- ID:
- ivo://CDS.VizieR/J/ApJ/678/116
- Title:
- AGNs in nuclear star clusters
- Short Name:
- J/ApJ/678/116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study galaxies that host both nuclear star clusters and AGNs, implying the presence of a massive black hole. We select a sample of 176 galaxies with previously detected nuclear star clusters that range from ellipticals to late-type spirals. We search for AGNs in this sample using optical spectroscopy and archival radio and X-ray data. We find galaxies of all Hubble types and with a wide range of masses (10^9^-10^11^M_{sun}_) hosting both AGNs and nuclear star clusters. From the optical spectra, we classify 10% of the galaxies as AGN and an additional 15% as composite, indicating a mix of AGN and star formation spectra. The fraction of nucleated galaxies with AGNs increases strongly as a function of galaxy and nuclear star cluster mass. For galaxies with both a nuclear star cluster and a black hole, we find that the masses of these two objects are quite similar. However, nondetections of black holes in Local Group nuclear star clusters show that not all clusters host black holes of similar masses. We discuss the implications of our results for the formation of nuclear star clusters and massive black holes.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/624/A145
- Title:
- Astrometric Catalogue 5, LQAC-5
- Short Name:
- J/A+A/624/A145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In addition to their great astrophysical interest, quasars represent quasi-ideal reference objects in the celestial sphere with, a priori, a lack of significant proper motion. Since the fourth release of the Large Quasar Astrometric Catalogue (LQAC-4), a large number of quasars have been discovered, in particular those coming from the DR14Q release of the SDSS. With the advent of the Gaia Data Release 2 (DR2), it is now also possible to fold in extremely accurate quasar positions. Following the same procedure as in the previous releases of the LQAC, our aim is to compile the large majority of the recorded quasars, with their best estimated coordinates and substantial information about their physical properties such as the redshift, multi-bands apparent, and absolute magnitudes. Emphasis is given to the results of the cross-matches with the Gaia DR2 catalogue, which considerably increases the positional accuracy. New quasars from the SDSS DR14Q release were cross-matched with the precedent LQAC-4 compilation with a 1" search radius, which leads to 149084 objects not present in the previous LQAC-4 release. Another cross-match was done with the Gaia DR2 catalogue, which enables us to considerably improve the positioning of these objects. For the first time, parallaxes and proper motions from the DR2, when available, are added to our compilation. Furthermore, a cross-identification of the LQAC-5 with the AllWISE survey gives additional mid-infrared information for an important percentage of objects. Our final catalogue, namely the LQAC-5, contains 592 809 quasars. This represents roughly a 34% increase with respect to the number of objects recorded in the LQAC-4. Among them, 398 697 objects were found in common with the Gaia DR2, within a 1" search radius. That corresponds to 67.26% of the whole population of the compilation. The LQAC-5 delivers a nearly complete catalogue of spectroscopically confirmed quasars (including a small proportion of 14126 compact AGN's) to the astronomical community, with the aim of giving their best equatorial coordinates with respect to the ICRF2 and with exhaustive additional information. For more than 50% of the sample, these coordinates are extracted from the very recent Gaia DR2.
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/177/131
- Title:
- CaII and MgII excess flux density in cool stars
- Short Name:
- J/A+A/177/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The relation between the CaII H and K line-tore flux density and rotation period is studied for a sample of 313 cool stars of luminosity classes ranging from II-III to V, and compared to similar relations for MgII h and k and soft X-ray.
- ID:
- ivo://CDS.VizieR/J/A+A/476/73
- Title:
- Calibration of Cepheid Period/Luminosity relation
- Short Name:
- J/A+A/476/73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The universality of the Cepheid period-luminosity (PL) relations has been under discussion since metallicity effects were assumed to play a role in the value of the intercept and, more recently, of the slope of these relations. The goal of the present study is to calibrate the Galactic PL relations in various photometric bands (from B to K) and to compare the results to the well-established PL relations in the LMC. We use a set of 59 calibrating stars, the distances of which are measured using five different distance indicators: Hubble Space Telescope and revised Hipparcos parallaxes, infrared surface brightness and interferometric Baade-Wesselink parallaxes, and classical Zero-Age-Main-Sequence-fitting parallaxes for Cepheids belonging to open clusters or OB stars associations. A detailed discussion of absorption corrections and projection factor to be used is given.
- ID:
- ivo://CDS.VizieR/J/A+A/390/967
- Title:
- Carbon-rich giants in the HR diagram
- Short Name:
- J/A+A/390/967
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- There are 513 entries corresponding to 513 SEDs of 410 carbon stars and related objects, and 70 Ba II stars. Absolute magnitude bolometric (Col. 7) are given for 348 348 (C & rel.) + 65 (Ba II) entries. Together with the effective temperatures previously obtained (Col. 5), they were used to draw the local HR diagram and the luminosity function for galactic carbon giants and related objects in the Sun vicinity. Also given in column 6, the apparent bolometric magnitudes, and in column 8 as ``remarks'', the variation phase information whenever available, the detection of circumstellar extinction and/or emission, the presence of Tc; the J-type, CH stars, carbon-Cepheids etc., are also shown. Our photometric solutions (photometric type in Col. 3 and interstellar extinction at J in Col. 4: to be multiplied by 1.145 to obtain E(B-V)).
