Connecting the cosmic infrared background to the X-ray background

Silva, Laura; Maiolino, R.; Granato, G. L.

doi:10.1111/j.1365-2966.2004.08380.x

Cited by 143 publications

(277 citation statements)

References 114 publications

(152 reference statements)

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“…At fluxes larger than 0.6 mJy, the density of AGN2 is about 60 deg −2 , while Matute et al (2006) predict a density of about 20 deg −2 . On the other hand, the predicted count of absorbed, Compton-thin AGN (10 21 < N H < 10 24 cm −2 ) by Silva et al (2004) are consistent with our estimates of the AGN2 counts. All the extragalactic sources, with 15 µm fluxes brighter than 0.6 mJy, produce a 15 µm background of νI(ν) = 0.343nW m −2 sm −1 , while the AGNs produce νI(ν) = 0.046nW m −2 sm −1 (∼13% contribution to the extragalactic background produced at fluxes brighter than 0.6 mJy).…”

Section: Revised Agn 15 µM Countssupporting

confidence: 80%

“…A cross correlation of X-ray and IR ISO sources detected in deep Chandra and XMM-Newton observations allowed Fadda et al (2002) to estimate that the maximum fraction of the CIRB produced by AGN is 17 ± 6%. This result is confirmed by Silva et al (2004), who used the X-ray AGN luminosity function (LF) and semi-empirical SEDs (linking the X-ray to the Infrared) to derive that the contribution of AGN and their host galaxy to the CIRB is 10-20% in the 1-20 µm range. These results recently have been confirmed and extended by the analysis of joint Spitzer and X-ray data, where a contribution of 3-11% is derived (see e.g.…”

Section: Introductionsupporting

confidence: 48%

“…6 (left) with the predictions from the AGN1 and AGN2 luminosity functions computed by Matute et al (2006), and in Fig. 6 (right) with the AGN counts predicted by Silva et al (2004) on the basis of the X-ray AGN luminosity function (LF) and semi-empirical SEDs (linking the X-ray to the infrared). It turns out that the AGN1 counts agree, within the uncertainties, with the counts predicted by both the AGN1 LF of Matute et al (2006) and the un-absorbed (N H ≤ 10 21 cm −2 ) AGN of Silva et al (2004).…”

Section: Revised Agn 15 µM Countsmentioning

confidence: 99%

“…Right. The short and long dashed lines are the predicted un-absorbed and Compton thin counts, respectively, by Silva et al (2004) on the basis of the X-ray AGN luminosity function and semi-empirical SEDs (linking the X-ray to the infrared). The continuous line is the prediction of the total AGN counts (including Compton-thin absorbed sources) by Silva et al (2004).…”

Section: The Newly Classified Agnmentioning

confidence: 99%

“…6 (right) with the AGN counts predicted by Silva et al (2004) on the basis of the X-ray AGN luminosity function (LF) and semi-empirical SEDs (linking the X-ray to the infrared). It turns out that the AGN1 counts agree, within the uncertainties, with the counts predicted by both the AGN1 LF of Matute et al (2006) and the un-absorbed (N H ≤ 10 21 cm −2 ) AGN of Silva et al (2004). Conversely, the new AGN2 counts are, as expected, about a factor of 2-3 higher than predicted Table 3.…”

Section: Revised Agn 15 µM Countsmentioning

confidence: 99%

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AGN counts at 15$\mu{\rm m}$

Franca¹,

Puccetti²,

Sacchi³

et al. 2007

A&A

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Context. The counts of galaxies and AGN in the mid infra-red (MIR) bands are important instruments for studying their cosmological evolution. However, the classic spectral line ratios techniques can become misleading when trying to properly separate AGN from starbursts or even from apparently normal galaxies. Aims. We use X-ray band observations to discriminate AGN activity in previously classified MIR-selected starburst galaxies and to derive updated AGN1 and (Compton thin) AGN2 counts at 15 µm. Methods. XMM observations of the ELAIS-S1 15 µm sample down to flux limits ∼2 × 10 −15 erg cm −2 s −1 (2-10 keV band) were used. We classified as AGN all those MIR sources with a unabsorbed 2-10 keV X-ray luminosity higher that ∼10 42 erg s −1 . Results. We find that at least about 13 ± 6% of the previously classified starburst galaxies harbor an AGN. According to these figures, we provide an updated estimate of the counts of AGN1 and (Compton thin) AGN2 at 15 µm. It turns out that at least 24% of the extragalactic sources brighter than 0.6 my at 15 µm are AGN (∼13% contribution to the extragalactic background produced at fluxes brighter than 0.6 mJy).

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Section: Revised Agn 15 µM Countssupporting

confidence: 80%

Section: Introductionsupporting

confidence: 48%

Section: Revised Agn 15 µM Countsmentioning

confidence: 99%

Section: The Newly Classified Agnmentioning

confidence: 99%

Section: Revised Agn 15 µM Countsmentioning

confidence: 99%

See 3 more Smart Citations

AGN counts at 15$\mu{\rm m}$

Franca¹,

Puccetti²,

Sacchi³

et al. 2007

A&A

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show abstract

Statistical algorithms for identification of astronomical X‐ray sources

Ziaeepour¹,

Rosen²

2008

Astron Nachr

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Observations of present and future X-ray telescopes include a large number of ipitous sources of unknown types. They are a rich source of knowledge about X-ray dominated astronomical objects, their distribution, and their evolution. The large number of these sources does not permit their individual spectroscopical follow-up and classification. Here we use Chandra Multi-Wavelength public data to investigate a number of statistical algorithms for classification of X-ray sources with optical imaging follow-up. We show that up to statistical uncertainties, each class of X-ray sources has specific photometric characteristics that can be used for its classification. We assess the relative and absolute performance of classification methods and measured features by comparing the behaviour of physical quantities for statistically classified objects with what is obtained from spectroscopy. We find that among methods we have studied, multi-dimensional probability distribution is the best for both classifying source type and redshift, but it needs a sufficiently large input (learning) data set. In absence of such data, a mixture of various methods can give a better final result. We discuss some of potential applications of the statistical classification and the enhancement of information obtained in this way. We also assess the effect of classification methods and input data set on the astronomical conclusions such as distribution and properties of X-ray selected sources.

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Evolution of the IR Energy Density and SFH up to Z ∼ 1: First Results from MIPS

et al. 2005

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Using deep observations of the Chandra Deep Field South obtained with MIPS at 24 µm, we present our preliminary estimates on the evolution of the infrared (IR) luminosity density of the Universe from z=0 to z∼1. We find that a pure density evolution of the IR luminosity function is clearly excluded by the data. The characteristic luminosity LIR* evolves at least by (1+z) 3.5 with lookback time, but our monochromatic approach does not allow us to break the degeneracy between a pure evolution in luminosity or an evolution in both density and luminosity. Our results imply that IR luminous systems (LIR ≥ 10 11 L⊙) become the dominant population contributing to the comoving IR energy density beyond z ∼ 0.5-0.6. The uncertainties affecting our measurements are largely dominated by the poor constraints on the spectral energy distributions that are used to translate the observed 24 µm flux into luminosities.

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Connecting the cosmic infrared background to the X-ray background

Cited by 143 publications

References 114 publications

AGN counts at 15$\mu{\rm m}$

AGN counts at 15$\mu{\rm m}$

Statistical algorithms for identification of astronomical X‐ray sources

Evolution of the IR Energy Density and SFH up to Z ∼ 1: First Results from MIPS

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