- ID:
- ivo://CDS.VizieR/J/A+AS/71/297
- Title:
- CCD UBV photometry of stars in Sex A
- Short Name:
- J/A+AS/71/297
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD UBV photometry of 2279 stars in Sextans A is presented. Differences with the photometric scales of Sandage and Carlson (1985AJ.....90.1019S) and Hoessel et al. (1983ApJ...274..577H) are discussed; recalibration of the Sandage and Carlson data for Cepheids in Sextans A results in a smaller value for the distance modulus, {mu}=25.6. A similar value for the distance modulus is obtained from the colour-colour diagram. Colour-colour and colour-magnitude diagrams for the whole galaxy and for different parts are presented indicating a general star formation activity all over Sextans A. The contribution of stars brighter than M_pg_=-3 to the total blue light of the galaxy amounts to 25%, a much higher value than what is found for other dwarf irregular galaxies in the Local Group. The integrated birthrate per unit mass of massive stars for the galaxy is found to be much higher than in the Magellanic Clouds, suggesting that the rate in Sextans A was probably smaller in the past. Different slopes for high mass and low mass IMF parts are needed to account for its low surface brightness. The formation of massive stars seems to be favoured for systems of decreasing mass or, given the relation between total mass and metal content, for galaxies of decreasing metallicity.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/497/1791
- Title:
- CCD Washington photometry of Antlia cluster
- Short Name:
- J/MNRAS/497/1791
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an extension of our previous research on the early-type galaxy population of the Antlia cluster (d~35Mpc), achieving a total coverage of ~2.6deg^2^ and performing surface photometry for ~300 galaxies, 130 of which are new uncatalogued ones. Such new galaxies mainly fall in the low surface brightness (LSB) regime, but there are also some lenticulars (S0) which support the existence of unique functions that connect bright and dwarf galaxies in the scaling relations. We analyse the projected spatial distribution of galaxies up to a distance of ~800kpc from NGC 3268, the adopted centre, as well as the radial velocity distribution and the correlation between galaxy colour and effective radius with the projected spatial distribution. We also obtain the luminosity function of the early-type galaxies and the distribution of stellar masses using the T1-band magnitudes and adopted mass-luminosity ratios. Additionally, we correlate the central galaxy distribution with an X-ray emission map from the literature. Based on the analysis of the radial velocities and galaxy colour distributions, we find that galaxies redder than the colour-magnitude relation (CMR) have a velocity distribution strongly concentrated towards the values of the dominant galaxies and are homogeneously distributed throughout the cluster. Those bluer than the CMR, in turn, have a much more extended radial velocity distribution and are concentrated towards the centre of the cluster. We also identify 12 candidates to ultra diffuse galaxies (UDG), that seem to be split into two families, and speculate about their origins in the context of the cluster structure.
- ID:
- ivo://CDS.VizieR/J/A+A/649/A31
- Title:
- [CCJ2015b] HZ4 [CII] 158um datacube
- Short Name:
- J/A+A/649/A31
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present new Atacama Large Millimeter/Submillimeter Array (ALMA) observations of the [CII] 158um transition and the dust continuum in HZ4, a typical star-forming galaxy when the Universe was only ~1Gyr old (z~5.5). Our high ~0.3" spatial resolution allows us to study the relationships between [CII] line emission, star formation rate, and far-infrared emission on spatial scales of ~2kpc. In the central ~4kpc of HZ4 the [CII]/FIR is ~3x10^-3^ on global scales as well as on spatially resolved scales of ~2kpc, comparable to the ratio observed in local moderate starburst galaxies such as M82 or M83. For the first time in an individual normal galaxy at this redshift, we find evidence for outflowing gas from the central star-forming region in the direction of the minor axis of the galaxy. The projected velocity of the outflow is ~400km/s, and the neutral gas-mass outflow rate is ~3-6 times higher than the star formation rate in the central region. Finally, we detect a diffuse component of [CII] emission, or [CII] halo, that extends beyond the star-forming disk and has a diameter of ~12kpc. The outflow, which has a velocity approximately half of the escape velocity of the system, most likely partly fuels the [CII] extended emission. Together with the kinematic analysis of HZ4 (presented in a forthcoming paper), the analysis supports the hypothesis that HZ4 is a typical star-forming disk at z~5 with interstellar medium conditions similar to present-day galaxies forming stars at a similar level, driving a galactic outflow that may already play a role in its evolution.
