- ID:
- ivo://CDS.VizieR/J/ApJS/173/185
- Title:
- GALEX ultraviolet atlas of nearby galaxies
- Short Name:
- J/ApJS/173/185
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present images, integrated photometry, and surface-brightness and color profiles for a total of 1034 nearby galaxies recently observed by the Galaxy Evolution Explorer (GALEX) satellite in its far-ultraviolet (FUV; lambda_eff_=1516{AA}) and near-ultraviolet (NUV; lambda_eff_=2267{AA}) bands. Our catalog of objects is derived primarily from the GALEX Nearby Galaxies Survey (NGS) supplemented by galaxies larger than 1' in diameter serendipitously found in these fields and in other GALEX exposures of similar of greater depth. The sample analyzed here adequately describes the distribution and full range of properties (luminosity, color, star formation rate [SFR]) of galaxies in the local universe.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/172/615
- Title:
- GALFIT result for GEMS galaxies
- Short Name:
- J/ApJS/172/615
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the context of measuring the structures of intermediate-redshift galaxies with HST ACS surveys, we tune, test, and compare two widely used fitting codes (GALFIT and GIM2D) for fitting single-component Sersic models to both simulated and real galaxy data. Our study focuses on the GEMS survey (Rix et al., 2004ApJS..152..163R) with the sensitivity of typical HST survey data, and we include our final catalog of fit results for all 41495 objects detected in GEMS. Using simulations, we find that fitting accuracy depends sensitively on galaxy profile shape.
- ID:
- ivo://CDS.VizieR/J/A+A/617/A113
- Title:
- GalMer S0 remnants morphological properties
- Short Name:
- J/A+A/617/A113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Major mergers are popularly considered too destructive to produce the relaxed regular structures and the morphological inner components (ICs) usually observed in lenticular (S0) galaxies. We have tested if major mergers can produce remnants with realistic S0 morphologies. We have selected a sample of relaxed discy remnants resulting from the dissipative merger simulations of the GalMer database and derived their morphological properties mimicking the typical conditions of current observational data. Only ~1-2Gyr after the full merger, we find that: 1) many remnants (67 major and 29 minor events) present relaxed structures and typical S0 or E/S0 morphologies, for a wide variety of orbits and even in gas-poor cases. 2) Most of them do not exhibit any morphological traces of their past merger origin under typical observing conditions and at distances as nearby as 30Mpc. 3) The merger relics are more persistent in minor mergers than in major ones for similar relaxing time periods. 4) No major-merger S0-like remnant develops a significant bar. 5) Nearly 58% of the major-merger S0 remnants host visually detectable ICs, such as embedded inner discs, rings, pseudo-rings, inner spirals, nuclear bars, and compact sources, very frequent in real S0s too. 6) All remnants contain a lens or oval, identically ubiquitous in local S0s. 7) These lenses and ovals do not come from bar dilution in major-merger cases, but are associated with stellar halos or embedded inner discs instead (thick or thin). We conclude that the relaxed morphologies, lenses, ovals, and other ICs of real S0s do not necessarily come from internal secular evolution, gas infall, or environmental mechanisms, as traditionally assumed, but they can result from major mergers as well.
