A X-ray View of Two Infrared Dark Clouds

Presentation of a recent paper: https://arxiv.org/abs/2010.08792

Transcript

1. An X-ray View of Two Infrared Dark Clouds G034.43+00.24 and G035.39-00.33 Yuhan Yao 20201204 @Journal Club Yu, Wang & Tan (2020) arXiv:2010.08792v1 1
2. Infrared Dark Clouds (IRDCs) !2 Cold, dense regions of GMC Earliest stage of star formation Dark in IR! 850 µm G11.11-0.11 FoV: 0.22° x 0.48° 8 µm 2.17 µm
3. Lada+1984 Andre+2011 !3
4. !4 Solar Corona Lemen+2012 Hartmann+2016 Magnetospheric Accretion of Young Stars • Some from accretion shocks • Majority from corona (magnetic field) YSOs are bright in X-ray:
5. !5 N. Brickhouse X-ray Spectrum of TW Hya (Class II YSO) 2.5 keV 0.6 keV
6. X-ray Flares: Magnetic Reconnection Grosso+2020 Class 0 YSO HOPS 383 Kusano+2020 Schematic illustration of our scenario for the magnetic energy release in a stellar flare !6 Benz+2010, NASA Solar Postflare Loop
7. !7 LX / Lbol Prot / τ Wright+2011 Rotation period Convection timescale Prot / τ For Young Stars: LX — M relation log(LX / Lbol) ~ -3 Lbol — M relation Small Prot Telleschi+2007 LX (erg/s) M / M☉ Smaller Prot, Stronger B Field, More Luminous in X-ray Observed in main sequence stars:
8. COUP: Chandra Orion Ultradeep Project COUP COUP ROSAT VLT !8 Orion: d = 0.4 kpc 1408 COUP sources
9. N Unobscured/lightly obscured Heavily obscured Feigelson+2005 !9 COUP X-ray Distribution Function XLF = IMF * (LX — M relation) Sensitivity Limit of unobscured sample
10. Goal: Probe the YSO Content of Two Filamentary IRDCs !10 G034.43+00.24 and G035.39-00.33 G34.4 G35.4 Spitzer 8µm image (inverted grey scale) FoV: 20’x20’ Yu, Wang & Tan (2020) arXiv:2010.08792v1
11. G34.4 G35.4 5 epochs in 2017, 182ks 2 epochs in 2013, 63ks 112 point sources, 10 with strong variability 209 point sources, 20 with strong variability 3.7 kpc 2.9 kpc X-ray Chandra/ACIS-I Observations !11
12. G34.4 !12 Spitzer 8µm image Chandra smoothed image 112 point sources FoV: 20’x20’ IR Counterpart Identification
13. G35.4 !13 Spitzer 8µm image Chandra smoothed image 209 point sources FoV: 20’x20’ IR Counterpart Identification
14. Rough Estimates of Age, Mass, Extinction J-H (mag) J (mag) G34.4 J-H (mag) J (mag) G35.4 Solid black line: 1 Myr isochrone Dashed grey line: 2 Myr isochrone !14
15. X-ray Spectral Fitting Model 1 Model 2 Model 3 Power-Law (tbabs*powerlaw) Single temperature thermal plasma (tbabs*vapec) Two-component thermal plasma (tbabs*vapec*vapec) powerlaw tbabs vapec !15 Astrophysical Plasma Emission Code Collisionally-ionized Diffuse Gas
16. X-ray Luminosity Function (XLF) G35.4 G34.4 !16 slope=-0.6 slope=-1.4 More X-ray luminous sources Top-heavy IMF To few sources to infer IMF
17. Implication XLF LX — M relation ONC as calibrator Stellar mass 1700 M☉ G35.4 MIR & NIR extinction mapping Total mass 33,900 M☉ Star formation efficiency 5% Kainulainen+2013 Reference: ONC ~ 50% !17
18. Cautions ⚠ • Foreground star contaminants? This can boost up high end of XLF !18 • AGN contaminants in X-ray point sources? • Flaring sources have more weight on Lh in the relatively short observations • IRDCs have very high column density. Can still hide lower-mass YSOs. Thank you