Extragalactic background light: inventory of light throughout the cosmic history

Abstract

The Extragalactic Background Light (EBL) stands for the mean surface brightness of the sky as we would see it from a representative vantage point in the intergalactic space outside of our Milky Way Galaxy. Averaged over the whole 4π solid angle it represents the collective light from all luminous matter radiated throughout the cosmic history. Part of the EBL is resolved into galaxies that, with the increasing detecting power of giant telescopes and sensitive detectors, are seen to deeper and deeper limiting magnitudes. This resolved part is now known to contribute a substantial or even the major part of the EBL. There still remains, however, the challenge of finding out to what extent galaxies too faint or too diffuse to be discerned individually, individual stars or emission by gas outside the galaxies, or -more speculatively -some hitherto unknown light sources such as decaying elementary particles are accounting for the remaining EBL. We review the recent progress that has been made in the measurement of EBL. The current photometric results suggest that there is, beyond the resolved galaxies, an EBL component that cannot be explained by diffuse galaxy halos or intergalactic stars.

GAMA/DEVILS: constraining the cosmic star formation history from improved measurements of the 0.3–2.2 μm extragalactic background light

“…In particular: ESO-VLT (Vernet et al 2009), Pan STARRS (Kaiser et al 2002), Subaru (Taniguchi et al 2007), and CFHT (Capak et al 2007). Nevertheless, the discrepancy between direct and indirect methods is far larger than expected, and the subject of much debate (Mattila & Väisänen 2019). At present the discrepancy in the CIB estimates are ∼ 75%, while in the COB the estimates vary by a factor of 3 to 5.…”

“…Unfortunately, despite significant efforts, the current measurements of the COB and CIB exhibit significant inconsistencies most likely associated with the measurement methods (see reviews by Hill et al 2018;Mattila & Väisänen 2019;Driver 2020). Conventionally, these efforts are classified as direct (background sky brightness; Matsumoto et al 2005;Cooray et al 2012;Matsuoka et al 2011;Zemcov et al 2013;Zemcov et al 2017;Kawara et al 2017), and indirect (based on counting galaxies; Madau & Pozzetti 2000;Totani et al 2001;Xu et al 2005;Grazian et al 2009;Keenan et al 2010;Driver et al 2016b).…”

The mysterious diffuse UV radiation and Axion Quark Nugget dark matter model

“…The discrepancy could be as large as factor ∼ (2 − 3) or even more, see e.g. recent review [26]. Our comment here is that the AQNs may fulfill this shortage as the spectrum (2) is very broad and includes optical and IR light.…”

Photon–Photon Interactions and the Opacity of the Universe in Gamma Rays

“…Unfortunately, direct measurements of EBL all-over its wavelength definition range are very difficult, and even largely impossible. Excellent reviews of the subject can be found in [55] for the IR part and in [56] for the optical-UV one. The situation is well illustrated in Figure 1, showing how the Earth is immersed, more than within the EBL photon field, inside a variety of radiations of local origin.…”