Examinando por Autor "Aravena, M."
Mostrando 1 - 7 de 7
Resultados por página
Opciones de ordenación
Ítem COLDz: Probing Cosmic Star Formation with Radio Free-Free Emission(IOP Publishing Ltd, 2022-01) Algera, H.; Hodge, J.; Riechers, D.; Leslie, S.; Smail, I.; Aravena, M.; Cunha, E.; Daddi, E.; Decarli, R.; Dickinson, M.; Gim, H.; Guaita, L.; Magnelli, B.; Murphy, E.; Pavesi, R.; Sargent, M.; Sharon, C.; Wagg, J.; Walter, F.; Yun, M.Radio free-free emission is considered to be one of the most reliable tracers of star formation in galaxies. However, as it constitutes the faintest part of the radio spectrum - being roughly an order of magnitude less luminous than radio synchrotron emission at the GHz frequencies typically targeted in radio surveys - the usage of free-free emission as a star formation rate tracer has mostly remained limited to the local universe. Here, we perform a multifrequency radio stacking analysis using deep Karl G. Jansky Very Large Array observations at 1.4, 3, 5, 10, and 34 GHz in the COSMOS and GOODS-North fields to probe free-free emission in typical galaxies at the peak of cosmic star formation. We find that z ∼ 0.5-3 star-forming galaxies exhibit radio emission at rest-frame frequencies of ∼65-90 GHz that is ∼1.5-2 times fainter than would be expected from a simple combination of free-free and synchrotron emission, as in the prototypical starburst galaxy M82. We interpret this as a deficit in high-frequency synchrotron emission, while the level of free-free emission is as expected from M82. We additionally provide the first constraints on the cosmic star formation history using free-free emission at 0.5 ≲ z ≲ 3, which are in good agreement with more established tracers at high redshift. In the future, deep multifrequency radio surveys will be crucial in order to accurately determine the shape of the radio spectrum of faint star-forming galaxies, and to further establish radio free-free emission as a tracer of high-redshift star formation.Ítem Learning strategies at a higher taxonomic level in primary education students in the digital age(Multidisciplinary Digital Publishing Institute (MDPI), 2020-11) Aravena, M.; Campos-Soto, M.N.; Rodríguez-Jiménez, C.The education system must respond to the demands and needs of today’s society. To meet this demand, teachers must identify the degree of cognitive skills that our students possess through digital learning strategies that encourage the development of these superior skills because of the impact of technological resources on student motivation. To carry out this assessment, two types of strategy tests were applied to evaluate cognitive skills, one determining the student’s ability to create an opinion of their own based on ideas and visions of other authors (perspective analysis) and the other strategy test to distinguish the main elements of an information, identifying a general pattern (abstraction), which were reviewed with a task performance instrument (rubrics). A mixed methodology was used through a case study, with a selected and intentional sample of 34 students of the Primary Education Grade. The results show that elaborating questions that go deeper into a topic and labelling contents is not an easy task and that abstraction is one of the most complex skills to develop in students. It should be noted that, in practically all areas, men’s averages exceed those of women. Finally, the use of digital strategies must be incorporated as permanent routines and the relationship between technology and pedagogy allows for the management of learning and therefore increases higher level cognitive abilities. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Ítem Megaparsec-scale structure around the protocluster core SPT2349-56 at z = 4.3(Oxford University Press, 2020-05) Hill, R.; Chapman, S.; Scott, D.; Apostolovski, Y.; Aravena, M.; Béthermin, M.; Bradford, C.M.; Canning, R.E.A.; De Breuck, C.; Dong, C.; González, A.; Greve, T.R.; Hayward, C.C.; Hezaveh, Y.; Litke, K.; Malkan, M.; Marrone, D.P.; Phadke, K.; Reuter, C.; Rotermund, K.; Spilker, J.; Vieira, J.D.; Weiß, A.We present an extensive ALMA spectroscopic follow-up programme of the $z\, {=}\, 4.3$ structure SPT2349-56, one of the most actively star-forming protocluster cores known, to identify additional members using their [C ii] 158 μm and CO(4-3) lines. In addition to robustly detecting the 14 previously published galaxies in this structure, we identify a further 15 associated