Searching for Faraday rotation in cosmic microwave background polarization

We use the Wilkinson Microwave Anisotropy Probe (WMAP) 9th-year foreground reduced data at 33, 41 and 61 GHz to derive a Faraday rotation at map and at angular power spectrum levels taking into account their observational errors. A processing mask provided by WMAP is used to avoid contamination from the disc of our Galaxy and local spurs. We have found a Faraday rotation component at both, map and power spectrum levels. The lack of correlation of the Faraday rotation with Galactic Faraday rotation, synchrotron and dust polarization from our Galaxy or with cosmic microwave background anisotropies or lensing suggests that it could be originated at reionization (ℓ ≲ 12). Even if the detected Faraday rotation signal is weak, the present study could contribute to establish magnetic fields strengths of B ~ 10 G at reionization.This work was partially supported by projects CSD2010-00064 and AYA2011-24728 of the Spanish Ministry of Economy and Competitiveness (MINECO) and by Junta de Andalucía Grant FQM-108.Peer Reviewe

Sociology and hierarchy of voids: A study of seven nearby CAVITY galaxy voids and their dynamical CosmicFlows-3 environment

The present study addresses a key question related to our understanding of the relation between void galaxies and their environment: the relationship between luminous and dark matter in and around voids. Aims. To explore the extent to which local Universe voids are empty of matter, we study the full (dark+luminous) matter content of seven nearby cosmic voids that are fully contained within the CosmicFlows-3 volume. Methods. We obtained the matter-density profiles of seven cosmic voids using two independent methods. These were built from the galaxy redshift space two-point correlation function in conjunction with peculiar velocity gradients from the CosmicFlows-3 dataset. Results. The results are striking, because when the redshift survey is used, all voids show a radial positive gradient of galaxies, while based on the dynamical analysis, only three of these voids display a clear underdensity of matter in their center. Conclusions. This work constitutes the most detailed observational analysis of voids conducted so far, and shows that void emptiness should be derived from dynamical information. From this limited study, the Hercules void appears to be the best candidate for a local Universe pure “pristine volume”, expanding in three directions with no dark matter located in that void.Institut Universitaire de FranceCentre National D'etudes SpatialesInstituto de Salud Carlos III Spanish GovernmentEuropean Commission PID2020-224414GB-I00 PID2020-113689GB-I00Spanish Ministerio de Ciencia e Innovacion (MCIN)Agencia Estatal de Investigacion (AEI)European Social Fund (ESF) 20215AT016 CEX2020-001058-MCentro Superior de Investigaciones Cientificas (CSIC) under the PIE project KR4598/2-1German Research Foundation (DFG) PID2019-105602GBI00Junta de AndaluciaSpanish Government FQM108MCIN/AEIEuropean Union NextGenerationEUAgencia Estatal de Investigacion Espanola (AEI)Center for Forestry Research & Experimentation (CIEF) CEX2021-001131-SEuropean Union-Next Generation EU FundsState Research Agency (AEI-MCINN) of the Spanish Ministry of Science and Innovation under the grant "The structure and evolution of galaxies and their central regions" - Ministry of Universitie

Towards a new classification of galaxies: principal component analysis of CALIFA circular velocity curves

We present a galaxy classification system for 238 (E1-Sdm) CALIFA (Calar Alto Legacy Integral Field Area) galaxies based on the shapes and amplitudes of their circular velocity curves (CVCs). We infer the CVCs from the de-projected surface brightness of the galaxies, after scaling by a constant mass-to-light ratio based on stellar dynamics - solving axisymmetric Jeans equations via fitting the second velocity moment $V_{\mathrm{rms}}=\sqrt{V^2+\sigma^2}$ of the stellar kinematics. We use principal component analysis (PCA) applied to the CVC shapes to find characteristic features and use a $k$-means classifier to separate circular curves into classes. This objective classification method identifies four different classes, which we name slow-rising (SR), flat (FL), round-peaked (RP) and sharp-peaked (SP) circular curves. SR are typical for low-mass, late-type (Sb-Sdm), young, faint, metal-poor and disc-dominated galaxies. SP are typical for high-mass, early-type (E1-E7), old, bright, metal-rich and bulge-dominated galaxies. FL and RP appear presented by galaxies with intermediate mass, age, luminosity, metallicity, bulge-to-disk ratio and morphologies (E4-S0a, Sa-Sbc). The discrepancy mass factor, $f_d=1-M_{*}/M_{dyn}$, have the largest value for SR and SP classes ($\sim$ 74 per cent and $\sim$ 71 per cent, respectively) in contrast to the FL and RP classes (with $\sim$ 59 per cent and $\sim$ 61 per cent, respectively). Circular curve classification presents an alternative to typical morphological classification and appears more tightly linked to galaxy evolution.Comment: Accepted for publication in MNRAS (Minor changes), 123 pages, 19 figures, 87 Tables (containing the basic properties of the 238 E1-Sdm galaxies; the five main Principal Component Eigenvectors; the five main Principal Components - PC_i; the Multi-Gaussian Expansion models - MGEs; the circular velocity curve models and their uncertainties

