- ID:
- ivo://CDS.VizieR/J/AJ/144/148
- Title:
- Infrared photometry of brown dwarf and Hyper-LIRG
- Short Name:
- J/AJ/144/148
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Spitzer 3.6 and 4.5{mu}m photometry and positions for a sample of 1510 brown dwarf candidates identified by the Wide-field Infrared Survey Explorer (WISE) all-sky survey. Of these, 166 have been spectroscopically classified as objects with spectral types M(1), L(7), T(146), and Y(12). Sixteen other objects are non-(sub)stellar in nature. The remainder are most likely distant L and T dwarfs lacking spectroscopic verification, other Y dwarf candidates still awaiting follow-up, and assorted other objects whose Spitzer photometry reveals them to be background sources. We present a catalog of Spitzer photometry for all astrophysical sources identified in these fields and use this catalog to identify seven fainter (4.5{mu}m~17.0mag) brown dwarf candidates, which are possibly wide-field companions to the original WISE sources. To test this hypothesis, we use a sample of 919 Spitzer observations around WISE-selected high-redshift hyper-luminous infrared galaxy candidates. For this control sample, we find another six brown dwarf candidates, suggesting that the seven companion candidates are not physically associated. In fact, only one of these seven Spitzer brown dwarf candidates has a photometric distance estimate consistent with being a companion to the WISE brown dwarf candidate. Other than this, there is no evidence for any widely separated (>20AU) ultra-cool binaries. As an adjunct to this paper, we make available a source catalog of ~7.33x10^5^ objects detected in all of these Spitzer follow-up fields for use by the astronomical community. The complete catalog includes the Spitzer 3.6 and 4.5{mu}m photometry, along with positionally matched B and R photometry from USNO-B; J, H, and K_s_ photometry from Two Micron All-Sky Survey; and W1, W2, W3, and W4 photometry from the WISE all-sky catalog.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/132/2243
- Title:
- Infrared properties of close pairs of galaxies
- Short Name:
- J/AJ/132/2243
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss spectroscopy and IR photometry for a complete sample of ~800 galaxies in close pairs objectively selected from the second Center for Astrophysics redshift survey. We use the Two Micron All Sky Survey to compare near-IR color-color diagrams for our sample with the Nearby Field Galaxy Sample and with a set of IRAS flux-limited pairs from Surace and coworkers. We construct a basic statistical model to explore the physical sources of the substantial differences among these samples. The model explains the spread of near-IR colors and is consistent with a picture in which central star formation is triggered by the galaxy-galaxy interaction before a merger occurs. For 160 galaxies we report new, deep JHK photometry within our spectroscopic aperture, and we use the combined spectroscopic and photometric data to explore the physical conditions in the central bursts.
- ID:
- ivo://CDS.VizieR/J/A+A/658/A21
- Title:
- Infrared-radio relation in the local universe
- Short Name:
- J/A+A/658/A21
- Date:
- 21 Mar 2022 09:38:59
- Publisher:
- CDS
- Description:
- The Square Kilometer Array (SKA) is expected to detect high-redshift galaxies with star formation rates (SFRs) up to two orders of magnitude lower than Herschel surveys and will thus boost the ability of radio astronomy to study extragalactic sources. The tight infrared-radio correlation offers the possibility of using radio emission as a dust-unobscured star formation diagnostic. However, the physics governing the link between radio emission and star formation is poorly understood, and recent studies have pointed to differences in the exact calibration required when radio is to be used as a star formation tracer. We improve the calibration of the relation of the local radio luminosity-SFR and to test whether there are nonlinearities in it. We used a sample of Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) sources and investigated their radio luminosity, which was derived using the NRAO VLA Sky Survey (NVSS) and Faint Images of the Radio Sky at Twenty-cm (FIRST) maps. We stacked the bins of infrared luminosity and SFR and accounted for bins with no detections in the stacked images using survival analysis fitting. This approach was tested using Monte Carlo simulations. After removing sources from the sample that have excess radio emission, which is indicative of nuclear radio activity, we found no deviations from linearity of the mean relations between radio luminosity and either SFR or infrared luminosity. We analyzed the link between radio emission and SFR or infrared luminosity using a local sample of star-forming galaxies without evidence of nuclear radio activity and found no deviations from linearity, although our data are also consistent with the small nonlinearity reported by some recent analyses. The normalizations of these relations are intermediate between those reported by earlier works.
