- ID:
- ivo://CDS.VizieR/J/MNRAS/360/587
- Title:
- K-band imaging of H{delta}-strong galaxies
- Short Name:
- J/MNRAS/360/587
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present UFTI K-band imaging observations of 222 galaxies that are selected from the Sloan Digital Sky Survey to have unusually strong H{delta} absorption equivalent widths, W(H{delta})>4{AA}. Using GIM2D, the images are fitted with two-dimensional surface-brightness models consisting of a simple disc and bulge component to derive the fraction of luminosity in the bulge B/T.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/312/557
- Title:
- K-band Luminosity Function of Field Galaxies
- Short Name:
- J/MNRAS/312/557
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a measurement of the K-band luminosity function (LF) of field galaxies obtained from near-infrared imaging of a sample of 345 galaxies selected from the Stromlo-APM Redshift Survey. The LF is reasonably well fitted over the 10-mag range -26 < M(K-band) < -16 by a Schechter function with the parameters {alpha}=-1.16+/-0.19, M*=-23.58+/-0.42 and {phi*}=0.012+/-0.008 Mpc-3, assuming a Hubble constant of 100 km.s-1.Mpc-1. We have also estimated the LF for two subsets of galaxies subdivided by the equivalent width of the H{alpha} emission line at EW(H{alpha})=1nm. There is no significant difference in LF shape between the two samples, although there is a hint (~1{sigma} significance) that emission-line galaxies (ELGs) have M* roughly 1 mag fainter than non-ELGs. Contrary to the optical LF, there is no difference in the faint end slope {alpha} between the two samples.
- ID:
- ivo://CDS.VizieR/J/ApJ/540/1016
- Title:
- K-band & NICMOS photometry of Trapezium Cluster
- Short Name:
- J/ApJ/540/1016
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained images of the Trapezium Cluster (140"x140"; 0.3pc x 0.3pc) with the Hubble Space Telescope Near-Infrared Camera and Multi-Object Spectrometer (NICMOS). Combining these data with new ground-based K-band spectra (R=800) and existing spectral types and photometry, we have constructed an H-R diagram and used it and other arguments to infer masses and ages.
- ID:
- ivo://CDS.VizieR/J/AJ/121/97
- Title:
- K-band spectroscopy of ULIRGs
- Short Name:
- J/AJ/121/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near-infrared spectroscopy for a complete sample of 33 ultraluminous infrared galaxies at a resolution of R~1000. Most of the wavelength range from 1.80-2.20{mu}m in the rest frame is covered, including the Pa{alpha} and Br{gamma} hydrogen recombination lines, and the molecular hydrogen vibration-rotation 1-0 S(1) and S(3) lines. Other species, such as He I, [Fe II], and [Si VI] appear in the spectra as well, in addition to a number of weaker molecular hydrogen lines. Nuclear extractions for each of the individual galaxies are presented here, along with spectra of secondary nuclei, where available. The Pa{alpha} emission is seen to be highly concentrated on the nuclei, typically with very little emission extending beyond a radius of 1kpc. This survey was carried out primarily to search for signatures of active nuclei via velocity-broadened hydrogen recombination or the presence of the [Si VI] coronal line. These signatures are rare in the present sample, occurring in only two of the 33 galaxies. The extinction to the hydrogen recombination lines is investigated via the Pa{alpha}/Br{gamma} line ratio. It is found that visual extinctions to the nuclei in excess of 10mag are relatively common among ULIRGs and that visual extinctions greater than 25mag are necessary to conceal a QSO emitting half the total bolometric luminosity. The ionized hydrogen regions in many ULIRGs are sufficiently obscured that dust-enshrouded active galactic nuclei would remain hidden at 2{mu}m at the current level of sensitivity. The vibration-rotation lines of molecular hydrogen appear to be predominantly thermal in origin, with effective temperatures generally around 2200K. The relative nuclear velocities between double nucleus ULIRGs are investigated, through which it is inferred that the maximum deprojected velocity difference is ~200km.s-1. This figure is lower than the velocities predicted by physical models of strong interactions/mergers of large, gas-rich galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/834/101
- Title:
- Keck/MOSFIRE spectroscopy of ZFOURGE galaxies
