Radiation Hydrodynamics of Turbulent H ii Regions in Molecular Clouds: A Physical Origin of LyC Leakage and the Associated Lyα Spectra

We examine Lyman continuum (LyC) leakage through H ii regions regulated by turbulence and radiative feedback in a giant molecular cloud in the context of fully coupled radiation hydrodynamics (RHD). The physical relations of the LyC escape with H i covering fraction, kinematics, ionizing photon production efficiency, and emergent Lyα line profiles are studied using a series of RHD turbulence simulations performed with ramses-rt. The turbulence-regulated mechanism allows ionizing photons to leak out at early times before the onset of supernova feedback. The LyC photons escape through turbulence-generated low column density channels that are evacuated efficiently by radiative feedback via photoheating-induced shocks across the D-type ionization fronts. The Lyα photons funnel through the photoionized channels along the paths of LyC escape, resulting in a diverse Lyα spectral morphology including narrow double-peaked profiles. The Lyα peak separation is controlled by the residual H i column density of the channels, and the line asymmetry correlates with the porosity and multiphase structure of the H ii region. This mechanism through the turbulent H ii regions can naturally reproduce the observed Lyα spectral characteristics of some of the LyC-leaking galaxies. This RHD turbulence origin provides an appealing hypothesis to explain high LyC leakage from very young (∼3 Myr) star-forming galaxies found in the local universe without need of extreme galactic outflows or supernova feedback. We discuss the implications of the turbulent H ii regions on other nebular emission lines and a possible observational test with the Magellanic System and local blue compact dwarf galaxies as analogs of reionization-era systems

Three Lyα Emitting Galaxies within a Quasar Proximity Zone at z ~ 5.8

Quasar proximity zones at z > 5.5 correspond to overdense and overionized environments. Galaxies found inside proximity zones can therefore display features that would otherwise be masked by absorption in the intergalactic medium. We demonstrate the utility of this quasar-galaxy synergy by reporting the discovery of the first three “proximate Lyα emitters” (LAEs) within the proximity zone of quasar J0836+0054 at z = 5.795 (Aerith A, B, and C). Aerith A, located behind the quasar with an impact parameter D^{\perp} = 278 \pm 8 pkpc, provides the first detection of an Lyα transverse proximity effect. We model the transmission and show that it constrains the onset of J0836ʼs quasar phase to 0.2Myr < 28Myr < t in the past. The second object, Aerith B at a distance D < 912 pkpc from the quasar, displays a bright and broad double-peaked Lyα emission line. The peak separation implies a low ionizing f_{esc} \leqslant 1%. We fit the Lyα line with an outflowing shell model, finding a typical central density log N_{HI}/cm^{-2} = 19.3_{-0.2}^{+0.8}, outflow velocity v_{out} = 16_{-11}^{+4}km s^{-1}, and gas temperature log T/K = 3.8_{-0.7}^{+0.8} compared to 2 < z < 3 analog LAEs. We detect object Aerith C via an Lyα emission line at z = 5.726. This corresponds with the edge of the quasar’s proximity zone (Dz < 0.02), suggesting that the proximity zone is truncated by a density fluctuation. Via the analyses conducted here, we illustrate how proximate LAEs offer unique insight into the ionizing properties of both quasars and galaxies during hydrogen reionization

Cosmic Galaxy-IGM HI Relation at z∼2−3{\it{z}}\sim 2-3 Probed in the COSMOS/UltraVISTA 1.61.6 deg2^2 Field

