30-Sep-2021 Bernhard Schulz
Last update 14-Oct-2021
The purpose of our first workshop was to determine the science requirements, so appropriate instrumental solutions can be developed and discussed in the second workshop. The first workshop took place from 26 to 28 of July 2021 with a total of 231 registered participants. The online workshop allowed for about 4.5 hours per day and had a typical online attendance in the eighties and nineties. Of the total of 56 presenters were 10 invited speakers, 32 gave contributed talks and 14 presentations were shown as posters, which nevertheless often included also a full recorded talk that was available to workshop participants to play at their leisure.
The workshop comprised of an introductory session, six science sessions and a summary session with open discussion segments at the end of each day. The science sessions were titled: Solar System with 5 talks, Star & Planet Formation with 6 talks, Interstellar Medium with 15 talks and 8 posters, Late Stellar Evolution with 2 talks, Nearby Galaxies with 8 talks and 3 posters, and High-Redshift Galaxies with 3 talks and 4 posters. It is remarkable that about a third of the presentations were focused on extragalactic objects.
We collected the slides of all speakers and prepared recordings of all talks. These materials where made available to all workshop participants online. In order to derive input for the second workshop, science cases were extracted from all 56 science contributions with the help of SOC members as well as workshop participants. The printout of the spreadsheet that served as the basis to this assessment is available. For each science case it lists a description and the required measurement. Other information like wavelength or frequency, spectral resolution, spatial resolution and typical flux were extracted but the way the information was collected led to a rather inhomogeneous coverage. Typically there is one science case per talk, unless independent cases could be identified. If both, spectrometers and photometers were needed, cases were split into two as well.
A more homogeneous picture was derived in a second spreadsheet, based on the first, and if necessary by going back to the original viewgraphs and recordings. Here a more consistent handle on required spectral resolution, and wavelength was achieved and specialty questions whether mapping, time sampling or polarization observations were needed.
From the total of 63 extracted science cases, two didn't provide enough information to derive required observations by airborne observatories. The remaining cases split into 46 spectrometry cases and 15 cases that required photometry. There was a clear bias towards heterodyne spectroscopy with 32 cases, certainly fueled in part by the quite successful GREAT instrument on SOFIA, but not only. However, in some cases the presentations were not specific enough and it appeared that the scientific goals could also be achieved with lower spectral resolution. In those cases two lower R solutions were marked as well for the same science case. In 19 cases the existing SOFIAS/FIFI-LS was sufficient, but in 13 cases it was stated that a higher spectral resolution was needed, although not quite as high as the sub-km/s resolution provided by GREAT. These cases were marked for a hypothetical R=5000 direct detection spectrometer, that had been suggested by several authors. The existing SOFIA/EXES spectrometer was only needed by 4 cases, although this may be more a reflection of the number of interested participants in this wavelength range at high spectral resolution than conceivable science cases there. Balloons were mentioned in 6 cases as preferred platform due to the higher achievable altitude and the resulting smaller atmospheric contamination of the data.
Photometry at long wavelengths was requested by 12 cases, while 3 cases asked for a near infrared camera and two cases required mid-infrared photometry. It is interesting to note that only 7 of the long wavelength photometry cases also asked for polarimetry to map magnetic fields. The rest was driven by SED assessments of faint extragalactic objects. Another specialty, the ability to have multiple observations at different times was requested by 5, which is more an observatory property. A majority of cases (37) asked for mapping of larger regions, while for only 21 a single pointing or a very localized map appeared to be sufficient.
The specific required wavelengths/frequencies and lines of equivalent atoms or molecules have been listed in the spreadsheet and can easily be traced back to the original presentation. The numbers quoted in the text have been summarized in Table 1 below.
The information provided in this summary should give a good idea for the second workshop as to what requirements there are for new instrumentation. It is obvious that spectroscopy is required a lot and towards extragalactic objects a trade is made, sacrificing spectral resolution for increased sensitivity as lines become broader as well. Nevertheless, other abilities like polarimetry and more sensitive broad band photometry to complete SEDs of fainter objects were interesting too.
Please note that this summary was produced under some time pressure in order to allow prospective speakers for the next workshop time to write an abstract. There could be minor updates and corrections to the numbers in the next days or weeks.
Table 1: Results quoted in the text in tabular form.