- Short Name:
- J/ApJ/834/101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare galaxy scaling relations as a function of environment at z~2 with our ZFIRE survey where we have measured H{alpha} fluxes for 90 star-forming galaxies selected from a mass-limited (log(M_*_/M_{sun}_)>9) sample based on ZFOURGE. The cluster galaxies (37) are part of a confirmed system at z=2.095 and the field galaxies (53) are at 1.9<z<2.4; all are in the COSMOS legacy field. There is no statistical difference between H{alpha}-emitting cluster and field populations when comparing their star formation rate (SFR), stellar mass (M_*_), galaxy size (r_eff_), SFR surface density ({Sigma}(H{alpha}_star_)), and stellar age distributions. The only difference is that at fixed stellar mass, the H{alpha}-emitting cluster galaxies are log(r_eff_)~0.1 larger than in the field. Approximately 19% of the H{alpha} emitters in the cluster and 26% in the field are IR-luminous (L_IR_>2x10^11^L_{sun}_). Because the luminous IR galaxies in our combined sample are ~5 times more massive than the low-IR galaxies, their radii are ~70% larger. To track stellar growth, we separate galaxies into those that lie above, on, or below the H{alpha} star-forming main sequence (SFMS) using {Delta}SFR(M*)=+/-0.2dex. Galaxies above the SFMS (starbursts) tend to have higher H{alpha} SFR surface densities and younger light-weighted stellar ages than galaxies below the SFMS. Our results indicate that starbursts (+SFMS) in the cluster and field at z~2 are growing their stellar cores. Lastly, we compare to the (SFR-M*) relation from Rhapsody-G cluster simulations and find that the predicted slope is nominally consistent with the observations. However, the predicted cluster SFRs tend to be too low by a factor of ~2, which seems to be a common problem for simulations across environment.
- ID:
- ivo://CDS.VizieR/J/MNRAS/338/253
- Title:
- K extinction near the Galactic Centre
- Short Name:
- J/MNRAS/338/253
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We extract J and Ks magnitudes from the 2MASS Point Source Catalog for approximately 6 million stars with 8<Ks<13 in order to build an A_K_ extinction map within 10 degrees of the Galactic centre. The extinction was determined by fitting the upper giant branch of (Ks, J-Ks) colour-magnitude diagrams to a dereddened upper giant branch mean locus built from previously studied Bulge fields. The extinction values vary from A_K=0.05 in the edges of the map up to A_K=3.2 close to the Galactic centre. The resulting extinction map is given in the file 'extmap.dat'.
- ID:
- ivo://CDS.VizieR/J/ApJ/884/4
- Title:
- KEYSTONE: ammonia structures in Galactic GMCs
- Short Name:
- J/ApJ/884/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present initial results from the K-band Focal Plane Array Examinations of Young STellar Object Natal Environments survey (KEYSTONE), a large project on the 100m Green Bank Telescope mapping ammonia emission across 11 giant molecular clouds at distances of 0.9-3.0kpc (Cygnus X North, Cygnus X South, M16, M17, Mon R1, Mon R2, NGC 2264, NGC 7538, Rosette, W3, and W48). This data release includes the NH_3_ (1,1) and (2,2) maps for each cloud, which are modeled to produce maps of kinetic temperature, centroid velocity, velocity dispersion, and ammonia column density. Median cloud kinetic temperatures range from 11.4+/-2.2K in the coldest cloud (Mon R1) to 23.0+/-6.5K in the warmest cloud (M17). Using dendrograms on the NH_3_ (1,1) integrated intensity maps, we identify 856 dense gas clumps across the 11 clouds. Depending on the cloud observed, 40%-100% of the clumps are aligned spatially with filaments identified in H2 column density maps derived from spectral energy distribution fitting of dust continuum emission. A virial analysis reveals that 523 of the 835 clumps (~63%) with mass estimates are bound by gravity alone. We find no significant difference between the virial parameter distributions for clumps aligned with the dust-continuum filaments and those unaligned with filaments. In some clouds, however, hubs or ridges of dense gas with unusually high mass and low virial parameters are located within a single filament or at the intersection of multiple filaments. These hubs and ridges tend to host water maser emission, multiple 70{mu}m detected protostars, and have masses and radii above an empirical threshold for forming massive stars.