524. 3C 236 CO maps
- ID:
- ivo://CDS.VizieR/J/A+A/549/A58
- Title:
- 3C 236 CO maps
- Short Name:
- J/A+A/549/A58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- There is growing observational evidence of active galactic nuclei (AGN) feedback on the ISM of radio-quiet and radio-loud galaxies. While AGN feedback is expected to be more common at high redshift objects, the study of local universe galaxies help to better characterize the different manifestations of AGN feedback.AIMS. Molecular line observations can be used to quantify the mass and energy budget of the gas affected by AGN feedback. We study the emission of molecular gas in 3C 236, a Faranoff-Riley type 2 (FR II) radio source at z~0.1, and search for the footprints of AGN feedback. 3C 236 shows signs of a reactivation of its AGN triggered by a recent minor merger episode. Observations have also previously identified an extreme HI outflow in this source. The IRAM Plateau de Bure interferometer (PdBI) has been used to study the distribution and kinematics of molecular gas in 3C 236 by imaging with high spatial resolution (0.6") the emission of the 2-1 line of ^12^CO in the nucleus of the galaxy. We have searched for outflow signatures in the CO map. We have also derived the star-formation rate (SFR) in 3C 236 using data available from the literature at UV, optical and IR wavelengths, to determine the star-formation efficiency of molecular gas. The CO emission in 3C 236 comes from a spatially resolved ~1.4" (2.6kpc)-diameter disk characterized by a regular rotating pattern. Within the limits imposed by the sensitivity and velocity coverage of the CO data, we do not detect any outflow signatures in the cold molecular gas. The disk has a cold gas mass M(H_2_)~2.1x10^9^M_{sun}_. Based on CO we determine a new value for the redshift of the source z_CO_=0.09927+/-0.0002. The similarity between the CO and HI profiles indicates that the deep HI absorption in 3C 236 can be accounted for by a rotating HI structure. This restricts the evidence of HI outflow only to the most extreme velocities. In the light of the new redshift value, the analysis of the ionized gas kinematics reveals a fast (~1000km/s) outflow. As for the CO emitting gas, outflow signatures are nevertheless absent in the warm molecular gas emission traced by infrared H_2_ lines. The star-formation efficiency in 3C 236 is consistent with the value measured in normal galaxies, which follow the canonical Kennicutt-Schmidt (KS) relation. This result, confirmed to hold in other young radio sources examined in this work, is in stark contrast with the factor of 10-50 lower SFE that has been claimed to characterize evolved powerful radio galaxies. There are no signs of ongoing AGN feedback on the molecular ISM of 3C 236. The recent reactivation of the AGN in 3C 236 (about ~10^5^yr ago) is a likely explanation for the early evolutionary status of its molecular disk.
- ID:
- ivo://CDS.VizieR/J/MNRAS/459/2948
- Title:
- Ccompact group galaxies UV and IR SFR
- Short Name:
- J/MNRAS/459/2948
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Compact groups of galaxies provide insight into the role of low-mass, dense environments in galaxy evolution because the low velocity dispersions and close proximity of galaxy members result in frequent interactions that take place over extended time-scales. We expand the census of star formation in compact group galaxies by Tzanavaris et al. (2010, Cat. J/ApJS/212/9) and collaborators with Swift UVOT, Spitzer IRAC and MIPS 24{mu}m photometry of a sample of 183 galaxies in 46 compact groups. After correcting luminosities for the contribution from old stellar populations, we estimate the dust-unobscured star formation rate (SFR_UV_) using the UVOT uvw2 photometry. Similarly, we use the MIPS 24 {mu}m photometry to estimate the component of the SFR that is obscured by dust (SFR_IR_). We find that galaxies which are MIR-active (MIR-'red'), also have bluer UV colours, higher specific SFRs, and tend to lie in HI-rich groups, while galaxies that are MIR-inactive (MIR-'blue') have redder UV colours, lower specific SFRs, and tend to lie in HI-poor groups. We find the SFRs to be continuously distributed with a peak at about 1M_{sun}_/yr, indicating this might be the most common value in compact groups. In contrast, the specific SFR distribution is bimodal, and there is a clear distinction between star-forming and quiescent galaxies. Overall, our results suggest that the specific SFR is the best tracer of gas depletion and galaxy evolution in compact groups.