- ID:
- ivo://CDS.VizieR/J/MNRAS/379/1343
- Title:
- Infrared study of UKIDSS massive supercluster
- Short Name:
- J/MNRAS/379/1343
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse the first publicly released deep field of the UK Infrared Deep Sky Survey (UKIDSS) Deep eXtragalactic Survey to identify candidate galaxy overdensities at z~1 across ~1deg^2^ in the ELAIS-N1 field. Using I-K, J-K and K-3.6um colours, we identify and spectroscopically follow up five candidate structures with Gemini/Gemini Multi-Object Spectrograph and confirm that they are all true overdensities with between five and 19 members each.
- ID:
- ivo://CDS.VizieR/J/A+A/609/A102
- Title:
- Inner/outer HII regions: galaxy sample
- Short Name:
- J/A+A/609/A102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using integral field spectroscopy (IFS) observations we aim to perform a systematic study and comparison of two inner and outer HII regions samples. The spatial resolution of the IFS, the number of objects and the homogeneity and coherence of the observations allow a complete characterization of the main observational properties and differences of the regions. We analyzed a sample of 725 inner HII regions and a sample of 671 outer HII regions, all of them detected and extracted from the observations of a sample of 263 nearby, isolated, spiral galaxies observed by the CALIFA survey. We find that inner HII regions show smaller equivalent widths, greater extinction and luminosities, along with greater values of [NII] {lambda}6583/H{alpha} and [OII] {lambda}3727/[OIII] {lambda}5007 emission-line ratios, indicating higher metallicities and lower ionization parameters. Inner regions have also redder colors and higher photometric and ionizing masses, although Mion/Mphot is slightly higher for the outer regions. This work shows important observational differences between inner and outer HII regions in star forming galaxies not previously studied in detail. These differences indicate that inner regions have more evolved stellar populations and are in a later evolution state with respect to outer regions, which goes in line with the inside-out galaxy formation paradigm.
- ID:
- ivo://CDS.VizieR/J/A+A/555/L4
- Title:
- Inner rings in disc galaxies from UV + H{alpha}
- Short Name:
- J/A+A/555/L4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this Letter, I distinguish "passive" inner rings to be those with no current star formation, as distinct from "active" inner rings which have undergone recent star formation. I built a sample of nearby galaxies with inner rings observed in the near- and mid-infrared by the NIRS0S and the S^4^G surveys. I used archival far-ultraviolet (FUV) and H{alpha} imaging of 319 galaxies to diagnose whether their inner rings are passive or active. I found that passive rings are found only in early-type disc galaxies (-3<=T<=2). In this range of stages, 21+/-3% and 28+/-5% of rings are passive according to the FUV and H{alpha} indicators, respectively. A ring which is passive according to FUV is always passive according to H{alpha}, but the reverse is not always true. Ring-lenses form 30-40% of passive rings, which is four times more than the fraction of ring-lenses found in active rings in the stage range -3<=T<=2. This is consistent with both a resonance and a manifold origin for the rings because both models predict purely stellar rings to be wider than their star-forming counterparts. In the case of resonance rings, the widening may be at least partly due to the dissolution of rings. If most inner rings have a resonance origin, I estimate 200Myr to be a lower bound for their dissolution time-scale. This time-scale is on the order of one orbital period at the radius of inner rings.
- ID:
- ivo://CDS.VizieR/J/ApJ/715/277
- Title:
- Insights into the Cepheid distance scale
- Short Name:
- J/ApJ/715/277
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed investigation of the Cepheid distance scale by using both theory and observations. Through the use of pulsation models for fundamental mode Cepheids, we found that the slope of the period-luminosity (P-L) relation covering the entire period range (0.40<=logP<=2.0) becomes steeper when moving from optical to near-infrared (NIR) bands, and that the metallicity dependence of the slope decreases from the B- to the K band. The sign of the metallicity dependence for the slopes of the P-LV and P-LI relation is at odds with some recent empirical estimates. We determined new homogeneous estimates of V- and I-band slopes for 87 independent Cepheid data sets belonging to 48 external galaxies with nebular oxygen abundance 7.5<=12+log(O/H)<=8.9. We investigated the dependence of the period-Wesenheit (P-W) relations on the metal content and we found that the slopes of optical and NIR P-W relations in external galaxies are similar to the slopes of Large Magellanic Cloud (LMC) Cepheids. They also agree with the theoretical predictions suggesting that the slopes of the P-W relations are independent of the metal content.
