# Program

• Tuesday, Aug 16th, 2016
• 13:00-13:15
• Opening Remarks
• 13:15-13:40
• ### The State of The Observatory

As we celebrate 17 years of new, exciting, high impact science, the Chandra X-ray Observatory continues to operate smoothly and efficiently. A 2014 detailed engineering study of the spacecraft subsystems found no show-stoppers to 10+ more years of operation, and we are planning for the long-term. Critical to this planning is the involvement of the whole community in discussing future scientific directions and new and continuing multi-wavelength observational opportunities, to ensure Chandra continues to play a key role in advancing our knowledge, addressing the most important science questions of the day, and maximizing its legacy.

In recent highlights, Chandra received an excellent report from the 2018 NASA Senior Review, ensuring continued NASA funding as we move forward. The Cycle 18 peer review was held in June, and the approved target list posted in mid July. The Chandra X-ray Center continues to deliver reduced, calibrated data to PIs within ~1 day of observation, and to provide the CIAO analysis software, accompanied by detailed analysis threads for both experienced and novice users, and backed up by our helpdesk. The use of the archive continues to grow along with its size, and version 2 of the Chandra Source Catalog, including ~350,000 sources, will be released in the fall, 2016.

I will review the capabilities, current state, and future prospects for Chandra, along with community access routes to Chandra observations, data, the archive, and relevant multi-wavelength facilities. I challenge this workshop to discuss and consider potential ways in which that access, and coordination with other current and future observatories, should/could evolve to maximize Chandra's science and impact over the next decade.

• Methods
• 13:40-13:55
• ### The Greater Observatories: the Need for Pan-spectral Coverage in 21st Century Astrophysics

For over three decades astronomers have become used to having access to the entire X-ray, UV, optical, infrared and radio spectrum. Many of these windows depend on space mission, with X-rays most notable among them. This access is now threatened: after the 2018 launch of the James Webb Space telescope (JWST) in the X-ray, UV or far-IR there will be no match to its sensitivity until the late 2020s at the earliest. Here I explain and address this crisis.

The first generation of these observatories - IUE, IRAS, and Einstein (rapidly followed by ROSAT and ASCA) - opened our eyes to the realization that virtually all astrophysical systems emit across the spectrum and that each band provides unique clues to how these systems work. Now we have three Great Observatories - Chandra, Hubble and Spitzer - that have extended this insight in far more detail.

As JWST itself has only a 5 - 10 year lifetime, it will be dead before any matching capability outside of the near-mid-IR can be operational. The rapid feedback from one band to another that keeps astronomy vital and making fast progress will thus be gone in the 2020s.

I suggest two ways to deal with this crisis in astrophysics.

First, thanks to a fortunate technological convergence, the X-ray, UV and far-IR bands all have ways to gain 1 - 2 orders of magnitude in capability at relatively low cost, such that all three may be realized for a total cost comparable to JWST. The thin mirror adjustable optics for the X-ray Surveyor is the example best known to this audience. These "Greater Observatories" - with JWST being the first - should, I believe, be the #1 recommendation of the 2020 Astronomy Decadal Review for large space missions.

Second, we should actively engage with the NewSpace community to bring down mission costs. Astronomers have not recently had to consider how our capabilities in space would be different by the time our next flagships start being built. But this is not the case this time. By the 2020 Decadal, and certainly by the time the next flagship missions are undertaken, the space industry will have changed greatly.

• 11:35-11:50
• ### Discovery of an extragalatic OVIII WHIM absorption line towards PG 1116+215

I present the discovery of a new 5.2 sigma OVIII K-alpha X-ray absorption line system towards the quasar PG 1116+215, observed with the Chandra LETGS grating spectrometer. This absorption line is in close association to a broad HI Lyman alpha absorption line discovered with HST by Tilton et al. in 2012. The X-ray absorption line system features also lower S/N OVIII K-beta and OVII K-alpha lines at the same redshift, indicating a very high temperature and column density and the possibility of significant non-thermal velocity structure. The absorption line system corresponds to filamentary galaxy structures we discovered in the SDSS data. The detection highlights the importance of FUV absorption line systems to uncover the notoriously hard-to-detect high-temperature WHIM.

• 11:50-12:05
• ### ISM analysis through high-resolution X-ray spectroscopy

High-resolution X-ray spectroscopy, provided by the grating instruments on board of Chandra and XMM-Newton, is a powerful technique to analyze the Galactic interstellar medium (ISM). Using a bright X-ray source the absorption features due to the environment located between the X-ray source and the observed can be analyzed, offering the opportunity to analyzed physical properties such as ionization degree, elemental abundances and column densities. I will present an analysis of the H, O, Ne, and Fe absorption in the X-ray spectra of 24 bright galactic sources obtained with the Chandra and XMM-Newton observatories. Finally, I will review the state-of-the-art of the field, including the importance of the atomic data, the local ISM structure, the detectability of X-ray absorption features due to the presence of molecules and the influence of dust scattering.

• 12:05-12:20
• ### A deep Chandra observation of the interacting star-forming galaxy Arp 299

We present results from a deep Chandra observation of the X-ray luminous interacting galaxy system Arp 299 (NGC 3690/IC 694). We detect 25 discrete X-ray sources with luminosities above ~4.0×1038 erg s-1 covering the entire Ultra Luminous X-ray source (ULX) regime. Based on the hard X-ray spectra of the non-nuclear discrete sources identified in Arp 299, and their association with young, actively star-forming region of Arp 299 we identify them as HMXBs. We find in total 20 off-nuclear sources with luminosities above the ULX limit, 14 of which are point-like sources. Furthermore we observe a marginally significant deficit in the number of ULXs, with respect to the number expected from scaling relations of X-ray binaries with the star formation rate (SFR). Although the high metallicity of the galaxy could result in lower ULX numbers, the good agreement between the observed total X-ray luminosity of ULXs, and that expected from the relevant scaling relation indicates that this deficit could be the result of confusion effects. Furthermore the integrated spectrum of the galaxy shows the presence of a hot gaseous component with kT=0.72±0.03 keV, contributing ~20% of the soft (0.1-2.0 keV) unabsorbed luminosity of the galaxy. A plume of soft X-ray emission in the west of the galaxy indicates a large scale outflow. Finally we discuss these results in the context of other star-forming galaxies with large ULX population and/or strong star-forming activity.

• 12:20-12:35
• ### Characterizing Interstellar Dust with Chandra in the Next Decade

We present the latest results on the chemistry study of the ISM based on the synergy between Chandra-HETG data and new synchrotron measurements of Interstellar Dust (ID) analogues (Costantini et al. 2013, Zeegers et al. 2016, submitted). These results open the door to a comprehensive study of the largely unknown ID composition using the unique capabilities of the Chandra X-ray observatory. Bright X-ray binaries can be used as background sources to probe the intervening dust along several sight lines. The shape and observed energy of the edges present in the spectra of these sources does reveal the composition and size of the intervening dust grains, as well as the elemental abundances and depletion values in different environments of the Galaxy.

• 12:35-13:35
• Closing Lunch
• 13:35
• Fin