- ID:
- ivo://CDS.VizieR/J/A+AS/142/353
- Title:
- CDD V photometry of B2 radio galaxies
- Short Name:
- J/A+AS/142/353
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of V-band CCD photometry for 72 low-luminosity radio galaxies from the B2 sample is presented. Most of these galaxies are of early type and their photometric and morphological properties are studied in the paper. We present the resulting surface brightness profiles and isophote parameters' profiles, including ellipticity, position angle, and B4, for 59 galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJS/179/19
- Title:
- CDFS survey: 2 Ms source catalogs
- Short Name:
- J/ApJS/179/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present point-source catalogs for the ~2Ms exposure of the Chandra Deep Field-South (CDF-S) this is one of the two most sensitive X-ray surveys ever performed. The survey covers an area of ~436arcmin^2^ and reaches on-axis sensitivity limits of ~1.9x10^-17^ and ~1.3x10^-16^ergs/cm^2^/s for the 0.5-2.0 and 2-8keV bands, respectively. Four hundred and sixty-two X-ray point sources are detected in at least one of three X-ray bands that were searched; 135 of these sources are new compared to the previous ~1Ms CDF-S detections. Source positions are determined using centroid and matched-filter techniques; the median positional uncertainty is ~0.36". The X-ray-to-optical flux ratios of the newly detected sources indicate a variety of source types; ~55% of them appear to be active galactic nuclei, while ~45% appear to be starburst and normal galaxies. In addition to the main Chandra catalog, we provide a supplementary catalog of 86 X-ray sources in the ~2Ms CDF-S footprint that was created by merging the ~250ks Extended Chandra Deep Field-South with the CDF-S this approach provides additional sensitivity in the outer portions of the CDF-S. A second supplementary catalog that contains 30 X-ray sources was constructed by matching lower significance X-ray sources to bright optical counterparts (R<23.8) the majority of these sources appear to be starburst and normal galaxies. The total number of sources in the main and supplementary catalogs is 578. Optical R-band counterparts and basic optical and infrared photometry are provided for the X-ray sources in the main and supplementary catalogs. We also include existing spectroscopic redshifts for 224 of the X-ray sources.
- ID:
- ivo://CDS.VizieR/VII/88
- Title:
- CEDAG Catalogue of Clusters of Galaxies
- Short Name:
- VII/88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains for 10411 objects, the Abell, Zwicky, and Kalinkov numbers of groups of galaxies. In addition, it contains: Abell or Zwicky coordinates, the Abell or Zwicky numbers of the supercluster which contains each group, the diameter (Zwicky), the magnitude (Abell), the compactness (Zwicky), the distance of the group (both Abell and Zwicky), the richness (Abell) and the population (Zwicky).
- ID:
- ivo://CDS.VizieR/J/MNRAS/436/1286
- Title:
- Cen A 118MHz MWA image
- Short Name:
- J/MNRAS/436/1286
- Date:
- 07 Feb 2022 14:36:33
- Publisher:
- CDS
- Description:
- We present new wide-field observations of Centaurus A (Cen A) and the surrounding region at 118MHz with the Murchison Widefield Array (MWA) 32-tile prototype, with which we investigate the spectral-index distribution of Cen A's giant radio lobes. We compare our images to 1.4GHz maps of Cen A and compute spectral indices using temperature-temperature plots and spectral tomography. We find that the morphologies at 118MHz and 1.4GHz match very closely apart from an extra peak in the southern lobe at 118MHz, which provides tentative evidence for the existence of a southern counterpart to the northern middle lobe of Cen A. Our spatially averaged spectral indices for both the northern and southern lobes are consistent with previous analyses, however we find significant spatial variation of the spectra across the extent of each lobe. Both the spectral-index distribution and the morphology at low radio frequencies support a scenario of multiple outbursts of activity from the central engine. Our results are consistent with inverse-Compton modelling of radio and gamma-ray data that support a value for the lobe age of between 10 and 80Myr.
- ID:
- ivo://CDS.VizieR/J/MNRAS/474/4056
- Title:
- Cen A MWA 154MHz image
- Short Name:
- J/MNRAS/474/4056
- Date:
- 07 Feb 2022 14:39:09
- Publisher:
- CDS
- Description:
- We present new radio and optical images of the nearest radio galaxy Centaurus A and its host galaxy NGC 5128. We focus our investigation on the northern transition region, where energy is transported from the ~5kpc (~5-arcmin) scales of the northern inner lobe (NIL) to the ~30kpc (~30-arcmin) scales of the northern middle lobe (NML). Our Murchison Widefield Array observations at 154MHz and our Parkes radio telescope observations at 2.3GHz show diffuse radio emission connecting the NIL to the NML, in agreement with previous Australia Telescope Compact Array observations at 1.4GHz. Comparison of these radio data with our wide-field optical emission-line images show the relationship between the NML radio emission and the ionized filaments that extend north from the NIL, and reveal a new ionized filament to the east, possibly associated with a galactic wind. Our deep optical images show clear evidence for a bipolar outflow from the central galaxy extending to intermediate scales, despite the non-detection of a southern radio counterpart to the NML. Thus, our observational overview of Centaurus A reveals a number of features proposed to be associated with active galactic nucleus feedback mechanisms, often cited as likely to have significant effects in galaxy evolution models. As one of the closest galaxies to us, Centaurus A therefore provides a unique laboratory to examine feedback mechanisms in detail.
