Magellan/MMIRS near-infrared multi-object spectroscopy of nebular emission from star forming galaxies at 2<z<3

To investigate the ingredients, which allow star-forming galaxies to present Lyalpha line in emission, we studied the kinematics and gas phase metallicity (Z) of the interstellar medium. We used multi-object NIR spectroscopy with Magellan/MMIRS to study nebular emission from z=2-3 star-forming galaxies discovered in 3 MUSYC fields. We detected emission lines from four active galactic nuclei and 13 high-z star-forming galaxies, including Halpha lines down to a flux of 4.E-17 erg/sec/cm^2. This yielded 7 new redshifts. The most common emission line detected is [OIII]5007, which is sensitive to Z. We were able to measure Z for 2 galaxies and to set upper(lower) limits for another 2(2). The Z values are consistent with 0.3<Z/Zsun<1.2. Comparing the Lyalpha central wavelength with the systemic redshift, we find Delta_v(Lyalpha-[OIII])=70-270 km/sec. High-redshift star-forming galaxies, Lyalpha emitting (LAE) galaxies, and Halpha emitters appear to be located in the low mass, high star-formation rate (SFR) region of the SFR versus stellar mass diagram, confirming that they are experiencing burst episodes of star formation, which are building up their stellar mass. Their Zs are consistent with the relation found for z<2.2 galaxies in the Z versus stellar mass plane. The measured Delta_v(Lyalpha-[OIII]) values imply that outflows of material, driven by star formation, could be present in the z=2-3 LAEs of our sample. Comparing with the literature, we note that galaxies with lower Z than ours are also characterized by similar Delta_v(Lyalpha-[OIII]) velocity offsets. Strong [OIII] is detected in many Lyalpha emitters. Therefore, we propose the Lyalpha/[OIII] flux ratio as a tool for the study of high-z galaxies; while influenced by Z, ionization, and Lyalpha radiative transfer in the ISM, it may be possible to calibrate this ratio to primarily trace one of these effects.Comment: 22 pages, 13 figures, 6 table

Preprint arXiv: 2204.02923 Submitted on 6 Apr 2022

We present an ansatz for the ground states of the Quantum Sherrington-Kirkpatrick model, a paradigmatic model for quantum spin glasses. Our ansatz, based on the concept of generalized coherent states, very well captures the fundamental aspects of the model, including the ground state energy and the position of the spin glass phase transition. It further enables us to study some previously unexplored features, such as the non-vanishing longitudinal field regime and the entanglement structure of the ground states. We find that the ground state entanglement can be captured by a simple ensemble of weighted graph states with normally distributed phase gates, leading to a volume law entanglement, contrasting with predictions based on entanglement monogamy

The use of carboxymethylcellulose for the tartaric stabilization of white wines, in comparison with other oenological additives

The aim of this study was to test the effectiveness of two types of carboxymethylcellulose (CMC), at different doses, for the prevention of tartaric precipitations in two white wines (Pinot Blanc and Chardonnay), in comparison with metatartaric acid and a commercial arabic gum. After the addition of the additives to the wines, the mini-contact test was carried out and the saturation temperature was determined by Ridomi’s method. The determination of the saturation temperature was then repeated on the same trials kept at -4 °C for 10 days. Both kinds of CMC caused a significant decrease in tartaric precipitations induced by the addition of potassium bitartrate (KHT) (mini-contact test), by limiting the growth of the added KHT crystals. Their effectiveness increased with the dose, following a hyperbolic trend. The stabilizing effect of the two kinds of CMC, particularly CMC2 (more viscous), was similar to the one of metatartaric acid. Their use must be considered complementary to the cold treatment (chillproofing).

Peering through the holes: the far UV color of star-forming galaxies at z~3-4 and the escaping fraction of ionizing radiation

We aim to investigate the effect of the escaping ionizing radiation on the color selection of high redshift galaxies and identify candidate Lyman continuum (LyC) emitters. The intergalactic medium prescription of Inoue et al.(2014) and galaxy synthesis models of Bruzual&Charlot (2003) have been used to properly treat the ultraviolet stellar emission, the stochasticity of the intergalactic transmission and mean free path in the ionizing regime. Color tracks are computed by turning on/off the escape fraction of ionizing radiation. At variance with recent studies, a careful treatment of IGM transmission leads to no significant effects on the high-redshift broad-band color selection. The decreasing mean free path of ionizing photons with increasing redshift further diminishes the contribution of the LyC to broad-band colors. We also demonstrate that prominent LyC sources can be selected under suitable conditions by calculating the probability of a null escaping ionizing radiation. The method is applied to a sample of galaxies extracted from the GOODS-S field. A known LyC source at z=3.795 is successfully recovered as a LyC emitter candidate and another convincing candidate at z=3.212 is reported. A detailed analysis of the two sources (including their variability and morphology) suggests a possible mixture of stellar and non-stellar (AGN) contribution in the ultraviolet. Conclusions: Classical broad-band color selection of 2.5<z<4.5 galaxies does not prevent the inclusion of LyC emitters in the selected samples. Large fesc in relatively bright galaxies (L>0.1L*) could be favored by the presence of a faint AGN not easily detected at any wavelength. A hybrid stellar and non-stellar (AGN) ionizing emission could coexist in these systems and explain the tensions found among the UV excess and the stellar population synthesis models reported in literature.Comment: Accepted for publication in Astronomy & Astrophysics. 13 pages, 7 figure

