The Cosmic Infrared Background at 1.25 and 2.2 Microns Using DIRBE and 2MASS: A Contribution Not Due to Galaxies?

Cambrésy, L.; Reach, W. T.; Beichman, Charles; Jarrett, T. H.

doi:10.1086/321470

Cited by 163 publications

(263 citation statements)

References 30 publications

Supporting

Mentioning

246

Contrasting

Order By: Relevance

“…This result is completely independent of any "direct" measurement of the EBL. Remarkably, it is in severe conflict with the claims of high EBL flux at NIR wavelengths 16,17 and, to a lesser extent, with the reported detections at 2.2 and 3.5 µm 1, 15 . The H.E.S.S.…”

mentioning

confidence: 61%

“…Here we leave its normalization as a free parameter, scaling P1.0 by different factors P (labelled accordingly, the curve scaled by 0.45× is "P0.45") down to the lower limit obtained by the resolved galaxy counts 8 (∼P0.4). To reproduce the excess around 1.5 µm claimed from the Infrared Telescope in Space (IRTS) data 16 (also argued by ref 17 ), an additional ad hoc component was considered, labelled "E NIR ". This feature is not expected from standard galaxy evolution models, and could be the spectral signature of radiation produced in the early universe, for example by the first stars formed (metal-free massive stars, called 'Population III'; see e.g.…”

mentioning

confidence: 99%

See 1 more Smart Citation

A low level of extragalactic background light as revealed by γ-rays from blazars

Aharonian¹,

Akhperjanian²,

Bazer‐Bachi³

et al. 2006

Nature

541

615

View full text Add to dashboard Cite

The diffuse extragalactic background light consists of the sum of the starlight emitted by galaxies through the history of the Universe, and it could also have an important contribution from the first stars, which may have formed before galaxy formation began. Direct measurements are difficult and1 not yet conclusive, owing to the large uncertainties caused by the bright foreground emission associated with zodiacal light 1 . An alternative approach 2-5 is to study the absorption features imprinted on the γ-ray spectra of distant extragalactic objects by interactions of those photons with the background light photons 6 . Here we report the discovery of γ-ray emission from the blazars 7 H 2356−309 and 1ES 1101−232, at redshifts z=0.165 and z=0.186, respectively. Their unexpectedly hard spectra provide an upper limit on the background light at optical/near-infrared wavelengths that appears to be very close to the lower limit given by the integrated light of resolved galaxies 8 . The background flux at these wavelengths accordingly seems to be strongly dominated by the direct starlight from galaxies, thus excluding a large contribution from other sources -in particular from the first stars formed 9 . This result also indicates that intergalactic space is more transparent to γ-rays than previously thought.The observations were carried out with the High Energy Stereoscopic System 10 (H.E.S.S. ), a system of four imaging atmospheric Cherenkov telescopes operating at energies E ≥ 0.1 TeV. These two blazars are at present the most distant sources for which spectra have been measured at these energies (Tab. 1).Intergalactic absorption is caused by the process of photon-photon collision and pair production. The original spectrum emitted by the source (which we call "intrinsic") is modified such that the observed flux E) , where the optical depth τ (E) depends on the Spectral Energy Distribution (SED) of the Extragalactic Background Light (EBL) (Fig. 1). Details are provided in the Supplementary Notes and Figures. For any reasonable range of fluxes at ultraviolet (UV) and optical/near-infrared wavelengths (O-NIR), τ (E) -and thus absorption -is larger at 1 TeV with respect to 0.2 TeV. This difference makes the observed spectrum steeper (that is, Γ obs > Γ int , for a power-law model dN/dE ∝ E −Γ ) The spectral change ∆Γ=Γ obs − Γ int scales linearly with the EBL normalization, and becomes more pronounced at larger redshifts. Thus more distant objects provide a more sensitive diagnostic tool.In general, if the intrinsic spectrum were sufficiently well known, τ (E) -and thus the EBL SEDcould be effectively measured by comparing intrinsic with observed spectra. Blazars, however, are characterized by a wide range of possible spectra, and the present understanding of their radiation processes is not yet complete enough to reliably predict their intrinsic γ-ray spectra. But for these two sources, with O-NIR fluxes at the level of the "direct" estimates, the intrinsic spectra needed to reproduce the H.E.S.S. data become extremely...