We present spatial correlations of galaxies and IGM HI in the COSMOS/UltraVISTA 1.62 deg$^2$ field. Our data consist of 13,415 photo-$z$ galaxies at $z\sim2-3$ with $K_s<23.4$ and the Ly$\alpha$ forest absorptions in the background quasar spectra selected from SDSS data with no signature of damped Ly$\alpha$ system contamination. We estimate a galaxy overdensity $\delta_{gal}$ in an impact parameter of 2.5 pMpc, and calculate the Ly$\alpha$ forest fluctuations $\delta_{\langle F\rangle}$ whose negative values correspond to the strong Ly$\alpha$ forest absorptions. We identify weak evidence of an anti-correlation between $\delta_{gal}$ and $\delta_{\langle F\rangle}$ with a Spearman's rank correlation coefficient of $-0.39$ suggesting that the galaxy overdensities and the Ly$\alpha$ forest absorptions positively correlate in space at the $\sim90\%$ confidence level. This positive correlation indicates that high-$z$ galaxies exist around an excess of HI gas in the Ly$\alpha$ forest. We find four cosmic volumes, dubbed $A_{obs}$-$D_{obs}$, that have extremely large (small) values of $\delta_{gal} \simeq0.8$ ($-1$) and $\delta_{\langle F\rangle}$ $\simeq0.1$ ($-0.4$), three out of which, $B_{obs}$-$D_{obs}$, significantly depart from the correlation, and weaken the correlation signal. We perform cosmological hydrodynamical simulations, and compare with our observational results. Our simulations reproduce the correlation, agreeing with the observational results. Moreover, our simulations have model counterparts of $A_{obs}$-$D_{obs}$, and suggest that the observations pinpoint, by chance, a galaxy overdensity like a proto-cluster, gas filaments lying on the sightline, a large void, and orthogonal low-density filaments. Our simulations indicate that the significant departures of $B_{obs}$-$D_{obs}$ are produced by the filamentary large-scale structures and the observation sightline effects.Comment: 14 pages, 12 figures. Accepted for publication in Ap

The role of galaxies and AGNs in reionizing the IGM – II. Metal-tracing the faint sources of reionization at 5 ≲ z ≲ 6

We present a new method to study the contribution of faint sources to the ultraviolet background using the 1D correlation of metal absorbers with the intergalactic medium transmission in a quasi-stellar object (QSO) sightline. We take advantage of a sample of 25 high signal-to-noise ratio QSO spectra to retrieve 150 triply-ionized carbon (C IV) absorbers at 4.5 ≲ z ≲ 6.2, of which 37 systems whose expected H I absorption lie in the Lyman-α forest. We derive improved constraints on the cosmic density of C IV at 4.3 < z < 6.2 and infer from abundance matching that C IV absorbers trace MUV ≲ −16 galaxies. Correlation with the Lyman-α forest of the QSOs indicates that these objects are surrounded by a highly opaque region at r ≲ 5 cMpc h−1 followed by an excess of transmission at r ≳ 10 cMpc h−1 detected at 2.7σ. This is in contrast to equivalent measurements at lower redshifts where only the opaque trough is detected. We interpret this excess as a statistical enhancement of the local photoionization rate due to clustered faint galaxies around the C IV absorbers. Using the analytical framework described in Paper I of this series, we derive a constraint on the average product of the escape fraction and the Lyman continuum photon production efficiency of the galaxy population clustered around the C IV absorbers, log⟨fescξion⟩/[erg−1Hz]=25.01+0.30−0.19⁠. This implies that faint galaxies beyond the reach of current facilities may have harder radiation fields and/or larger escape fractions than currently detected objects at the end of the reionization epoch

The role of galaxies and AGN in reionising the IGM -- III : IGM-galaxy cross-correlations at z~6 from 8 quasar fields with DEIMOS and MUSE

We present improved results of the measurement of the correlation between galaxies and the intergalactic medium transmission at the end of reionization. We have gathered a sample of 13 spectroscopically confirmed Lyman-break galaxies (LBGs) and 21 Lyman-α emitters (LAEs) at angular separations 20 arcsec ≲ θ ≲ 10 arcmin (∼0.1–4 pMpc at z ∼ 6) from the sightlines to eight background z ≳ 6 quasars. We report for the first time the detection of an excess of Lyman-α transmission spikes at ∼10–60 cMpc from LAEs (3.2σ) and LBGs (1.9σ). We interpret the data with an improved model of the galaxy–Lyman-α transmission and two-point cross-correlations, which includes the enhanced photoionization due to clustered faint sources, enhanced gas densities around the central bright objects and spatial variations of the mean free path. The observed LAE(LBG)–Lyman-α transmission spike two-point cross-correlation function (2PCCF) constrains the luminosity-averaged escape fraction of all galaxies contributing to reionization to ⟨fesc⟩MUV−20(2σ)⁠) is necessary to reproduce the observed 2PCCF and that reionization might be driven by different sub-populations around LBGs and LAEs at z ∼ 6

