SOFIA/FORCAST Observations of the Galactic Center Ryan M. Lau SOFIA Community Collaborators: T. L. Herter, M. R. Morris, E. E. Becklin, M. J. Hankins, Task Force Teletalks, J. D. Adams, G. E. Gull, C. P. Henderson, J. Schoenwald February 6, 2013 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Talk Outline • Background – The Galactic Center – Observations • Results and Science – The Circumnuclear Ring (CNR) (11 slides) – Quintuplet Proper Members (QPMs) (6 slides) – Pistol Nebula (10 slides) • Further Work 2 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau The Galactic Center • ~500 pc unique region containing a 4,000,000 solar mass black hole, massive stars, supernovae, and star formation regions QC & Pistol • 10% of present SF activity in Galaxy occurs in GC yet only tiny fraction of a percent of volume in Galactic disk CNR 10 pc • Contains ~4/12 of the LBVs and ~90/240 of Wolf-Rayet stars in galaxy 3 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau The Galactic Center: Inner 50 Pc • Circumnuclear Ring (CNR) – Dense ring of gas and dust surrounding Sgr A* by 1.4 pc • Quintuplet Cluster (QC) QC & Pistol – ~4 Myr cluster of hot, massive stars – Named after 5 bright IR sources within cluster (we observe 4 of them) • Pistol Nebula CNR – Asymmetric shell of dust and 10 pc gas surrounding the Pistol star – Appears to be shaped by 8 μm Spitzer/IRAC image of the inner interaction with QC winds 50 pc of the Galactic Center 4 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Observations • SOFIA/FORCAST Quintuplet Galactic Center Stars observations conducted during Basic Science flights 63 and 64 QC & Pistol Nebula Pistol on June 4, 2011 and 8, 2011, respectively. 40 pc CNR SOFIA/FORCAST images CNR at 19.7 (blue), 31.5 (green), 37.1 (red) mm 8 μm Spitzer/IRAC image of the inner 50 pc of the Galactic Center 5 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau FORCAST • Facility Instrument – LHe cooled (4.2 K), 700 lbs • Dual-Channel 256x256 Camera w/ Si BIB arrays – BIB: Blocked-Impurity-Band – 5-25 mm with Si:As array – 25-38 mm with Si:Sb array • Plate scale: 0.75 arcsec/pixel – 3.23.2 arcmin FOV • Selectable filters over the 5 - 38 mm range FORCAST commissioning in mid-March 2013 and available for Cycle 1B Above: FORCAST mounted on the SOFIA Telescope observations in early Summer 2013 Below: FORCAST in the DAOF lab 6 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau FORCASTFilter Profiles Filters 1.0 Filter (mm) R (l/Dl) 0.8 5.3 33 6.3 48 0.6 6.6 34 0.4 7.6 15 Filter Transmission 0.2 8.6 42 11.0 12 0.0 5 6 7 8 9 10 11 12 11.28 56 Wavelength (microns) Filter Profiles 19.5 3.8 1.0 19.7 31.5 37.1 24.4 7.5 0.8 30.6 5.7 0.6 33.4 18 34.8 8.3 0.4 37.1 8.8 Filter Transmission 0.2 Left: Representative FORCAST filter 0.0 curves (not including atmospheric 15 20 25 30 35 40 transmission or detector response). Wavelength (microns) Arrows indicate filters used in GC observations. 7 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Galactic Center Results: The Circumnuclear Ring QC & Pistol 40 pc CNR 8 μm Spitzer/IRAC image of the inner SOFIA/FORCAST false color image of the inner 6 pc of the GC at 19.7 50 pc of the Galactic Center 8 (blue), 31.5 (green), 37.1 (red) mm SOFIA/FORCAST Observations of the Galactic Center R. M. Lau The Ring around Sgr A* Face on View Observed View SOFIA/FORCAST Sgr A* Northern Arm East-West Bar Observed view of CNR model 1 pc Face-on view of CNR model SOFIA/FORCAST false-color CNR inclined by ~67 degrees and image of CNR has a radius of 1.4 pc 9 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Observations of the CNR Deconvolved and reconvolved to 2.5’’ beamsize Left: Observed SOFIA/FORCAST images of the CNR at different intensity stretches Right: Deconvolved and reconvolved CNR images 10 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Evidence for Central Heating b a c b c a e e d d Above: 37.1 mm intensity map Shifts in peaks across wavelengths indicate a Upper Right: Intensity line cut through center of ring radial temperature gradient and central heating11 Lower Right: Intensity line cut through south of ring SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Temperatures Across the Ring • Temperatures range from 70 - 85 K – Consistent with temperature calculations