Thick as thieves unveiling the most compact and obscured nuclei - PowerPoint PPT Presentation

Thick as thieves — unveiling the most compact and obscured nuclei Susanne Aalto Department of Space, Earth and Environment (SEE), Chalmers University of Technology Sweden +many collaborators

Outline • Dusty nuclei – Why do we care? – the torii – example NGC1068 – the Compact Obscured Nuclei (CONs) – example IC860 – ALMA CON-quest • Related posters: – CON-quest: Falstad, Onishi; – H 2 S: Sato • Dusty Feedback – AGN and starburst feedback – Collimated molecular outflows in dusty galaxies – example NGC1377

Dusty growth: U/LIRGs and obscured nuclei Luminous and Ultraluminous Infrared • Arp220 Galaxies, (U)LIRGs (L IR >10 11 L sun ), are dusty galaxies Often interacting - fundamental to our – understanding of galaxy evolution (e.g. Elbaz & NASA, ESA, and C. Wilson Cesarsky 2003; Sanders & Mirabel 1996). Some have even more embedded nuclei that harbour a Diaz-Santos+17 very active evolutionary stage of AGNs and/or starbursts. • Obscured AGNs Most AGNs in the universe are obscured (e.g. – The Antennae: Brandt and Alexander) 100 µ m PACS from Alexander 2011 on HST (Klaas +10) Shape and structure of torus linked to feeding of – SMBH and feedback Starburst-AGN connection – Winds How is the small scale (< 1 pc) obscuration linked – and to that at 10-100 pc – or on larger scales? jets • The nuclear activity will often drive mechanical feedback in the form of molecular winds, jets and outflows Garcia-Burillo+14

DUSTY NUCLEI

NGC1068: Imaging an AGN-obscuring dust torus with ALMA • High resolution (0.”06) ALMA λ =450 µ m observations reveal: • r =3.5 pc dusty turbulent torus with M gas =1x10 5 M sun (Garcia-Burillo+16, Gallimore+16). • Diagnostic HCN/HCO + line ratios change with distance to nucleus (Garcia- Burillo+14, Viti+14, Imanishi+16,18). • Even higher resolution observations (0.”02) (Garcia-Burillo+14,16) reveal apparent counter-rotation. (Imanishi+18, Impellizzeri+19, Garcia- From Garcia- Burillo+19 Burillo+19). Counter-rotation can be real, or an effect of inflow or ”outflowing torus”. • Column density estimated to N(H 2 )=10 23 cm -2 on scales of a few pc For more ALMA studies of AGN torii see e.g. Combes+19 (survey) , Izumi+18 (Circinus), Espada+17 (Cen A) , Aalto+17,20 (NGC1377)

OPAQUE NUCLEI – THE CONS

CONs – Compact Obscured Nuclei - N(H 2 )>10 25 cm -2 A v >>1000 Some (U)LIRGs harbour CONs - Still unknown how common they are. Extremely important to understand obscured phase: Hidden growth in our time: • – AGN statistics and/or growth of nuclear stellar spheroid. – Starburst-AGN connection. Relation to distant DOGs? SMGs? • Potential sources of cosmic neutrinos (e.g. Berezinskii & Ginzburg 1981; • Bahcall & Waxman 2001, Yoast-Hull+17). Example: NGC4418 (e.g Sakamoto+10,13, Costagliola+13 – see also Varenius+14 for VLBI imaging) mm/submm continuum NGC4418 0 5 10 15 • <0. “1 (<20 pc) nuclear (k) 860 µ m 1 1 emission Dec. offset [arcsec] • τ (860 μm) = 1 (i.e., N H >10 25 0 0 cm −2 ). − 1 − 1 0.35" x 0.26" 50 pc 1 1 0 0 − 1 − 1 R.A. offset [arcsec]

Buried nuclei can be traced by vibrationally excited molecules at long wavelengths – e.g. HCN Vibrationally excited HCN (HCN-VIB) Vibrationally excited HCN (HCN-VIB) ν =0 ladder ν 2 =2 ladder requires T B (14 µ m) > 100 K . Rotational transitions in the mm/submm. (e.g. Sakamoto+10, Aalto+15a,b, Imanishi+13, Martin+16, Aalto+16, Imanishi+16); cm wavelengths (e.g. Salter+08); mid-IR HCN absorption line (Lahuis+07) Cartoon by F. Costagliola 14 µ m IR field

ALMA 345-100 GHz, 25-90 mas observations of the early-type LIRG IC860 (Aalto+19) Major axis Ground state HCN, 14 pc 150 IC 860 HCO + , CS lines of rotation 100 continuum- and self MilliArc seconds absorbed in central 50 50 pc. 0 HCN-VIB -50 3-2 -100 100 50 0 -50 -100 -150 MilliArc seconds • HCN-VIB probes inner region – but opacities. T ex -T B matching: diminishing line-to-continuum ratio in inner r=4 pc. • mm continuum optically thick: – N(H 2 ) >10 26 cm -2 - ”brick wall” . Average gas densities n>10 7 cm -3 within r=9pc. (Assuming standard dust-gas ratio. Compare ULIRG core Arp220 (Scoville+17, Sakamoto+17, Barcos- Munos+18).(Beware of potential self-heating (Kaufman+98,Gonzalez- Alfonso+19). • Rotating thick turbulent nuclear disk + inflow+outflow Minor and major axis Nature of buried source: Accreting SMBH – potentially undermassive • position-velociy • A starburst consisting only of massive O-stars – i.e. extremely diagrams skewed initial mass function (IMF).