- ID:
- ivo://CDS.VizieR/J/ApJ/869/82
- Title:
- Carnegie-Chicago Hubble Program: RR Lyrae NIR obs.
- Short Name:
- J/ApJ/869/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometry of 30 Galactic RR Lyrae variables taken with HST WFC3/IR for the Carnegie-Chicago Hubble Program. These measurements form the base of the distance-ladder measurements that comprise a pure Population II base to a measurement of Ho at an accuracy of 3%. These data are taken with the same instrument and filter (F160W) as our observations of RR Lyrae stars in external galaxies so as to minimize sources of systematic error in our calibration of the extragalactic distance scale. We calculate mean magnitudes based on one to three measurements for each RR Lyrae star using star-by-star templates generated from densely time-sampled data at optical and midinfrared wavelengths. We use four RR Lyrae stars from our sample with well-measured HST parallaxes to determine a zero-point. This zero-point will soon be improved with the large number of precise parallaxes to be provided by Gaia. We also provide preliminary calibration with the TGAS and Gaia DR2 data, and all three zero points are in agreement, to within their uncertainties.
- ID:
- ivo://CDS.VizieR/J/AJ/145/31
- Title:
- Catalog of X-ray selected BL Lac objects
- Short Name:
- J/AJ/145/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents a catalog of 312 X-ray selected BL Lacertae objects (XBLs), optically identified through the end of 2011. It contains the names from different surveys, equatorial coordinates, redshifts, multifrequency flux values, and luminosities for each source. In addition, the different characteristics of XBLs are statistically investigated (redshift, radio/optical/X-ray luminosities, central black hole (BH) mass, synchrotron peak frequency, broadband spectral indices, optical flux variability). Their values are collected through an extensive bibliographic and database search or calculated by us. The redshifts range from 0.031 to 0.702 with a maximum of the distribution at z=0.223. The 1.4GHz luminosities of XBLs log{nu}L_{nu}_~39-42erg/s while optical V and X-ray 0.1-2.4keV bands show log{nu}L_{nu}_~43-46erg/s. The XBL hosts are elliptical galaxies with effective radii r_eff_=3.26-25.40kpc and ellipticities, {epsilon}=0.04-0.52. Their R-band absolute magnitudes M_R_ range from -21.11mag to -24.86mag with a mean value of -22.83mag. The V-R indices of the hosts span from 0.61 to 1.52 and reveal a fourth-degree polynomial relationship with z that enables us to evaluate the redshifts of five sources whose V-R indices were determined from the observations but whose redshifts values are either not found or not confirmed. The XBL nuclei show a wider range of 7.31mag for M_R_ with the highest luminosity corresponding to M_R_=-27.24mag. The masses of central BHs are found in the interval logM_BH_=7.39-9.30 solar masses (with distribution maximum at logM_BH_/M_{sun}_=8.30). The synchrotron peak frequencies are spread over the range log{nu}_peak_=14.56-19.18Hz with a peak of the distribution at log{nu}_peak_=16.60Hz. The broadband radio-to-optical ({alpha}_ro_), optical-to-X-ray ({alpha}_ox_), and radio-to-X-ray ({alpha}_rx_) spectral indices are distributed in the intervals (0.17,0.59), (0.56,1.48), and (0.41,0.75), respectively. In the optical energy range, the overall flux variability increases, on average, towards shorter wavelengths: <{Delta}m>=1.22,1.50, and 1.82mag through the R, V, B bands of Johnson-Cousins system, respectively. XBLs seem be optically less variable at the intranight timescales compared to the radio-selected BL Lacs (RBLs).
- ID:
- ivo://CDS.VizieR/J/AJ/129/2138
- Title:
- Centers of early-type galaxies with HST
- Short Name:
- J/AJ/129/2138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observations of 77 early-type galaxies imaged with the PC1 CCD of the Hubble Space Telescope (HST) WFPC2. "Nuker-law" parametric fits to the surface brightness profiles are used to classify the central structure into "core" or "power-law" forms.
- ID:
- ivo://CDS.VizieR/J/MNRAS/446/369
- Title:
- Colour and spectral index from the SLUGGS survey
- Short Name:
- J/MNRAS/446/369
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of the SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey, we stack 1137 Keck DEIMOS (Deep Imaging Multi-Object Spectrograph) spectra of globular clusters from 10 galaxies to study their stellar populations in detail. The stacked spectra have median signal-to-noise ratios of ~90 {AA}^-1^. Besides the calcium triplet, we study weaker sodium, magnesium, titanium and iron lines as well as the H{alpha} and higher order Paschen hydrogen lines. In general, the stacked spectra are consistent with old ages and a Milky Way-like initial mass function. However, we see different metal line index strengths at fixed colour and magnitude, and differences in the calcium triplet-colour relation from galaxy to galaxy. We interpret this as strong evidence for variations in the globular cluster colour-metallicity relation between galaxies. Two possible explanations for the colour-metallicity relation variations are that the average ages of globular clusters vary from galaxy to galaxy or that the average abundances of light elements (i.e. He, C, N and O) differ between galaxies. Stacking spectra by magnitude, we see that the colours become redder and metal line indices stronger with brighter magnitudes. These trends are consistent with the previously reported `blue tilts' being mass-metallicity relations.
