Deokkeun An: The Galactic Center: Not an active galactic nucleus

Focus on infrared
  • high gas surface density
  • cloud-cloud collisions
Spitzer IRS survey of CMZ
  • 107 candidates
  • 35 YSOs discovered
  • half of observing time spent on background
    • 428 total spectra on ISM lines of sight
  • NeII, SII, SiII maps
  • parameter maps:
    • ionization state
    • electron density
    • rad field hardness
Comparison to IRS observations of other galaxies
  • SINGS comparison + NeIII/NeII ratio vs O/H abundance + Galactic center is moderately inconsistent with AGN
  • Other line ratios (FeII/NeII vs SiII/SIII) - GC offset from AGNagain + Most CMZ points look like "normal" star forming regions + lots of scatter, but trend with longitude
  • photoionization by hot stars & shocks explain colors

Questions

  • Q: Is there any significance to the idea that high-latitude are most similar to AGN?
  • A: ...didn't understand question... talked about oxygen abundance determinations and statistical significance
  • Q: Is there any physical significance to the high-latitude points having AGN colors? Could it be from AGN being "turned off" years ago?
  • A: you tell me. Could be X-ray binaries, wolf-rayet stars. No clear evidence that Sgr A* excited it.
  • Q: Need bright source. XRBs would have to be very bright.
  • A: Our obs don't show much. Distance unknown. Could be foreground.
  • Q Stocke: - detections of Ne V. Couldn't see. How many had Ne V definitely detected? In infrared or diffuse?
  • A: ~12 out of 400 detected. Mostly Ne V in ISM, not in point sources.
  • Q Farhad: What does # of detected YSOs tell you about SFR? How are they distributed in plane?
  • A: Consistent with Schmidt law. Not far from Farhad's measurement. YSOs selected on IR photometry. 50% of sources from near Sgr B. Asymmetry: YSOs on left

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