Star formation history, dust attenuation, and extragalactic background light
- Inter-University Centre for Astronomy and Astrophysics (IUCAA), Post Bag 4, Pune 411007 (India)
At any given epoch, the extragalactic background light (EBL) carries imprints of integrated star formation activities in the universe until that epoch. On the other hand, in order to estimate the EBL when direct observations are not possible, one requires an accurate estimation of the star formation rate density (SFRD) and the dust attenuation (A{sub ν}) in galaxies. Here, we present a “progressive fitting method” that determines the global average SFRD(z) and A{sub ν}(z) for any given extinction curve by using the available multiwavelength, multiepoch galaxy luminosity function measurements. Using the available observations, we determine the best-fit combinations of SFRD(z) and A{sub ν}(z), in a simple fitting form, up to z∼8 for five well-known extinction curves. We find, irrespective of the extinction curve used, the z at which the SFRD(z) peaks is higher than the z above which A{sub ν}(z) begins to decline. For each case, we compute the EBL from ultraviolet to the far-infrared regime and the optical depth (τ{sub γ}) encountered by the high-energy γ-rays due to pair production upon collisions with these EBL photons. We compare these with measurements of the local EBL, γ-ray horizon, and τ{sub γ} measurements using Fermi-Large Area Telescope. All these and the comparison of independent SFRD(z) and A{sub ν}(z) measurements from the literature with our predictions favor an extinction curve similar to that of the Large Magellanic Cloud Supershell.
- OSTI ID:
- 22883193
- Journal Information:
- Astrophysical Journal, Vol. 805, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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