Browsing by Author "Benitez, N."
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- ItemCLASH-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.
- ItemDiscovery 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.
- ItemEvolution of Balmer jump selected galaxies in the ALHAMBRA survey(2016) Iribarren, P.; Infante Lira, Leopoldo; Padilla, Nelson; Lacerna Zambrano, Iván Andrés; Garcia, S.; Orsi, A.; Arancibia, A.; Moustakas, J.; Cristobal, D.; Moles, M.; Fernandez, A.; Martinez, V.; Cervino, M.; Alfaro, E.; Ascaso, B.; Arnalte, P.; Nieves, L.; Benitez, N.
- ItemGalaxy clusters and groups in the ALHAMBRA survey(2015) Ascaso, B.; Benitez, N.; Fernandez-Soto, A.; Arnalte-Mur, P.; Lopez-Sanjuan, C.; Molino, A.; Schoenell, W.; Jimenez-Teja, Y.; Merson, A. I.; Infante Lira, Leopoldo; Díaz-Garcia, L. A.; Martınez, V. J.; Cenarro, A. J.; Dupke, R.; Marquez, I.; Masegosa, J.; Nieves-Seoane, L.; Povic, M.; Varela, J.; Huertas-Company, M.
- ItemHubble 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.
- ItemHerschel 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.
- ItemStellar populations of galaxies in the ALHAMBRA survey up to z∼1 II. Stellar content of quiescent galaxies within the dust-corrected stellar mass–colour and the UVJ colour–colour diagrams(2019) Diaz-Garcia, L.A.; Cenarro, A.J.; Lopez-Sanjuan, C.; Ferreras, I.; Cervino, M.; Fernandez-Soto, A.; Delgado, R.M.G.; Marquez, I.; Povic, M.|Infante Lira, Leopoldo; San Roman, I.; Viironen, K.; Moles, M.; Cristobal-Hornillos, D.; Lopez-Comazzi, A.; Alfaro, E.; Aparicio-Villegas, T.; Benitez, N.; Broadhurst, T.; Cabrera-Cano, J.; Castander, F.J.; Cepa, J.; Husillos, César; Aguerri, J.A.L.; Martínez, V.J.; Masegosa, Josefa; Molino, A.; Olmo, Ascensión del; Perea, Jaime; Prada, Francisco; Quintana, José María
- ItemThe 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.
- ItemThe 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.
- ItemTHE 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.