Intensity, isotropy and origin of the cosmic infrared background

Details Intensity, isotropy and origin of the cosmic infrared background Intensity, isotropy and origin of the cosmic infrared background

Jun 2008

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008phdt........21l&link_type=abstract

Proquest Dissertations And Theses 2008. Section 0031, Part 0606 154 pages; [Ph.D. dissertation].United States -- California: Un

Physics

Cosmic Infrared Background, Zodiacal Light

Scientific paper

The near-infrared intensity of the Cosmic Infrared Background (CIRB) has been measured primarily using two methods. Foreground subtraction from DIRBE maps has enabled detections and measurements in the K and L bands and galaxy counting in Spitzer (L band), HST (J band) and ground-based (J, K band) images provides lower limits on the CIRB. Prior to this thesis work, these independent methods gave discrepant intensities, differing by a factor of 2 or more.
A three part investigation was developed to investigate this discrepancy. First, we have extended the foreground subtraction analysis, i.e. removing 2MASS stellar fluxes from the zodiacal-subtracted DIRBE maps, to 40 new regions of the sky and obtain a consistent residual intensity of 14.69 ± 4.49 kJy /sr and 15.62 ± 3.34 kJy/sr at 2.2 and 3.5 microns, respectively. The residual intensities at 1.25 microns are more scattered leading to a weak limit on the J-band CIRB of 8.88 ± 6.26 kJy/sr.
We have also observed the central square degree of three of the forty "DIRBE Minus 2MASS" regions with Spitzer. Galaxy counts were obtained in these three shallow surveys as well as deep images of the Extended Groth Strip and GOODS North. Using the profile-fit photometry package GIM2D along with a Monte Carlo Markov Chain simulation of our data analysis, used to obtain a rigorous estimate of the uncertainty in this measurement, we find a most probable contribution to the CIRB from galaxies at 3.6 mm of [Special characters omitted.] kJy sr -1 .
Finally, modifications to an existing model of the zodiacal light, including an added restriction to the model that the resulting residual sky be independent of ecliptic latitude, have been made. The new zodi-subtracted maps result in an ecliptic independent residual intensity that is reasonably consistent with that estimated using the previous model at K and L. The J-band value, however, appears to be unreasonably high.
The discrepancy between measurements of the CIRB has been greatly reduced through this work. Future work on the zodiacal light modeling, perhaps with new data, will still be required to ultimately measure the CIRB intensity to high precision.

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