assuming central 7 L ~ 2 x 10 Lsun heating source. • Fairly uniform temperature around ring – Heating dominated by radiation from central cluster Color temperature map of the inner – No star formation 6 pc of the GC derived from 19.7 and 37.1 µm intensity maps occurring in rung 12 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau CNR Column Density • Column densities range from 0.025 – 0.4 – They peak at the northern and southern clumps • A majority of the material in this region lies in the ring (not the Northern arm or East-West bar) • Total CNR gas mass is ~450 Solar masses* Optical depth map at 37.1 mm of the inner 6 pc of the GC. Contours at 0.025, 0.05, 0.1, 0.2, and 0.4 (dark) 13 *Assuming dust to gas mass ratio of 1/100 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Ring Morphology • We can determine the width of the CNR given our 2.5’’ resolution images Rin φo – We can also find the Sky Plane inclination angle θi (67°), θi and inner radius Rin (1.4 pc) • From the width we Line of determine the Sight opening angle φo (14°) h and ring height Cross section through CNR. The h (0.35 pc) orange regions indicate the illuminated region of the ring 14 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau CNR Intensity Model 37.1 µm 37.1 µm MODEL OBS Model 37.1 µm Intensity map of CNR Observed 37.1 µm Intensity map of Density at inner edge is n = 104 cm-3 the inner 6 pc of the GC Model has been convolved with 2.5’’ Gaussian to match beamsize of the observed image 15 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Model vs Observed 37.1 Intensity Map Radial Line Cuts: East-West 37.1 µm East-West Intensity Line Cut OBS Western Arc 15 Observed 10 Model Intensity (Jy) Intensity 5 0 -60 -40 -20 0 20 40 60 Pixel Western Arc Observed 37.1 µm Intensity map of the inner 6 pc of the GC with East- Model vs. Observed 37.1 µm West cut overlaid intensity line cut through CNR Model intensity peak location, width, and value at Western arc are consistent with observed data 16 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Model vs Observed 37.1 Intensity Map Radial Line Cuts: Diagonal 37.1 µm Diagonal Intensity Line Cut OBS Western Arc 15 Observed Model 10 Intensity (Jy) Intensity 5 0 -50 0 50 Pixel Western Arc Observed 37.1 µm Intensity map of the inner 6 pc of the GC with Model vs. Observed 37.1 µm intensity diagonal cut overlaid line cut through CNR. Model intensity peak location, width, and value at Western arc are consistent with observed data 17 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Inner Edge “Clumps” • We resolve “clumps” at the inner edge of the CNR • “Clumps” due to density enhancements (not embedded sources) • n ~ 2-3 x 104 cm-3 SOFIA/FORCAST false color image of the inner 6 pc of the GC at 19.7 • Periodic? (blue), 31.5 (green), 37.1 (red) mm. Inset shows zoom of inner edge “clumps” 18 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau CNR Results Summary • The CNR is heated by central cluster of stars • Observed temperatures consistent with heating by central source with total luminosity 7 L ~ 2 x 10 Lsun • No star formation occurring in CNR • Dust emission from CNR can be modeled as an inclined ring • Possibly periodic “clumps” occur SOFIA/FORCAST false color image in the inner edge of the CNR of the inner 6 pc of the GC at 19.7 (blue), 31.5 (green), 37.1 (red) mm 19 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Galactic Center Results: The Quintuplet Proper Members* Quintuplet Proper Members QC & Pistol 40 pc *Work lead by Matt Hankins, CNR senior undergrad at UCA 8 μm Spitzer/IRAC image of the inner SOFIA/FORCAST false color image of the Quintuplet cluster at 19.7 (blue), 50 pc of the Galactic Center 31.5 (green), 37.1 (red) mm 20 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau The Quintuplet Proper Members (QPMs) • Quintuplet cluster age ~4 Myrs – Cluster of hot, massive stars – Coeval formation Q9 Q4* Q1 Q2 • QPMs very luminous (L~105 Q3 LSun), cool (600-1200 K) sources with featureless K- band spectra – Extremely dusty Pistol • Late-type dusty Wolf-Rayet Nebula stars (DWCL) (Figer et al. 1999) SOFIA/FORCAST false color image of 1 pc the Quintuplet cluster at 19.7 (blue), 21 31.5 (green), 37.1 (red) mm *we barely observe Q4 SOFIA/FORCAST Observations of the Galactic Center R.