• Learning to Do (Full Appendix)

      Josephson, Anna; Univ Arizona, Dept Ag & Resource Econ (2019-01)
    • Learning to Do (Appendix Part B)

      Josephson, Anna (2019-01)
    • Learning to Do (Appendix Part C)

      Josephson, Anna (2019-01)
    • Learning to Do (Appendix Part D)

      Josephson, Anna (2019-01)
    • Learning to Do (Appendix Part A)

      Josephson, Anna; Univ Arizona, Dept Ag & Resource Econ (2019-01)
    • Research Practices of Indigenous Studies Scholars at the University of Arizona: An Ithaka S+R Report

      Reyes-Escudero, Verónica; Boyer-Kelly, Michelle Nicole; Sanchez, Anthony; Wallace, Niamh; University of Arizona Libraries (The University of Arizona., 2019-01)
      Introduction: This report was completed at the invitation of Ithaka S+R, as part of a multi‐university qualitative study on the research practices of Indigenous Studies scholars. The University of Arizona Libraries (UAL) joined 11 other participating academic libraries in conducting interviews with scholars at their own institutions. The results of the local study are synthesized here as well as compiled, along with the other institutions’ findings, into the final Ithaka S+R report. The University of Arizona is a large public research university and land‐grant institution, founded in 1885, and situated on the lands of the Tohono O’odham Nation. Its American Indian Studies program was the first of its kind in the country to offer a Master’s degree and Ph.D. degree, in 1982 and 1997, respectively. It is home to the renowned American Indian Language Development Institute, the Native Nations Institute, and the Native American Research Training Center.
    • The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Perseus Protostars. VI. Characterizing the Formation Mechanism for Close Multiple Systems

      Tobin, John J.; Looney, Leslie W.; Li, Zhi-Yun; Sadavoy, Sarah I.; Dunham, Michael M.; Segura-Cox, Dominique; Kratter, Kaitlin; Chandler, Claire J.; Melis, Carl; Harris, Robert J.; Perez, Laura; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-11-01)
      We present Atacama Large Millimeter/submillimeter Array observations of multiple protostar systems in the Perseus molecular cloud, previously detected by the Karl G. Jansky Very Large Array. We observe 17 close (<600 au separation) multiple systems at 1.3 mm in continuum and five molecular lines (i.e., (CO)-C-12, (CO)-O-18, (CO)-C-13, H2CO, SO) to characterize the circum-multiple environments in which these systems are forming. We detect at least one component in the continuum for the 17 multiple systems. In three systems one companion is not detected, and for two systems the companions are unresolved at our observed resolution. We also detect circum-multiple dust emission toward eight out of nine Class 0 multiples. Circum-multiple dust emission is not detected toward any of the eight Class I multiples. Twelve systems are detected in the dense gas tracers toward their disks/inner envelopes. For these 12 systems, we use the dense gas observations to characterize their formation mechanism. The velocity gradients in the circum-multiple gas are clearly orthogonal to the outflow directions in eight out of the 12 systems, consistent with disk fragmentation. Moreover, only two systems with separations <200 au are inconsistent with disk fragmentation, in addition to the two widest systems (>500 au). Our results suggest that disk fragmentation via gravitational instability is an important formation mechanism for close multiple systems, but further statistics are needed to better determine the relative fraction formed via this method.
    • Mapping Lyman Continuum Escape in Tololo 1247–232

      Micheva, Genoveva; Oey, M. S.; Keenan, Ryan P.; Jaskot, Anne E.; James, Bethan L.; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-11-01)
      Low-redshift, spatially resolved Lyman continuum (LyC) emitters allow us to clarify the processes for LyC escape from these starburst galaxies. We use Hubble Space Telescope (HST) WFC3 and ACS imaging of the confirmed low-redshift LyC emitter Tol 1247-232 to study the ionization structure of the gas and its relation to the ionizing star clusters. We perform ionization parameter mapping (IPM) using [O III] lambda lambda 4959, 5007 and [O II] lambda 3727 imaging as the high-and low-ionization tracers, revealing broad, large-scale, optically thin regions originating from the center and reaching the outskirts of the galaxy, consistent with LyC escape. We carry out stellar population synthesis modeling of the 26 brightest clusters using our HST photometry. Combining these data with the nebular photometry, we find a global LyC escape fraction of f(esc) = 0.12, with uncertainties also consistent with zero escape and all measured f(esc) values for this galaxy. Our analysis suggests that, similar to other candidate LyC emitters, a two-stage starburst has taken place in this galaxy, with a 12 Myr old, massive central cluster likely having precleared regions in and around the center and the second generation of 2-4 Myr old clusters dominating the current ionization, including some escape from the galaxy.
    • The Missing Satellites of the Magellanic Clouds? Gaia Proper Motions of the Recently Discovered Ultra-faint Galaxies

