Browsing by Author "Inami, Hanae"
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- ItemALMA [N II] 205 mu m Imaging Spectroscopy of the Interacting Galaxy System BRI 1202-0725 at Redshift 4.7(IOP PUBLISHING LTD, 2017) Lu, Nanyao; Zhao, Yinghe; Diaz Santos, Tanio; Kevin Xu, C.; Charmandaris, Vassilis; Gao, Yu; van der Werf, Paul P.; Privon, George C.; Inami, Hanae; Rigopoulou, Dimitra; Sanders, David B.; Zhu, LeiWe present the results from Atacama Large Millimeter/submillimeter Array imaging in the [N II] 205 mu m fine-structure line (hereafter [N II]) and the underlying continuum of BRI 1202-0725, an interacting galaxy system at z = 4.7, consisting of a quasi-stellar object (QSO), a submillimeter galaxy (SMG), and two Ly alpha emitters, all within similar to 25 kpc of the QSO. We detect the QSO and SMG in both [N II] and continuum. At the similar to 1 '' (or 6.6 kpc) resolution, both the QSO and SMG are resolved in [N II], with the de-convolved major axes of similar to 9 and similar to 14 kpc, respectively. In contrast, their continuum emissions are much more compact and unresolved even at an enhanced resolution of similar to 0 ''.7. The ratio of the [N II] flux to the existing CO(7-6) flux is used to constrain the dust temperature (T-dust) for a more accurate determination of the FIR luminosity L-FIR. Our best estimated T-dust equals 43 (+/- 2) K for both galaxies (assuming an emissivity index beta = 1.8). The resulting LCO(7-6)/LFIR ratios are statistically consistent with that of local luminous infrared galaxies, confirming that LCO(7-6) traces the star formation (SF) rate (SFR) in these galaxies. We estimate that the ongoing SF of the QSO (SMG) has an SFR of 5.1 (6.9) x 10(3) M-circle dot yr(-1) (+/- 30%) assuming Chabrier initial mass function, takes place within a diameter (at half maximum) of 1.3 (1.5) kpc, and will consume the existing 5 (5) x 10(11) M-circle dot of molecular gas in 10 (7) x 10(7) years.
- ItemALMA Observation of NGC 5135: The Circumnuclear CO (6-5) and Dust Continuum Emission at 45 pc Resolution(2018) Cao, Tianwen; Lu, Nanyao; Xu, C. Kevin; Zhao, Yinghe; Madhav Kalari, Venu; Gao, Yu; Charmandaris, Vassilis; Diaz Santos, Tanio; Van der Werf, Paul; Cao, Chen; Wu, Hong; Inami, Hanae; Evans, Aaron S.
- ItemInvestigating the Effect of Galaxy Interactions on Star Formation at 0.5 < z < 3.0(2022) Shah, Ekta A.; Kartaltepe, Jeyhan S.; Magagnoli, Christina T.; Cox, Isabella G.; Wetherell, Caleb T.; Vanderhoof, Brittany N.; Cooke, Kevin C.; Calabro, Antonello; Chartab, Nima; Conselice, Christopher J.; Croton, Darren J.; de la Vega, Alexander; Hathi, Nimish P.; Ilbert, Olivier; Inami, Hanae; Kocevski, Dale D.; Koekemoer, Anton M.; Lemaux, Brian C.; Lubin, Lori; Mantha, Kameswara Bharadwaj; Marchesi, Stefano; Martig, Marie; Moreno, Jorge; Pampliega, Belen Alcalde; Patton, David R.; Salvato, Mara; Treister, EzequielObservations and simulations of interacting galaxies and mergers in the local universe have shown that interactions can significantly enhance the star formation rates (SFRs) and fueling of active galactic nuclei (AGN). However, at higher redshift, some simulations suggest that the level of star formation enhancement induced by interactions is lower due to the higher gas fractions and already increased SFRs in these galaxies. To test this, we measure the SFR enhancement in a total of 2351 (1327) massive (M* > 10(10)M(?)) major (1 < M-1/M-2 < 4) spectroscopic galaxy pairs at 0.5 < z < 3.0 with delta V < 5000 km s-1 (1000 km s(-1)) and projected separation < 150 kpc selected from the extensive spectroscopic coverage in the COSMOS and CANDELS fields. We find that the highest level of SFR enhancement is a factor of 1.23 (-0.09) (+0.08) in the closest projected separation bin (< 25 kpc) relative to a stellar mass-, redshift-, and environment-matched control sample of isolated galaxies. We find that the level of SFR enhancement is a factor of similar to 1.5 higher at 0.5 < z < 1 than at 1 < z < 3 in the closest projected separation bin. Among a sample of visually identified mergers, we find an enhancement of a factor of 1.86 (-0.18) (+0.29) (similar to 3 sigma) for coalesced systems. For this visually identified sample, we see a clear trend of increased SFR enhancement with decreasing projected separation (2.40-+0.62versus + 0.37 1.58(-0.20) (+0.29) for 0.5 < z < 1.6 and 1.6 < z < 3.0, respectively). The SFR enhancements seen in our interactions and mergers are all lower than the level seen in local samples at the same separation, suggesting that the level of interaction-induced star formation evolves significantly over this time period.
