New RSRF ( #49) Corrects Resident PACS Lines for the Red Order Leak Steve Lord, NHSC Caltech. Steve Lord

Transcription

1 New RSRF ( #49) Corrects Resident PACS Lines for the Red Order Leak Steve Lord, NHSC Caltech

2 Understanding the Problem (I/II): Summary: The PACS spectrometer suffers an "order light leak" where flux from the 2 nd order regime μm leaks into the 1 st order regime μm. F(λ) is mapped into and adds to F(2 λ) Pre- March 2013, processing up to HIPE 10.0 level 2 spectra exhibited corrupted flux between μm. It was not calibrated. The new, parral cure has been to install a new RelaRve Spectral Response FuncRon - "RSRF" to calibrate the line flux alone. Background: Prior to Caltree #49 (installed 11 March '13, not yet released (as of 15 April '13) An RSRF was produced by RSRF = (Observed Spectrum/True Spectrum) for a source whose True Spectrum was fairly well known. It is used on all other objects' "observed spectrum" by dividing the RSRF into an observed spectrum: calibrated spectrum = (observed spectrum / RSRF)

3 Understanding the Problem (II/II): The Observed Spectrum used to make the RSRF had excess flux in the leak region, so the nominal RSFR came out too high (trying to compensate that extra flux). By "too high" we mean this: While diminishing the extra leaked flux, it also diminishes the true flux. All spectral lines observed in the red leak regime (which I call here "resident lines") are a_enuated. To correctly calibrate resident lines, a modified RSRF was constructed for PACS: One that does not try to get rid of leaked flux, One that just corrects the true μm observed light, which includes (at Rmes) unambiguous spectral lines in this regime. The revised RSRF was made using the known "True Spectrum" of a pair of black bodies (fortuitously observed pre- launch, in the lab): one at 34 K, another 3 K offset. The combinaron allowed the mathemarcal separaron of leaked emission It produced a soluron to the ideal RSRF for the flux from μm It allowed of a second RSRF for guest lines in the leak originarng from the 2 nd orderat lambda/2).

4 For when the Calibration Sets Available include #49 (soon) To see which Cal set you are using you can type: HIPE> print getcaltree().version To try to update run, from the HIPE tabs: Tools- > Pacs cal - > run update Be sure to accept the new calibraron sets. Soon they should run up to 49 and beyond. "Update of Spectrometer RSRF Red Leak Correction..."

5 (Click on "Files" and watch the progress...) Allow the calibration set files to load

6 The RSRF's are computed for each detector and each spaxel. The array is centered at spaxel 12 and the detectors at detectors: 7, 8. In the following, we show subtle differences between a few detectors of the center spaxel..

7 Spaxel 12, Det 1 original corrected Wavelength μm Example RSRF Replacements

8 Spaxel 12, Det 2 original corrected Wavelength um Example RSRF Replacements

9 Spaxel 12, Det 3 original corrected Wavelength μm Example RSRF Replacements

10 Spaxel 12, Det 4 original corrected Wavelength μm Example RSRF Replacements

11 Spaxel 12, Det 8 original corrected Wavelength μm Example RSRF Replacements

12 Spaxel 12, Det 9 original corrected Wavelength um Example RSRF Replacements

13 Test case of TMC1 (compared w/spire data) CO J= μm The flux in the leak regime is suppressed, in a T dependant way. Example Uncorrected Spectrum TMC 1

14 Line Flux of Uncorrected Spectrum CO J= μm Example Uncorrected Spectrum TMC 1

15 Corrected Spectrum CO J= μm Note the new, very different continuum shape Example Corrected Spectrum TMC 1

16 Line Flux of Corrected Spectrum CO J= μm Example Corrected Spectrum TMC 1

17 Result of this example for TMC 1 And General Recommendations - CO (J=13-12) μm: Flux Before Correction 0.6 Jy micron/pixel Flux After Correction 2.1 Jy micron/pixel A factor of 3 rise this agrees with SPIRE Flux now approximately (within 50%.) - Several other sources yielded agreement after correction within ~20% (E. Puga HSC) - Opens the possibility of many new fluxed lines including [NII] 205 μm. (Not done here due to lack of "off measurement"). - Easy to do just process with Calibration set 49 or higher - Caveat: If used for bulk reprocessing - will cause dominating red continua in HSA postcards. (Will be marked with light shading.)