      Kallivayalil, Nitya; Sales, Laura V.; Zivick, Paul; Fritz, Tobias K.; Del Pino, Andrés; Sohn, Sangmo Tony; Besla, Gurtina; van der Marel, Roeland P.; Navarro, Julio F.; Sacchi, Elena; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-11-01)
      According to LCDM theory, hierarchical evolution occurs on all mass scales, implying that satellites of the Milky Way should also have companions. The recent discovery of ultra-faint dwarf galaxy candidates in close proximity to the Magellanic Clouds provides an opportunity to test this theory. We present proper motion (PM) measurements for 13 of the 32 new dwarf galaxy candidates using Gaia data release 2. All 13 also have radial velocity measurements. We compare the measured 3D velocities of these dwarfs to those expected at the corresponding distance and location for the debris of a Large Magellanic Cloud (LMC) analog in a cosmological numerical simulation. We conclude that four of these galaxies (Hor1, Car2, Car3, and Hyi1) have come in with the Magellanic Clouds, constituting the first confirmation of the type of satellite infall predicted by LCDM. Ret2, Tuc2, and Gru1 have velocity components that are not consistent within 3 sigma of our predictions and are therefore less favorable. Hya2 and Dra2 could be associated with the LMC and merit further attention. We rule out Tuc3, Cra2, Tri2, and Aqu2 as potential members. Of the dwarfs without measured PMs, five of them are deemed unlikely on the basis of their positions and distances alone being too far from the orbital plane expected for LMC debris (Eri2, Ind2, Cet2, Cet3, and Vir1). For the remaining sample, we use the simulation to predict PMs and radial velocities, finding that Phx2 has an overdensity of stars in DR2 consistent with this PM prediction.
    • Resolved Kinematics of Runaway and Field OB Stars in the Small Magellanic Cloud

      Oey, M. S.; Jones, J. Dorigo; Castro, N.; Zivick, P.; Besla, G.; Januszewski, H. C.; Moe, M.; Kallivayalil, N.; Lennon, D. J.; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-11-01)
      We use Gaia Data Release 2 proper motions of field OB stars from the Runaways and Isolated O-Type Star Spectroscopic Survey of the Small Magellanic Cloud (SMC) to study the kinematics of runaway stars. The data reveal that the SMC Wing has a systemic peculiar motion relative to the SMC Bar of (v(alpha), v(delta)) = (62 +/- 7, -18 +/- 5) km s(-1) and relative radial velocity +4.5 +/- 5.0 km s(-1). This unambiguously demonstrates that these two regions are kinematically distinct: the Wing is moving away from the Bar, and towards the Large Magellanic Cloud with a 3D velocity of 64 +/- 10 km s(-1). This is consistent with models for a recent, direct collision between the Clouds. We present transverse velocity distributions for our field OB stars, confirming that unbound runaways comprise on the order of half our sample, possibly more. Using eclipsing binaries and double-lined spectroscopic binaries as tracers of dynamically ejected runaways, and high-mass X-ray binaries (HMXBs) as tracers of runaways accelerated by supernova kicks, we find significant contributions from both populations. The data suggest that HMXBs have lower velocity dispersion relative to dynamically ejected binaries, consistent with the former group corresponding to less energetic supernova kicks that failed to unbind the components. Evidence suggests that our fast runaways are dominated by dynamical, rather than supernova, ejections.
    • Using GRACE to Estitmate Snowfall Accumulation and Assess Gauge Undercatch Corrections in High Latitudes

