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- ID:
- ivo://CDS.VizieR/J/A+A/622/A8
- Title:
- NGC 3184, 4736, 5055 and 5194 LOFAR & WSRT maps
- Short Name:
- J/A+A/622/A8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radio continuum (RC) emission in galaxies allows us to measure star formation rates (SFRs) unaffected by extinction due to dust, of which the low-frequency part is uncontaminated from thermal (free-free) emission. We calibrate the conversion from the spatially resolved 140MHz RC emission to the SFR surface density (SFR) at 1kpc scale. Radio spectral indices give us, by means of spectral ageing, a handle on the transport of cosmic rays using the electrons as a proxy for GeV nuclei. We used recent observations of three galaxies (NGC 3184, 4736, and 5055) from the LOFAR Two-metre Sky Survey (LoTSS), and archival LOw Frequency ARay (LOFAR) data of NGC 5194. Maps were created with the facet calibration technique and converted to radio {Sigma}SFR maps using the Condon relation. We compared these maps with hybrid {Sigma}SFR maps from a combination of GALEX far-ultraviolet and Spitzer 24um data using plots tracing the relation at the highest angular resolution allowed by our data at 1.2x1.2-kpc^2^ resolution.
- ID:
- ivo://CDS.VizieR/J/A+A/632/A12
- Title:
- NGC 891 and NGC 4565 radio images
- Short Name:
- J/A+A/632/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cosmic-ray electrons (CREs) originating from the star-forming discs of spiral galaxies frequently form extended radio haloes that are best observable in edge-on galaxies, where their properties can be directly investigated as a function of vertical height above the disc. For the present study, we selected two nearby edge-on galaxies from the Continuum Halos in Nearby Galaxies - an EVLA Survey (CHANG-ES), NGC 891 and 4565, which differ largely in their detectable halo extent and their star- formation rates (SFRs). Our aim is to figure out how such differences are related to the (advective and/or diffusive) CRE transport in the disc and in the halo. We use wide-band 1.5 and 6GHz Very Large Array (VLA) observations obtained in the B, C, and D configurations, and combine the 6GHz images with Effelsberg observations to correct for missing short spacings. After subtraction of the thermal emission, we investigate the spatially resolved synchrotron spectral index distribution in terms of CRE spectral ageing. We further compute total magnetic field strengths assuming equipartition between the cosmic-ray (CR) energy density and the magnetic field, and measure synchrotron scale heights at both frequencies. Based on the fitted vertical profiles of the synchrotron intensity and on the spectral index profile between 1.5 and 6GHz, we create purely advective and purely diffusive CRE transport models by numerically solving the 1D diffusion-loss equation. In particular, we investigate for the first time the radial dependence of synchrotron and magnetic field scale heights, advection speeds, and diffusion coefficients, whereas previous studies of these two galaxies only determined global values of these quantities.
- ID:
- ivo://CDS.VizieR/J/A+A/629/A54
- Title:
- NGC4388 and NGC2110 spectral files
- Short Name:
- J/A+A/629/A54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to measure the physical properties of the hot X-ray corona of two active galactic nuclei, NGC 4388 and NGC 2110. We analysed the hard X-ray (20-300keV) INTEGRAL spectrum in conjunction with archival XMM-Newton and NuSTAR data. The X-ray spectrum of both sources is phenomenologically well described by an absorbed cut-off power law. In agreement with previous results, we find no evidence of a Compton reflection component in these sources. We obtain a high-energy cut-off of 200_-40_^+75^keV for NGC 4388 and 320_-60_^+100^keV for NGC 2110. A fit with a thermal Comptonisation model yields a coronal temperature of 80_-20_^+40^keV and 75_-15_^+20^keV, respectively, and an optical depth of approximately two, assuming a spherical geometry. The coronal temperature and luminosity of both sources are consistent with pair production that acts as a thermostat for the thermal plasma. These results emphasise the importance of good signal-to-noise X-ray data above 100keV to probe the high-energy emission of AGNs.
