Browsing by Author "Infante, L."

Now showing 1 - 18 of 18
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    A lack of Lyman α emitters within 5 Mpc of a luminous quasar in an overdensity at z=6.9: Potential evidence of negative quasar feedback at protocluster scales
    (2024) Lambert, Trystan S.; Assef, R. J.; Mazzucchelli, C.; Banados, E.; Aravena, M.; Barrientos, F.; Gonzalez-Lopez, J.; Hu, W.; Infante, L.; Malhotra, S.; Moya-Sierralta, C.; Rhoads, J.; Valdes, F.; Wang, J.; Wold, I. G. B.; Zheng, Z.
    High-redshift quasars are thought to live in the densest regions of space, which should be made evident by an overdensity of galaxies around them. However, campaigns to identify these overdensities by searching for Lyman-break galaxies (LBGs) and Lyman alpha emitters (LAEs) have had mixed results. These may be explained by either the small field of view of some of the experiments, the broad redshift ranges targeted by LBG searches, and the inherently high uncertainty of quasar redshifts estimated from ultraviolet emission lines, which makes it difficult to place the Ly-alpha emission line within a narrowband filter. Here, we present a 3 square degree search (similar to 1000 pMpc(2)) for LAEs around the z = 6.9 quasar VIK J2348-3054 using the Dark Energy CAMera (DECam) housed on the 4m Blanco telescope, finding 38 LAEs. The systemic redshift of VIK J2348-3054 is known from ALMA [CII] observations and places the Ly-alpha emission line of companions within the NB964 narrowband of DECam. This is the largest field-of-view LAE search around a z > 6 quasar conducted to date. We find that this field is similar to ten times more overdense than Chandra Deep-Field South, observed previously with the same instrumental setup as well as several combined blank fields. This is strong evidence that VIK J2348-3054 resides in an overdensity of LAEs over several Mpc. Surprisingly, we find a lack of LAEs within 5 physical Mpc of the quasar and take this to most likely be evidence of quasar-suppressing star formation in its immediate vicinity. This result highlights the importance of performing overdensity searches over large areas to properly assess the density of those regions of the Universe.
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    CLASH-VLT: spectroscopic confirmation of z=6.11 quintuply lensed galaxy in the Frontier Fields cluster RXC J2248.7-4431
    (2013) Balestra, I.; Vanzella, E.; Rosati, P.; Monna, A.; Grillo, C.; Nonino, M.; Mercurio, A.; Biviano, A.; Bradley, L.; Coe, D.; Fritz, A.; Postman, M.; Seitz, S.; Scodeggio, M.; Tozzi, P.; Zhengll, W.; Ziegler, B.; Zitrin, A.; Annunziatella, M.; Bartelmann, M.; Benitez, N.; Broadhurst, T.; Bouwens, R.; Czoske, O.; Donahue, M.; Ford, H.; Girardi, M.; Infante, L.; Jouvel, S.; Kelson, D.; Koekemoer, A.; Kuchner, U.; Lemze, D.; Lombardi, M.; Maier, C.; Medezinski, E.; Melchior, P.; Meneghetti, M.; Merten, J.; Molino, A.; Moustakas, L.; Presotto, V.; Smit, R.; Umetsu, K.
    We present VIsible Multi-Object Spectrograph (VIMOS) observations of a z similar to 6 galaxy quintuply imaged by the Frontier Fields galaxy cluster RXC J2248.7-4431 (z = 0.348). This sub-L*, high-z galaxy has been recently discovered by Monna et al. (2013) using dropout techniques with the 16-band HST photometry acquired as part of the Cluster Lensing And Supernova survey with Hubble (CLASH). Obtained as part of the CLASH-VLT survey, the VIMOS medium-resolution spectra of this source show a very faint continuum between similar to 8700 angstrom and similar to 9300 angstrom and a prominent emission line at 8643 angstrom, which can be readily identified with Lyman-alpha at z = 6.110 +/- 0.002. The emission line exhibits an asymmetric profile, with a more pronounced red wing. The rest-frame equivalent width of the line is EW = 79 +/- 10 angstrom, relatively well constrained thanks to the detection of the UV continuum, which is rarely achieved for a sub-L* galaxy at this redshift. After correcting for magnification, the star formation rate (SFR) estimated from the Ly alpha line is SFR(Ly alpha) = 11 M-circle dot yr(-l) and that estimated from the UV data is SFR(UV) = 3 M-circle dot yr(-1). We estimate that the effective radius of the source is R-e less than or similar to 0.4 kpc, which implies a star formation surface mass density Sigma(SFR) > 6 M(circle dot)yr(-1) kpc(-2) and, using the Kennicutt-Schmidt relation, a gas surface mass density Sigma(gas) > 10(3) M(circle dot)pc(-2). Our results support the idea that this magnified, distant galaxy is a young and compact object with luminosity 0.4 L* at z = 6, when the Universe was just 1 Gyr old, with a similar amount of mass in gas and stars. In the spirit of the Frontier Fields initiative, we also publish the redshifts of several multiply imaged sources and other background objects, which will help improving the strong-lensing model of this galaxy cluster.
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    Correlations between H α equivalent width and galaxy properties at z = 0.47: Physical or selection-driven?