      Behrangi, Ali; Gardner, Alex; Reager, John T.; Fisher, Joshua B.; Yang, Daqing; Huffman, George J.; Adler, Robert F.; Univ Arizona, Dept Hydrol & Atmospher Sci (AMER METEOROLOGICAL SOC, 2018-11)
      Ten years of terrestrial water storage anomalies from the Gravity Recovery and Climate Experiment (GRACE) were used to estimate high-latitude snowfall accumulation using a mass balance approach. The estimates were used to assess two common gauge-undercatch correction factors (CFs): the Legates climatology (CF-L) utilized in the Global Precipitation Climatology Project (GPCP) and the Fuchs dynamic correction model (CF-F) used in the Global Precipitation Climatology Centre (GPCC) monitoring product. The two CFs can be different by more than 50%. CF-L tended to exceed CF-F over northern Asia and Eurasia, while the opposite was observed over North America. Estimates of snowfall from GPCP, GPCC-L (GPCC corrected by CF-L), and GPCC-F (GPCC corrected by CF-F) were 62%, 64%, and 46% more than GPCC over northern Asia and Eurasia. The GRACE-based estimate (49% more than GPCC) was the closest to GPCC-F. We found that as near-surface air temperature decreased, the products increasingly underestimated the GRACE-based snowfall accumulation. Overall, GRACE showed that CFs are effective in improving GPCC estimates. Furthermore, our case studies and overall statistics suggest that CF-F is likely more effective than CF-L in most of the high-latitude regions studied here. GPCP showed generally better skill than GPCC-L, which might be related to the use of satellite data or additional quality controls on gauge inputs to GPCP. This study suggests that GPCP can be improved if it employs CF-L instead of CF-F to correct for gauge undercatch. However, this implementation requires further studies, region-specific analysis, and operational considerations.
    • Dynamical Constraints on the HR 8799 Planets with GPI

      Wang, Jason J.; Graham, James R.; Dawson, Rebekah; Fabrycky, Daniel; De Rosa, Robert J.; Pueyo, Laurent; Konopacky, Quinn; Macintosh, Bruce; Marois, Christian; Chiang, Eugene; Ammons, S. Mark; Arriaga, Pauline; Bailey, Vanessa P.; Barman, Travis; Bulger, Joanna; Chilcote, Jeffrey; Cotten, Tara; Doyon, Rene; Duchêne, Gaspard; Esposito, Thomas M.; Fitzgerald, Michael P.; Follette, Katherine B.; Gerard, Benjamin L.; Goodsell, Stephen J.; Greenbaum, Alexandra Z.; Hibon, Pascale; Hung, Li-Wei; Ingraham, Patrick; Kalas, Paul; Larkin, James E.; Maire, Jérôme; Marchis, Franck; Marley, Mark S.; Metchev, Stanimir; Millar-Blanchaer, Maxwell A.; Nielsen, Eric L.; Oppenheimer, Rebecca; Palmer, David; Patience, Jennifer; Perrin, Marshall; Poyneer, Lisa; Rajan, Abhijith; Rameau, Julien; Rantakyrö, Fredrik T.; Ruffio, Jean-Baptiste; Savransky, Dmitry; Schneider, Adam C.; Sivaramakrishnan, Anand; Song, Inseok; Soummer, Remi; Thomas, Sandrine; Wallace, J. Kent; Ward-Duong, Kimberly; Wiktorowicz, Sloane; Wolff, Schuyler; Univ Arizona, Lunar & Planetary Lab (IOP PUBLISHING LTD, 2018-11)
      The HR 8799 system uniquely harbors four young super-Jupiters whose orbits can provide insights into the system's dynamical history and constrain the masses of the planets themselves. Using the Gemini Planet Imager, we obtained down to one milliarcsecond precision on the astrometry of these planets. We assessed four-planet orbit models with different levels of constraints and found that assuming the planets are near 1:2:4:8 period commensurabilities, or are coplanar, does not worsen the fit. We added the prior that the planets must have been stable for the age of the system (40 Myr) by running orbit configurations from our posteriors through N-body simulations and varying the masses of the planets. We found that only assuming the planets are both coplanar and near 1:2:4:8 period commensurabilities produces dynamically stable orbits in large quantities. Our posterior of stable coplanar orbits tightly constrains the planets' orbits, and we discuss implications for the outermost planet b shaping the debris disk. A four-planet resonance lock is not necessary for stability up to now. However, planet pairs d and e, and c and d, are each likely locked in two-body resonances for stability if their component masses are above 6 M-Jup and 7 M-Jup, respectively. Combining the dynamical and luminosity constraints on the masses using hot-start evolutionary models and a system age of 42 +/- 5 Myr, we found the mass of planet b to be 5.8 +/- 0.5 M-Jup, and the masses of planets c, d, and e to be 7.2(-0.7)(+0.6) M-Jup each.
    • Atypical Flowers Can Be as Profitable as Typical Hummingbird Flowers