show abstract

mentioning

confidence: 61%

mentioning

confidence: 99%

A low level of extragalactic background light as revealed by γ-rays from blazars

Aharonian¹,

Akhperjanian²,

Bazer‐Bachi³

et al. 2006

Nature

541

615

View full text Add to dashboard Cite

show abstract

“…In fact, some fraction of the observed near-IR DIRBE excess could be produced by VMBHs. In a recent estimate of the cosmic background at 1.25 and 2.2 lm (corresponding to the J and K bands, respectively) using the Two Micron All Sky Survey (2MASS) and the DIRBE results, Cambresy et al (2001) also find an excess (significantly higher than the integrated galaxy counts in the J and K bands), suggesting the contribution of other sources. Population III stars and their VMBH remnants (accreting at very high redshifts) postulated here are likely candidates.…”

Section: Observational Constraintsmentioning

confidence: 92%

First Stars, Very Massive Black Holes, and Metals

Schneider

Ferrara

Natarajan

et al. 2002

ApJ

476

502

View full text Add to dashboard Cite

Recent studies suggest that the initial mass function (IMF) of the first stars (Population III) is likely to have been extremely top-heavy, unlike what is observed at present. We propose a scenario to generate fragmentation to lower masses once the first massive stars have formed and derive constraints on the primordial IMF. We estimate the mass fraction of pair-unstable supernovae (SN ), shown to be the dominant sources of the first heavy elements. These metals enrich the surrounding gas up to %10 À4 Z , when a transition to efficient cooling-driven fragmentation producing d1 M clumps occurs. We argue that the remaining fraction of the first stars ends up in %100 M VMBHs (very massive black holes). If we further assume that all these VMBHs are likely to end up in the centers of galactic nuclei constituting the observed supermassive black holes (SMBHs), then %6% of the first stars contributed to the initial metal enrichment and the IMF remained topheavy down to a redshift z % 18:5%. Interestingly, this is the epoch at which the cool metals detected in the Ly forest at z % 3 must have been ejected from galaxies. At the other extreme, if none of these VMBHs has as yet ended up in SMBHs, we expect them to be either (1) en route toward galactic nuclei, thereby accounting for the X-ray-bright off-center sources detected locally by ROSAT, or (2) the dark matter candidate composing the entire baryonic halos of galaxies. For case 1 we expect all but a negligible fraction of the primordial stars to produce metals, causing the transition at the maximum possible redshift of e22.1, and for case 2, $3 Â 10 5 , a very negligible fraction of the initial stars produce the metals and the transition redshift occurs at z f e5:4. In this paper, we present a framework (albeit one that is not stringently constrained at present) that relates the first episode of star formation to the fate of their remnants at late times. Clearly, further progress in understanding the formation and fragmentation of Population III stars within the cosmological context will provide tighter constraints in the future. We conclude with a discussion of several hitherto unexplored implications of a high-mass-dominated star formation mode in the early universe.

show abstract

“…4 we review the old (pre-Spitzer) measurements of the CIB and Sec. 5 gives an overview of the very recent results that were obtained from Spitzer IRAC deep exposures by our team (13). We conclude in Sec.…”

Section: Introductionmentioning

confidence: 92%

Cosmic infrared background and early stellar populations

Kashlinsky

2006

New Astronomy Reviews

View full text Add to dashboard Cite

Cosmic infrared background (CIB) contains information about galaxy luminosities over the entire history of the Universe and can be a powerful diagnostic of the early populations otherwise inaccessible to telescopic studies. Its measurements are very difficult because of the strong IR foregrounds from the Solar system and the Galaxy. Nevertheless, substantial recent progress in measuring the CIB and its structure has been made. The measurements now allow to set significant constraints on early galaxy evolution and, perhaps, even detect the elusive Population III era. We discuss briefly the theory behind the CIB, review the latest measurements of the CIB and its structure, and discuss their implications for detecting and/or constraining the first stars and their epochs.

show abstract

The Cosmic Infrared Background at 1.25 and 2.2 Microns Using DIRBE and 2MASS: A Contribution Not Due to Galaxies?

Cited by 163 publications

References 30 publications

A low level of extragalactic background light as revealed by γ-rays from blazars

A low level of extragalactic background light as revealed by γ-rays from blazars

First Stars, Very Massive Black Holes, and Metals

Cosmic infrared background and early stellar populations

Contact Info

Product

Resources

About