- ID:
- ivo://CDS.VizieR/J/ApJ/742/89
- Title:
- Relations between spectra and colors of SNe Ia
- Short Name:
- J/ApJ/742/89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To understand how best to use observations of Type Ia supernovae (SNe Ia) to obtain precise and accurate distances, we investigate the relations between spectra of SNe Ia and their intrinsic colors. Using a sample of 1630 optical spectra of 255 SNe, based primarily on data from the CfA Supernova Program, we examine how the velocity evolution and line strengths of SiII(6355) and CaII H&K are related to the B-V color at peak brightness. We find that the maximum-light velocity of SiII6355 and CaII H&K and the maximum-light pseudo-equivalent width of SiII6355 are correlated with intrinsic color, with intrinsic color having a linear relation with the SiII6355 measurements. CaII H&K does not have a linear relation with intrinsic color, but lower-velocity SNe tend to be intrinsically bluer. Combining the spectroscopic measurements does not improve intrinsic color inference. The intrinsic color scatter is larger for higher-velocity SNe Ia - even after removing a linear trend with velocity - indicating that lower-velocity SNe Ia are more "standard crayons". Employing information derived from SN Ia spectra has the potential to improve the measurements of extragalactic distances and the cosmological properties inferred from them.
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- ID:
- ivo://CDS.VizieR/J/ApJ/887/196
- Title:
- REQUIEM survey. I. Ly{alpha} halos around QSOs
- Short Name:
- J/ApJ/887/196
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The discovery of quasars a few hundred megayears after the Big Bang represents a major challenge to our understanding of black holes as well as galaxy formation and evolution. Quasars' luminosity is produced by extreme gas accretion onto black holes, which have already reached masses of M_BH_>10^9^M_{sun}_ by z~6. Simultaneously, their host galaxies form hundreds of stars per year, using up gas in the process. To understand which environments are able to sustain the rapid formation of these extreme sources, we started a Very Large Telescope/Multi-Unit Spectroscopic Explorer (MUSE) effort aimed at characterizing the surroundings of a sample of 5.7<z<6.6 quasars, which we have dubbed the Reionization Epoch QUasar InvEstigation with MUSE (REQUIEM) survey. We here present results of our searches for extended Ly{alpha} halos around the first 31 targets observed as part of this program. Reaching 5{sigma} surface brightness limits of 0.1-1.1x10^-17^erg/s/cm^2^/arcsec^2^ over a 1arcsec^2^ aperture, we were able to unveil the presence of 12 Ly{alpha} nebulae, eight of which are newly discovered. The detected nebulae show a variety of emission properties and morphologies with luminosities ranging from 8x10^42^ to 2x10^44^erg/s, FWHMs between 300 and 1700km/s, sizes <30pkpc, and redshifts consistent with those of the quasar host galaxies. As the first statistical and homogeneous investigation of the circumgalactic medium of massive galaxies at the end of the reionization epoch, the REQUIEM survey enables the study of the evolution of the cool gas surrounding quasars in the first 3Gyr of the universe. A comparison with the extended Ly{alpha} emission observed around bright (M_1450_<~-25mag) quasars at intermediate redshift indicates little variations on the properties of the cool gas from z~6 to z~3, followed by a decline in the average surface brightness down to z~2.
- ID:
- ivo://CDS.VizieR/J/ApJ/832/126
- Title:
- RESOLVE survey: 21cm obs. with GBT & Arecibo
- Short Name:
- J/ApJ/832/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the HI mass inventory for the REsolved Spectroscopy Of a Local VolumE (RESOLVE) survey, a volume-limited, multi-wavelength census of >1500 z=0 galaxies spanning diverse environments and complete in baryonic mass down to dwarfs of ~10^9^M_{sun}_. This first 21cm data release provides robust detections or strong upper limits (1.4M_HI_<5%-10% of stellar mass M*) for ~94% of RESOLVE. We examine global atomic gas-to-stellar mass ratios (G/S) in relation to galaxy environment using several metrics: group dark matter halo mass M_h_, central/satellite designation, relative mass density of the cosmic web, and distance to the nearest massive group. We find that at fixed M*, satellites have decreasing G/S with increasing M_h_ starting clearly at M_h_~10^12^M_{sun}_, suggesting the presence of starvation and/or stripping mechanisms associated with halo gas heating in intermediate-mass groups. The analogous relationship for centrals is uncertain because halo abundance matching builds in relationships between central G/S, stellar mass, and halo mass, which depend on the integrated group property used as a proxy for halo mass (stellar or baryonic mass). On larger scales G/S trends are less sensitive to the abundance matching method. At fixed M_h_<=10^12^M_{sun}_, the fraction of gas-poor centrals increases with large-scale structure density. In overdense regions, we identify a rare population of gas-poor centrals in low-mass (M_h_<10^11.4^M_{sun}_) halos primarily located within ~1.5x the virial radius of more massive (M_h_>10^12^M_{sun}_) halos, suggesting that gas stripping and/or starvation may be induced by interactions with larger halos or the surrounding cosmic web. We find that the detailed relationship between G/S and environment varies when we examine different subvolumes of RESOLVE independently, which we suggest may be a signature of assembly bias.