Recovering the H II region size statistics from 21-cm tomography

We introduce a novel technique, called ‘granulometry’, to characterize and recover the mean size and the size distribution of H II regions from 21-cm tomography. The technique is easy to implement, but places the previously not very well-defined concept of morphology on a firm mathematical foundation. The size distribution of the cold spots in 21-cm tomography can be used as a direct tracer of the underlying probability distribution of H II region sizes. We explore the capability of the method using large-scale reionization simulations and mock observational data cubes while considering capabilities of Square Kilometre Array 1 (SKA1) low and a future extension to SKA2. We show that the technique allows the recovery of the H II region size distribution with a moderate signal-to-noise ratio from wide-field imaging (SNR 3), for which the statistical uncertainty is sample variance dominated. We address the observational requirements on the angular resolution, the field of view, and the thermal noise limit for a successful measurement. To achieve a full scientific return from 21-cm tomography and to exploit a synergy with 21-cm power spectra, we suggest an observing strategy using wide- field imaging (several tens of square degrees) by an interferometric mosaicking/multibeam observation with additional intermediate baselines (∼2−4 km) in an SKA phase 2

Photometric IGM tomography with Subaru/HSC: the large-scale structure of Lyα emitters and IGM transmission in the COSMOS field at z ∼ 5

We present a novel technique called “photometric IGM tomography” to map the intergalactic medium (IGM) at z ≃ 4.9 in the COSMOS field. It utilizes deep narrow-band (NB) imaging to photometrically detect faint Lyα forest transmission in background galaxies across the Subaru/Hyper-Suprime Cam (HSC)’s 1.8sq.deg field of view and locate Lyα emitters (LAEs) in the same cosmic volume. Using ultra-deep HSC images and Bayesian spectral energy distribution fitting, we measure the Lyα forest transmission at z ≃ 4.9 along a large number (140) of background galaxies selected from the DEIMOS10k spectroscopic catalogue at 4.98 < z < 5.89 and the SILVERRUSH LAEs at z ≃ 5.7. We photometrically measure the mean Lyα forest transmission and achieve a result consistent with previous measurements based on quasar spectra. We also measure the angular LAE-Lyα forest cross-correlation and Lyα forest auto-correlation functions and place an observational constraint on the large-scale fluctuations of the IGM around LAEs at z ≃ 4.9. Finally, we present the reconstructed 2D tomographic map of the IGM, co-spatial with the large-scale structure of LAEs, at a transverse resolution of 11h−1cMpc across 140h−1cMpc in the COSMOS field at z ≃ 4.9. We discuss the observational requirements and the potential applications of this new technique for understanding the sources of reionization, quasar radiative history, and galaxy-IGM correlations across z ∼ 3 − 6. Our results represent the first proof-of-concept of photometric IGM tomography, offering a new route to examining early galaxy evolution in the context of the large-scale cosmic web from the epoch of reionization to cosmic noon

Cosmic Galaxy-IGM HI Relation at z similar to 2-3 Probed in the COSMOS/UltraVISTA 1.6 Deg(2) Field

We present spatial correlations of galaxies and IGM neutral hydrogen H i in the COSMOS/UltraVISTA 1.62 deg2 field. Our data consist of 13,415 photo-z galaxies at z ~ 2–3 with ${K}_{s}\lt 23.4$ and the Lyα forest absorption lines in the background quasar spectra selected from SDSS data with no signature of damped Lyα system contamination. We estimate a galaxy overdensity δ gal in an impact parameter of 2.5 (proper) Mpc, and calculate the Lyα forest fluctuations ${\delta }_{\langle F\rangle }$ whose negative values correspond to the strong Lyα forest absorption lines. We identify weak evidence of an anti-correlation between δ gal and ${\delta }_{\langle F\rangle }$ with a Spearman's rank correlation coefficient of −0.39 suggesting that the galaxy overdensities and the Lyα forest absorption lines positively correlate in space at the ~90% confidence level. This positive correlation indicates that high-z galaxies exist around an excess of H i gas in the Lyα forest. We find four cosmic volumes, dubbed A obs, B obs, C obs, and D obs, that have extremely large (small) values of δ gal sime 0.8 (−1) and ${\delta }_{\langle F\rangle }\simeq 0.1(-0.4)$, three of which, B obs–D obs, significantly depart from the δ gal–${\delta }_{\langle F\rangle }$ correlation, and weaken the correlation signal. We perform cosmological hydrodynamical simulations and compare with our observational results. Our simulations reproduce the δ gal–${\delta }_{\langle F\rangle }$ correlation, agreeing with the observational results. Moreover, our simulations have model counterparts of A obs–D obs, and suggest that the observations pinpoint, by chance, a galaxy overdensity like a proto-cluster, gas filaments lying on the quasar sightline, a large void, and orthogonal low-density filaments. Our simulations indicate that the significant departures of B obs–D obs are produced by the filamentary large-scale structures and the observation sightline effects

