scholarly journals Spectrophotometric measurement of the Extragalacic Background Light

2011 ◽  
Vol 7 (S284) ◽  
pp. 429-436 ◽  
Author(s):  
Kalevi Mattila ◽  
Kimmo Lehtinen ◽  
Petri Väisänen ◽  
Gerhard von Appen-Schnur ◽  
Christoph Leinert
Keyword(s):  
Scattered Light ◽  
Spectral Lines ◽  
Spectral Signature ◽  
Zodiacal Light ◽  
Differential Measurement ◽  
Extragalactic Background Light ◽  
Background Light ◽  
The Difference ◽  
Lower Limits ◽  
Night Sky Brightness

AbstractThe Extragalactic Background Light (EBL) at UV, optical and NIR wavelengths consists of the integrated light of all unresolved galaxies along the line of sight plus any contributions by intergalactic matter including hypothetical decaying relic particles. The measurement of the EBL has turned out to be a tedious problem. This is because of the foreground components of the night sky brightness, much larger than the EBL itself: the Zodiacal Light (ZL), Integrated Starlight (ISL), Diffuse Galactic Light (DGL) and, for ground-based observations, the Airglow (AGL) and the tropospheric scattered light. We have been developing a method for the EBL measurement which utilises the screening effect of a dark nebula on the EBL. A differential measurement in the direction of a high-latitude dark nebula and its surrounding area provides a signal that is due to two components only, i.e. the EBL and the diffusely scattered ISL from the cloud. We present a progress report of this method where we are now utilising intermediate resolution spectroscopy with ESO's VLT telescope. We detect and remove the scattered ISL component by using its characteristic Fraunhofer line spectral signature. In contrast to the ISL, in the EBL spectrum all spectral lines are washed out. We present a high quality spectrum representing the difference between an opaque position within our target cloud and several clear OFF positions around the cloud. We derive a preliminary EBL value at 400 nm and an upper limit to the EBL at 520 nm. These values are in the same range as the EBL lower limits derived from galaxy counts.Unit: We will use in this paper the abbreviation 1 cgs = 10−9erg s−1cm−2sr−1Å−1

scholarly journals Fitting Zodiacal Models

2001 ◽  
Vol 204 ◽  
pp. 157-160 ◽  
Author(s):  
Edward L. Wright
Keyword(s):  
Solar System ◽  
Radiation Field ◽  
Measured Data ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Zodiacal Light ◽  
Extragalactic Background Light ◽  
Background Light

Models of the zodiacal light are necessary to convert measured data taken from low Earth orbit into the radiation field outside the Solar System. The uncertainty in these models dominates the overall uncertainty in determining the extragalactic background light for wavelengths λ < 100 μm.

21. Light of the Night Sky (Lumiere Du Ciel Nocturne)

1988 ◽  
Vol 20 (1) ◽  
pp. 211-218
Author(s):  
K. Mattila ◽  
A. C. Levasseur-Regourd ◽  
R. Dumont ◽  
Yu. I. Galperin ◽  
R. H. Giese ◽  
...  
Keyword(s):  
Background Radiation ◽  
Scattered Light ◽  
Point Of View ◽  
Zodiacal Light ◽  
Extragalactic Background Light ◽  
Infrared Wavelength ◽  
Background Radiations ◽  
Infrared Background ◽  
Night Sky ◽  
Photometric Measurements

The different components of the light of the night sky have their origin in different formations of matter in the universe - encompassing a huge scale of distances ranging from a few kilometers in the earth’s atmosphere to the most distant known galaxies and beyond. Correspondingly, the borderlines to other Commissions are not very well defined and thus material relevant to Commission 21 can also be found in the reports of other Commissions on the following topics: zodiacal light and zodiacal IR emission (Comm. 22, 44), integrated starlight (33, 25), diffuse galactic light (34), extragalactic background light (47), airglow and atmospheric scattered light (50), and space-borne observations of the LONS (44). From the Commission 21 point of view the connecting link between these various fields is the special techniques utilized in the surface photometric measurements and reductions of background radiations which extend over the entire sky. One crucial problem is the separation of the LONS into its several components. The approach for solving this task is to utilize the different spatial distributions and different broad and narrow band spectral properties of each of the LONS component. Thus the successful measurement and separation of one of the LONS components requires a knowledge of the properties of all the other components. This situation has become apparent in recent years as the infrared background radiation database, provided by the Infrared Astronomical Satellite (IRAS), has been analyzed: both the zodiacal and galactic dust emissions have to be analyzed hand in hand, and both these components must be very accurately mastered before any conclusions are possible on the extragalactic component. It is also obvious that very similar problems are encountered in the ultraviolet and infrared wavelength regions as in the more traditional optical domain. Thus the techniques developed in one of these wavelength domains are directly applicable in the others.

