- ID:
- ivo://CDS.VizieR/J/A+A/606/A71
- Title:
- dSph RGB abundance and velocities
- Short Name:
- J/A+A/606/A71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From ESO VLT/FLAMES/GIRAFFE spectra, abundance measurements of Zn have been made in ~100 individual red giant branch (RGB) stars in the Sculptor dwarf spheroidal galaxy. This is the largest sample of individual Zn abundance measurements within a stellar system beyond the Milky Way. In the observed metallicity range, -2.7<=[Fe/H]<=-0.9, the general trend of Zn abundances in Sculptor is similar to that of {alpha}-elements. That is, super-solar abundance ratios of [Zn/Fe] at low metallicities, which decrease with increasing [Fe/H], eventually reaching subsolar values. However, at the higher metallicities in Sculptor, [Fe/H]>~-1.8, we find a significant scatter, -0.8<~[Zn/Fe]<~+0.4, which is not seen in any {alpha}-element. Our results are consistent with previous observations of a limited number of stars in Sculptor and in other dwarf galaxies. These results suggest that zinc has a complex nucleosynthetic origin, behaving neither completely like an {alpha}- nor an iron-peak element.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/779/7
- Title:
- dSph satellites of M31. I. Variables in And XIX
- Short Name:
- J/ApJ/779/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present B, V time-series photometry of Andromeda XIX (And XIX), the most extended (half-light radius of 6.2') of Andromeda's dwarf spheroidal companions, which we observed with the Large Binocular Cameras at the Large Binocular Telescope. We surveyed a 23'x23' area centered on And XIX and present the deepest color-magnitude diagram (CMD) ever obtained for this galaxy, reaching, at V~26.3mag, about one magnitude below the horizontal branch (HB). The CMD shows a prominent and slightly widened red giant branch, along with a predominantly red HB, which extends to the blue to significantly populate the classical instability strip. We have identified 39 pulsating variable stars, of which 31 are of RR Lyrae type and 8 are Anomalous Cepheids (ACs). Twelve of the RR Lyrae variables and three of the ACs are located within And XIX's half light radius. The average period of the fundamental mode RR Lyrae stars (<P_ab_>{=}0.62days, {sigma}=0.03days) and the period-amplitude diagram qualify And XIX as an Oosterhoff-Intermediate system. From the average luminosity of the RR Lyrae stars (<V(RR)>=25.34mag, {sigma}=0.10mag), we determine a distance modulus of (m-M)_0_=24.52+/-0.23mag in a scale where the distance to the Large Magellanic Cloud (LMC) is 18.5+/-0.1mag. The ACs follow a well-defined Period-Wesenheit (PW) relation that appears to be in very good agreement with the PW relationship defined by the ACs in the LMC.
- ID:
- ivo://CDS.VizieR/J/ApJ/835/208
- Title:
- 2D stellar kinematics of Mrk 1216
- Short Name:
- J/ApJ/835/208
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mrk 1216 is a nearby, early-type galaxy with a small effective radius of 2.8kpc and a large stellar velocity dispersion of 308km/s for its K-band luminosity of 1.4x10^11^L_{sun}_. Using integral field spectroscopy assisted by adaptive optics from Gemini North, we measure spatially resolved stellar kinematics within ~450pc of the galaxy nucleus. The galaxy exhibits regular rotation with velocities of +/-180km/s and a sharply peaked velocity dispersion profile that reaches 425km/s at the center. We fit axisymmetric, orbit-based dynamical models to the combination of these high angular resolution kinematics, large-scale kinematics extending to roughly three effective radii, and Hubble Space Telescope imaging, resulting in a constraint of the mass of the central black hole in Mrk 1216. After exploring several possible sources of systematics that commonly affect stellar-dynamical black hole mass measurements, we find a black hole mass of M_BH_=(4.9+/-1.7)x10^9^M_{sun}_ and an H-band stellar mass-to-light ratio of {Upsilon}_H_=1.3+/-0.4{Upsilon}_{sun}_ (1{sigma} uncertainties). Mrk 1216 is consistent with the local black hole mass-stellar velocity dispersion relation, but is a factor of ~5-10 larger than expectations from the black hole mass-bulge luminosity and black hole mass-bulge mass correlations when conservatively using the galaxy's total luminosity or stellar mass. This behavior is quite similar to the extensively studied compact galaxy NGC 1277. Resembling the z~2 quiescent galaxies, Mrk 1216 may be a passively evolved descendant, and perhaps reflects a previous era when galaxies contained over-massive black holes relative to their bulge luminosities/masses, and the growth of host galaxies had yet to catch up.