- ID:
- ivo://CDS.VizieR/J/A+A/592/A20
- Title:
- NGC 1316 and NGC 612 WISE images
- Short Name:
- J/A+A/592/A20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Most radio galaxies are hosted by giant gas-poor ellipticals, but some contain significant amounts of dust, which is likely to be of external origin. In order to characterize the mid-IR properties of two of the most nearby and brightest merger-remnant radio galaxies of the Southern hemisphere, NGC 1316 (Fornax A) and NGC 612 (PKS 0131-36), we used observations with the Wide-field Infrared Survey Explorer (WISE) at wavelengths of 3.4, 4.6, 12 and 22 micron and Spitzer mid-infrared spectra. By applying a resolution-enhancement technique, new WISE images were produced at angular resolutions ranging from 2.6" to 5.5". Global measurements were performed in the four WISE bands, and stellar masses and star-formation rates were estimated using published scaling relations. Two methods were used to uncover the distribution of dust, one relying on two-dimensional fits to the 3.4 micron images to model the starlight, and the other one using a simple scaling and subtraction of the 3.4 micron images to estimate the stellar continuum contribution to the emission in the 12 and 22 micron bands. The two galaxies differ markedly in their mid-IR properties. The 3.4 micron brightness distribution can be well represented by the superposition of two Sersic models in NGC 1316 and by a Sersic model and an exponential disk in NGC 612. The WISE colors of NGC 1316 are typical of those of early-type galaxies; those of NGC 612 are in the range found for star-forming galaxies. From the 22 micron luminosity, we infer a star-formation rate of about 0.7 solar masses per year in NGC 1316 and about 7 solar masses per year in NGC 612. Spitzer spectroscopy shows that the 7.7-to-11.3 micron PAH line ratio is significantly lower in NGC 1316 than in NGC 612. The WISE images reveal resolved emission from dust in the central 1'-2' of the galaxies. In NGC 1316, the extra-nuclear emission coincides with two dusty regions NW and SE of the nucleus seen in extinction in optical images and where molecular gas is known to reside. In NGC 612 it comes from a warped disk. This suggests a recent infall onto NGC 1316 and disruption of one or several smaller gas-rich galaxies, but a smoother accretion in NGC 612. While the nucleus of NGC 1316 is currently dormant and the galaxy is likely to evolve into a passive elliptical, NGC 612 has the potential of growing a larger disk and sustaining an active nucleus. NGC 1316 and NGC 612 represent interesting challenges to models of formation and evolution of galaxies and AGNs.
- ID:
- ivo://CDS.VizieR/J/A+A/554/A128
- Title:
- NGC 6824 and UGC 11919 data cubes
- Short Name:
- J/A+A/554/A128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss the results of a mass decomposition of two spiral galaxies, NGC 6824 and UGC 11919. In a previous analysis of the Hyperleda catalog, the galaxies were identified as having a peculiar dynamical mass-to-light ratio. The aim of this study is to confirm or disprove the preliminary findings, indicating a non-standard stellar initial mass function (IMF) for the galaxies. The surface photometry in B,V, and R bands was carried out with the Apache Point 0.5-m telescope and the HI data cubes were obtained with the Westerbork Synthesis Radio Telescope (WSRT). Photometric profiles were decomposed into bulge and exponential disk components.
2547. NGC 5548 BR photometry
- ID:
- ivo://CDS.VizieR/J/AJ/116/102
- Title:
- NGC 5548 BR photometry
- Short Name:
- J/AJ/116/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Deep Hubble Space Telescope Wide Field Camera (WFC-1) imaging of a region 3.7' east of the V=13mag Seyfert galaxy NGC 5548 in the F555W and F785LP bands, and deep ground-based V and I imaging, show a new extended, blue, low surface brightness structure, apparently a remnant of a tidal interaction associated with NGC 5548. If this straight, low surface brightness (V~27-28mag/arcsec^2^) tidal tail is associated with NGC 5548, it extends at least 80kpc from it and has an absolute magnitude of M_V~-16.4 (H_0_=65km/s/Mpc). Previous imaging surveys of Seyfert galaxies would have missed such low surface brightness tails. Morphologically similar to some brighter tails seen in other interacting systems and in simulations of merging galaxies, this faint tail is a useful diagnostic of an earlier interaction and of the progenitors' halo-to-disk mass ratios. Luminous ripples and a brighter tail wrapped around the galaxy are seen in the inner 1-10kpc region. Unresolved blue objects in the long tail have the colors and absolute magnitudes of young globular clusters. Taken together, the two tails and other features suggest that two spirals merged less than ~1Gyr ago. The inner luminosity profile of NGC 5548 is a good fit to a de Vaucouleurs profile with r_eff_=5.8kpc. Recent simulations of merged galaxies with high-mass halos fail to form lasting tidal tails, suggesting that the NGC 5548 progenitor spirals had modest halo masses.
