- ID:
- ivo://CDS.VizieR/J/ApJ/819/53
- Title:
- Magellan/M2FS spectroscopy of Tucana 2 and Grus 1
- Short Name:
- J/ApJ/819/53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from spectroscopic observations with the Michigan/Magellan Fiber System (M2FS) of 147 stellar targets along the line of sight to the newly discovered "ultrafaint" stellar systems Tucana 2 (Tuc 2) and Grus 1 (Gru 1). Based on simultaneous estimates of line of sight velocity and stellar-atmospheric parameters, we identify 8 and 7 stars as probable members of Tuc 2 and and Gru 1, respectively. Our sample for Tuc 2 is sufficient to resolve an internal velocity dispersion of 8.6^+4.4^_-2.7_km/s about a mean of -129.1+/-3.5km/s (solar rest frame), and to estimate a mean metallicity of [Fe/H]=-2.23^+0.18^_-0.12_. These results place Tuc 2 on chemodynamical scaling relations followed by dwarf galaxies, suggesting a dominant dark matter component with dynamical mass 2.7^+3.1^_-1.3_x10^6^M_{sun}_ enclosed within the central ~160pc, and dynamical mass-to-light ratio 1913^+2234^_-950_M_{sun}_/L_{nu},{sun}_. For Gru 1 we estimate a mean velocity of -140.5^+2.4^_-1.6_km/s and a mean metallicity of [Fe/H]=-1.42^+0.55^_-0.42_ but our sample does not resolve Gru 1's velocity dispersion. The radial coordinates of Tuc 2 and Gru 1 in Galactic phase space suggest that their orbits are among the most energetic within a distance of <~300pc. Moreover, their proximity to each other in this space arises naturally if both objects are trailing the Large Magellanic Cloud.
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- ID:
- ivo://CDS.VizieR/J/ApJ/779/87
- Title:
- MAGIICAT. III. Virial masses
- Short Name:
- J/ApJ/779/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In Churchill et al. (2013ApJ...763L..42C), we used halo abundance matching applied to 182 galaxies in the MgII Absorber-Galaxy Catalog (MAGIICAT) and showed that the mean MgII{lambda}2796 equivalent width follows a tight inverse-square power law, W_r_(2796){prop.to}(D/R_vir_)^-2^, with projected location relative to the galaxy virial radius and that the MgII absorption covering fraction is effectively invariant with galaxy virial mass, M_h_, over the range 10.7<=logM_h_/M_{sun}_<=13.9. In this work, we explore multivariate relationships between W_r_(2796), virial mass, impact parameter, virial radius, and the theoretical cooling radius that further elucidate self-similarity in the cool/warm (T=10^4^-10^4.5^K) circumgalactic medium (CGM) with virial mass. We show that virial mass determines the extent and strength of the MgII absorbing gas such that the mean W_r_(2796) increases with virial mass at fixed distance while decreasing with galactocentric distance for fixed virial mass. The majority of the absorbing gas resides within D=~0.3R_vir_, independent of both virial mass and minimum absorption threshold; inside this region, and perhaps also in the region 0.3<D/R_vir_<=1, the mean W_r_(2796) is independent of virial mass. Contrary to absorber-galaxy cross-correlation studies, we show there is no anti-correlation between W_r_(2796) and virial mass. We discuss how simulations and theory constrained by observations support self-similarity of the cool/warm CGM via the physics governing star formation, gas-phase metal enrichment, recycling efficiency of galactic scale winds, filament and merger accretion, and overdensity of local environment as a function of virial mass.
