which is flatter than the previous data. Therefore, detected galaxies in the SSDF have only negligible contribution to the near-infrared extragalactic background light (EBL), and the discrepancy claimed so far between the diffuse EBL measurements and the estimated EBL from galaxy count integration has become more serious. The size distribution of detected galaxies was obtained down to the area size of less than 0.1 arcsec2, which is less than half of that of the previous data in the K' band. We compared the observed size-magnitude relation with a simple pure luminosity evolution model allowing for intrinsic size evolution and found that a model with no size evolution gives the best fit to the data. It implies that the surface brightness of galaxies at high redshift is not much different from that expected from the size-luminosity relation of present-day galaxies.

Infrared Telescope in Space Observations of the Near‐Infrared Extragalactic Background Light

We have searched for near-infrared extragalactic background light (EBL) in the data from the Near-Infrared Spectrometer (NIRS) on the Infrared Telescope in Space (IRTS). After subtracting the contribution of faint stars and the zodiacal component based on modeling, a significant isotropic emission is obtained in the wavelength bands from 1.4 to 4.0 ?m. The spectrum is stellar-like but shows a spectral jump from the optical EBL. The emission obtained is isotropic over the observed sky, and the in-band flux amounts to ~35 nW?m-2?sr-1, which is too bright to be explained by the integrated light from faint galaxies. Analyses of COBE DIRBE data, after removal of starlight, show essentially the same result within the uncertainty in the zodiacal light model, which implies that the isotropic emission observed by IRTS NIRS is of extragalactic origin. Significant fluctuations in sky brightness were also detected that cannot be explained by fluctuations due to faint stars, zodiacal components, and normal galaxies. The excess fluctuation amounts to ~1/4 of the excess emission over the integrated light of galaxies and is consistent with fluctuations observed by COBE DIRBE. A two-point correlation analysis shows that IRTS NIRS data have an angular scale of fluctuations of a few degrees. The spectrum and brightness of the observed excess EBL emission could be explained by the redshifted UV radiation from the first generation of massive stars (Population III stars), which caused the reionization of the universe. Recent Wilkinson Microwave Anisotropy Probe (WMAP) observations of the cosmic microwave background (CMB) polarization have indicated that reionization occurred at z ~ 17 or earlier, while the spectral jump around 1 ?m in the observed excess EBL suggests that the Population III star formation terminated at z ~ 9. The observed fluctuations, however, are considerably larger than the theoretical predictions for the Population III stars.

Observations of the Near-Infrared Extragalactic Background Light

We searched for the near infrared extragalactic background light (IREBL) in data from the Near Infrared Spectrometer (NIRS) on the Infrared Telescope in Space (IRTS). After subtracting the contribution of faint stars and a modeled zodiacal component, a significant isotropic emission is detected whose in-band flux amounts to ~ 30 nWm−2sr−1. This brightness is consistent with upper limits of COBE/DIRBE, but is significantly brighter than the integrated light of faint galaxies. The star subtraction analyses from DIRBE data show essentially the same results apart from the uncertainty in the model of the zodiacal light. A significant fluctuation of the sky brightness was also detected. A 2-point correlation analysis indicates that the fluctuations have a characteristic spatial structure of 100 ~ 200 arcmin. This could be an indication of the large scale structure at high redshift. Combined with the far infrared and submillimeter EBL, the total energy flux amounts to 50 ~ 80 nWm−2sr−1 which is so bright that unknown energy sources at high redshifts are required.

A search for the near-infrared extragalactic background light

view Abstract Citations (63) References (44) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Search for the Near-Infrared Extragalactic Background Light Matsumoto, T. ; Akiba, M. ; Murakami, H. Abstract The diffuse celestial light at 1-5 microns was observed over a large portion of the sky including the Galactic pole with a rocket-born infrared telescope cooled by solid nitrogen. After subtracting the foreground components, there still remains an appreciable amount of isotropic diffuse radiation with complex spectral feature. A part of this isotropic radiation may be contaminated by the environmental emission due to rocket engine exhaust; however, the 2.2 micron data is free from contamination and possibly attributed to an extragalactic origin. Publication: The Astrophysical Journal Pub Date: September 1988 DOI: 10.1086/166678 Bibcode: 1988ApJ...332..575M Keywords: Big Bang Cosmology; Extraterrestrial Radiation; Near Infrared Radiation; Relic Radiation; Astronomical Models; Spaceborne Telescopes; Spectrum Analysis; Space Radiation; COSMIC BACKGROUND RADIATION; COSMOLOGY; INFRARED: SOURCES full text sources ADS |