- ID:
- ivo://CDS.VizieR/J/ApJ/746/L22
- Title:
- Dual AGNs in the nearby Universe
- Short Name:
- J/ApJ/746/L22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the fraction of dual active galactic nuclei (AGNs) in a sample of 167 nearby (z < 0.05), moderate-luminosity, ultra-hard X-ray-selected AGNs from the all-sky Swift Burst Alert Telescope (BAT) survey. Combining new Chandra and Gemini observations together with optical and X-ray observations, we find that the dual AGN frequency at scales <100 kpc is ~10% (16/167). Of the 16 dual AGNs, only 3 (19%) were detected using X-ray spectroscopy and were not detected using emission line diagnostics. Close dual AGNs (<30 kpc) tend to be more common among the most X-ray luminous systems. In dual AGNs, the X-ray luminosity of both AGNs increases strongly with decreasing galaxy separation, suggesting that the merging event is key in powering both AGNs. Fifty percent of the AGNs with a very close companion (<15 kpc) are dual AGNs. We also find that dual AGNs are more likely to occur in major mergers and tend to avoid absorption line galaxies with elliptical morphologies. Finally, we find that SDSS Seyferts are much less likely than BAT AGNs (0.25% versus 7.8%) to be found in dual AGNs at scales <30 kpc because of a smaller number of companion galaxies, fiber collision limits, a tendency for AGNs at small separations to be detected only in X-rays, and a higher fraction of dual AGN companions with increasing AGN luminosity.
- ID:
- ivo://CDS.VizieR/J/MNRAS/300/417
- Title:
- Durham/UKST Galaxy Redshift Survey
- Short Name:
- J/MNRAS/300/417
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the radial velocities and blue, optical magnitudes for all of the galaxies within the Durham/UKST Galaxy Redshift Survey. This catalogue consists of ~2500 galaxy redshifts to a limiting apparent magnitude of B_J_~17mag, covering a ~1500deg^2^ area around the South Galactic Pole. The galaxies in this survey were selected from the Edinburgh/Durham Southern Galaxy Catalogue and were sampled, in order of apparent magnitude, at a rate of one galaxy in every three. The spectroscopy was performed at the 1.2-m UK Schmidt Telescope in Australia using the FLAIR multi-object spectrograph. We show that our radial velocity measurements made with this instrument have an empirical accuracy of +/-150km/s. The observational techniques and data reduction procedures used in the construction of this survey are also discussed. This survey demonstrates that the UKST can be used to make a three-dimensional map of the large-scale galaxy distribution, via a redshift survey to b_J_~17mag, over a wide area of the sky.
- ID:
- ivo://CDS.VizieR/J/ApJ/790/124
- Title:
- Dust and gas physics of the GOALS sample
- Short Name:
- J/ApJ/790/124
- Date:
- 13 Dec 2021 06:47:30
- Publisher:
- CDS
- Description:
- The Great Observatories All-sky LIRG Survey (GOALS) is a comprehensive, multiwavelength study of luminous infrared galaxies (LIRGs) in the local universe. Here, we present the results of a multi-component, spectral decomposition analysis of the low-resolution mid-infrared (MIR) Spitzer Infrared Spectrograph spectra from 5-38 {mu}m of 244 LIRG nuclei. The detailed fits and high-quality spectra allow for characterization of the individual polycyclic aromatic hydrocarbon (PAH) features, warm molecular hydrogen emission, and optical depths for both silicate dust grains and water ices. We find that starbursting LIRGs, which make up the majority of the GOALS sample, are very consistent in their MIR properties (i.e., {tau}_9.7 {mu}m_, {tau}_ice_, neon line ratios, and PAH feature ratios). However, as their EQW_6.2 {mu}m_decreases, usually an indicator of an increasingly dominant active galactic nucleus (AGN), LIRGs cover a larger spread in these MIR parameters. The contribution from PAH emission to the total IR luminosity (L(PAH)/L(IR)) in LIRGs varies from 2%-29% and LIRGs prior to their first encounter show significantly higher L(PAH)/L(IR) ratios on average. We observe a correlation between the strength of the starburst (represented by IR8 = L_IR_/L_8 {mu}m_) and the PAH fraction at 8 {mu}m but no obvious link between IR8 and the 7.7 to 11.3 PAH ratio, suggesting that the fractional photodissociation region (PDR) emission, and not the overall grain properties, is associated with the rise in IR8 for galaxies off the starburst main sequence. We detect crystalline silicate features in ~6% of the sample but only in the most obscure sources (s_9.7 {mu}m_< -1.24). Ice absorption features are observed in ~11% (56%) of GOALS LIRGs (ULIRGs) in sources with a range of silicate depths. Most GOALS LIRGs have L(H_2_)/L(PAH) ratios elevated above those observed for normal star-forming galaxies and exhibit a trend for increasing L(H_2_)/L(PAH) ratio with increasing L(H_2_). While star formation appears to be the dominant process responsible for exciting the H_2_ in most of the GOALS galaxies, a subset of LIRGs (~10%) shows excess H_2_emission that is inconsistent with PDR models and may be excited by shocks or AGN-induced outflows.