- ID:
- ivo://CDS.VizieR/J/ApJ/776/114
- Title:
- MAGIICAT. I. MgII Absorber-Galaxy Catalog
- Short Name:
- J/ApJ/776/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the MgII Absorber-Galaxy Catalog, MAGIICAT, a compilation of 182 spectroscopically identified intermediate redshift (0.07<=z<=1.1) galaxies with measurements of MgII {lambda}{lambda}2796,2803 absorption from their circumgalactic medium within projected distances of 200kpc from background quasars. In this work, we present "isolated" galaxies, which are defined as having no spectroscopically identified galaxy within a projected distance of 100kpc and a line of sight velocity separation of 500km/s. We standardized all galaxy properties to the {Lambda}CDM cosmology and galaxy luminosities, absolute magnitudes, and rest-frame colors to the B- and K-band on the AB system. We present galaxy properties and rest-frame MgII equivalent width, W_r_(2796), versus galaxy redshift. The well-known anti-correlation between W_r_(2796) and quasar-galaxy impact parameter, D, is significant to the 8{sigma} level. The mean color of MAGIICAT galaxies is consistent with an Sbc galaxy for all redshifts. We also present B- and K-band luminosity functions for different W_r_(2796) and redshift subsamples: "weak absorbing" [W_r_(2796)<0.3{AA}], "strong absorbing" [W_r_(2796)>=0.3{AA}], low redshift (z{<}<z>), and high redshift (z{>=}<z>), where <z> = 0.359 is the median galaxy redshift. Rest-frame color B-K correlates with M_K_ at the 8{sigma} level for the whole sample but is driven by the strong absorbing, high-redshift subsample (6{sigma}). Using M_K_ as a proxy for stellar mass and examining the luminosity functions, we infer that in lower stellar mass galaxies, MgII absorption is preferentially detected in blue galaxies and the absorption is more likely to be weak.
- ID:
- ivo://CDS.VizieR/J/ApJ/857/145
- Title:
- MagLiteS Carina II and Carina III spectroscopy
- Short Name:
- J/ApJ/857/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Magellan/IMACS, Anglo-Australian Telescope/AAOmega+2dF, and Very Large Telescope/GIRAFFE+FLAMES spectroscopy of the Carina II (CarII) and Carina III (CarIII) dwarf galaxy candidates, recently discovered in the Magellanic Satellites Survey (MagLiteS). We identify 18 member stars in Car II, including two binaries with variable radial velocities and two RR Lyrae stars. The other 14 members have a mean heliocentric velocity v_hel_=477.2+/-1.2km/s and a velocity dispersion of {sigma}_v_=3.4_-0.8_^+1.2^km/s. Assuming Car II is in dynamical equilibrium, we derive a total mass within the half-light radius of 1.0_-0.4_^+0.8^x10^6^M_{sun}_, indicating a mass-to-light ratio of 369_-161_^+309^M_{sun}_/L_{sun}_. From equivalent width measurements of the calcium triplet lines of nine red giant branch (RGB) stars, we derive a mean metallicity of [Fe/H]=-2.44+/-0.09 with dispersion {sigma}_[Fe/H]_=0.22_-0.07_^+0.10^. Considering both the kinematic and chemical properties, we conclude that CarII is a dark-matter-dominated dwarf galaxy. For CarIII, we identify four member stars, from which we calculate a systemic velocity of v_hel_=284.6_-3.1_^+3.4^km/s. The brightest RGB member of CarIII has a metallicity of [Fe/H]=-1.97+/-0.12. Due to the small size of the Car III spectroscopic sample, we cannot conclusively determine its nature. Although these two systems have the smallest known physical separation ({Delta}d~10kpc) among Local Group satellites, the large difference in their systemic velocities, ~200km/s, indicates that they are unlikely to be a bound pair. One or both systems are likely associated with the Large Magellanic Cloud (LMC), and may remain LMC satellites today. No statistically significant excess of {gamma}-ray emission is found at the locations of Car II and Car III in eight years of Fermi-LAT data.
