arXiv subjects

A. Castillo-Morales

Publications and source records attributed to A. Castillo-Morales.

33 records · Page 2Linked to original sources

arXiv2011

CALIFA, the Calar Alto Legacy Integral Field Area survey: I. Survey presentation

We present here the Calar Alto Legacy Integral Field Area (CALIFA) survey, which has been designed to provide a first step in this direction.We summarize the survey goals and design, including sample selection and observational strategy.We also showcase the data taken during the first observing runs (June/July 2010) and outline the reduction pipeline, quality control schemes and general characteristics of the reduced data. This survey is obtaining spatially resolved spectroscopic information of a diameter selected sample of $\sim600$ galaxies in the Local Universe (0.005< z <0.03). CALIFA has been designed to allow the building of two-dimensional maps of the following quantities: (a) stellar populations: ages and metallicities; (b) ionized gas: distribution, excitation mechanism and chemical abundances; and (c) kinematic properties: both from stellar and ionized gas components. CALIFA uses the PPAK Integral Field Unit (IFU), with a hexagonal field-of-view of $\sim1.3\sq\arcmin'$, with a 100% covering factor by adopting a three-pointing dithering scheme. The optical wavelength range is covered from 3700 to 7000 Å, using two overlapping setups (V500 and V1200), with different resolutions: R\sim850 and R\sim1650, respectively. CALIFA is a legacy survey, intended for the community. The reduced data will be released, once the quality has been guaranteed. The analyzed data fulfill the expectations of the original observing proposal, on the basis of a set of quality checks and exploratory analysis. We conclude from this first look at the data that CALIFA will be an important resource for archaeological studies of galaxies in the Local Universe.

astro-ph.CO↗

arXiv2011

3D Spectroscopy of Local Luminous Compact Blue Galaxies: Kinematic Maps of a Sample of 22 Objects

We use three dimensional optical spectroscopy observations of a sample of 22 local Luminous Compact Blue Galaxies (LCBGs) to create kinematic maps. By means of these, we classify the kinematics of these galaxies into three different classes: rotating disk (RD), perturbed rotation (PR), and complex kinematics (CK). We find 48% are RDs, 28% are PRs, and 24% are CKs. RDs show rotational velocities that range between $\sim50$ and $\sim200 km s^{-1}$, and dynamical masses that range between $\sim1\times10^{9}$ and $\sim3\times10^{10} M_{\odot}$. We also address the following two fundamental questions through the study of the kinematic maps: \emph{(i) What processes are triggering the current starbust in LCBGs?} We search our maps of the galaxy velocity fields for signatures of recent interactions and close companions that may be responsible for the enhanced star formation in our sample. We find 5% of objects show evidence of a recent major merger, 10% of a minor merger, and 45% of a companion. This argues in favor of ongoing interactions with close companions as a mechanism for the enhanced star formation activity in these galaxies. \emph{(ii) What processes may eventually quench the current starbust in LCBGs?} Velocity and velocity width maps, together with emission line ratio maps, can reveal signatures of Active Galactic Nuclei (AGN) activity or supernova (SN) driven galactic winds that could halt the current burst. We find only 5% of objects with clear evidence of AGN activity, and 27% with kinematics consistent with SN-driven galactic winds. Therefore, a different mechanism may be responsible for quenching the star formation in LCBGs. Finally, from our analysis, we find that the velocity widths of RDs, rather than accounting exclusively for the rotational nature of these objects, may account as well for other kinematic components, and may not be good tracers of their dynamical masses.

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arXiv2010

Integral Field Spectroscopy of Local LCBGs: NGC 7673, a case study. Physical properties of star-forming regions