Cosmic Galaxy-IGM HI Relation at z similar to 2-3 Probed in the COSMOS/UltraVISTA 1.6 Deg(2) Field

We present spatial correlations of galaxies and IGM neutral hydrogen H i in the COSMOS/UltraVISTA 1.62 deg2 field. Our data consist of 13,415 photo-z galaxies at z ~ 2–3 with ${K}_{s}\lt 23.4$ and the Lyα forest absorption lines in the background quasar spectra selected from SDSS data with no signature of damped Lyα system contamination. We estimate a galaxy overdensity δ gal in an impact parameter of 2.5 (proper) Mpc, and calculate the Lyα forest fluctuations ${\delta }_{\langle F\rangle }$ whose negative values correspond to the strong Lyα forest absorption lines. We identify weak evidence of an anti-correlation between δ gal and ${\delta }_{\langle F\rangle }$ with a Spearman's rank correlation coefficient of −0.39 suggesting that the galaxy overdensities and the Lyα forest absorption lines positively correlate in space at the ~90% confidence level. This positive correlation indicates that high-z galaxies exist around an excess of H i gas in the Lyα forest. We find four cosmic volumes, dubbed A obs, B obs, C obs, and D obs, that have extremely large (small) values of δ gal sime 0.8 (−1) and ${\delta }_{\langle F\rangle }\simeq 0.1(-0.4)$, three of which, B obs–D obs, significantly depart from the δ gal–${\delta }_{\langle F\rangle }$ correlation, and weaken the correlation signal. We perform cosmological hydrodynamical simulations and compare with our observational results. Our simulations reproduce the δ gal–${\delta }_{\langle F\rangle }$ correlation, agreeing with the observational results. Moreover, our simulations have model counterparts of A obs–D obs, and suggest that the observations pinpoint, by chance, a galaxy overdensity like a proto-cluster, gas filaments lying on the quasar sightline, a large void, and orthogonal low-density filaments. Our simulations indicate that the significant departures of B obs–D obs are produced by the filamentary large-scale structures and the observation sightline effects

Calidad de servicio y su relación con la satisfacción del cliente en la empresa comercial y eventos Dibu E.I.R.L Juliaca, durante el año 2019

El objetivo de la presente investigación es determinar la calidad del servicio y su relación con la satisfacción del cliente de Comercial y eventos Dibu E.I.R.L Juliaca durante el año 2019, el tipo de investigación es descriptiva correlacional, de diseño no experimental de corte transversal. La muestra estuvo conformada por los clientes de la empresa, habiendo un total de 118 personas de manera aleatoria, la técnica que se utilizó fue la encuesta, a través de un cuestionario de 28 ítems correspondientes a las dimensiones de las variables, cuyas respuestas se midieron con la escala Likert de cinco alternativas. El procesamiento y generación de las tablas y figuras de los datos recolectados en este trabajo de investigación, fueron obtenidos con el programa SPSS. Los resultados de la investigación demuestran una correlación de Pearson R= 0.572 la cual nos indica que las variables calidad de servicio y satisfacción del cliente hay una correlación positiva moderada. Por lo que se concluye que los colaboradores de la empresa dan a sus clientes tangibilidad, fiabilidad y sobre todo la capacidad de respuesta eficiente logrando así una satisfacción grata en el cliente.Trabajo de investigaciónJULIACAEscuela Profesional de AdministraciónMarketin