galaxies at $z\, {=}\, 4.3$, resolving 55$\, {\pm }\,$5 per cent of the 870 μm flux density at 0.5 arcsec resolution compared to 21 arcsec single-dish data. These galaxies are distributed into a central core containing 23 galaxies extending out to 300 kpc in diameter, and a northern extension, offset from the core by 400 kpc, containing three galaxies. We discovered three additional galaxies in a red Herschel-SPIRE source 1.5 Mpc from the main structure, suggesting the existence of many other sources at the same redshift as SPT2349-56 that are not yet detected in the limited coverage of our data. An analysis of the velocity distribution of the central galaxies indicates that this region may be virialized with a mass of (9$\pm 5)\, {\times }\, 10^{12}$ M⊠, while the two offset galaxy groups are about 30 and 60 per cent less massive and show significant velocity offsets from the central group. We calculate the [C ii] and far-infrared number counts, and find evidence for a break in the [C ii] luminosity function. We estimate the average SFR density within the region of SPT2349-56 containing single-dish emission (a proper diameter of 720 kpc), assuming spherical symmetry, to be roughly 4$\, {\times }\, 10^4$ M⊠yr-1 Mpc-3; this may be an order of magnitude greater than the most extreme examples seen in simulations. © 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.Ítem Metal content of the circumgalactic medium around star-forming galaxies at z ~ 2.6 as revealed by the VIMOS Ultra-Deep Survey(EDP Sciences, 2022-10-01) Méndez Hernández, H.; Cassata, P.; Ibar, E.; Amorín, R.; Aravena, M.; Bardelli, S.; Cucciati, O.; Garilli, B.; Giavalisco, M.; Guaita, L.; Hathi, N.; Koekemoer, A.; Le Brun, V.; Lemaux, B.C.; MacCagni, D.; Ribeiro, B.; Tasca, L.; Tejos, N.; Thomas, R.; Tresse, L.; Vergani, D.; Zamorani, G.; Zucca, E.Context. The circumgalactic medium (CGM) is the location where the interplay between large-scale outflows and accretion onto galaxies occurs. Metals in different ionization states flowing between the circumgalactic and intergalactic mediums are affected by large galactic outflows and low-ionization state inflowing gas. Observational studies on their spatial distribution and their relation with galaxy properties may provide important constraints on models of galaxy formation and evolution. Aims. The main goal of this paper is to provide new insights into the spatial distribution of the circumgalactic of star-forming galaxies at 1.5 < z < 4.5 (z ~2.6) in the peak epoch of cosmic star formation activity in the Universe. We also look for possible correlations between the strength of the low- and high-ionization absorption features (LIS and HIS) and stellar mass, star formation rate, effective radius, and azimuthal angle φ that defines the location of the absorbing gas relative to the galaxy disc plane. Methods. The CGM has been primarily detected via the absorption features that it produces on the continuum spectrum of bright background sources. We selected a sample of 238 close pairs from the VIMOS Ultra Deep Survey to examine the spatial distribution of the gas located around star-forming galaxies and generate composite spectra by co-adding spectra of background galaxies that provide different sight-lines across the CGM of star-forming galaxies. Results. We detect LIS (CII and SiII) and HIS (SiIV, CIV) up to separations b = 172 kpc and 146 kpc. Beyond this separation, we do not detect any significant signal of CGM absorption in the background composite spectra. Our Lyα, LIS, and HIS rest-frame equivalent width (W0) radial profiles are at the upper envelope of the W0 measurements at lower redshifts, suggesting a potential redshift evolution for the CGM gas content producing these absorptions. We find a correlation between CII and CIV with star formation rate and stellar mass, as well as trends with galaxy size estimated by the effective radius and azimuthal angle. Galaxies with high star formation rate (log[SFR/(M⊙ yr-1)] > 1.5) and stellar mass (log[M∗/M⊙] > 10.2) show stronger CIV absorptions compared with those low SFR (log[SFR/(M⊙ yr-1)] < 0.9) and low stellar mass (log[M∗/M⊙] < 9.26). The latter population instead shows stronger CII absorption than their more massive or more star-forming counterparts. We compute the CII/CIVW0 line ratio that confirms the CII and CIV correlations with impact parameter, stellar mass, and star formation rate. We do not find any correlation with φ in agreement