- ID:
- ivo://CDS.VizieR/J/ApJS/237/11
- Title:
- Gal. redshift survey near HST/COS AGN sight lines
- Short Name:
- J/ApJS/237/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To establish the connection between galaxies and UV-detected absorption systems in the local universe, a deep (g<=20) and wide (~20' radius) galaxy redshift survey is presented around 47 sight lines to UV-bright AGNs observed by the Cosmic Origins Spectrograph (COS). Specific COS science team papers have used this survey to connect absorbers to galaxies, groups of galaxies, and large-scale structures, including voids. Here we present the technical details of the survey and the basic measurements required for its use, including redshifts for individual galaxies and uncertainties determined collectively by spectral class (emission-line, absorption-line, and composite spectra) and completeness for each sight line as a function of impact parameter and magnitude. For most of these sight lines, the design criteria of >90% completeness over a >1Mpc region down to <~0.1L* luminosities at z<=0.1 allows a plausible association between low-z absorbers and individual galaxies. Ly{alpha} covering fractions are computed to approximate the star-forming and passive galaxy populations using the spectral classes above. In agreement with previous results, the covering fraction of star-forming galaxies with L>=0.3L* is consistent with unity inside one virial radius and declines slowly to >50% at four virial radii. On the other hand, passive galaxies have lower covering fractions (~60%) and a shallower decline with impact parameter, suggesting that their gaseous halos are patchy but have a larger scale-length than star-forming galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/449/4277
- Title:
- GAMA blended spectra catalogue
- Short Name:
- J/MNRAS/449/4277
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the catalogue of blended galaxy spectra from the Galaxy And Mass Assembly (GAMA) survey. These are cases where light from two galaxies are significantly detected in a single GAMA fibre. Galaxy pairs identified from their blended spectrum fall into two principal classes: they are either strong lenses, a passive galaxy lensing an emission-line galaxy; or occulting galaxies, serendipitous overlaps of two galaxies, of any type. Blended spectra can thus be used to reliably identify strong lenses for follow-up observations (high-resolution imaging) and occulting pairs, especially those that are a late-type partly obscuring an early-type galaxy which are of interest for the study of dust content of spiral and irregular galaxies. The GAMA survey setup and its AUTOZ automated redshift determination were used to identify candidate blended galaxy spectra from the cross-correlation peaks. We identify 280 blended spectra with a minimum velocity separation of 600km/s, of which 104 are lens pair candidates, 71 emission-line-passive pairs, 78 are pairs of emission-line galaxies and 27 are pairs of galaxies with passive spectra. We have visually inspected the candidates in the Sloan Digital Sky Survey (SDSS) and Kilo Degree Survey (KiDS) images. Many blended objects are ellipticals with blue fuzz (Ef in our classification). These latter 'Ef' classifications are candidates for possible strong lenses, massive ellipticals with an emission-line galaxy in one or more lensed images. The GAMA lens and occulting galaxy candidate samples are similar in size to those identified in the entire SDSS. This blended spectrum sample stands as a testament of the power of this highly complete, second-largest spectroscopic survey in existence and offers the possibility to expand e.g. strong gravitational lens surveys.
- ID:
- ivo://CDS.VizieR/J/MNRAS/475/788
- Title:
- GAMA blue spheroids within 87 Mpc
- Short Name:
- J/MNRAS/475/788
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we test if nearby blue spheroid (BSph) galaxies may become the progenitors of star-forming spiral galaxies or passively evolving elliptical galaxies. Our sample comprises 428 galaxies of various morphologies in the redshift range 0.002<z<0.02 (8-87Mpc) with panchromatic data from the Galaxy and Mass Assembly survey. We find that BSph galaxies are structurally (mean effective surface brightness, effective radius) very similar to their passively evolving red counterparts. However, their star formation and other properties such as colour, age, and metallicity are more like star-forming spirals than spheroids (ellipticals and lenticulars). We show that BSph galaxies are statistically distinguishable from other spheroids as well as spirals in the multidimensional space mapped by luminosity-weighted age, metallicity, dust mass, and specific star formation rate. We use HI data to reveal that some of the BSphs are (further) developing their discs, hence their blue colours. They may eventually become spiral galaxies - if sufficient gas accretion occurs - or more likely fade into low-mass red galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/477/4116
- Title:
- GAMA. galaxy structure across green valley
- Short Name:
- J/MNRAS/477/4116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a sample of 472 local Universe (z<0.06) galaxies in the stellar mass range 10.25<logM*/M_{sun}_<10.75, we explore the variation in galaxy structure as a function of morphology and galaxy colour. Our sample of galaxies is sub-divided into red, green and blue colour groups and into elliptical and non-elliptical (disk-type) morphologies. Using KiDS and VIKING derived postage stamp images, a group of eight volunteers visually classified bars, rings, morphological lenses, tidal streams, shells and signs of merger activity for all systems. We find a significant surplus of rings (2.3{sigma}) and lenses (2.9{sigma}) in disk-type galaxies as they transition across the green valley. Combined, this implies a joint ring/lens green valley surplus significance of 3.3{sigma} relative to equivalent disk-types within either the blue cloud or the red sequence. We recover a bar fraction of ~44% which remains flat with colour, however, we find that the presence of a bar acts to modulate the incidence of rings and (to a lesser extent) lenses, with rings in barred disk-type galaxies more common by ~20-30 percentage points relative to their unbarred counterparts, regardless of colour. Additionally, green valley disk-type galaxies with a bar exhibit a significant 3.0{sigma} surplus of lenses relative to their blue/red analogues. The existence of such structures rules out violent transformative events as the primary end-of-life evolutionary mechanism, with a more passive scenario the favoured candidate for the majority of galaxies rapidly transitioning across the green valley.
