1. N159 Region of the LMC: Using Dendrograms to Explore the Relation Between CO and CS Molecular Gas to Star Formation in a Low Metallicity Environment Isha Nayak onayak1@jhu.edu M. Meixner, M. Sewilo, R. Indebetouw, Y. Fukui, T. Onishi, L. Carlson, K. Tachihara, K. Saigo April 7, 2016

2. Why Study the Large Magellanic Cloud? Distance ~ 50 kpc Face-on view Active star formation – Massive star formation – SAGE survey (Meixner et al. 2006) used to find YSOs Different environment than Milky Way – Low dust-to-gas ratio (1/3 of MW) – Low metallicity (0.5 solar) – SFR of 0.1 solar mass/year Meixner et al. (2006) R: MIPS 24, G: IRAC 8.0, B: IRAC 3.6

3. Why study the N159 GMC? One of the largest – Mass: – Size: Strongest CO peak Mizuno et al. (2009) Minamidani et al. (2008)Ott et al. (2008) MOPRAASTE NANTEN

4. N159W is Currently Forming Massive Stage 0/I Stars Fukui et al. (2015) White Crosses: YSOs (Chen et al. 2010) Red Crosses: 1.3mm continuum peak

5. What is a Dendrogram? Dendrogram algorithms look for the largest scale sizes first and then for smaller clumps embedded within the larger ones Dendrogram analysis provides a more accurate picture of the hierarchical structure of molecular clouds We use dendrograms to study the CO and CS molecular gas

6. Finding Additional YSO Candidates in SAGE Catalog Has it been previously identified? yes no It is a candidate Does it fit YSO SED? no It is not a candidate Does it fit stellar photosphere SED? no It is not a candidate It is a candidate yes

7. Potential YSO Candidate SEDs Good fit to YSO SED, bad fit to stellar photosphere SED. It is a candidate. Robitaille et al. (2006)

8. Potential YSO Candidate SEDs Good fit to YSO SED, good fit to stellar photosphere SED. It is not a candidate. Robitaille et al. (2006)

9. Potential YSO Candidate SEDs Bad fit to YSO SED. It is not a candidate. Robitaille et al. (2006)

10. CO gas, CS gas, Old YSOs, New YSOs Green Circles: Old YSOs Blue Circles: New YSOs Greyscale: CO molecular gas Red Contour: CS molecular gas

11. Spectra of N159W YSO-North wavelength [microns] log(flux) [mJy] 010 20 3040 -2 0 1 2

12. Spectra of N159W YSO-North PAH wavelength [microns] log(flux) [mJy] 010 20 3040 -2 0 1 2

13. Spectra of N159W YSO-North H2H2 wavelength [microns] log(flux) [mJy] 010 20 3040 -2 0 1 2

14. Spectra of N159W YSO-North ices wavelength [microns] log(flux) [mJy] 010 20 3040 0 1 2

15. Spectra of N159W YSO-North silicon absorption wavelength [microns] log(flux) [mJy] 010 20 3040 -2 0 1 2

16. Virial Parameter without YSO with YSO 5σ 2 r/GM log(clump mass) [solar mass] Large mass clumps are associated with massive YSO candidates.

17. Local Environment Affects Size-Linewidth Relation 30 Doradus CO clumps: N159W CO clumps: σ = 1.58 r 0.97 σ = 1.10 r 1.07 N159W CS clumps: σ = 0.98 r 1.65 Perseus Cloud: σ = 0.62 r 0.54 Shetty et al. (20012)

18. Conclusions N159W currently forming massive stars There are 9 YSO candidates have previously been identified There are 2 YSO candidates forming via filamentary collisions We identify 10 additional YSO candidates by SED fittings It is the massive clouds that are forming massive stars There are some clumps in N159W with elevated linewidths for a given size in comparison to Milky Way clumps in quiescent regions This is different from 30 Doradus where almost all the clumps, regardless of size scale or star formation activity, are offset from Milky Way clumps