Massive inflow + onset of extremely dusty feedback? Layered structure of non-circular motions: Assymmetric foreground absorption inflow: • Reversed P-Cygni in HCN, HCO +. Inflow on scales >50 pc down to nucleus. The time-scale of gas to reach the nucleus from r =50 pc is 1 Myr Compact, dense outflow: P-Cygni in CS 7-6, HC 15 N out to • -300 km/s. Broad, minor axis HCN-VIB features may be base of outflow. Vibrationally excited HC 3 N v 7 =2 also seen along minor axis. Extent of dense outflow: 20 pc B. A. Cartoons of two scenarios: Massive inflow supplies nuclear gas/dust A. near-face-on with out-of-plane inflow. column – what allows for the build-up of of B. Near-edge-on where obscuration consists of N(H 2 )=10 26 cm -2 ? torus and in-plane inflow Witnessing the onset of dense feedback? – Or a failed wind? Timescales? Ongoing radio studies (Merlin/VLA/VLBI) reveal compaxt collimated jet-like structures + SNRs

ALMA CON-quest survey (see posters by Falstad and Onishi) CON-quest : Deep survey of 38 nearby • ULIRGs, LIRGs and low luminosity dusty galaxies . (PI: S.Aalto) – HCN, HCO + , HOC + , HCN-VIB 3-2 – Dense outflow statistics – Resolved HCN/HCO + ratio maps – Nuclear dynamics and SMBH masses – Deep 1mm continuum images – Prime data analysts: König, Falstad, Onishi, Sample CON-quest HCN, Nishimura HCN/HCO + ratio, spectra and continuum maps • What are CONs and what are their timescales?? • How common are they? Is there a NGC4418 Zw049.057 luminosity dependence on their prevalence? – Preliminary: The CON detection rates are 20 − 25% in FIR-selected (U)LIRGs with L FIR >10 11 Example of LIRG CON hosts: L sun , and 0% in lower luminosity galaxies.’ Dusty S0/galaxies – minor • CON hosts? mergers: HST V-band Images Preliminary: Major merger ULIRGs – minor – merger LIRGs? Possible link to post- HST GO-1: J. Gallagher, starburst signatures still needs investigation. CON-quest members : S. Aalto; N. Falstad; S. König; K. Onishi; Y. Nishimura; G. Privon; ; J. Mangum; S. Martin; K. Sakamoto S. Muller; S. Garcia-Burillo; E. Gonzalez-Alfonso; G. Fuller; T. Greve; F. Combes; C. Henkel; A. Evans; S. Mühle; T. Diaz-Santos; C. Ricci; K. Kohno; N. Harada; T. Izumi; M. Imanishi; J. Gallagher III; S. Viti; P. van der Werf; L. Barcos- Munos; S. Linden

Hot and opaque cores – where are the outflows? (Hallqvist+17, Falstad+19) HCN-VIB luminous galaxies do not Plot from Falstad+19 • show strong FIR OH λ =119 µ m P- OH inflow signature Cygni profiles. But they do show inflows. Why? • Outflow collimation. • Obscured, compact flows • CO outflow signatures now found for most CONs: I17208 (Garcia-Burillo+14); Zw049 (Falstad+18);NGC4418 (Fluetsch+18); Arp220 (e.g. Barcos-Munos+17); ESO320 (Pereirs-Santaella+16); IC860 (Aalto+19) Follow up studies on MUSE,HST, VLA, Median OH outflow velocity as a function of the HCN-vib luminosity relative ALMA (CON-firm , PI: Falstad) to the the total infrared luminosity. Velocities V out (from Veilleux+13)

MOLECULAR OUTFLOWS

AGN and starburst feedback The nuclear activity will often drive mechanical feedback in the form of winds, jets and M82 outflows. The feedback may: Regulate SMBH growth and link it to the host – NGC1377 galaxy – Magorrian relation. help partially explain ” dead” properties of local – ellipticals. reduce star formation efficiency – Outflows and winds from galaxies are Artists impression multi-phase . There is mounting evidence NGC253 that cold (10-100 K) molecular gas in outflows is common and that the cold gas may in some cases dominate mass and momentum flux

MOLECULAR ”JETS” IN DUSTY NUCLEI?

Collimated outflows in CONs? Zw049.057 Arp220 400 km/s OH (4-6 GHz) VLA line wing seen with the VLA (Falstad+19 see also Baan+89). HST image of Zw049 (Falstad+18, Gallagher et al in prep.) Weak radio continuum • ALMA reveals very dense and (5 GHz associated with fast (850 km/s) outflow in collimated NIR dust ULIRG Arp220. T B (HCN) > feature or shadow. T B (CO) (Barcos-Munos+17). Very opaque dust in core and CO 2-1, 6-5 tracing outflow (Scoville+17, very dense nuclear Sakamoto+17) outflow . Also the 690 GHz dust is partially tracing the nuclear ouflow. (ALMA+SMA)

The most extreme FIR-excess, radio-quiet galaxy NGC1377 Small, lenticular galaxy HST v-band L FIR =5x10 9 Lsun Excess FIR emission with q>3.9 – off FIR-Radio correlation by factor >37 Roussel+06 Deep silicate absorption (Spoon+07). No P α , Br γ - Faint H α , [N II] and [Ne Featureless morphology apart from southern II] lines, Faint PAH (Roussel+03,06). minor axis dust structure Post- starburst/LINER optical characteristics What is powering the compact IR luminosity - Obscured AGN or nascent starburst?