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The SED of the nearby, HI-massive, LIRG HIZOA J0836-43: from the NIR to the radio domain

The SED of the nearby, HI-massive, LIRG HIZOA J0836-43: from the NIR to the radio domain. Renée C. Kraan-Korteweg Astronomy Department Centre for Astrophysics Cosmology and Gravity, UCT Michelle E. Cluver IPAC, CalTech(formerly UCT) Collaborators: T. Jarrett (IPAC CalTech )

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The SED of the nearby, HI-massive, LIRG HIZOA J0836-43: from the NIR to the radio domain

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  1. The SED of the nearby, HI-massive, LIRG HIZOA J0836-43: from the NIR to the radio domain Renée C. Kraan-Korteweg Astronomy Department Centre for Astrophysics Cosmology and Gravity, UCT Michelle E. Cluver IPAC, CalTech(formerly UCT) Collaborators: T. Jarrett (IPAC CalTech) B. Koribalski (ATNF CSIRO) P.N. Appleton (NHSC CalTech) J. Melbourne (IPAC CalTech) B. Emonts (ATNF CSIRO) SED 2011, Preston 5-9 September 2011

  2. Discovered in deep Parkes MB HI survey of southern ZOA (& HIPASS) • MHI = 7.5 х 1010M • Velocity width ~ 600 km/s • Vel = 10689 km/s • (D=148 Mpc) • HI diameter = 130 kpc • SFR 1.4 GHz = 35M/yr • Not AGN, Starburst? • Similar to Malin 1 • But not quiescent (0.38M/yr) • nor LSB (like most giant • HI galaxies) • Donley et al. (2006)

  3. But the galaxy lies in the ZOA; behind thick layer of dust l,b = 262°.48, -1°.64 Av = 7.5 mag DIRBE; Schlegel et al (1998) And behind the Vela SNR It is optically ~invisible Observations at higher λ are needed to learn more about this Galaxy NIR – environment with IRSF MIR – imaging & spectroscopy with Spitzer mm - Mopra Credit: Davide De Martin

  4. The Environment • NIR (JHK) imaging survey • of 2.24 ☐o 404 galaxies; • phot-z: quiet low density area 0.03 < z < 0.04 The galaxy lies in a region underdense in L* galaxies. This may have allowed its formation and survival, enabling it to evolve in the unusual LIRG  Grey: galaxies in 10Mpc volume around HIZOA

  5. Various composite images of HIZOA J0836-43 Cluver et al. ApJ 2010 Opt: nearly invisible NIR: prominent bulge; 20cm extended MIR: extended SF disk Similar to 20cm Extended SF also strong in PAHs (6.2,7.7, 11.3) And [NeII]  All SF indicators extend beyond the old evolved stellar pop.  50kpc SF disk

  6. Inside-out Disk Building Cluver et al. ApJL (2008) [Ne II] contours xxx SL Spectral Map of 11.3μm PAH Extended SF disk of about 50kpc

  7. SED of HIZOA J0836-43: NIR, IRAC, MIPS • LTIR = 1.2 ×1011 L Luminous Infrared Galaxy (LIRG) • SFR = 20.5 M/ yr (Kennicutt 1998) • resembles Sc-galaxy • Note:not S0/Sa as from NIR imaging/photometry • strong MIR emission (5-8μm)  but PAH’s • strong emission from cold dust (λ > 60μm) • But it does not match starburst (see M82) Cluver, Jarrett et al. ApJL (2008)

  8. Spitzer IRS Spectroscopy (MIR) of nucleus Combined SL (5-14μm) + SH (10-20μm) + LH (19-38μm) • Strong excited nebular lines • Typical of SF/SB regions but also of PDR (RN) • But no [Ne V] & [O IV] AGN absent (or weak) • Strong PAH Emission •  extended > nucleus • but weak MIR continuum • weak rotational H2 lines - T ~ 330K • - M = 1.3 × 107 M Strong PAH emission Relatively weak continuum Cluver et al. ApJ (2010)

  9. CO observations using Mopra (2009,2010) What about cold molecular gas? Observed: very little warm H2-gas Prediction: from LFIRMgas= 1.3 x 1010 M • - Rapidly rotating mol disk • - No low velocity gas • - Mcold gas = 3.9 x 109 M • lower than predicted • - M(H2)/M(HI)= 5 % • - fmol gas = 8% • - Gas fraction = 64 % Central pointing, 16.6 hrs, beam 30”; entire disk 1’ Most of gas in beam; lower limit for mass estimate

  10. What’s the connection? • Lots of stars + lots of gas + building • M* = 4.4×1010 M+MHI = 7.5×1010 M+MH2+He = 3.9 ×109 M • SFR = 20.5 M/yr & sSFR = 0.47 Gyr-1 • Gas Fraction~ 64% & Molecular Gas Fraction > 8% •  vigorously star-forming extended stellar disk (inside-out) • Properties as scaled-up version of local disk galaxies • (a) How does this compare to other local SF disk galaxies? • (b) How does this compare to more distant systems? • (c) Can we say something about the star formation processes, bimodality?