    (2021) Khostovan, A. A.; Malhotra, S.; Rhoads, J. E.; Harish, S.; Jiang, C.; Wang, J.; Wold, I.; Zheng, Z. -Y.; Barrientos, L. F.; Coughlin, A.; Hu, W.; Infante, L.; Perez, L. A.; Pharo, J.; Valdes, F.; Walker, A. R.
    The H alpha equivalent width (EW) is an observational proxy for specific star formation rate (sSFR) and a tracer of episodic, bursty star-formation activity. Previous assessments show that the H alpha EW strongly anticorrelates with stellar mass as M-0.25 similar to the sSFR - stellar mass relation. However, such a correlation could be driven or even formed by selection effects. In this study, we investigate how H alpha EW distributions correlate with physical properties of galaxies and how selection biases could alter such correlations using a z = 0.47 narrow-band-selected sample of 1572 H alpha emitters from the Ly alpha Galaxies in the Epoch of Reionization (LAGER) survey as our observational case study. The sample covers a 3 deg(2) area of COSMOS with a survey comoving volume of 1.1 x 10(5) Mpc(3). We assume an intrinsic EW distribution to form mock samples of H alpha emitters and propagate the selection criteria to match observations, giving us control on how selection biases can affect the underlying results. We find that H alpha EW intrinsically correlates with stellar mass as W-0 proportional to M-0.16 +/- 0.03 and decreases by a factor of similar to 3 from 10(7) M-circle dot to 10(10) M-circle dot, while not correcting for selection effects steepens the correlation as M-025 +/- 0.04, We find low-mass H alpha emitters to be similar to 320 times more likely to have rest-frame EW > 200 angstrom compared to high-mass H alpha emitters. Combining the intrinsic W-0-stellar mass correlation with an observed stellar mass function correctly reproduces the observed H alpha luminosity function, while not correcting for selection effects underestimates the number of bright emitters. This suggests that the W-0-stellar mass correlation when corrected for selection effects is physically significant and reproduces three statistical distributions of galaxy populations (line luminosity function, stellar mass function, EW distribution). At lower stellar masses, we find there are more high-EW outliers compared to high stellar masses, even after we take into account selection effects. Our results suggest that high sSFR outliers indicative of bursty star formation activity are intrinsically more prevalent in low-mass H alpha emitters and not a byproduct of selection effects.
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    Discovery of a very bright strongly lensed galaxy candidate at z ≈ 7.6
    (2008) Bradley, L. D.; Bouwens, R. J.; Ford, H. C.; Illingworth, G. D.; Jee, M. J.; Benitez, N.; Broadhurst, T. J.; Franx, M.; Frye, B. L.; Infante, L.; Motta, V.; Rosati, P.; White, R. L.; Zheng, W.
    Using Hubble Space Telescope (HST) and Spitzer IRAC imaging, we report the discovery of a very bright strongly lensed Lyman break galaxy (LBG) candidate at z similar to 7.6 in the field of the massive galaxy clusterAbell 1689 (z = 0.18). The galaxy candidate, which we refer to as A1689-zD1, shows a strong z(850) - J(110) break of at least 2.2 mag and is completely undetected (< 1 sigma) in HST Advanced Camera for Surveys (ACS) g(475), r(625), i(775), and z(850) data. These properties, combined with the very blue J(110) - H(160) and H(160) - [4.5 mu m] colors, are exactly the properties of an z similar to 7.6 LBG, and can only be reasonably fit by a star- forming galaxy at z = 7.6 +/- 0.4 (chi(2)(nu) = 1.1). Attempts to reproduce these properties with a model galaxy at z < 4 yield particularly poor fits (chi(2)(nu) >= 25). . A1689- zD1 has an observed (lensed) magnitude of 24.7 AB (8 sigma) in the NICMOS H(160) band and is similar to 1.3 mag brighter than the brightest known z(850)-dropout galaxy. When corrected for the cluster magnification of similar to 9.3 at z similar to 7.6, the candidate has an intrinsic magnitude of H(160) = 27.1 AB, or about an L(*) galaxy at z similar to 7: 6. The source- plane deprojection shows that the star formation is occurring in compact knots of size less than or similar to 300 pc. The best- fit stellar population synthesis models yield a median redshift of 7.6, stellar masses (1.6-3.9) x 10(9) M(circle dot), stellar ages 45-320 Myr, star formation rates less than or similar to 7.6M(circle dot) yr(-1), and low reddening with A(V) <= 0.3. These properties are generally similar to those of LBGs found at z similar to 5-6. The inferred stellar ages suggest a formation redshift of z similar to 8-10 (t less than or similar to 0.63 Gyr). A1689-zD1 is the brightest observed, highly reliable z > 7.0 galaxy candidate found to date.
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    Frontier Fields: Combining HST, VLT, and Spitzer data to explore the z ∼ 8 Universe behind the lensing cluster MACSJ0416.1-2403
    (2015) Laporte, N.; Streblyanska, A.; Kim, S.; Pello, R.; Bauer, F. E.; Bina, D.; Brammer, G.; De Leo, M. A.; Infante, L.; Perez-Fournon, I.