scholarly journals 21. Light of the Night Sky / Lumière du Ciel Nocturne

1997 ◽  
Vol 23 (1) ◽  
pp. 231-236
Author(s):  
Christoph Leinert
Keyword(s):  
Interstellar Dust ◽  
Thermal Emission ◽  
Scattered Light ◽  
Diffuse Radiation ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
Zodiacal Light ◽  
Interplanetary Dust Particles ◽  
Extragalactic Background Light ◽  
Night Sky

The light of the night sky is a difficult to disentangle mixture of tropospherically scattered light, airglow, zodiacal light (including the thermal emission by interplanetary dust particles), unresolved stellar light, diffuse scattering and emission by interstellar dust and gas, and finally an extragalactic component. It has the reputation of being a very traditional field of astronomy, which certainly is true if we look at the long history of the subject. The recent renewed interest in this topic, which continued during this triennium, appears mainly to come from three sources: - first from the impressive results of the IRAS and COBE infrared satellites. They brought to general consciousness the fact that the infrared sky is characterised by strong emission from interplanetary and interstellar dust, and made clear that this emission may interfere with the study of faint interesting sources. - then from the development of sensitive detectors and arrays for essentially all of the wavelength range to be covered in this report, from the Lyman limit to ≈ 300 μm. Now the difficult measurements of the ultraviolet diffuse radiation and of the extragalactic background light in the infrared cosmological windows around 3 μm and 200 μm have become feasible and state of the art projects. - finally, the threat to astronomical observations arising from man-made development and lighting has become important enough to further studies of uncontaminated and contaminated night sky brightnesses. This report will refer mainly to those areas and is meant to highlight noteworthy developments. It was prepared with the help of Drs. Bowyer and Mattila.

scholarly journals Extragalactic background light measurements and applications

2016 ◽  
Vol 3 (3) ◽  
pp. 150555 ◽  
Author(s):  
Asantha Cooray
Keyword(s):  
Solar System ◽  
Galaxy Formation ◽  
Interplanetary Dust ◽  
Absorption Feature ◽  
Electromagnetic Spectrum ◽  
Zodiacal Light ◽  
Small Aperture ◽  
Extragalactic Background Light ◽  
Background Light ◽  
Optical Background

This review covers the measurements related to the extragalactic background light intensity from γ-rays to radio in the electromagnetic spectrum over 20 decades in wavelength. The cosmic microwave background (CMB) remains the best measured spectrum with an accuracy better than 1%. The measurements related to the cosmic optical background (COB), centred at 1 μm, are impacted by the large zodiacal light associated with interplanetary dust in the inner Solar System. The best measurements of COB come from an indirect technique involving γ-ray spectra of bright blazars with an absorption feature resulting from pair-production off of COB photons. The cosmic infrared background (CIB) peaking at around 100 μm established an energetically important background with an intensity comparable to the optical background. This discovery paved the way for large aperture far-infrared and sub-millimetre observations resulting in the discovery of dusty, starbursting galaxies. Their role in galaxy formation and evolution remains an active area of research in modern-day astrophysics. The extreme UV (EUV) background remains mostly unexplored and will be a challenge to measure due to the high Galactic background and absorption of extragalactic photons by the intergalactic medium at these EUV/soft X-ray energies. We also summarize our understanding of the spatial anisotropies and angular power spectra of intensity fluctuations. We motivate a precise direct measurement of the COB between 0.1 and 5 μm using a small aperture telescope observing either from the outer Solar System, at distances of 5 AU or more, or out of the ecliptic plane. Other future applications include improving our understanding of the background at TeV energies and spectral distortions of CMB and CIB.

scholarly journals Study of electrolytic dissociation by the Raman effect. I.—Nitric acid