with other high-redshift studies and in contradiction to what is observed at low redshift where large-scale outflows along the minor axis forming bipolar outflows are detected. Conclusions. We find that the stronger CIV line absorptions in the outer regions of these star-forming galaxies could be explained by stronger outflows in galaxies with higher star formation rates and stellar masses that are capable of projecting the ionized gas up to large distances and/or by stronger UV ionizing radiation in these galaxies that is able to ionize the gas even at large distances. On the other hand, low-mass galaxies show stronger CII absorptions, suggesting larger reservoirs of cold gas that could be explained by a softer radiation field unable to ionize high-ionization state lines or by the galactic fountain scenario where metal-rich gas ejected from previous star formation episodes falls back to the galaxy. These large reservoirs of cold neutral gas around low-mass galaxies could be funnelled into the galaxies and eventually provide the necessary fuel to sustain star formation activity. © 2022 Authors.Ítem The ALMA Frontier Fields Survey: V. ALMA Stacking of Lyman-Break Galaxies in Abell 2744, Abell 370, Abell S1063, MACSJ0416.1-2403 and MACSJ1149.5+2223(EDP Sciences, 2020-01) Carvajal, R.; Bauer, F.; Bouwens, R.; Oesch, P.; Gonzalez-Lopez, J.; Anguita, T.; Aravena, M.; Demarco, R.; Guaita, L.; Infante, L.; Kim, S.; Kneiss., R.; Koekemoer, A.; Messias, H.; Treister, E.; Villard, E.; Zitrin, A.; Troncoso, P.Context. The Hubble Frontier Fields offer an exceptionally deep window into the high-redshift universe, covering a substantially larger area than the Hubble Ultra-Deep field at low magnification and probing 1-2 mag deeper in exceptional high-magnification regions. This unique parameter space, coupled with the exceptional multi-wavelength ancillary data, can facilitate for useful insights into distant galaxy populations. Aims. We aim to leverage Atacama Large Millimetre Array (ALMA) band 6 (≈263 GHz) mosaics in the central portions of five Frontier Fields to characterize the infrared (IR) properties of 1582 ultraviolet (UV)-selected Lyman-Break Galaxies (LBGs) at redshifts of z ∼ 2-8. We investigated individual and stacked fluxes and IR excess (IRX) values of the LBG sample as functions of stellar mass (M⋆ ), redshift, UV luminosity and slope β, and lensing magnification. Methods. LBG samples were derived from color-selection and photometric redshift estimation with Hubble Space Telescope photometry. Spectral energy distributions -templates were fit to obtain luminosities, stellar masses, and star formation rates for the LBG candidates. We obtained individual IR flux and IRX estimates, as well as stacked averages, using both ALMA images and u-v visibilities. Results. Two (2) LBG candidates were individually detected above a significance of 4.1-σ, while stacked samples of the remaining LBG candidates yielded no significant detections. We investigated our detections and upper limits in the context of the IRX-M⋆ and IRX-β relations, probing at least one dex lower in stellar mass than past studies have done. Our upper limits exclude substantial portions of parameter space and they are sufficiently deep in a handful of cases to create mild tension with the typically assumed attenuation and consensus relations. We observe a clear and smooth trend between M⋆ and β, which extends to low masses and blue (low) β values, consistent with expectations from previous works.Ítem The alma spectroscopic survey in the hubble ultra deep field: search for [CII] line and dust emission in 6 < z < 8 galaxies(Institute of Physics Publishing, 2016-12) Aravena, M.; Decarli, R.; Walter, F.; Bouwens, R.; Oesch, P.A.; Carilli, C.L.; Bauer, F.E.; Cunha, E. Da; Daddi, E.; Gónzalez-López, J.; Ivison, R.J.; Riechers, D.A.; Smail, I.; Swinbank, A.M.; Weiss, A.; Anguita, T.; Bacon, R.; Bell, E.; Bertoldi, F.; Cortes, P.; Cox, P.; Hodge, J.; Ibar, E.; Inami, H.; Infante, L.; Karim, A.; Magnelli, B.; Ota, K.; Popping, G.; Van Der, Werf P.; Wagg, J.; Fudamoto, Y.We present a search for [C II] line and dust continuum emission from optical dropout galaxies at z > 6 using ASPECS, our Atacama Large Millimeter submillimeter Array Spectroscopic Survey in the Hubble Ultra-deep Field (UDF). Our observations, which cover the frequency range of 212–272 GHz, encompass approximately the range of 6 < z < 8 for [C II] line emission and reach a limiting luminosity of