    Context. The Hubble Space Telescope (HST) Frontier Fields (HFFs) project started at the end of 2013 with the aim of providing extremely deep images of six massive galaxy clusters. One of the main goals of this program is to push several telescopes to their limits to provide the best current view of the earliest stages of the Universe. The analysis of the initial data has already demonstrated the huge capabilities of the program.
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    Herschel FIR counterparts of selected Lyα emitters at z ∼ 2.2 Fast evolution since z ∼ 3 or missed obscured AGNs?
    (2010) Bongiovanni, A.; Oteo, I.; Cepa, J.; Perez Garcia, A. M.; Sanchez-Portal, M.; Ederoclite, A.; Aguerri, J. A. L.; Alfaro, E. J.; Altieri, B.; Andreani, P.; Aparicio-Villegas, M. T.; Aussel, H.; Benitez, N.; Berta, S.; Broadhurst, T.; Cabrera-Cano, J.; Castander, F. J.; Cava, A.; Cervino, M.; Chulani, H.; Cimatti, A.; Cristobal-Hornillos, D.; Daddi, E.; Dominguez, H.; Elbaz, D.; Fernandez-Soto, A.; Schreiber, N. Foerster; Genzel, R.; Gomez, M. F.; Gonzalez Delgado, R. M.; Grazian, A.; Gruppioni, C.; Herreros, J. M.; Iglesias Groth, S.; Infante, L.; Lutz, D.; Magnelli, B.; Magdis, G.; Maiolino, R.; Marquez, I.; Martinez, V. J.; Masegosa, J.; Moles, M.; Molino, A.; Nordon, R.; del Olmo, A.; Perea, J.; Poglitsch, A.; Popesso, P.; Pozzi, F.; Prada, F.; Quintana, J. M.; Riguccini, L.; Rodighiero, G.; Saintonge, A.; Sanchez, S. F.; Santini, P.; Shao, L.; Sturm, E.; Tacconi, L.; Valtchanov, I.
    Ly alpha emitters (LAEs) are seen everywhere in the redshift domain from local to z similar to 7. Far-infrared (FIR) counterparts of LAEs at different epochs could provide direct clues on dust content, extinction, and spectral energy distribution (SED) for these galaxies. We search for FIR counterparts of LAEs that are optically detected in the GOODS-North field at redshift z similar to 2.2 using data from the Herschel Space Telescope with the Photodetector Array Camera and Spectrometer (PACS). The LAE candidates were isolated via color-magnitude diagram using the medium-band photometry from the ALHAMBRA Survey, ancillary data on GOODS-North, and stellar population models. According to the fitting of these spectral synthesis models and FIR/optical diagnostics, most of them seem to be obscured galaxies whose spectra are AGN-dominated. From the analysis of the optical data, we have observed a fraction of AGN or composite over source total number of similar to 0.75 in the LAE population at z similar to 2.2, which is marginally consistent with the fraction previously observed at z = 2.25 and even at low redshift (0.2 < z < 0.45), but significantly different from the one observed at redshift similar to 3, which could be compatible either with a scenario of rapid change in the AGN fraction between the epochs involved or with a non detection of obscured AGN in other z = 2-3 LAE samples due to lack of deep FIR observations. We found three robust FIR (PACS) counterparts at z similar to 2.2 in GOODS-North. This demonstrates the possibility of finding dust emission in LAEs even at higher redshifts.
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    Hubble Space Telescope ACS multiband coronagraphic imaging of the debris disk around β pictoris
    (2006) Golimowski, D. A.; Ardila, D. R.; Krist, J. E.; Clampin, M.; Ford, H. C.; Illingworth, G. D.; Bartko, F.; Benitez, N.; Blakeslee, J. P.; Bouwens, R. J.; Bradley, L. D.; Broadhurst, T. J.; Brown, R. A.; Burrows, C. J.; Cheng, E. S.; Cross, N. J. G.; Demarco, R.; Feldman, P. D.; Franx, M.; Goto, T.; Gronwall, C.; Hartig, G. F.; Holden, B. P.; Homeier, N. L.; Infante, L.; Jee, M. J.; Kimble, R. A.; Lesser, M. P.; Martel, A. R.; Mei, S.; Menanteau, F.; Meurer, G. R.; Miley, G. K.; Motta, V.; Postman, M.; Rosati, P.; Sirianni, M.; Sparks, W. B.; Tran, H. D.; Tsvetanov, Z. I.; White, R. L.; Zheng, W.; Zirm, A. W.
