Keck OSIRIS AO LIRG Analysis (KOALA)

Co-leads: Vivian U (UCI), Anne Medling (Toledo), in collaboration with the GOALS Team

We investigate the co-evolution of black holes and their host galaxies through studying the detailed gas and stellar kinematics in the nuclei of nearby infrared-luminous interacting galaxies. The adaptive optics-assisted near-infrared integral-field spectrograph OSIRIS on the 10-meter Keck Telescopes provides us a high angular resolution 3D view of the gas feeding and feedback at this critical transformation stage within a massive galaxy's lifetime.

HST-ACS images of galaxies placed along the merger sequence; taken as part of the GOALS campaign. Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)

Check out our survey's sample, data, and publications down below.

Sample of Nearby (U)LIRGs

A Local Census of Infrared-Luminous Galaxy Mergers from the 3D Near-Infrared Perspective

The Great Observatories All-sky LIRGs Survey (GOALS; Armus et al. 2009) consists of just over 200 of the brightest and closest luminous and ultra-luminous infrared galaxies ((U)LIRGs) in the local universe, a complete subset of the flux-limited IRAS Revised Bright Galaxy Sample (Sanders et al. 2003). The HST-ACS coverage of the survey consists of the most luminous 86 objects within GOALS, complete down to LIR ≥ 1011.4. Given that high spatial resolution images with precision astrometry are critical for planning AO observations with OSIRIS's small field-of-view, we draw from within this HST-GOALS sample those that host suitable guide stars for the Keck AO system as our primary targets.


From the HST-GOALS sample (Kim et al. 2013; Evans et al., in prep), our Keck program has observed ∼30 galaxy systems. Our target list is included here:

KOALA Target List
Galaxy RA Dec z log LIR Merger Class
CGCG 436−030 01:20:02.634 +14:21:42.260 0.0315 11.68 2
IRAS F01364−1042 01:38:52.882 −10:27:11.480 0.0490 11.79 5
III Zw 035 01:44:30.537 +17:06:08.900 0.0278 11.62 3
IRAS F03359+1523 03:38:47.070 +15:32:53.740 0.0365 11.51 3
MCG +08−11−002 05:40:43.783 +49:41:42.150 0.0195 11.46 6
IRAS F06076−2139N 06:09:45.817 −21:40:23.660 0.0374 11.65⋆ 3
IRAS F06076−2139S 06:09:46.025 −21:40:31.460 0.0374 11.65⋆ 3
NGC 2623 08:38:24.087 +25:45:16.590 0.0196 11.58 5
UGC 05101 09:35:51.611 +61:21:11.600 0.0390 12.00 5
UGC 08058 / Mrk 231 12:56:14.231 +56:52:25.250 0.0433 12.53 5
ESO 507−G070 13:02:52.354 -23:55:17.730 0.0217 11.53 6
VV 250a 13:15:35.116 +62:07:28.540 0.0308 11.77 2
VV 250b 13:15:30.819 +62:07:45.320 0.0308 11.77 2
UGC 08387 13:20:35.350 +34:08:21.750 0.0239 11.72 5
UGC 08696 / Mrk 273 13:44:42.140 +55:53:13.700 0.0380 12.18 5
IRAS F14348−1447 14:37:38.299 -15:00:23.950 0.0830 12.37 4
VV 340a 14:57:00.701 +24:37:02.220 0.0344 11.79 1
VV 705N 15:18:06.140 +42:44:45.100 0.0402 11.88 4
VV 705S 15:18:06.339 +42:44:38.230 0.0402 11.88 4
IRAS F15250+3608 15:26:59.443 +35:58:37.010 0.0563 12.07 5
NGC 6090 16:11:40.865 +52:27:27.640 0.0303 11.55 4
NGC 6240 16:52:58.870 +02:24:04.380 0.0244 11.93⋆ 4
IRAS F17207−0014 17:23:22.010 −00:17:00.200 0.0432 12.46⋆ 5
IRAS F18090+0130E 18:11:38.380 +01:31:39.820 0.0286 11.65⋆ 2
IRAS F18090+0130W 18:11:33.367 +01:31:42.370 0.0292 11.65⋆ 2
NGC 6670E 18:33:37.617 +59:53:23.280 0.0291 11.65⋆ 2
NGC 6670W 18:33:33.927 +59:53:17.080 0.0291 11.65⋆ 2
IRAS F20351+2521 20:37:17.743 +25:31:37.750 0.0344 11.61⋆ 0
IRAS F22491−1808 22:51:49.220 −17:52:23.400 0.0781 12.19 5
NGC 7469N 23:03:17.985 +08:53:37.750 0.0163 11.58 2
NGC 7469S 23:03:15.616 +08:52:26.830 0.0163 11.58 2
NGC 7674W 23:27:56.726 +08:46:44.660 0.0289 11.51 1
NGC 7674E 23:27:58.770 +08:46:58.190 0.0289 11.51 1

Table notes: Logarithmic infrared luminosity defined as log LIR [8−1000μm] was adopted from U et al. (2012) and ⋆Armus et al. (2009); Merger classification was adopted from Haan et al. (2011) and Kim et al. (2013).

Keck OSIRIS Observations

Our observing campaign has been ongoing since 2009. The observations were taken with OSIRIS on the Keck II and Keck I Telescopes before and after January 3, 2012, respectively.