Physical properties of the star-forming regions in the local Luminous Compact Blue Galaxy NGC 7673 are studied in detail using 3D spectroscopic data taken with the PPAK IFU at the 3.5-m telescope in CAHA. We derive integrated and spatially resolved properties such as extinction, star formation rate and metallicity for this galaxy. Our data show an extinction map with maximum values located at the position of the main clumps of star formation showing small spatial variations (E(B-V)_{t}=0.12-0.21 mag). We derive a Hα-based SFR for this galaxy of 6.2 \pm 0.8 M_{\odot}/yr in agreement with the SFR derived from infrared and radio continuum fluxes. The star formation is located mainly in clumps A, B, C and F. Different properties measured in clump B makes this region peculiar. We find the highest Hαluminosity with a SFR surface density of 0.5 M_{\odot}yr^{-1}kpc^{-2} in this clump. In our previous work, the kinematic analysis for this galaxy shows an asymmetrical ionized gas velocity field with a kinematic decoupled component located at the position of clump B. This region shows the absence of strong absorption features and the presence of a Wolf-Rayet stellar population indicating this is a young burst of massive stars. Furthermore, we estimate a gas metallicity of 12+log(O/H)=8.20\pm0.15 for the integrated galaxy using the R23 index. The values derived for the different clumps with this method show small metallicity variations in this galaxy, with values in the range 8.12 (for clump A) - 8.23 (for clump B) for 12+log(O/H). The analysis of the emission line ratios discards the presence of any AGN activity or shocks as the ionization source in this galaxy. Between the possible mechanisms to explain the starburst activity in this galaxy, our 3D spectroscopic data support the scenario of an on-going interaction with the possibility for clump B to be the dwarf satellite galaxy.

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arXiv2010

Blasts and shocks in the disc of NGC 4258

We present integral field spectroscopic observations of the central region of the active galaxy NGC 4258 obtained with the fibre IFU system INTEGRAL. We have been able to detect cold neutral gas by means of the interstellar NaD doublet absorption and to trace its distribution and kinematics with respect to the underlying disc. The neutral gas is blue-shifted with projected velocities in the 120--370 km/s range. We have also detected peculiar kinematics in part of the ionized gas in this region by means of a careful kinematic decomposition. The bipolar spatial distribution of the broader component is roughly coincident with the morphology of the X-ray diffuse emission. The kinematics of this gas can be explained in terms of expansion at very high (projected) velocities of up to 300 km/s. The observations also reveal the existence of a strip of neutral gas, parallel to the major kinematic axis, that is nearly coincident with a region of very high [SII]/H$α$ ratio tracing the shocked gas. Our observations are consistent with the jet model presented by \cite{wilsonetal01} in which a cocoon originating from the nuclear jet is shocking the gas in the galaxy disc. Alternatively, our observations are also consistent with the bipolar hypershell model of \cite{Sofue80} and \cite{SofueandVogler01}. On balance, we prefer the latter model as the most likely explanation for the puzzling features of this peculiar object.

astro-ph.GA↗

arXiv2009

3D Spectroscopy of Local Luminous Compact Blue Galaxies: Kinematics of NGC 7673

The kinematic properties of the ionized gas of local Luminous Compact Blue Galaxy (LCBG) NGC 7673 are presented using three dimensional data taken with the PPAK integral field unit at the 3.5-m telescope in the Centro Astronómico Hispano Alemán. Our data reveal an asymmetric rotating velocity field with a peak to peak difference of 60 km s$^{-1}$. The kinematic centre is found to be at the position of a central velocity width maximum ($σ=54\pm1$ km s$^{-1}$), which is consistent with the position of the luminosity-weighted centroid of the entire galaxy. The position angle of the minor rotation axis is 168$^{\circ}$ as measured from the orientation of the velocity field contours. At least two decoupled kinematic components are found. The first one is compact and coincides with the position of the second most active star formation region (clump B). The second one is extended and does not have a clear optical counterpart. No evidence of active galactic nuclei activity or supernovae galactic winds powering any of these two components has been found. Our data, however, show evidence in support of a previously proposed minor merger scenario in which a dwarf galaxy, tentatively identified with clump B, is falling into NGC 7673. and triggers the starburst. Finally, it is shown that the dynamical mass of this galaxy may be severely underestimated when using the derived rotation curve or the integrated velocity width, under the assumption of virialization.