HERÓI OU VILÃO? O PAPEL DO PROFESSOR DE EDUCAÇÃO FÍSICA ESCOLAR FRENTE À INDÚSTRIA CULTURAL

One of the most evident aspects in the contemporary world is the central place occupied by the technological ways of production and reproduction of information. They take an always larger space in our lives, catalyzing our emotions and our attitudes facing the world and showing their gloomier side when collaborating with the maintenance of the status quo. We observed the influence of the Cultural Industry in several ambits, as well as in the school. Than we discussed the teacher&#39;s role taking the media in account: is he a hero or a villain? The discussion had as a starting point the fact that the teacher is inserted in that society, feeling and thinking according its concepts, often commercial, unjust and prejudicious. The study goes then, in the direction of a valorization of the teacher&#39;s education in humanities, starting from a reflection on himself and, so, transporting it into his pedagogic practice.&nbsp;Uno de los aspectos m&aacute;s evidentes en el mundo contempor&aacute;neo es el lugar central ocupado por las tecnolog&iacute;as de producci&oacute;n y reproducci&oacute;n de informaci&oacute;n. Ellas toman un siempre m&aacute;s grande espacio en nuestras vidas, catalizando nuestras emociones y nuestros posicionamientos frente al mundo y mostrando su lado m&aacute;s oscuro al colaborar con el mantenimiento del statu quo. Nosotros observamos la influencia de la Industria Cultural en varios &aacute;mbitos, as&iacute; como en la escuela. Discutimos el papel del maestro, tomando los medios midi&aacute;ticos de comunicaci&oacute;n en la cuenta: &iquest;&eacute;l es un h&eacute;roe o un villano? La discusi&oacute;n ten&iacute;a como un punto de arranque el hecho que el maestro se inserta en esa sociedad, sentindo y pensando de acordo con sus conceptos, a menudo comerciales, injustos y preconceptuosos. El estudio va entonces en la direcci&oacute;n de una valorizaci&oacute;n de la formaci&oacute;n del maestro en las humanidades, empezando por una reflexi&oacute;n sobre &eacute;l mismo, para entonces transport&aacute;rla para su pr&aacute;ctica pedag&oacute;gica.&nbsp;&nbsp;Um dos aspectos mais evidentes no mundo contempor&acirc;neo &eacute; o lugar central ocupado pelos meios tecnol&oacute;gicos de produ&ccedil;&atilde;o e reprodu&ccedil;&atilde;o de informa&ccedil;&otilde;es, que abrem um espa&ccedil;o cada vez maior em nossas vidas, catalisando as emo&ccedil;&otilde;es e posicionamentos diante o mundo e mostrando seu lado mais sombrio ao colaborar com a manuten&ccedil;&atilde;o do status quo. Observamos a influ&ecirc;ncia da Ind&uacute;stria Cultural nos mais diversos &acirc;mbitos, inclusive na escola. A partir disso discutimos o papel do professor diante dos meios de comunica&ccedil;&atilde;o de massa: Her&oacute;i ou vil&atilde;o? A discuss&atilde;o parte do fato de que o professor est&aacute; inserido nessa sociedade, sentindo e pensando a partir de seus pressupostos, muitas vezes comerciais, injustos e preconceituosos. O estudo parte ent&atilde;o, na dire&ccedil;&atilde;o de uma maior valoriza&ccedil;&atilde;o da forma&ccedil;&atilde;o do professor dentro da &aacute;rea de ci&ecirc;ncias humanas, partindo de uma reflex&atilde;o sobre si mesmo e desta forma transportando-a para sua pr&aacute;tica pedag&oacute;gica

The Lyman Alpha Reference Sample: V. The impact of neutral ISM kinematics and geometry on Lyman Alpha escape