- ID:
- ivo://CDS.VizieR/J/MNRAS/462/4336
- Title:
- GAMA. Stellar mass budget
- Short Name:
- J/MNRAS/462/4336
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We build on a recent photometric decomposition analysis of 7506 Galaxy and Mass Assembly (GAMA) survey galaxies to derive stellar mass function fits to individual spheroid and disc component populations down to a lower mass limit of log(M_*_/M_{sun}_)=8. We find that the spheroid/disc mass distributions for individual galaxy morphological types are well described by single Schechter function forms. We derive estimates of the total stellar mass densities in spheroids ({rho}_spheroid_=1.24+/-0.49x10^8^M_{sun}_Mpc^-3^h_0.7_) and discs ({rho}_disc_=1.20+/-0.45x10^8^M_{sun}_Mpc^-3^h_0.7_), which translates to approximately 50 per cent of the local stellar mass density in spheroids and 48 per cent in discs. The remaining stellar mass is found in the dwarf 'little blue spheroid' class, which is not obviously similar in structure to either classical spheroid or disc populations. We also examine the variation of component mass ratios across galaxy mass and group halo mass regimes, finding the transition from spheroid to disc mass dominance occurs near galaxy stellar mass ~10^11^M_{sun}_ and group halo mass ~10^12.5^M_{sun}_/h. We further quantify the variation in spheroid-to-total mass ratio with group halo mass for central and satellite populations as well as the radial variation of this ratio within groups.
- ID:
- ivo://CDS.VizieR/J/ApJ/894/88
- Title:
- {gamma}-ray emission of star-forming galaxies
- Short Name:
- J/ApJ/894/88
- Date:
- 19 Jan 2022 13:04:51
- Publisher:
- CDS
- Description:
- A majority of the {gamma}-ray emission from star-forming galaxies is generated by the interaction of high-energy cosmic rays with the interstellar gas and radiation fields. Star-forming galaxies are expected to contribute to both the extragalactic {gamma}-ray background and the IceCube astrophysical neutrino flux. Using roughly 10yr of {gamma}-ray data taken by the Fermi Large Area Telescope, in this study we constrain the {gamma}-ray properties of star-forming galaxies. We report the detection of 11 bona fide {gamma}-ray-emitting galaxies and 2 candidates. Moreover, we show that the cumulative {gamma}-ray emission of below-threshold galaxies is also significantly detected at ~5{sigma} confidence. The {gamma}-ray luminosity of resolved and unresolved galaxies is found to correlate with the total (8-1000{mu}m) infrared luminosity as previously determined. Above 1GeV, the spectral energy distribution of resolved and unresolved galaxies is found to be compatible with a power law with a photon index of ~2.2-2.3. Finally, we find that star-forming galaxies account for roughly 5% and 3% of the extragalactic {gamma}-ray background and the IceCube neutrino flux, respectively.
1230. {gamma}-ray loud blazars
- ID:
- ivo://CDS.VizieR/J/ApJ/726/16
- Title:
- {gamma}-ray loud blazars
- Short Name:
- J/ApJ/726/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The radio properties of blazars detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been observed as part of the VLBA Imaging and Polarimetry Survey. This large, flux-limited sample of active galactic nuclei (AGNs) provides insights into the mechanism that produces strong {gamma}-ray emission. At lower flux levels, radio flux density does not directly correlate with {gamma}-ray flux. We find that the LAT-detected BL Lac objects tend to be similar to the non-LAT BL Lac objects, but that the LAT-detected FSRQs are often significantly different from the non-LAT FSRQs. The differences between the {gamma}-ray loud and quiet FSRQs can be explained by Doppler boosting; these objects appear to require larger Doppler factors than those of the BL Lac objects. It is possible that the {gamma}-ray loud FSRQs are fundamentally different from the {gamma}-ray quiet FSRQs. Strong polarization at the base of the jet appears to be a signature for {gamma}-ray loud AGNs.