astro-ph.CO↗

arXiv2007

Discovery of a galactic wind in the central region of M100

We report the discovery of a galactic wind in the central region of the galaxy M100. This result is based on a careful 2D spectroscopic study performed on observations made with the fibre system INTEGRAL on the WHT. The primary evidence of the wind is the presence of blueshifted interstellar NaD absorption lines. The velocity field of the absorbers show a clear rotation pattern but globally blueshifted ($\sim$ -115 km/s) with respect to the systemic velocity of the galaxy. The emission lines also present a blueward component arising from the ionized gas phase of the galactic wind. The velocity field of the ionized gas wind component shows no evidences of rotation but exhibits a pattern that can be interpreted in terms of the projection of an outflowing cone or shell. The wind component has [NII]/H$α$ ratios of about 1.8, typical of shock ionization. The ionized component of the wind can be identified with an expanding shell of shocked gas, and the neutral component with disk gas entrained in the wind at the interface of the expanding shell with the galactic ISM. The galactic wind seems to be driven uniquely by the nuclear starburst. Our analysis indicates that a non negligible fraction of the wind material might escape to the IGM. In this case, if the wind detected in M100 were representative of similar phenomena in other galaxies with low to moderate activity, the current estimates of metal and dust content of the IGM might be drastically underestimated.

astro-ph↗

arXiv2007

Non-circular motion evidences in the circumnuclear region of M100 (NGC 4321)

We analyse new integral field spectroscopy of the inner region (central 2.5 kpc) of the spiral galaxy NGC 4321 to study the peculiar kinematics of this region. Fourier analysis of the velocity residuals obtained by subtracting an axisymmetric rotation model from the $\rm Hα$ velocity field, indicates that the distortions are {\em global} features generated by an $m=2$ perturbation of the gravitational potential which can be explained by the nuclear bar. This bar has been previously observed in the near-infrared but not in the optical continuum dominated by star formation. We detect the optical counterpart of this bar in the 2D distribution of the old stellar population (inferred from the equivalent width map of the stellar absorption lines). We apply the Tremaine--Weinberg method to the stellar velocity field to calculate the pattern speed of the inner bar, obtaining a value of $Ω_b$=160$\pm70\rm km s^{-1} kpc^{-1} $. This value is considerably la rger than the one obtained when a simple bar model is considered. However the uncertainties in the pattern speed determination prevent us to give support to alternative scenarios.

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arXiv2006

Truncated stellar disks in the near infrared. I. Observations

We present NIR surface photometry of 11 edge-on galaxies obtained in the course of a long term project aimed at analysing the occurrence and type of the truncation of the outer disks. Observations were carried out at the 1.5 m CST (Carlos Sánchez Telescope) in Tenerife (Spain) using the CAIN infrared camera. 7 galaxies exhibit clear truncation on their disk profiles and 4 galaxies were observed to be clearly untruncated within observational limits. We describe the truncations as real, smooth and complete (as suggested by extrapolation and in the sense that the measured truncation curve goes into the noise at a truncation radius $R_{tr}$), following a decline proportional to $(R_{tr} -R)^{-n}$ (where $R$ is the radius). Despite its deep photometric reach, the data presented do not permit a detailed exploration of the region where optical data show a second slope. Special care was taken concerning the surface brightness deprojection of edge-on galaxies, which was carried out by two methods, one comprising the inversion of Abel's integral equation and the other following a numerical method. These methods gave nearly identical results. NIR observations of truncations could differ from observations in the optical, since the two domains trace different stellar populations.

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arXiv2006

Truncated stellar discs in the near infrared. II. Statistical properties and interpretation

The results obtained in paper I are used to study possible relationships between the truncation radius of stellar discs in the NIR and structural parameters of the galaxies. The NIR truncation radius is larger for brighter galaxies, being proportional to $V_m^c$ with $c \approx 3/2$, and with $V_m$ being the asymptotic rotation velocity at large radii (when the rotation curve becomes flat), and is lower for higher wavelengths. When it is normalized to the scalelength, the truncation is an increasing function of the central surface brightness and is lower for late type galaxies, although these correlations are weaker. These relations are in agreement with the scenario of magnetically driven truncations.