- ID:
- ivo://CDS.VizieR/J/ApJS/251/23
- Title:
- K2 GAP DR2: campaigns 4, 6 & 7
- Short Name:
- J/ApJS/251/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Studies of Galactic structure and evolution have benefited enormously from Gaia kinematic information, though additional, intrinsic stellar parameters like age are required to best constrain Galactic models. Asteroseismology is the most precise method of providing such information for field star populations en masse, but existing samples for the most part have been limited to a few narrow fields of view by the CoRoT and Kepler missions. In an effort to provide well-characterized stellar parameters across a wide range in Galactic position, we present the second data release of red giant asteroseismic parameters for the K2 Galactic Archaeology Program (GAP). We provide {nu}_max_ and {Delta}{nu} based on six independent pipeline analyses; first-ascent red giant branch (RGB) and red clump (RC) evolutionary state classifications from machine learning; and ready-to-use radius and mass coefficients, {kappa}_R_ and {kappa}_M_, which, when appropriately multiplied by a solar-scaled effective temperature factor, yield physical stellar radii and masses. In total, we report 4395 radius and mass coefficients, with typical uncertainties of 3.3% (stat.) +/-1% (syst.) for {kappa}_R_ and 7.7% (stat.) +/-2% (syst.) for {kappa}_M_ among RGB stars, and 5.0% (stat.) +/-1% (syst.) for {kappa}_R_ and 10.5% (stat.) +/-2% (syst.) for {kappa}_M_ among RC stars. We verify that the sample is nearly complete- except for a dearth of stars with {nu}_max_<~10-20{mu}Hz-by comparing to Galactic models and visual inspection. Our asteroseismic radii agree with radii derived from Gaia Data Release 2 parallaxes to within 2.2%+/-0.3% for RGB stars and 2.0%+/-0.6% for RC stars.
- ID:
- ivo://CDS.VizieR/J/A+A/426/81
- Title:
- Kinematic analysis of the Minispiral
- Short Name:
- J/A+A/426/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained BEAR spectro-imaging data of the Galactic Center HII region "Sgr A West", also known as the "Minispiral", in the hydrogen Brackett {gamma} line (2.166 microns). Through multi-component line fitting, we have decomposed this HII region into nine overlapping velocity structures, for which we have extracted the line flux and radial velocity maps. We have then fitted a set of Keplerian orbits onto the radial velocity map of the most extended structure (the "Northern Arm"), assuming that it was orbiting the central black hole candidate Sgr A*. This fit allows us to propose a three-dimensional kinematic model for this structure, which is hereby given as a set of FITS files. In this model, the central mass, its location in the field, and the distance to the Galactic Center are fixed: we use a mass of 3e6 solar masses and a distance of 8kpc; the pixel scale is 0.353 arcsec/pix, Sgr A* is considered to be located at pixel (59.2538, 38.9849) (IDL notation: (0, 0) is the center of the lower-left pixel, add 1 for FITS convention).
- ID:
- ivo://CDS.VizieR/J/ApJ/753/62
- Title:
- Kinematic distance ambiguity in HII regions
- Short Name:
- J/ApJ/753/62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using H I absorption spectra from the International Galactic Plane Survey, a new method is implemented to resolve the kinematic distance ambiguity for 75 H II regions with known systemic velocities from radio recombination lines. A further 40 kinematic distance determinations are made for H II region candidates without known systemic velocities through an investigation of the presence of H I absorption around the terminal velocity. New kinematic distance determinations can be used to further constrain spiral arm parameters and the location and extent of other structures in the Milky Way disk. H I absorption toward continuum sources beyond the solar circle is also investigated. Follow-up studies of H I at higher resolution than the 1' to 2' of existing Galactic Plane Surveys will provide kinematic distances to many more H II regions on the far side of the Galactic center. On the basis of the velocity channel summation technique developed in this paper, a much larger sample of H II regions will be analyzed in a future paper to remove the near-far distance ambiguity.