      Waser, Nickolas M.; CaraDonna, Paul J.; Price, Mary V.; Univ Arizona, Sch Nat Resources & Environm (UNIV CHICAGO PRESS, 2018-11)
      In western North America, hummingbirds can be observed systematically visiting flowers that lack the typical reddish color, tubular morphology, and dilute nectar of hummingbird flowers. Curious about this behavior, we asked whether these atypical flowers are energetically profitable for hummingbirds. Our field measurements of nectar content and hummingbird foraging speeds, taken over four decades at multiple localities, show that atypical flowers can be as profitable as typical ones and suggest that the profit can support 24-h metabolic requirements of the birds. Thus, atypical flowers may contribute to successful migration of hummingbirds, enhance their population densities, and allow them to occupy areas seemingly depauperate in suitable resources. These results illustrate what can be gained by attending to the unexpected.
    • The Gemini/Hubble Space Telescope Galaxy Cluster Project: Stellar Populations in the Low-redshift Reference Cluster Galaxies

      Jørgensen, Inger; Chiboucas, Kristin; Webb, Kristi; Woodrum, Charity; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-11)
      In order to study stellar populations and galaxy structures at intermediate and high redshift (z = 0.2-2.0) and link these properties to those of low-redshift galaxies, there is a need for well-defined local reference samples. Especially for galaxies in massive clusters, such samples are often limited to the Coma cluster galaxies. We present consistently calibrated velocity dispersions and absorption-line indices for galaxies in the central 2 R-500 x 2 R-500 of four massive clusters at z < 0.1: Abell 426/Perseus, Abell 1656/Coma, Abell 2029, and Abell 2142. The measurements are based on data from the Gemini Observatory, McDonald Observatory, and Sloan Digital Sky Survey. For bulge-dominated galaxies, the samples are 95% complete in Perseus and Coma and 74% complete in A2029 and A2142, to a limit of M-B,M-abs <= -18.5 mag. The data serve as the local reference for our studies of galaxy populations in the higher-redshift clusters that are part of the Gemini/HST Galaxy Cluster Project (GCP). We establish the scaling relations between line indices and velocity dispersions as a reference for the GCP. We derive stellar population parameters, ages, metallicities [M/H], and abundance ratios from line indices, both averaged in bins of velocity dispersion and from individual measurements for galaxies in Perseus and Coma. The zero points of relations between the stellar population parameters and the velocity dispersions limit the allowed cluster-to-cluster variation of the four clusters to +/- 0.08 dex in age, +/- 0.06 dex in [M/H], +/- 0.07 dex in [CN/Fe], and +/- 0.03 dex in [Mg/Fe].
    • Polar Dust, Nuclear Obscuration, and IR SED Diversity in Type-1 AGNs