- ID:
- ivo://CDS.VizieR/J/ApJ/806/109
- Title:
- Rest-frame optical spectra of 3<z<6 QSOs
- Short Name:
- J/ApJ/806/109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the rest-frame optical spectral properties of 155 luminous quasars at 3.3<z<6.4 taken with the AKARI space telescope, including the first detection of the H{alpha} emission line as far out as z~6. We extend the scaling relation between the rest-frame optical continuum and the line luminosity of active galactic nuclei (AGNs) to the high-luminosity, high-redshift regime that has rarely been probed before. Remarkably, we find that a single log-linear relation can be applied to the 5100{AA} and H{alpha} AGN luminosities over a wide range of luminosity (10^42^<L_5100_<10^47^ergs/s) or redshift (0<z<6), suggesting that the physical mechanism governing this relation is unchanged from z=0 to 6, over five decades in luminosity. Similar scaling relations are found between the optical and the UV continuum luminosities or line widths. Applying the scaling relations to the H{beta} black hole (BH) mass (M_BH_) estimator of local AGNs, we derive the M_BH_ estimators based on the H{alpha}, MgII, and CIV lines, finding that the UV-line-based masses are overall consistent with the Balmer-line-based, but with a large intrinsic scatter of 0.40dex for the CIV estimates. Our 43 M_BH_ estimates from H{alpha} confirm the existence of BHs as massive as ~10^10^M_{sun}_ out to z~5 and provide a secure footing for previous results from MgII-line-based studies that a rapid M_BH_ growth has occurred in the early universe.
- ID:
- ivo://CDS.VizieR/J/ApJ/755/60
- Title:
- Reverberation mapping for five Seyfert 1 galaxies
- Short Name:
- J/ApJ/755/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results from a detailed analysis of photometric and spectrophotometric data on five Seyfert 1 galaxies observed as a part of a recent reverberation mapping program. The data were collected at several observatories over a 140 day span beginning in 2010 August and ending in 2011 January. We obtained high sampling-rate light curves for Mrk 335, Mrk 1501, 3C 120, Mrk 6, and PG 2130+099, from which we have measured the time lag between variations in the 5100 {AA} continuum and the H{beta} broad emission line. We then used these measurements to calculate the mass of the supermassive black hole at the center of each of these galaxies. Our new measurements substantially improve previous measurements of M_BH_ and the size of the broad line-emitting region for four sources and add a measurement for one new object. Our new measurements are consistent with photoionization physics regulating the location of the broad line region in active galactic nuclei.
- ID:
- ivo://CDS.VizieR/J/ApJ/753/L2
- Title:
- Reverberation mapping of AGNs
- Short Name:
- J/ApJ/753/L2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Estimates of the mass of super-massive black holes (BHs) in distant active galactic nuclei (AGNs) can be obtained efficiently only through single-epoch (SE) spectra, using a combination of their broad emission line widths and continuum luminosities. Yet the reliability and accuracy of the method and the resulting mass estimates, M_BH_, remain uncertain. A recent study by Croom using a sample of Sloan Digital Sky Survey, 2dF QSO Redshift Survey, and 2dF-SDSS LRG and QSO Survey quasars suggests that line widths contribute little information about the BH mass in these SE estimates and can be replaced by a constant value without significant loss of accuracy. In this Letter, we use a sample of nearby reverberation-mapped AGNs to show that this conclusion is not universally applicable. We use the bulge luminosity (L_Bulge_) of these local objects to test how well the known M_BH_-L_Bulge_correlation is recovered when using randomly assigned line widths instead of the measured ones to estimate M_BH_. We find that line widths provide significant information about M_BH_, and that for this sample, the line width information is just as significant as that provided by the continuum luminosities. We discuss the effects of observational biases upon the analysis of Croom and suggest that the results can probably be explained as a bias of flux-limited, shallow quasar samples.
- ID:
- ivo://CDS.VizieR/J/ApJ/886/42
- Title:
- Reverberation mapping & opt. spectra data of AGNs
- Short Name:
- J/ApJ/886/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The radius-luminosity (R_H{beta}_-L_5100_) relationship of active galactic nuclei (AGNs) established by the reverberation mapping (RM) observations has been widely used as a single-epoch black hole mass estimator in the research of large AGN samples. However, the recent RM campaigns discovered that the AGNs with high-accretion rates show shorter time lags by factors of a few comparing with the predictions from the R_H{beta}_-L_5100_ relationship. The explanation of the shortened time lags has not been finalized yet. We collect eight different single-epoch spectral properties to investigate how the shortening of the time lags correlates with those properties and to determine the origin of the shortened lags. We find that the flux ratio between FeII and H{beta} emission lines shows the most prominent correlation, thus confirming that accretion rate is the main driver for the shortened lags. In addition, we establish a new scaling relation including the relative strength of FeII emission. This new scaling relation can provide less biased estimates of the black hole mass and accretion rate from the single-epoch spectra of AGNs.