    We present F435W(B), F606W (broad V), and F814W(broad I) coronagraphic images of the debris disk around beta Pictoris obtained with the Hubble Space Telescope's Advanced Camera for Surveys. These images provide the most photometrically accurate and morphologically detailed views of the disk between 30 and 300 AU from the star ever recorded in scattered light. We confirm that the previously reported warp in the inner disk is a distinct secondary disk inclined by similar to 5 degrees from the main disk. The projected spine of the secondary disk coincides with the isophotal inflections, or "butterfly asymmetry,'' previously seen at large distances from the star. We also confirm that the opposing extensions of the main disk have different position angles, but we find that this "wing-tilt asymmetry'' is centered on the star rather than offset from it, as previously reported. The main disk's northeast extension is linear from 80 to 250 AU, but the southwest extension is distinctly bowed with an amplitude of similar to 1 AU over the same region. Both extensions of the secondary disk appear linear, but not collinear, from 80 to 150 AU. Within similar to 120 AU of the star, the main disk is similar to 50% thinner than previously reported. The surface brightness profiles along the spine of the main disk are fitted with four distinct radial power laws between 40 and 250 AU, while those of the secondary disk between 80 and 150 AU are fitted with single power laws. These discrepancies suggest that the two disks have different grain compositions or size distributions. The F606W/F435W and F814W/F435W flux ratios of the composite disk are nonuniform and asymmetric about both projected axes of the disk. The disk's northwest region appears 20%-30% redder than its southeast region, which is inconsistent with the notion that forward scattering from the nearer northwest side of the disk should diminish with increasing wavelength. Within similar to 120 AU, the m(F435W)-m(F606W) and m(F435W)-m(F814W) colors along the spine of the main disk are similar to 10% and similar to 20% redder, respectively, than those of beta Pic. These colors increasingly redden beyond similar to 120 AU, becoming 25% and 40% redder, respectively, than the star at 250 AU. These measurements overrule previous determinations that the disk is composed of neutrally scattering grains. The change in color gradient at similar to 120 AU nearly coincides with the prominent inflection in the surface brightness profile at similar to 115 AU and the expected water-ice sublimation boundary. We compare the observed red colors within similar to 120 AU with the simulated colors of nonicy grains having a radial number density alpha r(-3) and different compositions, porosities, and minimum grain sizes. The observed colors are consistent with those of compact or moderately porous grains of astronomical silicate and/or graphite with sizes greater than or similar to 0.15-0.20 mu m, but the colors are inconsistent with the blue colors expected from grains with porosities greater than or similar to 90%. The increasingly red colors beyond the ice sublimation zone may indicate the condensation of icy mantles on the refractory grains, or they may reflect an increasing minimum grain size caused by the cessation of cometary activity.
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    MOONS: The New Multi-Object Spectrograph for the VLT
    (2020) Cirasuolo, M.; Fairley, A.; Rees, P.; González, O. A.; Taylor, W.; Maiolino, R.; Afonso, J.; Evans, C.; Flores, H.; Lilly, S.; Oliva, E.; Paltani, S.; Vanzi, L.; Abreu, M.; Accardo, M.; Adams, N.; Álvarez Méndez, D.; Amans, J. -P.; Amarantidis, S.; Atek, H.; Atkinson, D.; Banerji, M.; Barrett, J.; Barrientos, F.; Bauer, F.; Beard, S.; Béchet, C.; Belfiore, A.; Bellazzini, M.; Benoist, C.; Best, P.; Biazzo, K.; Black, M.; Boettger, D.; Bonifacio, P.; Bowler, R.; Bragaglia, A.; Brierley, S.; Brinchmann, J.; Brinkmann, M.; Buat, V.; Buitrago, F.; Burgarella, D.; Burningham, B.; Buscher, D.; Cabral, A.; Caffau, E.; Cardoso, L.; Carnall, A.; Carollo, M.; Castillo, R.; Castignani, G.; Catelan, Márcio; Cicone, C.; Cimatti, A.; Cioni, M. -R. L.; Clementini, G.; Cochrane, W.; Coelho, J.; Colling, M.; Contini, T.; Contreras, R.; Conzelmann, R.; Cresci, G.; Cropper, M.; Cucciati, O.; Cullen, F.; Cumani, C.; Curti, M.; Da Silva, A.; Daddi, E.; Dalessandro, E.; Dalessio, F.; Dauvin, L.; Davidson, G.; de Laverny, P.; Delplancke-Ströbele, F.; De Lucia, G.; Del Vecchio, C.; Dessauges-Zavadsky, M.; Di Matteo, P.; Dole, H.; Drass, H.; Dunlop, J.; Dünner, R.; Eales, S.; Ellis, R.; Enriques, B.; Fasola, G.; Ferguson, A.; Ferruzzi, D.; Fisher, M.; Flores, M.; Fontana, A.; Forchi, V.; Francois, P.; Franzetti, P.; Gargiulo, A.; Garilli, B.; Gaudemard, J.; Gieles, M.; Gilmore, G.; Ginolfi, M.; Gomes, J. M.; Guinouard, I.; Gutierrez, P.; Haigron, R.; Hammer, F.; Hammersley, P.; Haniff, C.; Harrison, C.; Haywood, M.; Hill, V.; Hubin, N.; Humphrey, A.; Ibata, R.; Infante, L.; Ives, D.; Ivison, R.; Iwert, O.; Jablonka, P.; Jakob, G.; Jarvis, M.; King, D.; Kneib, J. -P.; Laporte, P.; Lawrence, A.; Lee, D.; Li