We present high-resolution far-UV spectroscopy of the 14 galaxies of the Lyman Alpha Reference Sample; a sample of strongly star-forming galaxies at low redshifts ($0.028 < z < 0.18$). We compare the derived properties to global properties derived from multi band imaging and 21 cm HI interferometry and single dish observations, as well as archival optical SDSS spectra. Besides the Lyman $\alpha$ line, the spectra contain a number of metal absorption features allowing us to probe the kinematics of the neutral ISM and evaluate the optical depth and and covering fraction of the neutral medium as a function of line-of-sight velocity. Furthermore, we show how this, in combination with precise determination of systemic velocity and good Ly$\alpha$ spectra, can be used to distinguish a model in which separate clumps together fully cover the background source, from the "picket fence" model named by Heckman et al. (2011). We find that no one single effect dominates in governing Ly$\alpha$ radiative transfer and escape. Ly$\alpha$ escape in our sample coincides with a maximum velocity-binned covering fraction of $\lesssim 0.9$ and bulk outflow velocities of $\gtrsim 50$ km s$^{-1}$, although a number of galaxies show these characteristics and yet little or no Ly$\alpha$ escape. We find that Ly$\alpha$ peak velocities, where available, are not consistent with a strong backscattered component, but rather with a simpler model of an intrinsic emission line overlaid by a blueshifted absorption profile from the outflowing wind. Finally, we find a strong anticorrelation between H$\alpha$ equivalent width and maximum velocity-binned covering factor, and propose a heuristic explanatory model.Comment: 28 pages, 19 figures, 5 table

The Lyman alpha Reference Sample: Extended Lyman alpha Halos Produced at Low Dust Content

We report on new imaging observations of the Lyman alpha emission line (Lya), performed with the Hubble Space Telescope, that comprise the backbone of the Lyman alpha Reference Sample (LARS). We present images of 14 starburst galaxies at redshifts 0.028 < z < 0.18 in continuum-subtracted Lya, Halpha, and the far ultraviolet continuum. We show that Lya is emitted on scales that systematically exceed those of the massive stellar population and recombination nebulae: as measured by the Petrosian 20 percent radius, RP20, Lya radii are larger than those of Halpha by factors ranging from 1 to 3.6, with an average of 2.4. The average ratio of Lya-to-FUV radii is 2.9. This suggests that much of the Lya light is pushed to large radii by resonance scattering. Defining the "Relative Petrosian Extension" of Lya compared to Halpha, \xi_ext = RP20_Lya / RP20_Ha, we find \xi_ext to be uncorrelated with total Lya luminosity. However \xi_ext is strongly correlated with quantities that scale with dust content, in the sense that a low dust abundance is a necessary requirement (although not the only one) in order to spread Lya photons throughout the interstellar medium and drive a large extended Lya halo.Comment: Published in ApJ Letters ~~ 6 pages using emulateapj, 4 figures ~~ Higher-resolution, larger, nicer jpeg versions of Figures 1 and 2 can be found here: http://xayes.org/pub/press_lars.htm

Limits on the LyC signal from z~3 sources with secure redshift and HST coverage in the E-CDFS field

Aim: We aim to measure the LyC signal from a sample of sources in the Chandra deep field south. We collect star-forming galaxies (SFGs) and active galactic nuclei (AGN) with accurate spectroscopic redshifts, for which Hubble Space Telescope (HST) coverage and multi-wavelength photometry are available. Method: We selected a sample of about 200 sources at z~3. Taking advantage of HST resolution, we applied a careful cleaning procedure and rejected sources showing nearby clumps with different colours, which could be lower-z interlopers. Our clean sample consisted of 86 SFGs (including 19 narrow-band selected Lya emitters) and 8 AGN (including 6 detected in X-rays). We measured the LyC flux from aperture photometry in four narrow-band filters covering wavelengths below a 912 A rest frame (3.11<z<3.53). We estimated the ratio between ionizing (LyC flux) and 1400 A non-ionizing emissions for AGN and galaxies. Results: By running population synthesis models, we assume an average intrinsic L(1400 A)/L(900 A) ratio of 5 as the representative value for our sample. With this value and an average treatment of the lines of sight of the inter-galactic medium, we estimate the LyC escape fraction relative to the intrinsic value (fesc_rel(LyC)). We do not directly detect ionizing radiation from any individual SFG, but we are able to set a 1(2)sigma upper limit of fesc_rel(LyC)<12(24)%. This result is consistent with other non-detections published in the literature. No meaningful limits can be calculated for the sub-sample of Lya emitters. We obtain one significant direct detection for an AGN at z=3.46, with fesc_rel(LyC) = (72+/-18)%. Conclusions: Our upper limit on fescrel(LyC) implies that the SFGs studied here do not present either the physical properties or the geometric conditions suitable for efficient LyC-photon escape.Comment: Accepted for publication in A&A on Jan 5th, 201