1. XGAL 2016, Charlottesville, April 5 th 2016 Sergio Martín Ruiz Joint ALMA Office The unbearable opaqueness of obscured nuclei

2. Compact Obscured Nuclei (CON): The need for new molecular probes LIRGs and ULIRGs Radiating most of their energy as thermal dust emission in the IR Very compact (~few 10 pc) Important population among the most luminous extragalactic objects Power source: Early obscured stages of compact SBs and AGNs?  If AGN it might double the number of local AGNs (Maiolino+2013)  If SB it is an unusually intense and compact SF mode

3. Compact Obscured Nuclei (CON): The need for new molecular probes ARP 220: The ULIRG X Rays – CHANDRA Mc Dowell et al. 2002 NIR – HST Scoville et al. 1998 850um – SMA Sakamoto et al. 2008 LIRGs and ULIRGs Radiating most of their energy as thermal dust emission in the IR Very compact (~few 10 pc) Important population among the most luminous extragalactic objects Power source: Early obscured stages of compact SBs and AGNs?  If AGN it might double the number of local AGNs (Maiolino+2013)  If SB it is an unusually intense and compact SF mode

4. Compact Obscured Nuclei (CON): The need for new molecular probes NGC 4418 : The LIRG? SMA+MERLIN Existence of ~20pc dusty core with L bol ~10 11 L o (Sakamoto+2013, Costagliola+2013) ARP 220: The ULIRG X Rays – CHANDRA Mc Dowell et al. 2002 NIR – HST Scoville et al. 1998 850um – SMA Sakamoto et al. 2008

5. Chemically enhanced molecular tracers?

6. IRAM 30 m Aladro+2015 Low resolution e-line surveys have a limited potential and mostly for large scale heating mechanisms … SB evolution

7. HCN/HCO + /CS as diagnostic tools…some truth in them Izumi+2015 Observational Diagnostic Diagrams: Kohno +2002, Krips et al. 2008, Izumi +2013 Chemical Models: Harada+2010, 2013 Imanishi+2014 LIRG Sample resolution>500 pc! 4 2 HCN/HNC 4-3 0 0.5 1 1.5 2 HCN/HCO+ 4-3

8. Chemically enhanced molecular tracers?

9. Excitation

10. http://wchem.cup.uni-muenchen.de/wvib/hcn.html v 2 E u > 1000 K v 1 E u > 4500 K v 3 E u > 3000K Vibrationally excited emission is a new key to unlock obscured nuclei

11. Aalto+2015 Collisionally excited? n crit > 10 11 cm -3 Radiatively excited? T dust >100 K Vibrationally excited emission is a new key to unlock obscured nuclei

12. Aalto+2015 T(14um)>100K Collisionally excited? n crit > 10 11 cm -3 Radiatively excited? T dust >100 K Vibrationally excited emission is a new key to unlock obscured nuclei

13. Aalto+2015 T(14um)>100K Salter+2008 First detection in absorption with Arecibo towards Arp220 Direct l-type transitions T ex ~150K Free-free attenuation of J=2 Tau (1.6 GHz) >1.5 (consistent with recent findings by Barcoz- Muñoz+2015) Vibrationally excited emission is a new key to unlock obscured nuclei

14. T(14um)>100K LIRG NGC4418 in HCN (SMA, Sakamoto+2010) and HC 3 N (IRAM 30m/JCMT, Costagliola & Aalto 2010, SMA, Costagliola+2013, ALMA, Costagliola+2015) ULIRGs Arp220 in HCN (Arecibo, Salter+2008) and HC 3 N (SMA, Martin+2011) IRAS20551-4250 in HCN (ALMA, Imanishi & Nakanishi 2013) Mrk231 in HCN (Aalto+2015) Imanishi & Nakanishi 2013 Vibrationally excited emission might be the key to unlock obscured nuclei

15. Aalto+2015 LIRGs ULIRGs PdBI ALMA Small sample: 4 sources with evidence of compact nuclear activity (CII deficit and HCN 14um absorption) Vibrationally excited emission is a new key to unlock obscured nuclei High HCNvib/HCN ratio Lower L vib /L FIR related to high observed outflow speed? Total of 8 sources detected “so far” (already outdated!)

