- ID:
- ivo://CDS.VizieR/J/MNRAS/404/1801
- Title:
- Horizon MareNostrum cosmological run
- Short Name:
- J/MNRAS/404/1801
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The correlation between the large-scale distribution of galaxies and their spectroscopic properties at z=1.5 is investigated using the Horizon MareNostrum cosmological run. We have extracted a large sample of 105 galaxies from this large hydrodynamical simulation featuring standard galaxy formation physics. Spectral synthesis is applied to these single stellar populations to generate spectra and colours for all galaxies. We use the skeleton as a tracer of the cosmic web and study how our galaxy catalogue depends on the distance to the skeleton. We show that galaxies closer to the skeleton tend to be redder but that the effect is mostly due to the proximity of large haloes at the nodes of the skeleton, rather than the filaments themselves. The virtual catalogues (spectroscopical properties of the MareNostrum galaxies at various redshifts) are available online at http://www.iap.fr/users/pichon/MareNostrum/catalogues.
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- ID:
- ivo://CDS.VizieR/J/A+A/563/A13
- Title:
- Horizontal branch stars in M22
- Short Name:
- J/A+A/563/A13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We obtained high-resolution spectra for 94 candidate stars belonging to the HB of M 22 with FLAMES. Previous works have indicated that this cluster has split subgiant (SGB) and red giant branches (RGB) and hosts two different stellar populations, differing in overall metal abundance and both exhibiting a Na-O anti-correlation. The HB stars we observed span a restricted temperature range (7800<Teff<11000K), where about 60% of the HB stars of M 22 are. Within our sample, we can distinguish three groups of stars segregated (though contiguous) in colours: Group 1 (49 stars) is metal-poor, N-normal, Na-poor and O-rich: our abundances for this (cooler) group match very well those determined for the primordial group of RGB stars (a third of the total) from previous studies. Group 2 (23 stars) is still metal-poor, but it is N- and Na-rich, though only very mildly depleted in O. We can identify this intermediate group as the progeny of the metal-poor RGB stars that occupy an intermediate location along the Na-O anti-correlation and include about 10% of the RGB stars. The third group (20 stars) is metal-rich, Na-rich, and O-rich. This hotter group likely corresponds to the most O-rich component of the previously found metal-rich RGB population (a quarter of the total). We did not observe any severely O-depleted stars and we think that the progeny of these stars falls on the hotter part of the HB. Furthermore, we found that the metal-rich population is also over-abundant in Sr, in agreement with results for corresponding RGB and SGB stars. However, we do not find any significant variation in the ratio between the sum of N and O abundances to Fe. We do not have C abundances for our stars. There is some evidence of an enhancement of He content for Groups 2 and 3 stars (Y=0.338+/-0.014+/-0.05); the error bar due to systematics is large, but a consistent analysis of data for several GCs confirms that stars in these groups within M22 are likely overabundant in He. We conclude that on the whole, our results agree with the proposition that chemical composition drives the location of stars along the HB of a GC. Furthermore, we found a number of fast rotators. They are concentrated in a restricted temperature range along the HB of M22. Fast rotating stars might be slightly less massive and bluer than slowly rotating ones, but other interpretations are possible.
- ID:
- ivo://CDS.VizieR/J/A+A/573/A92
- Title:
- Horizontal branch stars in NGC 6723
- Short Name:
- J/A+A/573/A92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used FLAMES+GIRAFFE (Medusa mode) at the VLT to obtain moderately high resolution spectra for 30 red horizontal branch (RHB) stars, 4 RR Lyrae variables, and 17 blue horizontal branch (BHB) stars in the low-concentration, moderately metal-rich globular cluster NGC 6723 ([Fe/H]=-1.22+/-0.08 from our present sample). The spectra were optimized to derive O and Na abundances. In addition, we obtained abundances for other elements, including N, Fe, Mg, Ca, Ni, and Ba. We used these data to discuss the evidence of a connection between the distribution of stars along the horizontal branch (HB) and the multiple populations that are typically present in globular clusters. We found that all RHB and most (13 out of 17) BHB stars are O-rich, Na-poor, and N-poor; these stars probably belong to the first stellar generation in this cluster. Only the four warmest observed stars are (moderately) O-poor, Na-rich, and N-rich, and they probably belong to the second generation. While our sample is not fully representative of the whole HB population in NGC 6723, our data suggest that in this cluster only HB stars warmer than ~9000K, that is one fourth of the total, belong to the second generation, if at all. Since in many other clusters this fraction is about two thirds, we conclude that the fraction of first/second generation in globular clusters may be strongly variable. In addition, the wide range in colour of chemically homogeneous first-generation HB stars requires a considerable spread in mass loss (>0.10M_{sun}_). The reason for this spread is yet to be understood. Finally, we found a high Ba abundance, with a statistically significant radial abundance gradient.
