- ID:
- ivo://CDS.VizieR/J/AJ/131/2035
- Title:
- B and R magnitudes for spiral galaxies
- Short Name:
- J/AJ/131/2035
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is an observational fact that bulges of spiral galaxies contain a high fraction of old and metal-rich stars. Following this observational fact, we have investigated the colors of 21 bulges hosted by a selected sample of high surface brightness spiral galaxies and low surface brightness galaxies observed in the B and R optical bands and the J and Ks near-IR bands.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/355/1251
- Title:
- Bar-induced strengths in spiral galaxies
- Short Name:
- J/MNRAS/355/1251
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Bar-induced perturbation strengths are calculated for a well-defined magnitude-limited sample of 180 spiral galaxies, based on the Ohio State University Bright Galaxy Survey. We use a gravitational torque method, the ratio of the maximal tangential force to the mean axisymmetric radial force, as a quantitative measure of the bar strength.
- ID:
- ivo://CDS.VizieR/J/ApJ/869/50
- Title:
- Barium abundances of red giant branch stars
- Short Name:
- J/ApJ/869/50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- There are many candidate sites of the r-process: core-collapse supernovae (CCSNe; including rare magnetorotational core-collapse supernovae), neutron star mergers (NSMs), and neutron star/black hole mergers. The chemical enrichment of galaxies --specifically dwarf galaxies-- helps distinguish between these sources based on the continual build-up of r-process elements. This technique can distinguish between the r-process candidate sites by the clearest observational difference --how quickly these events occur after the stars are created. The existence of several nearby dwarf galaxies allows us to measure robust chemical abundances for galaxies with different star formation histories. Dwarf galaxies are especially useful because simple chemical evolution models can be used to determine the sources of r-process material. We have measured the r-process element barium with Keck/DEIMOS medium-resolution spectroscopy. We present the largest sample of barium abundances (almost 250 stars) in dwarf galaxies ever assembled. We measure [Ba/Fe] as a function of [Fe/H] in this sample and compare with existing [{alpha}/Fe] measurements. We have found that a large contribution of barium needs to occur at more delayed timescales than CCSNe in order to explain our observed abundances, namely the significantly more positive trend of the r-process component of [Ba/Fe] versus [Fe/H] seen for [Fe/H]<~-1.6 when compared to the [Mg/Fe] versus [Fe/H] trend. We conclude that NSMs are the most likely source of r-process enrichment in dwarf galaxies at early times.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A34
- Title:
- Barlenses in the CALIFA survey
- Short Name:
- J/A+A/618/A34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is theoretically predicted that, at low galaxy inclinations, boxy/peanut bar components have a barlens appearance of a round central component embedded in the narrow bar. We investigate barlenses in the Calar Alto Legacy Integral Field Area (CALIFA) survey galaxies, studying their morphologies, stellar populations, and metallicities. We show that, when present, barlenses account for a significant portion of light of photometric bulges, i.e., the excess light on top of the disks, which highlights the importance of bars in accumulating central galaxy mass concentrations in the cosmic timescale. We made multi-component decompositions for a sample of 46 barlens galaxies drawn from the CALIFA survey, where M_{star}_/M_{sun}_=10^9.7^-10^11.4^ and z=0.005-0.03. Unsharp masks of the Sloan Digital Sky Survey (SDSS) r'-band mosaics were used to identify the boxy/peanut or X-shaped features. Barlenses are identified in the images using our simulation snapshots as an additional guide. Our decompositions with GALFIT include bulges, disks, and bars as well as barlenses as a separate component. For 26 of the decomposed galaxies the CALIFA DR2 V500 grating data cubes were used to explore stellar ages and metallicities at the regions of various structure components. We find that 25+/-2% of the 1064 galaxies in the whole CALIFA sample show either X-shaped or barlens features. In the decomposed galaxies with barlenses, on average 13%+/-2% of the total galaxy light belongs to this component, leaving less than 10% for possible separate bulge components. Most importantly, bars and barlenses are found to have similar cumulative stellar age and metallicity distributions. The metallicities in barlenses are on average near solar, but exhibit a large range. In some of the galaxies barlenses and X-shaped features appear simultaneously, in which case the bar origin of the barlens is unambiguous. This is the first time that a combined morphological and stellar population analysis is used to study barlenses. We show that their stars are accumulated in a prolonged time period concurrently with the evolution of the narrow bar.