No direct coupling between bending of galaxy disc stellar age and light profiles as seen from CALIFA

Recent theoretical and observational works claim the existence of galaxies with a characteristic age profile consisting on a negative radial trend followed by a smooth age upturn in its outskirts (``U-shape''). This shape has been generally related to down-bending light distributions; however, the existence of a real link between observed Surface Brightness (SB) profiles and changes in stellar properties such as age is still unclear

The Mice at play in the CALIFA survey: A case study of a gas-rich major merger between first passage and coalescence

We present optical integral field spectroscopy (IFS) observations of the Mice, a major merger between two massive (>10^11Msol) gas-rich spirals NGC4676A and B, observed between first passage and final coalescence. The spectra provide stellar and gas kinematics, ionised gas properties and stellar population diagnostics, over the full optical extent of both galaxies. The Mice provide a perfect case study highlighting the importance of IFS data for improving our understanding of local galaxies. The impact of first passage on the kinematics of the stars and gas has been significant, with strong bars likely induced in both galaxies. The barred spiral NGC4676B exhibits a strong twist in both its stellar and ionised gas disk. On the other hand, the impact of the merger on the stellar populations has been minimal thus far: star formation induced by the recent close passage has not contributed significantly to the global star formation rate or stellar mass of the galaxies. Both galaxies show bicones of high ionisation gas extending along their minor axes. In NGC4676A the high gas velocity dispersion and Seyfert-like line ratios at large scaleheight indicate a powerful outflow. Fast shocks extend to ~6.6kpc above the disk plane. The measured ram pressure and mass outflow rate (~8-20Msol/yr) are similar to superwinds from local ULIRGs, although NGC4676A has only a moderate infrared luminosity of 3x10^10Lsol. Energy beyond that provided by the mechanical energy of the starburst appears to be required to drive the outflow. We compare the observations to mock kinematic and stellar population maps from a merger simulation. The models show little enhancement in star formation during and following first passage, in agreement with the observations. We highlight areas where IFS data could help further constrain the models.Comment: 23 pages, 13 figures, accepted to A&A. A version with a complete set of high resolution figures is available here: http://www-star.st-and.ac.uk/~vw8/resources/mice_v8_astroph.pd

Influencia de los campos magnéticos en la morfología de las galaxias espirales

Ejemp. xerocopiadoUniversidad de Granad

New calibrations for estimating the N/O ratio in H II regions

We thank the anonymous referee for his/her constructive report that improved the clarity of the manuscript. This work is supported by the Spanish 'Ministerio de Ciencia e Innovacion' and from the European Regional Development Fund (FEDER) via grants PID2020114414GB-I00 and PID2020-113689GB-I00, and from the 'Junta de Andalucia' (Spain) local government through the FQM108 and AFQM-510-UGR20 projects. EPM acknowledges financial support from the State Agency for Research of the Spanish 'Ministerio de Ciencia, Innovacon y Universidades' through the 'Center of Excellence Severo Ochoa' award to the Instituto de Astrofisica de Andalucia (SEV-2017-0709) and to projects 'Estallidos7' PID2019107408GB-C44 (Spanish 'Ministerio de Ciencia e Innovacion'), and from the 'Junta de Andalucia' Excellence project EXC/2011 FQM7058, and also the assistance from his guide dog Rocko without whose daily help this work would have been much more difficult.We use a sample of 536 H II regions located in nearby spirals, with a homogeneous determination of their T e -based abundances, to obtain new empirical calibrations of the N2O2, N2S2, O3N2, and N2 strong-line indices to estimate the nitrogen-to-oxygen abundance ratio when auroral lines are not detected. All indices are strongly correlated with the T e -based log (N/O) for our H II re gion sample, ev en more strongly than with 12 + log (O/H). N2O2 is the most strongly correlated index, and the best fit to the log (N/O)–N2O2 relation is obtained with a second-order polynomial. The derived relation has a low dispersion (rms < 0.09 dex), being valid in the range −1.74 < N2O2 < 0.62 (or −1.81 < log (N/O) < −0.13). We have compared our calibration with previous ones and have discussed the differences between them in terms of the nature of the objects used as calibrators.Instituto de Salud Carlos III Spanish Government European Commission PID2020114414GB-I00 PID2020-113689GB-I00'Junta de Andalucia' (Spain) local government FQM108 AFQM-510-UGR20State Agency for Research of the Spanish 'Ministerio de Ciencia, Innovacon y Universidades' through the 'Center of Excellence Severo Ochoa' SEV-2017-0709 PID2019107408GB-C44Junta de Andalucia EXC/2011 FQM705