L[C II] ∼ (1.6–2.5) × 108 Le. We identify 14 [C II] line emitting candidates in this redshift range with significances >4.5σ, two of which correspond to blind detections with no optical counterparts. At this significance level, our statistical analysis shows that about 60% of our candidates are expected to be spurious. For one of our blindly selected [C II] line candidates, we tentatively detect the CO(6-5) line in our parallel 3 mm line scan. None of the line candidates are individually detected in the 1.2 mm continuum. A stack of all [C II] candidates results in a tentative detection with S1.2 mm = 14 ± 5 μJy. This implies a dust-obscured star-formation rate (SFR) of (3 ± 1) Me yr−1 . We find that the two highest-SFR objects have candidate [C II] lines with luminosities that are consistent with the low-redshift L[C II] versus SFR relation. The other candidates have significantly higher [C II] luminosities than expected from their UV-based SFR. At the current sensitivity, it is unclear whether the majority of these sources are intrinsically bright [C II] emitters, or spurious sources. If only one of our line candidates was real (a scenario greatly favored by our statistical analysis), we find a source density for [C II] emitters at 6 < z < 8 that is significantly higher than predicted by current models and some extrapolations from galaxies in the local universe.Ítem Tomography of the environment of the COSMOS/AzTEC-3 submillimeter galaxy at z ∼ 5.3 revealed by Ly α and MUSE observations(EDP Sciences, 2022-04-01) Guaita, L.; Aravena, M.; Gurung-Lopez, S.; Cantalupo, S.; Marino, R.; Riechers, D.; Da Cunha, E.; Wagg, J.; Algera, H.S.B.; Dannerbauer, H.; Cox, P.Context. Submillimeter galaxies (SMGs) have been proposed as the progenitors of massive ellipticals in the local Universe. Mapping the neutral gas distribution and investigating the gas accretion toward the SMGs at high redshift can provide information on the way SMG environments can evolve into clusters at z = 0. Aims. In this work, we study the members of the protocluster around AzTEC-3, a submillimeter galaxy at z = 5.3. We use Lyα emission and its synergy with previous CO and [CII]158 μm observations. Methods. We analyzed the data from the Multi Unit Spectroscopic Explorer (MUSE) instrument in an area of 1.4×1.4 arcmin2 around AzTEC-3 and derived information on the Lyα line in emission. We compared the Lyα profile of various regions of the environment with the zELDA radiative transfer model, revealing the neutral gas distribution and kinematics. Results. We identified ten Lyα emitting sources, including two regions with extended emission: one embedding AzTEC-3 and LBG-3, which is a star-forming galaxy located 2′ (12 kpc) north of the SMG and another toward LBG-1, which is a star-forming galaxy located 15′ (90 kpc) to the southeast. The two regions extend for ∼27×38 kpc2 (∼170×240 ckpc2) and ∼20×20 kpc2 (∼125×125 ckpc2), respectively. The sources appear distributed in an elongated configuration of about 70′ (430 kpc) in extent. The number of sources confirms the overdensity around AzTEC-3. We study the MUSE spectra of the AzTEC-3+LBG-3 system and LBG-1 in detail. For the AzTEC-3+LBG-3 system, the Lyα emission appears redshifted and more spatially extended than the [CII] line emission. Similarly, the Lyα line spectrum is broader in velocity than [CII] for LBG-1. In the former spectrum, the Lyα emission is elongated to the north of LBG-3 and to the south of AzTEC-3, where a faint Lyα emitting galaxy is also located. The elongated structures could resemble tidal features due to the interaction of the two galaxies with AzTEC-3. Also, we find a bridge of gas, revealed by the Lyα emission between AzTEC-3 and LBG-3. The Lyα emission toward LBG-1 embeds its three components. The HI kinematics support the idea of a merger of the three components. Conclusions. Given the availability of CO and [CII] observations from previous campaigns, and the Lyα information from our MUSE dataset, we find evidence of starburst-driven phenomena and interactions around AzTEC-3. The stellar mass of the galaxies of the overdensity and the Lyα luminosity of the HI nebula associated with AzTEC-3 imply a dark matter halo of ∼1012 M· at z = 5.3. By comparing this with semi-analytical models, the dark matter halo mass indicates that the region could evolve into a cluster of 2×1013 M· by z = 2 and into a Fornax-type cluster at z = 0 with a typical mass of 2×1014âà €à † M·. © 2022 Authors