2548. NGC 1316 BVI images
- ID:
- ivo://CDS.VizieR/J/A+A/552/A106
- Title:
- NGC 1316 BVI images
- Short Name:
- J/A+A/552/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The distance of NGC1316, the brightest galaxy in the Fornax cluster, provides an interesting test for the cosmological distance scale. First, because Fornax is the second largest cluster of galaxies within <~25Mpc after Virgo and, in contrast to Virgo, has a small line-of-sight depth; and second, because NGC1316 is the single galaxy with the largest number of detected Type Ia supernovae (SNe Ia), giving the opportunity to test the consistency of SNe Ia distances both internally and against other distance indicators. We measure surface brightness fluctuations (SBF) in NGC1316 from ground- and space-based imaging data. The sample provides a homogeneous set of measurements over a wide wavelength interval. The SBF magnitudes, coupled with empirical and theoretical absolute SBF calibrations, are used to estimate the distance to the galaxy. We also present the first B-band SBF measurements of NGC1316 and use them together with the optical and near-IR SBF data to analyze the properties of field stars in the galaxy. We obtain m-M=31.59+/-0.05(stat)+/-0.14(sys.)mag, or d=20.8+/-0.5(stat)+/-1.5(sys.)Mpc. When placed in a consistent Cepheid distance scale, our result agrees with the distances from other indicators. On the other hand, our distance is ~17% larger than the most recent estimate based on SNe Ia. Possible explanations for this disagreement are the uncertain level of internal extinction, and/or calibration issues. Concerning the stellar population analysis, we confirm the results from other spectro-photometric indicators: the field stars in NGC1316 are dominated by a component with roughly solar metallicity and intermediate age. A non-negligible mismatch exists between B-band SBF models and data. We confirm that such behavior can be accounted for by an enhanced percentage of hot horizontal branch stars. Our study of the SBF distance to NGC1316, and the comparison with distances from other indicators, raises some concern about the homogeneity between the calibrations of different indicators. If not properly placed in the same reference scale, significant differences can occur, with dramatic impact on the cosmological distance ladder. Our results on the stellar populations properties show that SBF data over a broad wavelength interval are an efficient means of studying the properties of unresolved systems in peculiar cases like NGC1316.
- ID:
- ivo://CDS.VizieR/J/AJ/106/66
- Title:
- NGC 1560 BVRI CCD photometry
- Short Name:
- J/AJ/106/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present BVRI CCD photometry of ~600 stars in the central region of a resolved spiral galaxy NGC 1560 which is seen almost edge-on, apparently located in the IC 342 group. The V-(B-V) diagram shows a dominant group of significantly reddened blue plume stars consisting of young massive main-sequence and evolved blue supergiant stars. The tip of the blue plume is found to be at V~21 mag and (B-V)~0.4mag. The I-(R-I) diagram shows a large group of red supergiants the brightest of which are extending to I~19.5mag at (R-I)~1.1mag. The logarithmic slope of the V luminosity function of the blue plume stars is 0.69+/-0.10, similar to that for other nearby galaxies. The mean color of the blue plume stars is <(B-V)>=0.25+/-0.03mag. The total reddening, including both foreground and internal reddening, is estimated from the mean color of the blue plume stars, to be E(B-V)=0.40+/-0.10mag, whereas the foreground reddening based on the H I column density and faint galaxy counts is E(B-V)=0.16mag. Combining our results with those in the literature, we have obtained distance estimates using four methods: brightest blue stars [(m-M)_0_=27.11mag], brightest red stars [(m-M)_0_=27.02mag], B-band Tully-Fisher relation [(m-M)_0_=26.96mag], and H-band Tully-Fisher relation [(m-M)_0_=26.86mag]. These four estimates agree very well. Taking the average of these four estimates, we obtain a value for the true distance modulus to NGC 1560, (m-M)_0_=27.0+/-0.1mag, corresponding to a distance of 2.5+/-0.1Mpc.
2550. NGC 205 BVRI photometry
- ID:
- ivo://CDS.VizieR/J/AJ/112/1438
- Title:
- NGC 205 BVRI photometry
- Short Name:
- J/AJ/112/1438
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- BVRI/CCD photometry of ~2,300 stars in the central 2.2'x3.5' area of the dwarf elliptical galaxy NGC205 in the Local Group is presented. The color-magnitude diagrams of NGC 205 show: (1) a blue plume around (B-V)~0.0mag, extending up to V~19.3mag (M_V_~-5.4mag); and (2) a strong asymptotic giant branch (AGB) population, the brightest of which reaches I~19.0mag, 1.5 mag brighter than the tip of the red giant branch. BVRI photometry of three globular clusters (Hubble IV. V, and VI) is also presented. Hubble V is much bluer [(B-V)=0.37] than other globular clusters. This blue color of Hubble V leads to an estimate of the age, ~300Myrs. A V luminosity function for the blue stars has been derived: the logarithmic slope of the luminosity function for -5.7<M_V_<-3.2 is 0.64+/-0.12, which is similar to those of other nearby galaxies. The AGB stars extend to Mbol~-5.7mag, which is ~0.7mag brighter than those in NGC 185. The bolometric luminosity function of the AGB stars in NGC 205 is found to be flatter than that of the similar dwarf elliptical galaxy NGC 185, but similar to that of a bulge field 4' of the nucleus of M31. Surface photometry for the central area within R=50" is presented, showing that the colors get bluer as the galactocentric radius decreases except for the nucleus region within R=1.6" where the colors get redder inward. Star formation history in NGC 205 is briefly discussed.