- ItemInvestigating the Effect of Galaxy Interactions on the Enhancement of Active Galactic Nuclei at 0.5 < z < 3.0(2020) Shah, Ekta A.; Kartaltepe, Jeyhan S.; Magagnoli, Christina T.; Cox, Isabella G.; Wetherell, Caleb T.; Vanderhoof, Brittany N.; Calabro, Antonello; Chartab, Nima; Conselice, Christopher J.; Croton, Darren J.; Donley, Jennifer; de Groot, Laura; de la Vega, Alexander; Hathi, Nimish P.; Ilbert, Olivier; Inami, Hanae; Kocevski, Dale D.; Koekemoer, Anton M.; Lemaux, Brian C.; Mantha, Kameswara Bharadwaj; Marchesi, Stefano; Martig, Marie; Masters, Daniel C.; McGrath, Elizabeth J.; McIntosh, Daniel H.; Moreno, Jorge; Nayyeri, Hooshang; Pampliega, Belen Alcalde; Salvato, Mara; Snyder, Gregory F.; Straughn, Amber N.; Treister, Ezequiel; Weston, Madalyn E.Galaxy interactions and mergers are thought to play an important role in the evolution of galaxies. Studies in the nearby universe show a higher fraction of active galactic nuclei (AGNs) in interacting and merging galaxies than in their isolated counterparts, indicating that such interactions are important contributors to black hole growth. To investigate the evolution of this role at higher redshifts, we have compiled the largest known sample of major spectroscopic galaxy pairs (2381 with Delta V < 5000 km s(-1)) at 0.5 < z < 3.0 from observations in the COSMOS and CANDELS surveys. We identify X-ray and IR AGNs among this kinematic pair sample, a visually identified sample of mergers and interactions, and a mass-, redshift-, and environment-matched control sample for each in order to calculate AGN fractions and the level of AGN enhancement as a function of relative velocity, redshift, and X-ray luminosity. While we see a slight increase in AGN fraction with decreasing projected separation, overall, we find no significant enhancement relative to the control sample at any separation. In the closest projected separation bin (< 25 kpc, Delta V < 1000 km s(-1)), we find enhancements of a factor of 0.94(-0.16)(+0.21) and 1.00(-0.31)(+0.58) for X-ray and IR-selected AGNs, respectively. While we conclude that galaxy interactions do not significantly enhance AGN activity on average over 0.5 < z < 3.0 at these separations, given the errors and the small sample size at the closest projected separations, our results would be consistent with the presence of low-level AGN enhancement.