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arXiv2004

Asymmetrical structure of ionization and kinematics in the Seyfert galaxy NGC 5033

We present integral field spectroscopy of NGC 5033, a low luminosity Seyfert galaxy. The observations were made with INTEGRAL, a fiber based system operating at the WHT. The intensity map of the H$β$ emission line represents a spiral or ring-like pattern of HII regions. On the contrary, the [OIII] intensity map morphology is markedly anisotropic. The strong morphological differences imply that the [OIII] emitters represent highly ionized gas illuminated by the central source. The [OIII] map morphology is compatible with a biconical structure of ionization induced by strong extinction in the galaxy disc that also obscures half of the spheroidal stellar bulge. We identify the spectrum corresponding to the Seyfert 1 nucleus from the presence of H$β$ broad emission lines. This spectrum is located in a region where strong extinction is expected but exhibits the bluest spectral energy distribution. The Seyfert 1 nucleus seems to be offcenter with respect to the stellar rotation center. This result has been also found in other Seyfert galaxies and interpreted in terms of a past merger. The offcentering could indicate the presence of nonsymmetric departures in the gravitational potential which could be fueling the active nucleus. The kinematics of the [OIII] emitters show important deviations at a kpc scale with respect to the stellar velocity field and show features related to the asymmetrical morphology of the high ionization region.

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arXiv2003

XMM observation of the dynamically young galaxy cluster CL 0939+4713

We present an XMM observation of the distant galaxy cluster CL 0939+4713. The X-ray image shows pronounced substructure, with two main subclusters forming the cluster core. This is an indication that the cluster is a dynamically young system. This conclusion is supported by the temperature distribution: a hot region is found between the two main subclusters indicating that they are at the beginning of a major merger, and that they will collide in a few hundreds of Myr. The intra-cluster gas of CL 0939+4713 shows inhomogeneities in the metal distribution, with the optically richer subcluster having a higher metallicity.

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arXiv2003

Distribution of dark and baryonic matter in clusters of galaxies

We present the analysis of baryonic and non-baryonic matter distribution in a sample of ten nearby clusters (0.03<z<0.09) with temperatures between 4.7 and 9.4 keV. These galaxy clusters are studied in detail using X-ray data and global physical properties are determined. Correlations between these quantities are analysed and compared with the results for distant clusters. We find an interesting correlation between the extent of the intra-cluster gas relative to the dark matter distribution. The extent of the gas relative to the extent of the dark matter tends to be larger in less massive clusters. This correlation might give us some hints on non-gravitational processes in clusters. We do not see evolution in the gas mass fraction out to a redshift of unity. Within r_{500}, the mean gas mass fraction obtained is 0.16\pm0.02 h_{50}^{-3/2}.

astro-ph↗

arXiv2002

Recent CHANDRA and XMM observations of two very different galaxy clusters: RBS797 and CL 0939+4713

RBS797 and CL 0939+4713 are two intermediate red-shift clusters ($z=0.35-0.41$). They have very different morphologies but both show surprisingly interesting structures. RBS797 looks relaxed, with an almost circular morphology; a CHANDRA observation of this cluster has revealed two deep depressions in the X-ray emission near the core. CL 0939+4713 has instead an irregular morphology with evident substructures which seem to be in the process of merging.

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arXiv2001

Discovery of depressions in the X-ray emission of the distant galaxy cluster RBS797 in a CHANDRA observation

We present CHANDRA observations of the X-ray luminous, distant galaxy cluster RBS797 at z=0.35. In the central region the X-ray emission shows two pronounced X-ray minima, which are located opposite to each other with respect to the cluster centre. These depressions suggest an interaction between the central radio galaxy and the intra-cluster medium, which would be the first detection in such a distant cluster. The minima are symmetric relative to the cluster centre and very deep compared to similar features found in a few other nearby clusters. A spectral and morphological analysis of the overall cluster emission shows that RBS797 is a hot cluster (T=7.7^{+1.2}_{-1.0} keV) with a total mass of M_{tot}(r_{500})=6.5^{+1.6}_{-1.2} 10^{14} \msol.

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arXiv2001

Distribution of baryonic and non-baryonic matter in clusters of galaxies

We present the analysis of baryonic and non-baryonic matter distributions in a sample of eleven nearby clusters (0.03<z<0.09) with temperatures between 4.4 and 9.4 keV. These galaxy clusters have been studied in detail using X-ray data and global physical properties have been determined. Correlations between these quantities have been analysed and compared with the results for distant clusters. We found an interesting dependence between the relative gas extent (expressed as the ratio of gas mass fractions at different radii) and the total cluster mass. The extent of the gas relative to the extent of the dark matter tends to be larger in less massive clusters. This dependence might give us some hints about non-gravitational processes in clusters.

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