Causi, G.; Lorenzoni, S.; Lucatello, S.; Luco, Y.; Macleod, A.; Magliocchetti, M.; Magrini, L.; Mainieri, V.; Maire, C.; Mannucci, F.; Martin, N.; Matute, I.; Maurogordato, S.; McGee, S.; Mcleod, D.; McLure, R.; McMahon, R.; Melse, B. -T.; Messias, H.; Mucciarelli, A.; Nisini, B.; Nix, J.; Norberg, P.; Oesch, P.; Oliveira, A.; Origlia, L.; Padilla, N.; Palsa, R.; Pancino, E.; Papaderos, P.; Pappalardo, C.; Parry, I.; Pasquini, L.; Peacock, J.; Pedichini, F.; Pello, R.; Peng, Y.; Pentericci, L.; Pfuhl, O.; Piazzesi, R.; Popovic, D.; Pozzetti, L.; Puech, M.; Puzia, T.; Raichoor, A.; Randich, S.; Recio-Blanco, A.; Reis, S.; Reix, F.; Renzini, A.; Rodrigues, M.; Rojas, F.; Rojas-Arriagada, Á.; Rota, S.; Royer, F.; Sacco, G.; Sanchez-Janssen, R.; Sanna, N.; Santos, P.; Sarzi, M.; Schaerer, D.; Schiavon, R.; Schnell, R.; Schultheis, M.; Scodeggio, M.; Serjeant, S.; Shen, T. -C.; Simmonds, C.; Smoker, J.; Sobral, D.; Sordet, M.; Spérone, D.; Strachan, J.; Sun, X.; Swinbank, M.; Tait, G.; Tereno, I.; Tojeiro, R.; Torres, M.; Tosi, M.; Tozzi, A.; Tresiter, E.; Valenti, E.; Valenzuela Navarro, Á.; Vanzella, E.; Vergani, S.; Verhamme, A.; Vernet, J.; Vignali, C.; Vinther, J.; Von Dran, L.; Waring, C.; Watson, S.; Wild, V.; Willesme, B.; Woodward, B.; Wuyts, S.; Yang, Y.; Zamorani, G.; Zoccali, M.; Bluck, A.; Trussler, J.
    MOONS is the new Multi-Object Optical and Near-infrared Spectrograph currently under construction for the Very Large Telescope (VLT) at ESO. This remarkable instrument combines, for the first time, the collecting power of an 8-m telescope, 1000 fibres with individual robotic positioners, and both low- and high-resolution simultaneous spectral coverage across the 0.64-1.8 μm wavelength range. This facility will provide the astronomical community with a powerful, world-leading instrument able to serve a wide range of Galactic, extragalactic and cosmological studies. Construction is now proceeding full steam ahead and this overview article presents some of the science goals and the technical description of the MOONS instrument. More detailed information on the MOONS surveys is provided in the other dedicated articles in this Messenger issue....
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    The ALHAMBRA survey
    (2008) Moles, M.; Benitez, N.; Aguerri, J. A. L.; Alfaro, E. J.; Broadhurst, T.; Cabrera-Cano, J.; Castander, F. J.; Cepa, J.; Cervino, M.; Cristobal-Hornillos, D.; Fernandez-Soto, A.; Delgado, R. M. Gonzalez; Infante, L.; Marquez, I.; Martinez, V. J.; Masegosa, J.; del Olmo, A.; Perea, J.; Prada, F.; Quintana, J. M.; Sanchez, S. F.
    Here we describe the first results of the Advanced Large Homogeneous Area Medium-Band Redshift Astronomical (ALHAMBRA) survey, which provides cosmic tomography of the evolution of the contents of the universe overmost of cosmic history. Our novel approach employs 20 contiguous, equal-width, medium-band filters covering from 3500 angstrom to 9700 angstrom, plus the standard JHK(s) near-infrared (NIR) bands, to observe a total area of 4 deg(2) on the sky. The optical photometric system has been designed to maximize the number of objects with accurate classification by spectral energy distribution type and redshift, and to be sensitive to relatively faint emission features in the spectrum. The observations are being carried out with the Calar Alto 3.5 m telescope using the wide-field cameras in the optical, Large Area Imager for Calar Alto, and in the NIR, Omega-2000. The first data confirm that we are reaching the expected magnitude limits (for a total of 100 ks integration time per pointing) of AB <= 25 mag (for an unresolved object, signal-to-noise ratio = 5) in the optical filters from the blue to 8300 angstrom, and from AB = 24.7 to 23.4 for the redder ones. The limit in the NIR, for a total of 15 ks exposure time per pointing, is (in the Vega system) K-s approximate to 20 mag, H approximate to 21 mag, J approximate to 22 mag. Some preliminary results are presented here to illustrate the capabilities of the ongoing survey. We expect to obtain accurate redshift values, Delta z/(1+z) <= 0.03 for about five x 10(5) galaxies with 1 <= 25 (60% completeness level), and z(med) = 0.74. This accuracy, together with the homogeneity of the selection function, will allow for the study of the redshift evolution of the large-scale structure, the galaxy population and its evolution with redshift, the identification of clusters of galaxies, and many other studies, without the need for any further follow-up. It will also provide targets for detailed studies with 10 m class telescopes. Given its area, spectral coverage, and its depth, apart from those main goals, the ALHAMBRA survey will also produce valuable data for galactic studies.
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    The ALHAMBRA survey: Discovery of a faint QSO at z=5.41 (Research Note)
    (2013) Matute, I.; Masegosa, J.; Marquez, I.; Fernandez-Soto, A.; Husillos, C.; del Olmo, A.; Perea, J.; Povic, M.; Ascaso, B.; Alfaro, E. J.; Moles, M.; Aguerri, J. A. L.; Aparicio-Villegas, T.; Benitez, N.; Broadhurst, T.; Cabrera-Cano, J.; Castander, F. J.; Cepa, J.; Cervino, M.; Cristobal-Hornillos, D.; Infante, L.; Gonzalez Delgado, R. M.; Martinez, V. J.; Molino, A.; Prada, F.; Quintana, J. M.