- ID:
- ivo://CDS.VizieR/J/A+A/590/A9
- Title:
- RGB stars in Galactic GC stellar parameters
- Short Name:
- J/A+A/590/A9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Globular clusters trace the formation and evolution of the Milky Way and surrounding galaxies, and outline their chemical enrichment history. To accomplish these tasks it is important to have large samples of clusters with homogeneous data and analysis to derive kinematics, chemical abundances, ages and locations. We aim to obtain homogeneous metallicities and alpha-element enhancement for 51 Galactic bulge, disc, and halo globular clusters that are among the most distant and/or highly reddened in the Galaxy's globular cluster system. We also provide membership selection based on stellar radial velocities and atmospheric parameters. The implications of our results are discussed. We observed R~2000 spectra in the wavelength interval 456-586nm for over 800 red giant stars in 51 Galactic globular clusters. We applied full spectrum fitting with the code ETOILE together with libraries of observed and synthetic spectra. We compared the mean abundances of all clusters with previous work and with field stars. We used the relation between mean metallicity and horizontal branch morphology defined by all clusters to select outliers for discussion. [Fe/H], [Mg/Fe], and [alpha/Fe] were derived in a consistent way for almost one-third of all Galactic globular clusters. We find our metallicities are comparable to those derived from high-resolution data to within sigma=0.08dex over the interval -2.5<[Fe/H]<0.0. Further, a comparison of previous metallicity scales with ours yields sigma<0.16dex. We also find that the distribution of [Mg/Fe] and [alpha/Fe] with [Fe/H] for the 51 clusters follows the general trend exhibited by field stars. It is the first time that the following clusters are included in a large sample of homogeneous stellar spectroscopic observations and metallicity derivation: BH 176, Djorg 2, Pal 10, NGC 6426, Lynga 7, and Terzan 8. In particular, the first three clusters only had photometric metallicities previously and the available metallicity for NGC 6426 was based only on integrated spectroscopy and photometry. Two other clusters, HP 1 and NGC 6558, are confirmed as candidates for the oldest globular clusters in the Milky Way. Stellar spectroscopy in the visible at R~2000 for a large sample of globular clusters is a robust and efficient way to trace the chemical evolution of the host galaxy and to detect interesting objects for follow-up at higher-resolution and with forthcoming giant telescopes. The technique used here can also be applied to globular cluster systems in nearby galaxies with current instruments and to distant galaxies with the advent of ELTs.
- ID:
- ivo://CDS.VizieR/J/AJ/142/61
- Title:
- RGB stars in LMC outer disk
- Short Name:
- J/AJ/142/61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The outer disk of the Large Magellanic Cloud (LMC) is studied in order to unveil clues about its formation and evolution. Complementing our previous studies in innermost fields (3kpc<~R<~7kpc), we obtained deep color-magnitude diagrams in six fields with galactocentric distances from 5.2kpc to 9.2kpc and different azimuths. The comparison with isochrones shows that while the oldest population is approximately coeval in all fields, the age of the youngest populations increases with increasing radius. This agrees with the results obtained in the innermost fields. Low-resolution spectroscopy in the infrared CaII triplet region has been obtained for about 150 stars near the tip of the red giant branch in the same fields. Radial velocities and stellar metallicities have been obtained from these spectra. The metallicity distribution of each field has been analyzed together with those previously studied.
- ID:
- ivo://CDS.VizieR/J/ApJ/818/L14
- Title:
- RM AGNs accretion rates and BH masses
- Short Name:
- J/ApJ/818/L14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Broad emission lines in active galactic nuclei (AGNs) mainly arise from gas photoionized by continuum radiation from an accretion disk around a central black hole. The shape of the broad-line profile, described by D_H{beta}_=FWHM/{sigma}_H{beta}_, the ratio of full width at half maximum to the dispersion of broad H{beta}, reflects the dynamics of the broad-line region (BLR) and correlates with the dimensionless accretion rate (dM/dt) or Eddington ratio (L_bot_/L_Edd_). At the same time, dM/dt and (L_bot_/L_Edd_ correlate with R_Fe_, the ratio of optical Fe ii to H{beta} line flux emission. Assembling all AGNs with reverberation mapping measurements of broad H{beta}, both from the literature and from new observations reported here, we find a strong bivariate correlation of the form log((dM/dt.L_bot_/L_Edd_)={alpha}+{beta}D_H{beta}_+{gamma}R_Fe_ where {alpha}=(2.47,0.31), {beta}=-(1.59,0.82), and {gamma}=(1.34,0.80). We refer to this as the fundamental plane of the BLR. We apply the plane to a sample of z<0.8 quasars to demonstrate the prevalence of super-Eddington accreting AGNs are quite common at low redshifts.