  11. (a) Comparison to SINGS galaxies (Dale et al. 2009)

  12. (a) Comparison to sample of local LIRG’s (z < 0.1) (Wang et al.; 2006) M*= 4.4 x 1010M (using Bell et al.; 2003) - implies young stellar-building phase - sSFR = 0.47 Gyr-1 - can double stellar mass in 2Gyr HIZOA J0836-43  (hashed lines indicate SFR of 10, 30, 100M/yr)

  13. (b) Comparison to higher redshift SF Galaxies HIZOA J0836-43 is building stellar mass…   Bell et al. (2005) →HIZOA J0836-43 is more similar to the z ~ 0.7 galaxies than local star forming galaxies

  14. (b) Gas-Star Formation relation over Cosmic Time Genzel et al. (2010) for normal SF galaxies (crosses from CO-line emission) SFR = 150(M★/1011)0.8 ([1+z]/3.2)2.7 (Bouché et al. 2010) The so-called main sequence of SF at a given M★as a f(z) 20.5 M/yr corresponds to z ~ 0.95 Grey crosses: Noeske et al (2007), Daddi et al. (2007)

  15. Discussion z ~ 0 • LIRGs are relatively rare locally (5% of EDIR) • Local ones: mostly major mergers • HIZOA is coldest LIRG (MIR cont) compared to GOALS  scaled-up galaxy wrt gas mass, SF properties From z~ 0.1 - 1.0 LIRG;s show little evidences of major merging, mostly minor; heightened SF because of high gas fraction (e.g. Bell 2005, Melbourne et al 2008, Robaine2009, … Noorden et al. 2011) z ~ 1.0 • LIRGs are more common (70% of EDIR) • Have high gas fraction, hence high SF BUT low SF efficiency  similar to scaled-up local disk galaxies Noorden et al. 2011: ”Larger gas fractions at higher redshift permit larger LIR before invoking special events like mergers and will shift correlations with LIR.

  16. (c) Understanding Star Formation : Gas content  SFR  Stellar mass Daddi et al. 2010 ApJL

  17. Main points: a local LIRG • Rapidly rotating HI and CO (molecular gas) disk • - “large gas reservoir”; is it accreting? • Old bulge + ‘new’ (forming) stellar disk • - not a major merger • instead it is a "disk" starburst --> we see clear *inside-out* disk building • consistent to higher z: larger SFR is due to larger gas reservoirs • Similarities to *z~1* (gas content, stellar mass, SFR -but not molecular gas fraction) • - study mechanism of "big disk" star formation (inside-out formation) • - at an observationally feasible distance (z~0.036) compared to distant disks at *epoch of peak stellar building*

  18. The End

  19. Future Plans • ATCA : long baselines = higher angular resolution • Distributionand kinematics of HI (and warp) • Probe interface between H2 and HI •  DONE (Feb 2011) • Herschel Proposal • Some of the results: • Cluver et al. 2008 ApJL 686, L17 (arXiv:0808.4040) • Cluver et al. 2010 ApJ 725, 1550 (arXiv: 1010.3550) • - Michelle Cluver at : mcluver@ipac.caltech.edu

  20. (c) Understanding Star Formation : Gas content  SFR  Stellar mass Noeske et al. (2007) : • AEGIS galaxies form a “main-sequence” with a limited range of SFRs at a given Mstellar and z • MS as a whole moves to higher SFR as z increases • LIRGs at z~1 mostly reflect the high SFR typical for massive galaxies at that epoch Daddi et al. (2010): • Two modes of SF : long-lasting for disks vs rapid for starbursts • Difference due to fraction of molecular gas in dense clouds? • Different αCO for mergers vs non-mergers

  21. Molecular gas fractions and star formation mechanisms 34% @ z~1.2 (update 45%) 44% @ z~2.2 (update 56%) HIZOA (from CO): 3.9 x 109 M  8.8 % (lower limit) Genzel et al. (2010) Tacconi et al. (2010) HIZOA lies on the line of actively starforming galaxies,  and not on the line of of major merger

  22. MIR diagnostic diagram (Armuses al. 2007) Lack of warm dust continuum and strong PAH emission N3256 ` SB Resembles Galactic PDR Emission Similar to Galactic Reflexion Neb For λ < 20μm Indicative of soft Radiation field Arp 220 ULIRG Mrk 231 ULIRG HIZOA HIZOA Peeters et al. (2004)

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