16. Imanishi+2014 Vibrationally excited emission is a new key to unlock obscured nuclei Still a limited sample of sources detected in HCN vib

17. What is the origin of vibrationally excited emission? Can it be linked to either AGN or SB activity?

18. Vibrational HC 3 N Tex ~ 300-500 K Martin+2011 What is the origin of vibrationally excited emission?

19. Sgr B2 region (de Vicente+1997,2000) HC 3 N* Vibrational HC 3 N Tex ~ 300-500 K What is the origin of vibrationally excited emission? Martin+2011

20. WATER H 18 O/C 18 O => water abundance ~2x10 5 Similar abundance to that in Sgr B2 hot core 2–8x10 6 Sgr B2-like hot cores In a <<700 pc region !!! Vibrational HC 3 N Tex ~ 300-500 K What is the origin of vibrationally excited emission?

21. Sgr A* CND Martin+2011 What is the origin of vibrationally excited emission? Mills+2013 Evidence of hot dust with T dust >150 K in the CND

22. Aalto+2015 Buried AGN or Hot optically thick Starburst? HCN vib requires: T(14um)>100K Optically thick Mid-IR source N(H 2 )>10 23 cm -2 Self-absorption consequence of the temperature gradient What is the origin of vibrationally excited emission?

23. Vibrational emission towards ARP 220 with ALMA

24. ARP 220: Surprises at high resolution Sakamoto+2009 HCO+ P-cygni profiles, SMA Tunnard+2015 SiO P-cygni profiles, PdBI 0.1”offset between emission/absorption ~100 km/s outward motions from the nuclei Bipolar Outflows Vibrational emission at high resolution towards Arp220

25. ARP 220: The ULIRG in the ALMA spotlight Tdust = 200 K (Western) and 80 K (eastern) Sizes of 70 pc (W) and 100 (E) pc Wilson+2014 Kinematic deconvolution of HCN Disk model fit Scoville+2015 Vibrational emission at high resolution towards Arp220 Sizes of 70 (W) and 100 (E) pc from VLA Optically thick <1mm (dust) and < 5GHz (Free-free) Barcos-Muñoz+2015 OUTDATED

26. ARP 220: The ULIRG in the ALMA spotlight Rangwala+2015 CO (6-5) Model: Highly turbulent rotating disk with high line center opacity and large T gradient Vibrational emission at high resolution towards Arp220

27. Martín+In prep Vibrational emission at high resolution towards Arp220

28. Martín+2016 up to 70% of the emission is absorbed in almost all emission lines HCN 3-2 HCN 4-3 HCO + 3-2 HCO + 4-3 Vibrational emission at high resolution Martín+2016 0 km/s -150 km/s-550 km/s

29. Change of slope claimed as increased SFE of the dense gas in LIRGs and ULIRGs Effect of absorption in the most luminous galaxies??? Gracia-Carpio+2008 Vibrational emission at high resolution towards Arp220

30. Vibrational emission at high resolution BOTH NUCLEI SHOW SIMILAR PROPERTIES Dust temperature & sizes (Wilson+2014) - EAST: 80 K ~100 pc - WEST: 200 K ~70pc HCN vib → T dust > 100K (Aalto+2015) HC 3 N vib T ex ~>300 E or W??? (Martin+2011) Continuum & Self- absorption Vib emission within 50-60 pc inside the dust cores and centered at the systemic velocity of each nucleus Martín+2016

31. Vibrational emission at high resolution towards Arp220 HCN vib is not correlated to the Lfir High Lvib/LFIR compared to Galactic hot cores Again Arp 220 stands out as the brightest in vib emission Eastern nucleus in Arp220 is by far the brightest Σ SFR ∼ 10 3.7 (East) ∼ 10 4.1 (West) M yr −1 kpc −2 (Barcos-Muñoz+2015) HCN vib 3-2 HCN vib 4-3 Sgr B2 M Arp220 E Arp220 W

32. So…can we use the vibrationally excited emission as an obscured nuclei diagnostic?

33. Tracing the most extreme environments Gonzalez-Alfonso+ in prep. Accurate diagnostic only in the optically thin regime. In both NGC4418 and Arp220 the vib 4-3/3-2 ratio is compatible with optically thick HCN vib emission This nuclei are unbearably opaque!

34. SUMMARY: Vibrational emission is either tracing deeply buried AGNs or the most extreme SB Σ IR >10 14 L o /kpc 2 & N(H 2 ) > 10 25 cm -2 No matter what the power source is, it will be interesting Vibrational emission gets us as close to the obscured nuclear power source as we can get …to be continued