C. Díaz

Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas

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J. Casaus

Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas

J. Marín

Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas

C. Mañá

Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas

G. Laurenti

Istituto Nazionale di Fisica Nucleare, Sezione di Bologna

E. S. Seo

University of Maryland, College Park

C. Delgado Mendez

Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas

E. V. Ryan‐Weber

ARC Centre of Excellence for All-sky Astrophysics

L. Arruda

LIP - Laboratory of Instrumentation and Experimental Particle Physics

F. Barão

LIP - Laboratory of Instrumentation and Experimental Particle Physics

A. Menchaca-Rocha

Universidad Nacional Autónoma de México

Cooperative Institutions

Centre National de la Recherche Scientifique

261

National Institute for Subatomic Physics

126

Istituto Nazionale di Fisica Nucleare

118

Université Paris Cité

111

Chinese Academy of Sciences

103

Laboratoire AstroParticule et Cosmologie

Parc Científic de la Universitat de València

Aix-Marseille Université

Massachusetts Institute of Technology

Institute of High Energy Physics

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Large-scale environment of z ∼ 5.7 C iv absorption systems –II. Spectroscopy of Lyman α emitters★

Monthly Notices of the Royal Astronomical Society (2015)

C. Díaz E. V. Ryan‐Weber Jeff Cooke Yusei Koyama Masami Ouchi

The flow of baryons to and from a galaxy, which is fundamental for galaxy formation and evolution, can be studied with galaxy-metal absorption system pairs. Our search for galaxies around CIV absorption systems at $z\sim5.7$ showed an excess of photometric Lyman-$\alpha$ emitter (LAE) candidates in the fields J1030+0524 and J1137+3549. Here we present spectroscopic follow-up of 33 LAEs in both fields. In the first field, three out of the five LAEs within 10$h^{{-}1}$ projected comoving Mpc from the CIV system are within $\pm500$ km s$^{{-}1}$ from the absorption at $z_{\text{CIV}}=5.7242\pm0.0001$. The closest candidate (LAE 103027+052419) is robustly confirmed at $212.8^{+14}_{-0.4}h^{-1}$ physical kpc from the CIV system. In the second field, the LAE sample is selected at a lower redshift ($\Delta z\sim0.04$) than the CIV absorption system as a result of the filter transmission and, thus, do not trace its environment. The observed properties of LAE 103027+052419 indicate that it is near the high-mass end of the LAE distribution, probably having a large HI column density and large-scale outflows. Therefore, our results suggest that the CIV system is likely produced by a star-forming galaxy which has been injecting metals into the intergalactic medium since $z>6$. Thus, the CIV system is either produced by LAE 103027+052419, implying that outflows can enrich larger volumes at $z>6$ than at $z\sim3.5$, or an undetected dwarf galaxy. In either case, CIV systems like this one trace the ionized intergalactic medium at the end of cosmic hydrogen reionization and may trace the sources of the ionizing flux density.

10.1093/mnras/stu2738

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Citations (26)

Proton Flux PhysRevLett.114.171103

M. Aguilar D. Aisa B. Alpat A. Alvino G. Ambrosi

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Properties of Daily Helium Fluxes

Physical Review Letters (2022)

M. Aguilar L. Ali Cavasonza G. Ambrosi L. Arruda N. Attig

We present the precision measurement of 2824 daily helium fluxes in cosmic rays from May 20, 2011 to October 29, 2019 in the rigidity interval from 1.71 to 100 GV based on 7.6×10^{8} helium nuclei collected with the Alpha Magnetic Spectrometer (AMS) aboard the International Space Station. The helium flux and the helium to proton flux ratio exhibit variations on multiple timescales. In nearly all the time intervals from 2014 to 2018, we observed recurrent helium flux variations with a period of 27 days. Shorter periods of 9 days and 13.5 days are observed in 2016. The strength of all three periodicities changes with time and rigidity. In the entire time period, we found that below ∼7 GV the helium flux exhibits larger time variations than the proton flux, and above ∼7 GV the helium to proton flux ratio is time independent. Remarkably, below 2.4 GV a hysteresis between the helium to proton flux ratio and the helium flux was observed at greater than the 7σ level. This shows that at low rigidity the modulation of the helium to proton flux ratio is different before and after the solar maximum in 2014.