- ItemLuminosity functions of local infrared galaxies with AKARI : implications for the cosmic star formation history and AGN evolution.(2011) Goto, T.; Treister, Ezequiel; Arnouts, Stephane; Inami, Hanae; Matsuhara, Hideo; Pearson, Chris; Takeuchi, Tsutomu T.; Le Floc'h, Emeric; Takagi, Toshinobu; Wada, Takehiko; Nakagawa, Takao
- ItemMeasuring the Average Molecular Gas Content of Star-forming Galaxies at z=3-4(2021) Boogaard, Leindert A.; Bouwens, Rychard J.; Riechers, Dominik; van der Werf, Paul; Bacon, Roland; Matthee, Jorryt; Stefanon, Mauro; Feltre, Anna; Maseda, Michael; Inami, Hanae; Aravena, Manuel; Brinchmann, Jarle; Carilli, Chris; Contini, Thierry; Decarli, Roberto; Gonzalez-Lopez, Jorge; Nanayakkara, Themiya; Walter, FabianWe study the molecular gas content of 24 star-forming galaxies at z = 3-4, with a median stellar mass of 10(9.1) M-circle dot, from the MUSE Hubble Ultra Deep Field (HUDF) Survey. Selected by their Ly alpha lambda 1216 emission and H (F160W)-band magnitude, the galaxies show an average < EWLy alpha 0 > approximate to 20 angstrom, below the typical selection threshold for Ly alpha emitters (EWLy alpha 0 > 25 angstrom), and a rest-frame UV spectrum similar to Lyman-break galaxies. We use rest-frame optical spectroscopy from KMOS and MOSFIRE, and the UV features observed with MUSE, to determine the systemic redshifts, which are offset from Ly alpha by = 346 km s(-1), with a 100 to 600 km s(-1) range. Stacking (CO)-C-12 J = 4 -> 3 and [C I]P-3(1) -> P-3(0) (and higher-J CO lines) from the ALMA Spectroscopic Survey of the HUDF, we determine 3 sigma upper limits on the line luminosities of 4.0 x 10(8) K km s(-1)pc(2) and 5.6 x 10(8) K km s(-1)pc(2), respectively (for a 300 km s(-1) line width). Stacking the 1.2 mm and 3 mm dust-continuum flux densities, we find a 3 sigma upper limits of 9 mu Jy and 1.2 mu Jy, respectively. The inferred gas fractions, under the assumption of a "Galactic" CO-to-H-2 conversion factor and gas-to-dust ratio, are in tension with previously determined scaling relations. This implies a substantially higher alpha(CO) >= 10 and delta(GDR) >= 1200, consistent with the subsolar metallicity estimated for these galaxies (12 + log(O/H) approximate to 7.8 +/- 0.2). The low metallicity of z >= 3 star-forming galaxies may thus make it very challenging to unveil their cold gas through CO or dust emission, warranting further exploration of alternative tracers, such as [C II].
- ItemWarm Molecular Hydrogen in Nearby, Luminous Infrared Galaxies(2018) Petric, Andreea O.; Armus, Lee; Flagey, Nicolas; Guillard, Pierre; Howell, Justin; Inami, Hanae; Charmandaris, Vassillis; Evanss, Aaron; Stierwalt, Sabrina; Diaz-Santos, Tanio; Lu, Nanyao; Spoon, Henrik; Mazzarella, Joe; Appleton, Phil; Chan, Ben; Chu, Jason; Hand, Derek; Privon, George; Sanders, David; Surace, Jason; Xu, Kevin; Zhao, YingheMid-infrared molecular hydrogen (H-2) emission is a powerful cooling agent in galaxy mergers and in radio galaxies; it is a potential key tracer of gas evolution and energy dissipation associated with mergers, star formation, and accretion onto supermassive black holes. We detect mid-IR H-2 line emission in at least one rotational transition in 91% of the 214 Luminous Infrared Galaxies (LIRGs) observed with Spitzer as part of the Great Observatories All-sky LIRG Survey. We use H-2 excitation diagrams to estimate the range of masses and temperatures of warm molecular gas in these galaxies. We find that LIRGs in which the IR emission originates mostly from the Active Galactic Nuclei (AGN) have about 100 K higher H-2 mass-averaged excitation temperatures than LIRGs in which the IR emission originates mostly from star formation. Between 10% and 15% of LIRGs have H-2 emission lines that are sufficiently broad to be resolved or partially resolved by the high-resolution modules of Spitzer's Infrared Spectrograph (IRS). Those sources tend to be mergers and contain AGN. This suggests that a significant fraction of the H-2 line emission is powered by AGN activity through X-rays, cosmic rays, and turbulence. We find a statistically significant correlation between the kinetic energy in the H-2 gas and the H-2 to IR luminosity ratio. The sources with the largest warm gas kinetic energies are mergers. We speculate that mergers increase the production of bulk inflows leading to observable broad H-2 profiles and possibly denser gas.