1930 ◽  
Vol 127 (805) ◽  
pp. 279-289 ◽  
Keyword(s):  
Nitric Acid ◽  
Raman Effect ◽  
Scattered Light ◽  
Monochromatic Light ◽  
Ultra Violet ◽  
Spectral Lines ◽  
Electrolytic Dissociation ◽  
Infra Red ◽  
The Difference

In a recent discovery Raman found that when monochromatic light of frequency v is incident upon a substance, the scattered light contains not only light of the original frequency v hut also light of modified frequency v 1 , and the difference in frequency between the two corresponds to an infra-red character­istic frequency v 0 of the molecules constituting the substance. Thus a new field of work has been opened up, in which the infra-red characteristic frequencies of molecules can be determined with as much precision as is possible in the visible and ultra-violet regions of the spectrum. The present investigation has shown a further possibility of the new discovery. On studying the Raman effect in solutions of nitric acid at different concentrations, the author was able to trace the progress in the electrolytic dissociation of the acid by measuring the changes in the intensities of the Raman lines due to the undissociated molecules and of the ions. Thus the method not only gives direct evidence of the phenomenon of dissociation, but enables the determination of its amount as accurately as is possible in the measurement of intensities of spectral lines. The only defect of the method lies in the fact that it cannot be extended to those electrolytes that do not show any Raman lines. The purpose of the present communication is to describe the results with nitric acid.

THE EXTRAGALACTIC BACKGROUND LIGHT: LOWER VERSUS UPPER LIMITS

2009 ◽  
Vol 18 (10) ◽  
pp. 1633-1637 ◽  
Author(s):  
MARTIN RAUE
Keyword(s):  
High Energy ◽  
Energy Spectra ◽  
Extragalactic Background Light ◽  
Background Light ◽  
Upper Limits ◽  
Very High Energy ◽  
Γ Rays ◽  
Deep Source ◽  
Lower Limits ◽  
Very High

The discovery of distant sources of very high energy (VHE) γ-rays with hard energy spectra enabled to derive strong upper limits on the density of the extragalactic background light (EBL). These limits are close to the lower limits derived from deep source counts. A recent re-dertemination of the EBL contribution from resolved sources at 3.6 μm finds a higher EBL density, which is claimed to be in conflict with the assumptions utilized to derive the EBL upper limits from VHE spectra. Here, it is shown that is possible to recover the canonical Γ ~ 1.5 intrinsic spectra for such a higher EBL density.

scholarly journals Observations of the Near-Infrared Extragalactic Background Light

2001 ◽  
Vol 204 ◽  
pp. 87-100
Author(s):  
Toshio Matsumoto
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
High Redshift ◽  
Far Infrared ◽  
Zodiacal Light ◽  
Extragalactic Background Light ◽  
Background Light ◽  
Infrared Telescope ◽  
Total Energy Flux ◽  
Infrared Spectrometer

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.

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

2019 ◽  
Vol 71 (4) ◽  
Author(s):  
Min Gyu Kim ◽  
Toshio Matsumoto ◽  
Hyung Mok Lee ◽  
Woong-Seob Jeong ◽  
Kohji Tsumura ◽  
...  
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
High Redshift ◽  
Zodiacal Light ◽  
Extragalactic Background Light ◽  
Background Light ◽  
Normal Galaxies ◽  
Infrared Telescope ◽  
Angular Scale ◽  
Using Data

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.

scholarly journals 21. Light of the Night Sky

1982 ◽  
Vol 18 (1) ◽  
pp. 211-218
Author(s):  
H. Tanabe ◽  
R.H. Giese ◽  
R. Dumont ◽  
M. Harwit ◽  
C. Leinert ◽  
...  
Keyword(s):  
Light Source ◽  
Large Distance ◽  
Zodiacal Light ◽  
Extragalactic Background Light ◽  
Background Light ◽  
Night Sky ◽  
Light Components ◽  
Celestial Sphere

The light of the night sky includes several components which spread all over the celestial sphere. These light components are terrestrial (airglow), interplanetary (zodiacal light), galactic (integrated starlight, diffuse galactic light) and extragalactic (extragalactic background light). Thus the study of nature of each light source, covering large distance, is pursued in different fields of astronomy. However, the techniques of measurement for respective components are similar and the knowledge of other lights is indispensable even in the study of a particular component.

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