- ID:
- ivo://CDS.VizieR/J/A+A/576/A58
- Title:
- Integral Field 560-680nm observation of M81
- Short Name:
- J/A+A/576/A58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- M81 has the nearest active nucleus with broad H{alpha} emission. A detailed study of this galaxy's centre is important for understanding the innermost structure of the AGN phenomenon. Our goal is to seek previously undetected structures using additional techniques to reanalyse a data cube obtained with the GMOS-IFU installed on the Gemini North telescope (Schnorr Muller et al., 2011MNRAS.413..149S). We analysed the data cube using techniques of noise reduction, spatial deconvolution, starlight subtraction, PCA Tomography and comparison with HST images. We identified a hot bubble with T>43500K that is associated with strong emission of [NII]{lambda}5755{AA} and large [OI]{lambda}6300/H{alpha} ratio, as well as with a bluish continuum, surrounded by a thin shell of H{alpha}+[NII] emission. We also reinterpret the outflow found by Schnorr Muller et al. (2011MNRAS.413..149S) showing that the blueshifted cone nearly coincides with the radio jet, as expected. We interpret the hot bubble as likely to be caused by post starburst events that left one or more clusters of young stars, somewhat similar to the ones found at the centre of the Milky Way, like the Arches and the IRS 16 clusters. Shocked structures from combined young stellar winds or supernova remnants are probably the cause of this hot gas and the low ionization emission.
- ID:
- ivo://CDS.VizieR/J/A+A/577/A21
- Title:
- Integral Field Spectroscopy of 8 BCGs
- Short Name:
- J/A+A/577/A21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Blue Compact Galaxies (BCG) are gas rich, low luminosity, low metallicity systems, undergoing a violent burst of star formation. These galaxies offer us a unique opportunity to investigate collective star formation and its effects on galaxy evolution in a relatively simple environment. Spatially resolved spectrophotometric studies of BCGs are essential for a better understanding of the role of starburst-driven feedback processes on the kinematical and chemical evolution of low-mass galaxies near and far. We carry out an integral field spectroscopic study of a sample of BCGs, with the aim to probe the morphology, kinematics, dust extinction, and excitation mechanisms of their warm interstellar medium. Eight BCGs were observed with the VIMOS integral field unit at the Very Large Telescope using blue and orange grisms in high resolution mode. At a spatial sampling of 0.67 per spaxel we covered about 30x30-arcsec on the sky, with a wavelength range of 4150...7400{AA}. Emission lines were fitted with a single Gaussian profiles to measure their wavelength, flux, and width. From these data we built two-dimensional maps of the continuum and the most prominent emission-lines, as well as diagnostic line ratios, extinction, and kinematic maps. An atlas of emission-line fluxes and continuum emission; ionization, interstellar extinction, and electron density maps from line ratios; velocity and velocity dispersion fields. Additionally, from integrated spectroscopy, tables of the extinction corrected line fluxes and equivalent widths, diagnostic-line ratios, physical parameters and abundances for the brightest star-forming knots and for the whole galaxy.
- ID:
- ivo://CDS.VizieR/J/AJ/149/32
- Title:
- Integrated radio continuum spectra of galaxies
- Short Name:
- J/AJ/149/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the spectral shape of the total continuum radiation, between 74MHz and 5GHz (400-6cm in wavelength), for a large sample of bright galaxies. We take advantage of the overlapping survey coverage of the VLA Low-Frequency Sky Survey, the Westerbork Northern Sky Survey, the NRAO VLA Sky Survey, and the Green Bank 6cm Survey to achieve significantly better resolution, sensitivity, and sample size compared to prior efforts of this nature. For our sample of 250 bright galaxies we measure a mean spectral index, {alpha}, of -0.69 between 1.4 and 4.85GHz, -0.55 between 325MHz and 1.4GHz, and -0.45 between 74 and 325MHz, which amounts to a detection of curvature in the mean spectrum. The magnitude of this curvature is approximately {Delta}{alpha}=-0.2 per logarithmic frequency decade when fit with a generalized function having constant curvature. No trend in low-frequency spectral flattening versus galaxy inclination is evident in our data, suggesting that free-free absorption is not a satisfying explanation for the observed curvature. The ratio of thermal to non-thermal emission is estimated through two independent methods: (1) using the IRAS far-IR fluxes and (2) with the value of the total spectral index. Method (1) results in a distribution of 1.4GHz thermal fractions of 9%+/-3%, which is consistent with previous studies, while method (2) produces a mean 1.4GHz thermal fraction of 51% with dispersion 26%. The highly implausible values produced by method (2) indicate that the sum of typical power-law thermal and non-thermal components is not a viable model for the total spectral index between 325 and 1.4GHz. An investigation into relationships between spectral index, infrared-derived quantities, and additional source properties reveals that galaxies with high radio luminosity in our sample are found to have, on average, a flatter radio spectral index, and early types tend to have excess radio emission when compared to the radio-infrared ratio of later types. Early types also have radio emission that is more compact than later type galaxies, as compared to the optical size of the galaxy. Despite these differences, no relation between spectral index and galaxy type is detected.