      Lyu, Jianwei; Rieke, George H.; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-10-20)
      Despite the hypothesized similar face-on viewing angles, the infrared emission of type-1 active galactic nuclei (AGNs) has diverse spectral energy distribution (SED) shapes that deviate substantially from the well-characterized quasar templates. Motivated by the commonly seen UV-optical obscuration and the discovery of parsec-scale mid-IR polar dust emission in some nearby AGNs, we develop semi-empirical SED libraries for reddened type-1 AGNs built on quasar intrinsic templates, assuming low-level extinction caused by an extended distribution of large dust grains. We demonstrate that this model can reproduce the nuclear UV to IR SED and the strong mid-IR polar dust emission of NGC 3783, the type-1 AGN with the most relevant and robust observational constraints. In addition, we compile 64 low-z Seyfert-1 nuclei with negligible mid-IR star formation contamination and satisfactorily fit the individual IR SEDs as well as the composite UV to mid-IR composite SEDs. Given the success of these fits, we characterize the possible infrared SED of AGN polar dust emission and utilize a simple but effective strategy to infer its prevalence among type-1 AGNs. The SEDs of high-z peculiar AGNs, including the extremely red quasars, mid-IR warm-excess AGNs, and hot dust-obscured galaxies, can be also reproduced by our model. These results indicate that the IR SEDs of most AGNs, regardless of redshift or luminosity, arise from similar circumnuclear torus properties but differ mainly due to the optical depths of extended obscuring dust components.
    • The VLA Nascent Disk and Multiplicity Survey of Perseus Protostars (VANDAM). V. 18 Candidate Disks around Class 0 and I Protostars in the Perseus Molecular Cloud

      Segura-Cox, Dominique M.; Looney, Leslie W.; Tobin, John J.; Li, Zhi-Yun; Harris, Robert J.; Sadavoy, Sarah; Dunham, Michael M.; Chandler, Claire; Kratter, Kaitlin; Pérez, Laura; Melis, Carl; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-10-20)
      We present the full disk-fit results VANDAM survey of all Class 0 and I protostars in the Perseus molecular cloud. We have 18 new protostellar disk candidates around Class 0 and I sources, which are well described by a simple, parametrized disk model fit to the 8 mm VLA dust continuum observations. 33% of Class 0 protostars and just 11% of Class I protostars have candidate disks, while 78% of Class 0 and I protostars do not have signs of disks within our 12 au disk diameter resolution limit, indicating that at 8 mm most disks in the Class 0 and I phases are <10 au in radius. These small radii may be a result of surface brightness sensitivity limits. Modeled 8 mm radii are similar to the radii of known Class 0 disks with detected Keplerian rotation. Since our 8 mm data trace a population of larger dust grains that radially drift toward the protostar and are lower limits on true disk sizes, large disks at early times do not seem to be particularly rare. We find statistical evidence that Class 0 and I disks are likely drawn from the same distribution, meaning disk properties may be defined early in the Class 0 phase and do not undergo large changes through the Class I phase. By combining our candidate disk properties with previous polarization observations, we find a qualitative indication that misalignment between inferred envelope-scale magnetic fields and outflows may indicate disks on smaller scales in Class 0 sources.
    • Velocity-resolved Reverberation Mapping of Five Bright Seyfert 1 Galaxies