- ID:
- ivo://CDS.VizieR/J/A+A/527/A109
- Title:
- Dust and PAH emission SEDs of disk galaxies
- Short Name:
- J/A+A/527/A109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a self-consistent model of the spectral energy distributions (SEDs) of spiral galaxies from the ultraviolet (UV) to the mid-infrared (MIR)/far-infrared (FIR)/submillimeter (submm) based on a full radiative transfer calculation of the propagation of starlight in galaxy disks. This model predicts not only the total integrated energy absorbed in the UV/optical and re-emitted in the infrared/submm, but also the colours of the dust emission based on an explicit calculation of the strength and colour of the UV/optical radiation fields heating the dust, and incorporating a full calculation of the stochastic heating of small dust grains and PAH molecules. The geometry of the translucent components of the model is empirically constrained using the results from the radiation transfer analysis of Xilouris et al. on spirals in the middle range of the Hubble sequence, while the geometry of the optically thick components is constrained from physical considerations with a posteriori checks of the model predictions with observational data. These geometrical constraints enable the dust emission to be predicted in terms of a minimum set of free parameters: the central face-on dust opacity in the B-band {tau}^f^_B_, a clumpiness factor F for the star-forming regions, the star-formation rate SFR, the normalised luminosity of the old stellar population old and the bulge-to-disk ratio B/D. The results of the calculations are made available in the form of a large library of simulated dust emission SEDs spanning the whole parameter space of our model, together with the corresponding library of dust attenuation calculated using the same model.
- ID:
- ivo://CDS.VizieR/J/MNRAS/452/1412
- Title:
- Dust and SSP-stellar parameters of M82
- Short Name:
- J/MNRAS/452/1412
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use near ultraviolet and optical photometry to investigate the dust properties in the nearby starburst galaxy M82. By combining imaging from the Swift/UVOT instrument and optical data from the Sloan Digital Sky Survey, we derive the extinction curve parametrized by the standard R_V_ factor, and the strength of the NUV 2175 {AA} feature - quantified by a parameter B - out to projected galactocentric distances of 4 kpc. Our analysis is robust against possible degeneracies from the properties of the underlying stellar populations. Both B and R_V_ correlate with galactocentric distance, revealing a systematic trend of the dust properties. Our results confirm previous findings that dust in M82 is better fitted by a Milky Way standard extinction curve, in contrast to a Calzetti law. We find a strong correlation between R_V_ and B, towards a stronger NUV bump in regions with higher R_V_, possibly reflecting a distribution with larger dust grain sizes. The data we use were taken before SN2014J, and therefore can be used to probe the properties of the interstellar medium before the event. Our R_V_ values around the position of the supernova are significantly higher than recent measurements post-SN2014J (R_V_~1.4). This result is consistent with a significant change in the dust properties after the supernova event, either from disruption of large grains or from the contribution by an intrinsic circumstellar component. Intrinsic variations among supernovae not accounted for could also give rise to this mismatch.
- ID:
- ivo://CDS.VizieR/J/A+A/557/A137
- Title:
- Dust effects on photometric parameters in spirals
- Short Name:
- J/A+A/557/A137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a study to quantify the effects of dust on the derived photometric parameters of disk and bulges obtained from bulge-disk decomposition: scale-length, effective radius, Sersic index, disk axis-ratio, and bulge-to-disk ratio. The dust induced changes in these parameters were obtained by fitting simulated images of composite systems (containing a disk and a bulge) produced using radiative transfer calculations. The simulations were fitted with the GALFIT 3.0.2 data analysis algorithm. Fits were done with both a combination of an exponential plus a variable- index Sersic function as well as with a combination of two variable-index Sersic functions.
- ID:
- ivo://CDS.VizieR/J/A+A/553/A80
- Title:
- Dust effects on photometric parameters in spirals
- Short Name:
- J/A+A/553/A80
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a study made to quantify the effects of dust on the derived photometric parameters of disks (old and young stellar disks) and bulges: disk scale-lengths, axis-ratios, central surface-brightness, bulge effective radii, and Sersic indices. The changes in the derived photometric parameters from their intrinsic values (as would be seen in the absence of dust) were obtained by fitting simulated images of disks and bulges produced using radiative transfer calculations. The simulations were fitted with the GALFIT 3.0.2 data analysis algorithm and the fitted models were the commonly used infinitely thin disks described by exponential, general Sersic and de Vaucouleurs distributions.