- ID:
- ivo://CDS.VizieR/J/A+A/642/A118
- Title:
- Magnetized disk-halo transition region of M51
- Short Name:
- J/A+A/642/A118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An excellent laboratory for studying large scale magnetic fields is the grand design face-on spiral galaxy M51. Due to wavelength-dependent Faraday depolarization, linearly polarized synchrotron emission at different radio frequencies gives a picture of the galaxy at different depths: Observations at L-band (1-2GHz) probe the halo region while at C- and Xband (4-8GHz) the linearly polarized emission probe the disk region of M51. We present new observations of M51 using the Karl G. Jansky Very Large Array (VLA) at S-band (2-4GHz), where previously no polarization observations existed, to shed new light on the transition region between the disk and the halo. We discuss a model of the depolarization of synchrotron radiation in a multilayer magneto-ionic medium and compare the model predictions to the multi-frequency polarization data of M51 between 1-8GHz. The new S-band data are essential to distinguish between different models. Our study shows that the initial model parameters, i.e. the total regular and turbulent magnetic field strengths in the disk and halo of M51, need to be adjusted to successfully fit the models to the data.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A146
- Title:
- MAGNUM survey galaxies images
- Short Name:
- J/A+A/622/A146
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the interstellar medium (ISM) properties of the disk and outflowing gas in the central regions of nine nearby Seyfert galaxies, all characterised by prominent single- or bi-conical outflows. These objects are part of the MAGNUM (Measuring Active Galactic Nuclei Under MUSE Microscope) survey, that aims at probing their physical conditions and ionisation mechanism, by exploiting the unprecedented sensitivity of the Multi Unit Spectroscopic Explorer (MUSE), combined with its spatial and spectral coverage. Specifically, we study the different properties of the gas in the disk and in the outflow with spatially and kinematically resolved maps, by dividing the strongest emission lines in velocity bins. We associate the core of the lines to the disk, consistent with the stellar velocity, and the redshifted and the blueshifted wings to the outflow. We measure the reddening, density, ionisation parameter and dominant ionisation source of the emitting gas for both components in each galaxy. We find that the outflowing gas is characterised by higher values of density and ionisation parameter than the disk, which presents a higher dust extinction. Moreover, we distinguish high- and low-ionisation regions across the portion of spatially resolved narrow line region (NLR) traced by the outflowing gas. The high ionisation regions characterised by the lowest [NII]/H{alpha} and [SII]/H{alpha} line ratios, generally trace the innermost parts along the axis of the emitting cones, where the [SIII]/[SII] line ratio is enhanced, while the low ionisation ones follow the cone edges and/or the regions perpendicular to the axis of the outflows, characterised also by a higher [OIII] velocity dispersion. A possible scenario to explain these features relies on the presence of two distinct population of line emitting clouds: one is optically thin to the radiation and characterised by the highest excitation, while the other, optically thick, is impinged by a filtered - and thus harder - radiation field, which generates strong low-excitation lines. The highest values of [NII]/H{alpha} and [SII]/H{alpha} line ratios may be due to shocks and/or a hard filtered radiation field from the AGN.
- ID:
- ivo://CDS.VizieR/J/AJ/126/1183
- Title:
- Major galaxy mergers at z<~3
- Short Name:
- J/AJ/126/1183
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents direct evidence for hierarchical galaxy assembly out to redshifts z~3. We identify major mergers using the model-independent CAS (concentration, asymmetry, clumpiness) physical morphological system on galaxies detected, and photometrically selected, in the WFPC2 and NICMOS Hubble Deep Field North. We specifically use the asymmetric distributions of rest-frame optical light measured through the asymmetry parameter (A) to determine the fraction of galaxies undergoing major mergers as a function of redshift (z), stellar mass (M*), and absolute magnitude (M_B_).