    Aims. We aim to illustrate the potentiality of the Advanced Large, Homogeneous Area, Medium-Band Redshift Astronomical (ALHAMBRA) survey to investigate the high-redshift universe through the detection of quasi stellar objects (QSOs) at redshifts higher than 5.
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    The ALMA Frontier Fields Survey. IV. Lensing-corrected 1.1 mm number counts in Abell 2744, MACS J0416.1-2403, and MACS J1149.5+2223 (Corrigendum)
    (2019) Muñoz Arancibia, A. M.; González-López, J.; Ibar, E.; Bauer, F. E.; Carrasco, M.; Laporte, N.; Anguita, T.; Aravena, M.; Barrientos, F.; Bouwens, R. J.; Demarco, R.; Infante, L.; Kneissl, R.; Nagar, N.; Padilla, N.; Romero-Cañizales, C.; Troncoso, P.; Zitrin, A.
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    The Atacama Cosmology Telescope (ACT): Beam Profiles and First SZ Cluster Maps
    (2010) Hincks, A. D.; Acquaviva, V.; Ade, P. A. R.; Aguirre, P.; Amiri, M.; Appel, J. W.; Barrientos, L. F.; Battistelli, E. S.; Bond, J. R.; Brown, B.; Burger, B.; Chervenak, J.; Das, S.; Devlin, M. J.; Dicker, S. R.; Doriese, W. B.; Dunkley, J.; Dünner, R.; Essinger-Hileman, T.; Fisher, R. P.; Fowler, J. W.; Hajian, A.; Halpern, M.; Hasselfield, M.; Hernández-Monteagudo, C.; Hilton, G. C.; Hilton, M.; Hlozek, R.; Huffenberger, K. M.; Hughes, D. H.; Hughes, J. P.; Infante, L.; Irwin, K. D.; Jimenez, R.; Juin, J. B.; Kaul, M.; Klein, J.; Kosowsky, A.; Lau, J. M.; Limon, M.; Lin, Y. -T.; Lupton, R. H.; Marriage, T. A.; Marsden, D.; Martocci, K.; Mauskopf, P.; Menanteau, F.; Moodley, K.; Moseley, H.; Netterfield, C. B.; Niemack, M. D.; Nolta, M. R.; Page, L. A.; Parker, L.; Partridge, B.; Quintana, H.; Reid, B.; Sehgal, N.; Sievers, J.; Spergel, D. N.; Staggs, S. T.; Stryzak, O.; Swetz, D. S.; Switzer, E. R.; Thornton, R.; Trac, H.; Tucker, C.; Verde, L.; Warne, R.; Wilson, G.; Wollack, E.; Zhao, Y.
    The Atacama Cosmology Telescope (ACT) is currently observing the cosmic microwave background with arcminute resolution at 148 GHz, 218 GHz, and 277 GHz. In this paper, we present ACT's first results. Data have been analyzed using a maximum-likelihood map-making method which uses B-splines to model and remove the atmospheric signal. It has been used to make high-precision beam maps from which we determine the experiment's window functions. This beam information directly impacts all subsequent analyses of the data. We also used the method to map a sample of galaxy clusters via the Sunyaev-Zel'dovich (SZ) effect and show five clusters previously detected with X-ray or SZ observations. We provide integrated Compton-y measurements for each cluster. Of particular interest is our detection of the z = 0.44 component of A3128 and our current non-detection of the low-redshift part, providing strong evidence that the further cluster is more massive as suggested by X-ray measurements. This is a compelling example of the redshift-independent mass selection of the SZ effect.
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    The Atacama Cosmology Telescope: A Measurement of the 600 < ell < 8000 Cosmic Microwave Background Power Spectrum at 148 GHz
    (2010) Fowler, J. W.; Acquaviva, V.; Ade, P. A. R.; Aguirre, P.; Amiri, M.; Appel, J. W.; Barrientos, L. F.; Battistelli, E. S.; Bond, J. R.; Brown, B.; Burger, B.; Chervenak, J.; Das, S.; Devlin, M. J.; Dicker, S. R.; Doriese, W. B.; Dunkley, J.; Dünner, R.; Essinger-Hileman, T.; Fisher, R. P.; Hajian, A.; Halpern, M.; Hasselfield, M.; Hernández-Monteagudo, C.; Hilton, G. C.; Hilton, M.; Hincks, A. D.; Hlozek, R.; Huffenberger, K. M.; Hughes, D. H.; Hughes, J. P.; Infante, L.; Irwin, K. D.; Jimenez, R.; Juin, J. B.; Kaul, M.; Klein, J.; Kosowsky, A.; Lau, J. M.; Limon, M.; Lin, Y. -T.; Lupton, R. H.; Marriage, T. A.; Marsden, D.; Martocci, K.; Mauskopf, P.; Menanteau, F.; Moodley, K.; Moseley, H.; Netterfield, C. B.; Niemack, M. D.; Nolta, M. R.; Page, L. A.; Parker, L.; Partridge, B.; Quintana, H.; Reid, B.; Sehgal, N.; Sievers, J.; Spergel, D. N.; Staggs, S. T.; Swetz, D. S.; Switzer, E. R.; Thornton, R.; Trac, H.; Tucker, C.; Verde, L.; Warne, R.; Wilson, G.; Wollack, E.; Zhao, Y.