- ID:
- ivo://CDS.VizieR/J/ApJ/685/235
- Title:
- Host and companion galaxies in the SDSS
- Short Name:
- J/ApJ/685/235
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We measure the number of companions per galaxy (N_c_) as a function of r-band absolute magnitude for both the Sloan Digital Sky Survey (DR5) and the Croton and coworkers semianalytic catalog, 2006MNRAS.365...11C, applied to the Millennium Run simulation (Springel et al., 2005Natur.435..629S). For close pairs with projected separations of 5-20kpc/h, velocity differences less than 500km/s, and luminosity ratios between 1:2 and 2:1, we find good agreement between the observations and simulations, with N_c_ consistently close to 0.02 over the range -22<M_r_<-18. For larger pair separations, N_c_(M_r_) instead becomes increasingly steep toward the faint end, implying that luminosity-dependent clustering plays an important role on small scales. Using the simulations to assess and correct for projection effects, we infer that the real-space N_c_(M_r_) for close pairs peaks at about M^*^ and declines by at least a factor of 2 as M_r_ becomes fainter. Conversely, by measuring the number density of close companions, we estimate that at least 90% of all major mergers occur between galaxies which are fainter than L^*^. Finally, measurements of the luminosity density of close companions indicate that L^*^ galaxies likely dominate in terms of the overall importance of major mergers in the evolution of galaxy populations at low redshift.
- ID:
- ivo://CDS.VizieR/J/ApJ/473/713
- Title:
- Host galaxies of powerful radio sources
- Short Name:
- J/ApJ/473/713
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper describes those properties of the host galaxies of powerful radio sources that are unique to radio galaxies. The radio galaxies have redshifts up to z=0.5 and radio powers, P(408MHz), ranging from 10^25^ to 10^28^W.Hz^-1^ (H_0_=50km.s^-1^.Mpc^-1^ and q_0_=0). We find that the magnitudes, colors, and surface brightness profiles of these radio galaxies are very diverse. Their rest frame V magnitudes range from -24th to -20th magnitude and are 0.55+/-0.06mag fainter than those of brightest cluster members. Their (B-V) colors can be as red as those of brightest cluster members but may also be ~1 mag bluer. The optical structure of the low-redshift (0.03<z<0.25) radio galaxies may vary ranging from cD to N galaxy behaviour. Although the host galaxies of the low-redshift radio sources are generally "elliptical-like" galaxies, a comparison of the overall structure of radio galaxies to those of radio- quiet "generalized elliptical galaxies" of Schombert shows that only 17% are genuine elliptical galaxies, 9% have elliptical profiles with truncated halos, 26% are roughly elliptical but have disturbed surface brightness profiles, 16% are cD or D galaxies, 7% have double nuclei, and 21% are N galaxies. The only property that radio galaxies, as a class, have in common is that their sizes are relatively larger than those of normal elliptical galaxies of the same absolute magnitude. At the 22d isophote (in V) radio galaxies are 11% larger, at the 24th isophote they are 15% larger, and at the 25th isophote they are 20% larger. The host galaxies of the low-redshift (0.03<z<0.25) FR I and FR II sources have different properties. 69% of all FR I's are associated with cD-like or double nucleus galaxies, 19% with smooth ellipticals, and 13% with disturbed ellipticals; no FR I's are associated with N galaxies. 41% of all FR IIs are associated with N galaxies, 26% with smooth ellipticals, and 26% with disturbed ellipticals; no FR II's are associated with cD-like galaxies. The colors and color gradients are also different, with the FR II's having both bluer colors and a larger dispersion in their color gradients. Powerful FR I and FR II sources exhibit differing cosmological evolutions in their number counts. At low redshifts, almost all powerful sources are FR I's, and at high redshifts they are predominantly FR II's. We suggest that powerful FR I's prefer host galaxies that are the dominant central galaxies of relaxed groups and clusters, while FR II's are most often associated with violent galaxy encounters.
- ID:
- ivo://CDS.VizieR/J/ApJ/722/566
- Title:
- Host galaxies of SNe Ia in SDSS-II SN survey
- Short Name:
- J/ApJ/722/566
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the host galaxy dependences of Type Ia Supernovae (SNe Ia) from the full three year sample of the SDSS-II Supernova Survey. We re-discover, to high significance, the strong correlation between host galaxy type and the width of the observed SN light curve, i.e., fainter, quickly declining SNe Ia favor passive host galaxies, while brighter, slowly declining Ia's favor star-forming galaxies. We also find evidence (at between 2{sigma} and 3{sigma}) that SNe Ia are ~0.1+/-0.04mag brighter in passive host galaxies than in star-forming hosts, after the SN Ia light curves have been standardized using the light-curve shape and color variations. This difference in brightness is present in both the SALT2 and MCLS2k2 light-curve fitting methodologies. We see evidence for differences in the SN Ia color relationship between passive and star-forming host galaxies, e.g., for the MLCS2k2 technique, we see that SNe Ia in passive hosts favor a dust law of R_V_=1.0+/-0.2, while SNe Ia in star-forming hosts require R_V_=1.8^+0.2^_-0.4_. The significance of these trends depends on the range of SN colors considered. We demonstrate that these effects can be parameterized using the stellar mass of the host galaxy (with a confidence of >4{sigma}) and including this extra parameter provides a better statistical fit to our data. Our results suggest that future cosmological analyses of SN Ia samples should include host galaxy information.