- ID:
- ivo://CDS.VizieR/J/MNRAS/473/4731
- Title:
- Barred galaxies structural decomposition
- Short Name:
- J/MNRAS/473/4731
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of two-component (disc+bar) and three-component (disc+bar+bulge) multiwavelength 2D photometric decompositions of barred galaxies in five Sloan Digital Sky Survey (SDSS) bands (ugriz). This sample of ~3500 nearby (z<0.06) galaxies with strong bars selected from the Galaxy Zoo citizen science project is the largest sample of barred galaxies to be studied using photometric decompositions that include a bar component. With detailed structural analysis, we obtain physical quantities such as the bar- and bulge-to-total luminosity ratios, effective radii, Sersic indices and colours of the individual components. We observe a clear difference in the colours of the components, the discs being bluer than the bars and bulges. An overwhelming fraction of bulge components have Sersic indices consistent with being pseudo-bulges. By comparing the barred galaxies with a mass-matched and volume-limited sample of unbarred galaxies, we examine the connection between the presence of a large-scale galactic bar and the properties of discs and bulges. We find that the discs of unbarred galaxies are significantly bluer compared to the discs of barred galaxies, while there is no significant difference in the colours of the bulges. We find possible evidence of secular evolution via bars that leads to the build-up of pseudo-bulges and to the quenching of star formation in the discs. We identify a subsample of unbarred galaxies with an inner lens/oval and find that their properties are similar to barred galaxies, consistent with an evolutionary scenario in which bars dissolve into lenses. This scenario deserves further investigation through both theoretical and observational work.
- ID:
- ivo://CDS.VizieR/J/MNRAS/439/1749
- Title:
- Barred S0 galaxies in the Coma cluster
- Short Name:
- J/MNRAS/439/1749
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This study uses r-band images from the Eighth Data Release of the Sloan Digital Sky Survey (SDSS DR8) to study bars in lenticular (S0) galaxies in one of the nearest rich cluster environments, the Coma cluster. We develop techniques for bar detection and assess their success when applied to SDSS image data. To detect and characterize bars, we perform 2D bulge+disc+bar light decompositions of galaxy images with galfit. Using a sample of artificial galaxy images, we determine the faintest magnitude at which bars can be successfully measured at the depth and resolution of SDSS. We perform detailed decompositions of 83 S0 galaxies in Coma, 64 from a central sample, and 19 from a cluster outskirt sample. For the central sample, the S0 bar fraction is 72^+5^_-6_%. This value is significantly higher than that obtained using an ellipse-fitting method for bar detection, 48^+6^_-6_%. At a fixed luminosity, barred S0s are redder in g-r colour than unbarred S0s by 0.02mag. The frequency and strength of bars increase towards fainter luminosities. Neither central metallicity nor stellar age distributions differ significantly between barred and unbarred S0s. There is an increase in the bar fraction towards the cluster core, but this is at a low significance level. Bars have at most a weak correlation with cluster-centric radius.
- ID:
- ivo://CDS.VizieR/J/A+A/584/A88
- Title:
- Barred & unbarred galaxies N, O abundance ratio
- Short Name:
- J/A+A/584/A88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Bar-induced gas inflows towards galaxy centres are recognised as a key agent for the secular evolution of galaxies. One immediate consequence of this inflow is the accumulation of gas in the centre of galaxies where it can form stars and alter the chemical and physical properties. Our aim is to study whether the properties of the ionised gas in the central parts of barred galaxies are altered by the presence of a bar and whether the change in central properties is related to bar and/or parent galaxy properties. We use a sample of nearby face-on disc galaxies with available SDSS spectra, morphological decomposition, and information on the stellar population of their bulges, to measure the internal Balmer extinction from the H{alpha} to H{beta} line ratio, star formation rate, and relevant line ratios to diagnose chemical abundances and gas density.