    We present a measurement of the angular power spectrum of the cosmic microwave background (CMB) radiation observed at 148 GHz. The measurement uses maps with 1'.4 angular resolution made with data from the Atacama Cosmology Telescope (ACT). The observations cover 228 deg(2) of the southern sky, in a 4 degrees.2 wide strip centered on declination 53 degrees south. The CMB at arcminute angular scales is particularly sensitive to the Silk damping scale, to the Sunyaev-Zel'dovich (SZ) effect from galaxy clusters, and to emission by radio sources and dusty galaxies. After masking the 108 brightest point sources in our maps, we estimate the power spectrum between 600 < l < 8000 using the adaptive multi-taper method to minimize spectral leakage and maximize use of the full data set. Our absolute calibration is based on observations of Uranus. To verify the calibration and test the fidelity of our map at large angular scales, we cross-correlate the ACT map to the WMAP map and recover the WMAP power spectrum from 250 < l < 1150. The power beyond the Silk damping tail of the CMB (l similar to 5000) is consistent with models of the emission from point sources. We quantify the contribution of SZ clusters to the power spectrum by fitting to a model normalized to sigma(8) = 0.8. We constrain the model's amplitude A(SZ) < 1.63 (95% CL). If interpreted as a measurement of sigma(8), this implies sigma(SZ)(8) < 0.86 (95% CL) given our SZ model. A fit of ACT and WMAP five-year data jointly to a six-parameter Lambda CDM model plus point sources and the SZ effect is consistent with these results.
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    THE CLUSTER LENSING AND SUPERNOVA SURVEY WITH HUBBLE (CLASH): STRONG-LENSING ANALYSIS OF A383 FROM 16-BAND HST/WFC3/ACS IMAGING
    (2011) Zitrin, A.; Broadhurst, T.; Coe, D.; Umetsu, K.; Postman, M.; Benitez, N.; Meneghetti, M.; Medezinski, E.; Jouvel, S.; Bradley, L.; Koekemoer, A.; Zheng, W.; Ford, H.; Merten, J.; Kelson, D.; Lahav, O.; Lemze, D.; Molino, A.; Nonino, M.; Donahue, M.; Rosati, P.; Van der Wel, A.; Bartelmann, M.; Bouwens, R.; Graur, O.; Graves, G.; Host, O.; Infante, L.; Jha, S.; Jimenez-Teja, Y.; Lazkoz, R.; Maoz, D.; McCully, C.; Melchior, P.; Moustakas, L. A.; Ogaz, S.; Patel, B.; Regoes, E.; Riess, A.; Rodney, S.; Seitz, S.
    We examine the inner mass distribution of the relaxed galaxy cluster A383 (z = 0.189), in deep 16 band Hubble Space Telescope/ACS+WFC3 imaging taken as part of the Cluster Lensing And Supernova survey with Hubble (CLASH) multi-cycle treasury program. Our program is designed to study the dark matter distribution in 25 massive clusters, and balances depth with a wide wavelength coverage, 2000-16000 angstrom, to better identify lensed systems and generate precise photometric redshifts. This photometric information together with the predictive strength of our strong-lensing analysis method identifies 13 new multiply lensed images and candidates, so that a total of 27 multiple images of nine systems are used to tightly constrain the inner mass profile gradient, d log Sigma/d log r similar or equal to -0.6 +/- 0.1 (r < 160 kpc). We find consistency with the standard distance-redshift relation for the full range spanned by the lensed images, 1.01 < z < 6.03, with the higher-redshift sources deflected through larger angles as expected. The inner mass profile derived here is consistent with the results of our independent weak-lensing analysis of wide-field Subaru images, with good agreement in the region of overlap (similar to 0.7-1 arcmin). Combining weak and strong lensing, the overall mass profile is well fitted by a Navarro-Frenk-White profile with M-vir = (5.37(-0.63)(+0.70) +/- 0.26) x 10(14) M-circle dot h(-1) and a relatively high concentration, c(vir) = 8.77(-0.42)(+0.44) +/- 0.23, which lies above the standard c-M relation similar to other well-studied clusters. The critical radius of A383 is modest by the standards of other lensing clusters, r(E) similar or equal to 16 +/- 2 '' (for z(s) = 2.55), so the relatively large number of lensed images uncovered here with precise photometric redshifts validates our imaging strategy for the CLASH survey. In total we aim to provide similarly high-quality lensing data for 25 clusters, 20 of which are X-ray-selected relaxed clusters, enabling a precise determination of the representative mass profile free from lensing bias.
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    The nature of sub-millimetre galaxies II: an ALMA comparison of SMG dust heating mechanisms
    (2022) Ansarinejad, B.; Shanks, T.; Bielby, R. M.; Metcalfe, N.; Infante, L.; Murphy, D. N. A.; Rosario, D. J.; Stach, S. M.