OSIRIS Observing Modes

  • AO Mode: With LGS and NGS (typical FWHM ∼0.05")
  • Filters: mostly Kbb/Kcb (1965nm ≤ λ ≤ 2381nm with spectral resolution R∼3800), but also occasionally Kn5/Kc5, Kn4, Kn3, Hn4, and Jbb
  • Plate scale: mostly 100mas and 35mas, but also sometimes 50mas
  • Lines targeted: H2, Brγ, Brδ, He I, [Si VI], the CO absorption bandheads, and sometimes [Fe II]

1D K-band Spectrum

Example K−band spectrum from the nuclear region of NGC 2623. The open downward triangles mark the five H2 transitions, the filled downward triangles mark the two Brackett transitions (Brγ and Brδ), while the filled bars mark the CO bandheads. Not marked are Paβ (λrest = 1.875 μm), He I (λrest = 2.059 μm), and [Si VI] (λrest = 1.964 μm). (Figure adopted from U et al. 2019)

Science Result Highlights

Mrk 273

We found a nuclear molecular outflow, measured the black hole mass, and confirmed the dual AGN within this spectacular ULIRG Mrk 273! Our results were also featured in the press by Universe Today!

IRAS F17207-0014

We found nuclear shocked molecular gas at the base of a large galactic-scale wind in IRAS F17207-0014 when we connected IFU observations with different plate scales and field of views!

MCG +08−11−002

We determined nuclear star cluster ages with resolved CO absorption and Brγ emission to explore the star formation and interaction history of MCG +08−11−002 as an ongoing galaxy merger!


Nuclear Disks

We found that nuclear disks of gas and stars are nearly ubiquitous within late-stage galaxy mergers and determined their physical properties!

Black Hole Masses

We measured dynamical black hole masses for late-stage gas-rich galaxy mergers and found that they all lie on or above black hole scaling relations!

Nuclear Feedback

We employed near-infrared diagnostics such as Brγ and the ro-vibrationally excited H2 lines to identify feedback associated with shocked molecular gas, found preferentially in ULIRGs!

Publication List

  1. Kool, E.C., Reynolds, T.M., Mattila, S., Kankare, E., Pérez-Torres, M.A., Efstathiou, A., Ryder, S., Romero-Cañizales, C., Lu, W., Heikkilä, T., Anderson, G.E., Berton, M., Bright, J., Cannizzaro, ., Eappachen, D., Fraser, M., Gromadzki, M., Jonker, P.G., Kuncarayakti, H., Lundqvist, P., Maeda, K., McDermid, R.M., Medling, A.M., Moran, S., Reguitti, A., Shahbandeh, M., Tsygankov, S., U, V., Wevers, T. 2020, "AT 2017gbl: a dust obscured TDE candidate in a luminous infrared galaxy.", MNRAS, in review, arXiv:2006.01518
  2. U, V., Medling, A.M., Inami, H., Armus, L., Díaz-Santos, T., Charmandaris, V., Howell, J., Stierwalt, S., Privon, G.C., Linden, S., Sanders, D.B., Max, C.E., Evans, A.S., Barcos-Muñoz, L., Rich, J.A., Larson, K., Appleton, P., Iwasawa, K., Surace, J., Mazzarella, J., Murphy, E., Canalizo, G., & Fazio, G. 2019, "The GOALS-Keck OSIRIS AO LIRG Analysis (KOALA) Survey: Feedback in the Nuclei of Luminous Infrared Galaxies.", ApJ, 871, 166 (ADS)
  3. Davies, R.L. Medling, A.M., U, V., Max, C.E., Sanders, D.B., & Kewley, L.J. 2016, "Reconstructing Merger Timelines Using Star Cluster Age Distributions: The Case of MCG+08−11−002", MNRAS, 458, 158 (ADS)
  4. Medling, A.M., U, V., Max, C.E., Sanders, D., Armus, L., Holden, B., Mieda, E., Wright, S.A., & Larkin, J. 2015, "Following Black Hole Scaling Relations Through Gas-Rich Mergers", ApJ, 803,61 (ADS)
  5. Medling, A.M., U, V., Rich, J.A., Kewley, L.J., Armus, L., Dopita, M.A., Max, C.E., Sanders, D., & Sutherland, R. 2015, "Shocked Gas in RAS F17207-0014: ISM Collisions and Outflows", MNRAS, 448, 2301 (ADS)
  6. Medling, A.M., U, V., Guedes, J., Max, C.E., Mayer, L., Armus, L., Holden, B., Roškar, R., & Sanders, D. 2014, "Stellar and Gaseous Nuclear Disks Observed in Nearby (U)LIRGs", ApJ, 784, 70 (ADS)
  7. U, V., Medling, A.M., Sanders, D., Max, C., Armus, L., Iwasawa, K., Evans, A., Kewley, L. & Fazio, G. 2013, "The Inner Kiloparsec of Mrk 273 with Keck Adaptive Optics", ApJ, 775, 115 (ADS)

Contact Us

Let us know if you'd like to collaborate with us on our data sets and/or have any questions about our survey!
We can be reached at vivianu [at] uci [dot] edu and anne.medling [at] utoledo [dot] edu.