- ID:
- ivo://CDS.VizieR/J/A+A/542/A34
- Title:
- Baryon Acoustic Oscillations in LRGs
- Short Name:
- J/A+A/542/A34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Baryon Acoustic Oscillations (BAO) have been previously detected using correlation functions and power spectra of the galaxy distribution. In this work, we present a new method for the detection of the real-space structures associated with this feature. These baryon acoustic structures are spherical shells with a relatively small density contrast, surrounding high density central regions. We design a specific wavelet adapted to the search for shells, and exploit the physics of the process by making use of two different mass tracers, introducing a specific statistic to detect the BAO features. We apply our method to the detection of BAO in a galaxy sample drawn from the Sloan Digital Sky Survey (SDSS). We use the 'Main' catalogue to trace the shells, and the Luminous Red Galaxies (LRG) as tracers of the high density central regions.
- ID:
- ivo://CDS.VizieR/J/ApJ/791/128
- Title:
- Basic galaxy data for spiral-rich group members
- Short Name:
- J/ApJ/791/128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope, the COS Science Team has conducted a high signal-to-noise survey of 14 bright QSOs. In a previous paper (Savage et al., 2014ApJS..212....8S), these far-UV spectra were used to discover 14 "warm" (T >= 10^5^ K) absorbers using a combination of broad Ly{alpha} and broad O VI absorptions. A reanalysis of a few of this new class of absorbers using slightly relaxed fitting criteria finds as many as 20 warm absorbers could be present in this sample. A shallow, wide spectroscopic galaxy redshift survey has been conducted around these sight lines to investigate the warm absorber environment, which is found to be spiral-rich groups or cluster outskirts with radial velocity dispersions {sigma}=250-750 km/s. While 2{sigma} evidence is presented favoring the hypothesis that these absorptions are associated with the galaxy groups and not with the individual, nearest galaxies, this evidence has considerable systematic uncertainties and is based on a small sample size so it is not entirely conclusive. If the associations are with galaxy groups, the observed frequency of warm absorbers (idN/dz = 3.5-5 per unit redshift) requires them to be very extended as an ensemble on the sky (~1 Mpc in radius at high covering factor). Most likely these warm absorbers are interface gas clouds whose presence implies the existence of a hotter (T ~ 10^6.5^ K), diffuse, and probably very massive (>10^11^ M_{sun}_) intra-group medium which has yet to be detected directly.
- ID:
- ivo://CDS.VizieR/J/ApJS/252/29
- Title:
- BAT AGN Spectroscopic Survey. XX. Molecular gas
- Short Name:
- J/ApJS/252/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the host-galaxy molecular gas properties of a sample of 213 nearby (0.01<z<0.05) hard-X-ray-selected active galactic nucleus (AGN) galaxies, drawn from the 70-month catalog of Swift's Burst Alert Telescope (BAT), with 200 new CO(2-1) line measurements obtained with the James Clerk Maxwell Telescope and the Atacama Pathfinder Experiment telescope. We find that AGN in massive galaxies (log(M_*_/M_{sun}_)>10.5) tend to have more molecular gas and higher gas fractions than inactive galaxies matched in stellar mass. When matched in star formation, we find AGN galaxies show no difference from inactive galaxies, with no evidence that AGN feedback affects the molecular gas. The higher molecular gas content is related to AGN galaxies hosting a population of gas-rich early types with an order of magnitude more molecular gas and a smaller fraction of quenched, passive galaxies (~5% versus 49%) compared to inactive galaxies. The likelihood of a given galaxy hosting an AGN (L_bol_>10^44^erg/s) increases by ~10-100 between a molecular gas mass of 10^8.7^M_{sun}_ and 10^10.2^M_{sun}_. AGN galaxies with a higher Eddington ratio (log(L/L_Edd_)>-1.3) tend to have higher molecular gas masses and gas fractions. The log(NH/cm^-2^)>23.4) of AGN galaxies with higher column densities are associated with lower depletion timescales and may prefer hosts with more gas centrally concentrated in the bulge that may be more prone to quenching than galaxy-wide molecular gas. The significant average link of host-galaxy molecular gas supply to supermassive black hole (SMBH) growth may naturally lead to the general correlations found between SMBHs and their host galaxies, such as the correlations between SMBH mass and bulge properties, and the redshift evolution of star formation and SMBH growth.
