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Manuel Aravena, Jeff Wagg, Padelis Papadopoulos, Ilana Feain

A study of a ULIRG-to-QSO transition object: possibly another gas-rich/gas-poor merger and a serendipitous line detection. Manuel Aravena, Jeff Wagg, Padelis Papadopoulos, Ilana Feain. Outline. Introduction: the ULIRG to QSO evolutionary scenario

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Manuel Aravena, Jeff Wagg, Padelis Papadopoulos, Ilana Feain

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  1. A study of a ULIRG-to-QSO transition object: possibly another gas-rich/gas-poor merger and a serendipitous line detection Manuel Aravena, Jeff Wagg, Padelis Papadopoulos, IlanaFeain

  2. Outline • Introduction: the ULIRG to QSO evolutionary scenario • A high-resolution search for molecular gas in optically bright QSOs with elliptical hosts. • HE 0450-2958, the “naked” QSO • First results: High-resolution CO imaging of H1821+643 at z=0.3

  3. An evolutionary scenario for galaxy evolution • Starbursting Ultra Luminous Infrared Galaxies (ULIRGs): • LIR > 0.9 LBOL • LBOL > 1012 LSUN • Powered mostly by star-formation • Interacting systems • QSOs (Quasi-Stellar Objects) • Lbol >1012Lsun • Point-like sources • Emission is powered by an AGN

  4. An evolutionary scenario for galaxy evolution Observations (Sanders et al. 1988a) and simulations (Mihos & Hernquist 1996)

  5. Molecular gas in starbursts/QSOs Evans et al. (2002) Early evidence for vast amounts of gas in merger-like systems and starburst-to-QSO transition objects. Detections consistent with the evolutionary scenario. Solomon et al. (1997)

  6. Molecular gas in late systems Scoville et al. (2003): large amounts of gas in post-merger systems; optically luminous QSOs with MB<-23 Taken as evidence for late type spirals host galaxies. Most optically luminous QSOs have elliptical-like light profiles (Dunlop 2001; McLeod & McLeod 2000; Floyd et al. 2004) Possible that some of these sources are not optically luminous QSOs with gas rich host galaxy?

  7. HE 0450-2958: the naked QSO • Host galaxy undetected • Based on MbhvsMbulge relation, the host galaxy should be >10x brighter Magain et al. (2006): “We report … a quasar lying at the edge of a gas cloud, whose size is comparable to that of a small galaxy, but whose spectrum shows no evidence for stars. The gas cloud is excited by the quasar itself. If a host galaxy is present, it is at least six times fainter than would normally be expected for such a bright quasar. The quasar is interacting dynamically with a neighbouring galaxy – which matter might be feeding the black hole.”

  8. HE 0450-2958: the naked QSO • CO imaging with Australia Telescope compact Array (ATCA) showed that lots of gas are associated with the companion galaxy and not with the AGN • Mid-IR high-resolution imaging confirmed this. The stellar mass of the companion would bring the system to the local Mbh to Mstar relation if it were to merge with the QSO. • (Papadopoulos et al. 2008; Elbaz et al. 2009)

  9. HE 0450-2958: the naked QSO A series of arguments suggest that the radio jet has an important role in the formation of the companion galaxy (Elbaz et al. 2009)

  10. Our little project: High-resolution CO imaging of optically luminous QSOs • Question: Is it possible that in some of the most optically luminous QSOs the gas is not coming from its elliptical host (as predicted by the Starburst/QSO scenario) but from a gas-rich companion? If so, what are the implications in the derivation of dynamical masses and the formation of a Mbh vs. Mstar relation? • CO imaging with CARMA and ATCA of the most optically luminous QSOs in the local Universe for which PSF subtracted HST images are available.

  11. H1821+643: an interesting source • H1821+643 is one of the most luminous objects in the local Universe with Mv=-27.1 • Hosted by a giant elliptical galaxy 14 kpc in size. • Right at the middle of a cool-cluster core • Radio jet 250 kpc in size • Radio quiet, about to become radio-loud; jet structure in the transition between FRI and FRII

  12. CARMA observations of H1821+643: A hyper-luminous IR starburst/QSO system at z=0.3 • - CO emission offset by more than 1 beam from the nuclei position • Continuum 3mm does coincide with the radio-nuclei. • CO aligned with radio-jet? • Coincidence with optical feature: another gas-poor/gas-rich merger? Or tail structure from past merger? Aravena et al. (2011, submitted)

  13. CARMA observations of H1821+643: A hyper-luminous IR starburst/QSO system at z=0.3 • Spectral energy distribution • Two components: • optical/mid-IR resembles AGN • FIR resembles starburst • radio: QSO emission • Hot dust with Td~130 K and Md~106Msun • Cold dust with Td~50 K and dust mass of Md~1.4x108Msun Needed to disentangle starburst: - Spatially resolved IR observations

  14. CARMA observations of H1821+643: Implications for dynamical mass measurements • - Usually the line width of the CO line is used to estimate the dynamical mass of the system. • Can we recover the dynamical mass of this galaxy based on CO profile? • From the optical imaging Floyd et al. (2004) find a total mass of 2x1012Msun. • Assuming a spherical geometry (usually assumed) we find a mass of ~9x1011Msun (> 2x lower than the actual mass). • Apparently due to the complex dynamical configuration, we underestimate the dynamical mass of this system. • Only possible to measure this underestimation in the local Universe with good optical imaging • - Consistent with similar results found with detailed modeling of disk galaxies at z=1.5, where the underestimation can amount up to 15-20% (Daddi et al 2010).

  15. Any sign of cold gas flows?: A simple exercise H1821+643 is right at the center of a massive cluster of galaxies (Abell class 2). Has any more gas been deposited in other galaxies in the environment of this QSO?

  16. A simple exercise: stacking analysis Upper limit to the molecular gas content of 1.1x109Msun Upper limit to the continuum emission of 175 uJy.

  17. Bonus point: Another CO bright QSO or molecular line in a carbon star? • Serendipitous detection of an emission line • Is it another QSO at a similar redshift? • Or a carbon star? Possible molec. Lines: C5H, HCO+, HCN, SiC4, etcs

  18. Another CO bright QSO or molecular line in a carbon star? • - Small uncertainties – expect perfect fit • If it is a star, the spectral clasification (G5III) and B-Voptical color would imply and absolute magnitude of roughly +1 mag,and thus would imply a distance in the range 50=150 pc distance fromus • If a QSO, it must be at z=0.3.

  19. Conclusions • CO detection of H1821+643 at z=0.3 • CO is considerably offset from the nuclei: gas poor/rich merger or tail? • SED presents evidence for two components: starburst and QSO • Stacking analysis of galaxies in the field shows no detection, consistent with ellipticals • - Serendipitous detection of “gas” line emission: star or QSO at z=0.3?

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