    We compare the contribution of active galactic nuclei (AGNs) and star formation towards dust heating in sub-mm galaxies (SMGs). We have used ALMA at 0.1-arcsec resolution to image a complete flux-limited sample of seven sub-mm sources previously shown to have spectral energy distributions that were as well-fitted by obscured AGN as star-forming galaxy templates. Indeed, two sub-mm sources were known to be quasars from their absorbed X-ray emission. We find the sub-mm sizes of all SMGs to be small (approximate to 1-2 kpc) and generally similar to 3 times smaller than any host detected in the near-infrared (NIR). In all cases, the five SMGs are comparable in sub-mm size to the two known quasars and four z approximate to 6 quasars, also observed with ALMA. We detect no evidence of diffuse spiral arms in this complete sample. We then convert the far-infrared (FIR) luminosities to star formation rate (SFR) surface densities and find that the SMGs occupy the same range as the known quasars in our sample. We conclude that in terms of sub-mm size, extent relative to host and SFR density as well as luminosity and mid-IR (MIR) colour, there is little distinction between the SMGs and sub-mm bright quasars. Finally, we present preliminary evidence that SMGs with higher MIR luminosities and sub-mm loud quasars tend to have dust components that range to hotter temperatures than their less luminous SMG counterparts. In light of these results, we continue to suggest that luminous SMGs may host dust-absorbed quasars that may simultaneously dominate the FIR and hard X-ray backgrounds.
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    The nature of sub-millimetre galaxies II: an ALMA comparison of SMG dust heating mechanisms
    (2022) Ansarinejad, B.; Shanks, T.; Bielby, R. M.; Metcalfe, N.; Infante, L.; Murphy, D. N. A.; Rosario, D. J.; Stach, S. M.
    We compare the contribution of active galactic nuclei (AGNs) and star formation towards dust heating in sub-mm galaxies (SMGs). We have used ALMA at 0.1-arcsec resolution to image a complete flux-limited sample of seven sub-mm sources previously shown to have spectral energy distributions that were as well-fitted by obscured AGN as star-forming galaxy templates. Indeed, two sub-mm sources were known to be quasars from their absorbed X-ray emission. We find the sub-mm sizes of all SMGs to be small (approximate to 1-2 kpc) and generally similar to 3 times smaller than any host detected in the near-infrared (NIR). In all cases, the five SMGs are comparable in sub-mm size to the two known quasars and four z approximate to 6 quasars, also observed with ALMA. We detect no evidence of diffuse spiral arms in this complete sample. We then convert the far-infrared (FIR) luminosities to star formation rate (SFR) surface densities and find that the SMGs occupy the same range as the known quasars in our sample. We conclude that in terms of sub-mm size, extent relative to host and SFR density as well as luminosity and mid-IR (MIR) colour, there is little distinction between the SMGs and sub-mm bright quasars. Finally, we present preliminary evidence that SMGs with higher MIR luminosities and sub-mm loud quasars tend to have dust components that range to hotter temperatures than their less luminous SMG counterparts. In light of these results, we continue to suggest that luminous SMGs may host dust-absorbed quasars that may simultaneously dominate the FIR and hard X-ray backgrounds.
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    The nature of UCDs
    (2008) Mieske, S.; Hilker, M.; Jordan, A.; Infante, L.; Kissler-Patig, M.; Rejkuba, M.; Richtler, T.; Cote, P.; Baumgardt, H.; West, M. J.; Ferrarese, L.; Peng, E. W.
    Context. The internal dynamics of ultra-compact dwarf galaxies (UCDs) has attracted increasing attention, with most of the UCDs studied to date located in the Virgo cluster.
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    The VLT LBG redshift survey - VI. Mapping HI in the proximity of z similar to 3 LBGs with X-Shooter
    (OXFORD UNIV PRESS, 2017) Bielby, R. M.; Shanks, T.; Crighton, N. H. M.; Bornancini, C. G.; Infante, L.; Lambas, D. G.; Minniti, D.; Morris, S. L.; Tummuangpak, P.
    We present an analysis of the spatial distribution and dynamics of neutral hydrogen gas around galaxies using new X-Shooter observations of z similar to 2.5-4 quasars. Adding the X-Shooter data to our existing data set of high-resolution quasar spectroscopy, we use a total sample of 29 quasars alongside similar to 1700 Lyman Break Galaxies (LBGs) in the redshift range 2 less than or similar to z less than or similar to 3.5. We measure the Ly alpha forest auto-correlation function, finding a clustering length of s(0) = 0.081 +/- 0.006 h(-1) Mpc, and the cross-correlation function with LBGs, finding a cross-clustering length of s0 = 0.27 +/- 0.14 h(-1) Mpc and power-law slope gamma = 1.1 +/- 0.2. Our results highlight the weakly clustered nature of neutral hydrogren systems in the Ly alpha forest. Building on this, we make a first analysis of the dependence of the clustering on absorber strength, finding a clear preference for stronger Ly alpha forest absorption features to be more strongly clustered around the galaxy population, suggesting that they trace on average higher mass haloes. Using the projected and 2-D cross-correlation functions, we constrain the dynamics of Ly alpha forest clouds around z similar to 3 galaxies. We find a significant detection of large-scale infall of neutral hydrogen, with a constraint on the Ly alpha forest infall parameter of beta(F) = 1.02 +/- 0.22.