      De Rosa, G.; Fausnaugh, M. M.; Grier, C. J.; Peterson, B. M.; Denney, K. D.; Horne, Keith; Bentz, M. C.; Ciroi, S.; Bontà, E. Dalla; Joner, M. D.; Kaspi, S.; Kochanek, C. S.; Pogge, R. W.; Sergeev, S. G.; Vestergaard, M.; Adams, S. M.; Antognini, J.; Salvo, C. Araya; Armstrong, E.; Bae, J.; Barth, A. J.; Beatty, T. G.; Bhattacharjee, A.; Borman, G. A.; Boroson, T. A.; Bottorff, M. C.; Brown, J. E.; Brown, J. S.; Brotherton, M. S.; Coker, C. T.; Clanton, C.; Cracco, V.; Crawford, S. M.; Croxall, K. V.; Eftekharzadeh, S.; Eracleous, M.; Fiorenza, S. L.; Frassati, A.; Hawkins, K.; Henderson, C. B.; Holoien, T. W.-S.; Hutchison, T.; Kellar, J.; Kilerci-Eser, E.; Kim, S.; King, A. L.; Mura, G. La; Laney, C. D.; Li, M.; Lochhaas, C.; Ma, Z.; MacInnis, F.; Manne-Nicholas, E. R.; Mason, M.; McGraw, S. M.; Mogren, K.; Montouri, C.; Moody, J. W.; Mosquera, A. M.; Mudd, D.; Musso, R.; Nazarov, S. V.; Nguyen, M. L.; Ochner, P.; Okhmat, D. N.; Onken, C. A.; Ou-Yang, B.; Pancoast, A.; Pei, L.; Penny, M.; Poleski, R.; Portaluri, E.; Prieto, J.-L.; Price-Whelan, A. M.; Pulatova, N. G.; Rafter, S.; Roettenbacher, R. M.; Romero-Colmenero, E.; Runnoe, J.; Schimoia, J. S.; Shappee, B. J.; Sherf, N.; Simonian, G. V.; Siviero, A.; Skowron, D. M.; Skowron, J.; Somers, G.; Spencer, M.; Starkey, D. A.; Stevens, D. J.; Stoll, R.; Tamajo, E.; Tayar, J.; Saders, J. L. van; Valenti, S.; Villanueva, Jr., S.; Villforth, C.; Weiss, Y.; Winkler, H.; Zastrow, J.; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-10-20)
      We present the first results from a reverberation-mapping campaign undertaken during the first half of 2012, with additional data on one active galactic nucleus (AGN) (NGC 3227) from a 2014 campaign. Our main goals are (1) to determine the black hole masses from continuum-H beta reverberation signatures, and (2) to look for velocity-dependent time delays that might be indicators of the gross kinematics of the broad-line region. We successfully measure H beta time delays and black hole masses for five AGNs, four of which have previous reverberation mass measurements. The values measured here are in agreement with earlier estimates, though there is some intrinsic scatter beyond the formal measurement errors. We observe velocity-dependent H beta lags in each case, and find that the patterns have changed in the intervening five years for three AGNs that were also observed in 2007.
    • SMASHing the LMC: A Tidally Induced Warp in the Outer LMC and a Large-scale Reddening Map

      Choi, Yumi; Nidever, David L.; Olsen, Knut; Blum, Robert D.; Besla, Gurtina; Zaritsky, Dennis; van der Marel, Roeland P.; Bell, Eric F.; Gallart, Carme; Cioni, Maria-Rosa L.; Clifton Johnson, L.; Katherina Vivas, A.; Saha, Abhijit; de Boer, Thomas J. L.; Noël, Noelia E. D.; Monachesi, Antonela; Massana, Pol; Conn, Blair C.; Martinez-Delgado, David; Muñoz, Ricardo R.; Stringfellow, Guy S.; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-10-20)
      We present a study of the three-dimensional (3D) structure of the Large Magellanic Cloud (LMC) using similar to 2.2 million red clump (RC) stars selected from the Survey of the MAgellanic Stellar History. To correct for line-of-sight dust extinction, the intrinsic RC color and magnitude and their radial dependence are carefully measured by using internal nearly dust-free regions. These are then used to construct an accurate 2D reddening map (165 deg(2) area with similar to 10' resolution) of the LMC disk and the 3D spatial distribution of RC stars. An inclined disk model is fit to the 2D distance map, yielding a best-fit inclination angle i = 25.86(-1.39)(+0.73) degrees with random errors of +/- 0 degrees.19 and line-of-nodes position angle 149.23(-8.35)(+6.43) degrees with random errors of +/- 0 degrees.49. These angles vary with galactic radius, indicating that the LMC disk is warped and twisted likely due to the repeated tidal interactions with the Small Magellanic Cloud (SMC). For the first time, our data reveal a significant warp in the southwestern part of the outer disk starting at rho similar to 7 degrees that departs from the defined LMC plane up to similar to 4 kpc toward the SMC, suggesting that it originated from a strong interaction with the SMC. In addition, the inner disk encompassing the off-centered bar appears to be tilted up to 5 degrees-15 degrees relative to the rest of the LMC disk. These findings on the outer warp and the tilted bar are consistent with the predictions from the Besla et al. simulation of a recent direct collision with the SMC.
    • Dust Emission in an Accretion-rate-limited Sample of z ≳ 6 Quasars