Rigidity (electromagnetism)

Isotopes of helium

10.1103/physrevlett.128.231102

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Citations (30)

Renormalized perturbation theory by the moment method for degenerate states: Anharmonic oscillators

International Journal of Quantum Chemistry (1998)

Marcelo D. Radicioni C. Díaz Francisco M. Ferńndez

We apply renormalized perturbation theory by the moment method to an anharmonic oscillator in two dimensions with a perturbation that couples unperturbed degenerate states. The method leads to simple recurrence relations for the perturbation corrections to the energy and moments of the eigenfunction. We calculate accurate energy eigenvalues, illustrate the general features of the method, and comment on the application of the approach to other quantum mechanical models. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 66: 261–272, 1998

Eigenfunction

Poincaré–Lindstedt method

Hamiltonian (control theory)

Transition of state

10.1002/(sici)1097-461x(1998)66:4<261::aid-qua1>3.0.co;2-t

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Citations (6)

Perturbation treatment of local-mode stretching vibrations

Journal of Molecular Structure THEOCHEM (2001)

C. Díaz Francisco M. Fernández

Morse potential

10.1016/s0166-1280(00)00738-7

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Citations (5)

La utilización de sistemas gráficos en arqueología

Comunicación y Pedagogía: nuevas tecnologías y recursos didácticos (1996)

C. Díaz

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Lyman continuum galaxies: Observed Lyman continuum flux measurements at z ~ 3-4 and mechanisms behind the escape

AAS (2016)

Jeff Cooke E. V. Ryan‐Weber Thibault Garel C. Díaz

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The faint host galaxies of C IV absorbers at z > 5

Monthly Notices of the Royal Astronomical Society (2020)

Kristian Finlator Caitlin Doughty Zheng Cai C. Díaz

We explore the expected galaxy environments of CIV absorbers at z>5 using the Technicolor Dawn simulations. These simulations reproduce the observed history of reionization, the z~6 galaxy stellar mass function, the Ly$\alpha$ forest transmission at z>5, and the SiIV column density distribution (CDD) at z~5.5. Nonetheless, the CIV CDD remains underproduced. Comparison with observed CII/SiII equivalent width ratios and the CII line incidence suggests that a low carbon yield accounts for some, but not all, of the CIV discrepancy. Alternatively, a density-bounded escape scenario could harden the metagalactic ionizing background more dramatically even than binary stellar evolution, boosting the CIV CDD into near-agreement with observations. In this case galaxies ionize more efficiently and fewer are required to host a given high-ionization absorber. Absorbers' environments therefore constrain ionizing escape. Regardless of the escape scenario, galaxies correlate with CIV absorbers out to 300 proper kpc (pkpc). The correlation strengthens independently with galaxy luminosity and CIV column density. Around strong systems (log(N$_{\rm CIV}$/cm$^{-2}$)>14)), the overdensity of galaxies with M$_{\rm UV}$<-18 or log($L_{{\rm Ly}\alpha}$/erg s$^{-1}$) > 41.9 declines from 200-300 within 100 pkpc to 40-60 within 250 pkpc. The previously-suggested association between strong CIV absorbers and Ly$\alpha$ emitters at z>5 is not expected. It may arise if both populations inhabit large-scale voids, but for different reasons. Although most neighboring galaxies are too faint for HST, JWST will, with a single pointing, identify ~10 neighboring galaxies per strong CIV absorber at z > 5. Ground-based tests of these predictions are possible via deep surveys for Ly$\alpha$ emission using integral field units.

10.1093/mnras/staa377

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Citations (19)

Collisional activation of asteroids in cometary orbits

Astronomy and Astrophysics (2008)

C. Díaz R. Gil-Hutton

Aims. We study the time an asteroid in a cometary orbit must wait to receive a collision producing a crater depth enough to expose subsurface volatiles, aiming to analyze the possibility of collisional reactivation of these objects if they are dormant comets.

Orbit (dynamics)

10.1051/0004-6361:20079236

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Citations (4)

Spectroscopic observations of the machine-learning selected anomaly catalogue from the AllWISE Sky Survey

Astronomy and Astrophysics (2020)

A. Solarz R. Thomas F. M. Montenegro‐Montes M. Gromadzki E. Donoso

We present the results of a programme to search and identify the nature of unusual sources within the All-sky Wide-field Infrared Survey Explorer (WISE) that is based on a machine-learning algorithm for anomaly detection, namely one-class support vector machines (OCSVM). Designed to detect sources deviating from a training set composed of known classes, this algorithm was used to create a model for the expected data based on WISE objects with spectroscopic identifications in the Sloan Digital Sky Survey (SDSS). Subsequently, it marked as anomalous those sources whose WISE photometry was shown to be inconsistent with this model. We report the results from optical and near-infrared spectroscopy follow-up observations of a subset of 36 bright ($g_{AB}$<19.5) objects marked as 'anomalous' by the OCSVM code to verify its performance. Among the observed objects, we identified three main types of sources: i) low redshift (z~0.03-0.15) galaxies containing large amounts of hot dust (53%), including three Wolf-Rayet galaxies; ii) broad-line quasi-stellar objects (QSOs) (33%) including low-ionisation broad absorption line (LoBAL) quasars and a rare QSO with strong and narrow ultraviolet iron emission; iii) Galactic objects in dusty phases of their evolution (3%). The nature of four of these objects (11%) remains undetermined due to low signal-to-noise or featureless spectra. The current data show that the algorithm works well at detecting rare but not necessarily unknown objects among the brightest candidates. They mostly represent peculiar sub-types of otherwise well-known sources.

QSOS

10.1051/0004-6361/202038439

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Citations (2)