- ID:
- ivo://CDS.VizieR/J/ApJ/770/107
- Title:
- Host galaxies of SNIa from SNfactory
- Short Name:
- J/ApJ/770/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometric and spectroscopic observations of galaxies hosting Type Ia supernovae (SNe Ia) observed by the Nearby Supernova Factory. Combining Galaxy Evolution Explorer (GALEX) UV data with optical and near-infrared photometry, we employ stellar population synthesis techniques to measure SN Ia host galaxy stellar masses, star formation rates (SFRs), and reddening due to dust. We reinforce the key role of GALEX UV data in deriving accurate estimates of galaxy SFRs and dust extinction. Optical spectra of SN Ia host galaxies are fitted simultaneously for their stellar continua and emission lines fluxes, from which we derive high-precision redshifts, gas-phase metallicities, and H{alpha}-based SFRs. With these data we show that SN Ia host galaxies present tight agreement with the fiducial galaxy mass-metallicity relation from Sloan Digital Sky Survey (SDSS) for stellar masses log(M_*_/M_{sun}_)>8.5 where the relation is well defined. The star formation activity of SN Ia host galaxies is consistent with a sample of comparable SDSS field galaxies, though this comparison is limited by systematic uncertainties in SFR measurements. Our analysis indicates that SN Ia host galaxies are, on average, typical representatives of normal field galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/458/84
- Title:
- Host galaxies of Superluminous Supernovae
- Short Name:
- J/MNRAS/458/84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Hubble Space Telescope (HST) Wide Field Camera 3 UV and near-IR (nIR) imaging of 21 Superluminous Supernovae (SLSNe) host galaxies, providing a sensitive probe of star formation and stellar mass within the hosts. Comparing the photometric and morphological properties of these host galaxies with those of core-collapse supernovae (CCSNe) and long-duration gamma-ray bursts (LGRBs), we find SLSN hosts are fainter and more compact at both UV and nIR wavelengths, in some cases we barely recover hosts with absolute magnitude around M_V_~=-14. With the addition of ground based optical observations and archival results, we produce spectral energy distribution fits to these hosts, and show that SLSN hosts possess lower stellar mass and star formation rates. This is most pronounced for the hydrogen deficient Type-I SLSN hosts, although Type-II H-rich SLSN host galaxies remain distinct from the bulk of CCSNe, spanning a remarkably broad range of absolute magnitudes, with ~30 per cent of SLSNe-II arising from galaxies fainter than M_nIR_~-14. The detection of our faintest SLSN hosts increases the confidence that SLSNe-I hosts are distinct from those of LGRBs in star formation rate and stellar mass, and suggests that apparent similarities in metallicity may be due to the limited fraction of hosts for which emission line metallicity measurements are feasible. The broad range of luminosities of SLSN-II hosts is difficult to describe by metallicity cuts, and does not match the expectations of any reasonable UV-weighted luminosity function, suggesting additional environmental constraints are likely necessary to yield hydrogen rich SLSNe.
- ID:
- ivo://CDS.VizieR/J/ApJ/830/13
- Title:
- Host-galaxy NUV-NIR data of 32 superluminous SNe
- Short Name:
- J/ApJ/830/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ultraviolet through near-infrared photometry and spectroscopy of the host galaxies of all superluminous supernovae (SLSNe) discovered by the Palomar Transient Factory prior to 2013 and derive measurements of their luminosities, star formation rates, stellar masses, and gas-phase metallicities. We find that Type I (hydrogen-poor) SLSNe (SLSNe I) are found almost exclusively in low-mass (M_*_<2x10^9^M_{sun}_) and metal-poor (12+log_10_[O/H]<8.4) galaxies. We compare the mass and metallicity distributions of our sample to nearby galaxy catalogs in detail and conclude that the rate of SLSNe I as a fraction of all SNe is heavily suppressed in galaxies with metallicities >~0.5Z_{sun}_. Extremely low metallicities are not required and indeed provide no further increase in the relative SLSN rate. Several SLSN I hosts are undergoing vigorous starbursts, but this may simply be a side effect of metallicity dependence: dwarf galaxies tend to have bursty star formation histories. Type II (hydrogen-rich) SLSNe (SLSNe II) are found over the entire range of galaxy masses and metallicities, and their integrated properties do not suggest a strong preference for (or against) low-mass/low-metallicity galaxies. Two hosts exhibit unusual properties: PTF 10uhf is an SLSN I in a massive, luminous infrared galaxy at redshift z=0.29, while PTF 10tpz is an SLSN II located in the nucleus of an early-type host at z=0.04.
- ID:
- ivo://CDS.VizieR/J/ApJ/614/671
- Title:
- Hot, dusty ultraluminous galaxies at z~2
- Short Name:
- J/ApJ/614/671
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report spectroscopic redshifts for 18 {mu}Jy radio galaxies at a mean redshift of z=2.2 that are faint at both submillimeter and optical wavelengths. While the radio fluxes of these galaxies could indicate far-IR luminosities comparable to high-redshift submillimeter-selected galaxies (>~10^12^L{Sun}), none are detected in the submillimeter.