- ID:
- ivo://CDS.VizieR/J/MNRAS/494/1276
- Title:
- MALATANG survey NGC253 dense gas & SFR formation
- Short Name:
- J/MNRAS/494/1276
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to study the high-transition dense-gas tracers and their relationships to the star formation of the inner ~2kpc circumnuclear region of NGC 253, we present HCN J=4-3 and HCO^+^ J=4-3 maps obtained with the James Clerk Maxwell Telescope(JCMT). With the spatially resolved data, we compute the concentration indices r90/r50 for the different tracers. HCN and HCO^+^ 4-3 emission features tend to be centrally concentrated, which is in contrast to the shallower distribution of CO 1-0 and the stellar component. The dense-gas fraction (fdense, traced by the velocity-integrated-intensity ratios of HCN/CO and HCO^+^/CO) and the ratio R31 (CO 3-2/1-0) decline towards larger galactocentric distances, but increase with higher SFR surface density. The radial variation and the large scatter of fdense and R31 imply distinct physical conditions in different regions of the galactic disc. The relationships of fdense versus Sigma_stellar, and SFE_dense versus Sigma_stellar are explored. SFE_dense increases with higher Sigma_stellar in this galaxy, which is inconsistent with previous work that used HCN 1-0 data. This implies that existing stellar components might have different effects on the high-J HCN and HCO+ than their low-J emission. We also find that SFE_dense seems to be decreasing with higher f_dense which is consistent with previous works, and it suggests that the ability of the dense gas to form stars diminishes when the average density of the gas increases. This is expected in a scenario where only the regions with high-density contrast collapse and form stars.
- ID:
- ivo://CDS.VizieR/J/A+A/593/A126
- Title:
- Malin 1 images at 6 wavelengths
- Short Name:
- J/A+A/593/A126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Low surface brightness galaxies (LSBGs) represent a significant percentage of local galaxies but their formation and evolution remain elusive. They may hold crucial information for our understanding of many key issues (i.e., census of baryonic and dark matter, star formation in the low density regime, mass function). The most massive examples - the so called giant LSBGs - can be as massive as the Milky Way, but with this mass being distributed in a much larger disk. Malin 1 is an iconic giant LSBG - perhaps the largest disk galaxy known. We attempt to bring new insights on its structure and evolution on the basis of new images covering a wide range in wavelength. We have computed surface brightness profiles (and average surface brightnesses in 16 regions of interest), in six photometric bands (FUV, NUV, u, g, i, z). We compared these data to various models, testing a variety of assumptions concerning the formation and evolution of Malin 1.
2170. MALT90 Catalogue
- ID:
- ivo://CDS.VizieR/J/other/PASA/33.30
- Title:
- MALT90 Catalogue
- Short Name:
- J/other/PASA/33.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Millimetre Astronomy Legacy Team 90GHz survey aims to characterise the physical and chemical evolution of high-mass clumps. Recently completed, it mapped 90GHz line emission towards 3246 high-mass clumps identified from the ATLASGAL 870um Galactic plane survey. By utilising the broad frequency coverage of the Mopra telescope's spectrometer, maps in 16 different emission lines were simultaneously obtained. Here, we describe the first catalogue of the detected line emission, generated by Gaussian profile fitting to spectra extracted towards each clumps' 870um dust continuum peak. Synthetic spectra show that the catalogue has a completeness of >95%, a probability of a false-positive detection of <0.3%, and a relative uncertainty in the measured quantities of <20% over the range of detection criteria. The detection rates are highest for the (1-0) transitions of HCO^+^, HNC, N_2_H^+^, and HCN (~77-89%). Almost all clumps (~95%) are detected in at least one of the molecular transitions, just over half of the clumps (~53%) are detected in four or more of the transitions, while only one clump is detected in 13 transitions. We find several striking trends in the ensemble of properties for the different molecular transitions when plotted as a function of the clumps' evolutionary state as estimated from Spitzer mid-IR images, including (1) HNC is relatively brighter in colder, less evolved clumps than those that show active star formation, (2) N2H+ is relatively brighter in the earlier stages, (3) that the observed optical depth decreases as the clumps evolve, and (4) the optically thickest HCO^+^ emission shows a 'blue-red asymmetry' indicating overall collapse that monotonically decreases as the clumps evolve. This catalogue represents the largest compiled database of line emission towards high-mass clumps and is a valuable data set for detailed studies of these objects.