      Venemans, Bram P.; Decarli, Roberto; Walter, Fabian; Bañados, Eduardo; Bertoldi, Frank; Fan, Xiaohui; Farina, Emanuele Paolo; Mazzucchelli, Chiara; Riechers, Dominik; Rix, Hans-Walter; Wang, Ran; Yang, Yujin; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-10-20)
      We present Atacama Large Millimeter Array 1 mm observations of the rest-frame far-infrared (FIR) dust continuum in 27 quasars at redshifts 6.0 less than or similar to z < 6.7. We detect FIR emission at greater than or similar to 3 sigma in all quasar host galaxies with flux densities at similar to 1900 GHz in the rest-frame of 0.12 < S-rest,S- (1900) (GHz) < 5.9 mJy, with a median (mean) flux density of 0.88 mJy (1.59 mJy). The implied FIR luminosities range from L-FIR = (0.27-13) x 10(12) L-circle dot, with 74% of our quasar hosts having L-FIR > 10(12) L-circle dot The estimated dust masses are M-dust = 10(7)-10(9) M-circle dot. If the dust is heated only by star formation, then the star formation rates in the quasar host galaxies are between 50 and 2700 M-circle dot yr(-1). In the framework of the host galaxy-black hole coevolution model a correlation between ongoing black hole growth and star formation in the quasar host galaxy would be expected. However, combined with results from the literature to create a luminosity-limited quasar sample, we do not find a strong correlation between quasar UV luminosity (a proxy for ongoing black hole growth) and FIR luminosity (star formation in the host galaxy). The absence of such a correlation in our data does not necessarily rule out the coevolution model, and could be due to a variety of effects (including different timescales for black hole accretion and FIR emission).
    • AKARI mid-infrared slitless spectroscopic survey of star-forming galaxies at z ≲ 0.5

      Ohyama, Y.; Wada, T.; Matsuhara, H.; Takagi, T.; Malkan, M.; Goto, T.; Egami, E.; Lee, H.-M.; Im, M.; Kim, J.H.; Pearson, C.; Inami, H.; Oyabu, S.; Usui, F.; Burgarella, D.; Mazyed, F.; Imanishi, M.; Jeong, W.-S.; Miyaji, T.; Díaz Tello, J.; Nakagawa, T.; Serjeant, S.; Takeuchi, T. T.; Toba, Y.; White, G. J.; Hanami, H.; Ishigaki, T.; Univ Arizona, Steward Observ (EDP SCIENCES S A, 2018-10-18)
      Context. Deep mid-infrared (MIR) surveys have revealed numerous strongly star-forming galaxies at redshift z less than or similar to 2. Their MIR fluxes are produced by a combination of continuum and polycyclic aromatic hydrocarbon (PAH) emission features. The PAH features can dominate the total MIR flux, but are difficult to measure without spectroscopy. Aims. We aim to study star-forming galaxies by using a blind spectroscopic survey at MIR wavelengths to understand evolution of their star formation rate (SFR) and specific SFR (SFR per stellar mass) up to z similar or equal to 0.5, by paying particular attention to their PAH properties. Methods. We conducted a low-resolution (R similar or equal to 50) slitless spectroscopic survey at 5-13 mu m of 9 mu m flux-selected sources (> 0.3 mJy) around the north ecliptic pole with the infrared camera (IRC) onboard AKARI. After removing 11 AGN candidates by using the IRC photometry, we identify 48 PAH galaxies with PAH 6.2, 7.7, and 8.6 mu m features at z < 0.5. The rest-frame optical-MIR spectral energy distributions (SEDs) based on CFHT and IRC imaging covering 0.37-18 mu m were produced, and analysed in conjunction with the PAH spectroscopy. We defined the PAH enhancement by using the luminosity ratio of the 7.7 mu m PAH feature over the 3.5 mu m stellar component of the SEDs. Results. The rest-frame SEDs of all PAH galaxies have a universal shape with stellar and 7.7 mu m bumps, except that the PAH enhancement significantly varies as a function of the PAH luminosities. We identify a PAH-enhanced population at z greater than or similar to 0.35, whose SEDs and luminosities are typical of luminous infrared galaxies. They show particularly larger PAH enhancement at high luminosity, implying that they are vigorous star-forming galaxies with elevated specific SFR. Our composite starburst model that combines a very young and optically very thick starburst with a very old population can successfully reproduce most of their SED characteristics, although we cannot confirm this optically think component from our spectral analysis.