- ID:
- ivo://CDS.VizieR/J/ApJ/873/35
- Title:
- Gemini GNIRS NIR spectroscopy of 50 QSOs at z>~5.7
- Short Name:
- J/ApJ/873/35
- Date:
- 19 Jan 2022 09:09:09
- Publisher:
- CDS
- Description:
- We report initial results from a large Gemini program to observe z>~5.7 quasars with GNIRS near-IR spectroscopy. Our sample includes 50 quasars with simultaneous ~0.85-2.5{mu}m spectra covering the rest-frame ultraviolet and major broad emission lines from Ly{alpha} to MgII. We present spectral measurements for these quasars and compare with their lower redshift counterparts at z=1.5-2.3. We find that when quasar luminosity is matched, there are no significant differences between the rest-UV spectra of z>~5.7 quasars and the low-z comparison sample. High-z quasars have similar continuum and emission line properties and occupy the same region in the black hole mass and luminosity space as the comparison sample, accreting at an average Eddington ratio of ~0.3. There is no evidence for super-Eddington accretion or hypermassive (>10^10^M_{sun}_) black holes within our sample. We find a mild excess of quasars with weak CIV lines relative to the control sample. Our results, corroborating earlier studies but with better statistics, demonstrate that these high-z quasars are already mature systems of accreting supermassive black holes operating with the same physical mechanisms as those at lower redshifts.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/603/L7
- Title:
- 6 giants atomic data and equivalent widths
- Short Name:
- J/A+A/603/L7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We observed six He-clump stars of the intermediate-age stellar cluster Gaia1 with the MIKE/MAGELLAN spectrograph. A possible extra-galactic origin of this cluster, recently discovered thanks to the first data release of the ESA Gaia mission, has been suggested, based on its orbital parameters. Abundances for Fe, {alpha}, proton- and neutron-capture elements have been obtained. We find no evidence of intrinsic abundance spreads. The iron abundance is solar ([FeI/H]=+0.00+/-0.01; {sigma}=0.03dex). All the other abundance ratios are generally solar-scaled, similar to the Galactic thin disk and open cluster stars of similar metallicity. The chemical composition of Gaia1 does not support an extra-galactic origin for this stellar cluster, which can be considered as a standard Galactic open cluster.
- ID:
- ivo://CDS.VizieR/J/A+A/645/A14
- Title:
- GIBS sources equivalent widths
- Short Name:
- J/A+A/645/A14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We developed a set of procedures to automatically detect and measure the DIB around 8620{AA} (the Gaia DIB) for a wide range of temperatures. The method was tested on about 5000 spectra from the Giraffe Inner Bulge Survey (GIBS; Zoccali et al., 2014A&A...562A..66Z), and 4194 reasonable fitting results were got. We made use of the reddenings, E(J-Ks), from the extinction map developed by Surot et al. (2020arXiv201002723S). A linear correlation between the equivalent width (EW) and E(J-Ks) was derived as E(J-Ks)/EW = 1.875, according to E(B-V)/EW = 2.721, which is highly consistent with previous results toward similar sightlines. After a correction based on the Vista Variables in the Via Lactea (VVV; Minniti et al., 2010NewA...15..433M) database for both EW and E(J-Ks), the coefficient derived from individual GIBS fields, E(J-Ks)/EW=1.884, is also in perfect agreement with literature values. Based on a subsample of 1015 stars toward the Galactic center, we determined a rest-frame wavelength of the Gaia DIB as 8620.55{AA}. A Gaussian profile is proved to be a proper and stable assumption for the Gaia DIB as no intrinsic asymmetry is found.
- ID:
- ivo://CDS.VizieR/J/ApJ/901/23
- Title:
- Gjoll stream stars & detailed abund. of 4 members
- Short Name:
- J/ApJ/901/23
- Date:
- 15 Feb 2022 14:07:06
- Publisher:
- CDS
- Description:
- Recent analysis of the second data release of Gaia has revealed a number of new stellar streams surrounding the Milky Way. It has been suggested that one of these streams, Gjoll, is associated with the globular cluster NGC 3201, but thus far the association has only been based on kinematics of the stream stars. In this work we identify five likely stream members in the Gaia data that are bright enough for high-resolution spectroscopic follow-up with the Harlan J. Smith telescope at McDonald Observatory. One star is ruled out as a member based on its radial velocity. Abundance analysis of the remaining four kinematic members reveals a good chemical match to NGC 3201 for two of the stars, driven by their similar Al and {alpha}-element abundances. Of the remaining two, one shows no chemical similarity to NGC 3201 and is likely an unassociated Milky Way halo field star, while the other exhibits a similar Al abundance but has somewhat lower {alpha}-element abundances. The chemical tagging of stars in the Gjoll stream to NGC3201 confirms this association and provides direct proof of the hierarchical formation of the Milky Way.
- ID:
- ivo://CDS.VizieR/J/ApJ/833/178
- Title:
- GLASS. VII. H{alpha} maps
- Short Name:
- J/ApJ/833/178
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Exploiting the slitless spectroscopy taken as part of the Grism Lens-Amplified Survey from Space (GLASS), we present an extended analysis of the spatial distribution of star formation in 76 galaxies in 10 clusters at 0.3<z<0.7. We use 85 foreground and background galaxies in the same redshift range as a field sample. The samples are well matched in stellar mass (10^8^-10^11^M_{sun}_) and star formation rate (0.5-50M_{sun}_/yr). We visually classify galaxies in terms of broad band morphology, H{alpha} morphology, and likely physical process acting on the galaxy. Most H{alpha} emitters have a spiral morphology (41%+/-8% in clusters, 51%+/-8% in the field), followed by mergers/interactions (28%+/-8%, 31%+/-7%, respectively) and early-type galaxies (remarkably as high as 29%+/-8% in clusters and 15%+/-6% in the field). A diversity of H{alpha} morphologies is detected, suggesting a diversity of physical processes. In clusters, 30%+/-8% of the galaxies present a regular morphology, mostly consistent with star formation diffused uniformly across the stellar population (mostly in the disk component, when present). The second most common morphology (28%+/-8%) is asymmetric/jellyfish, consistent with ram-pressure stripping or other non-gravitational processes in 18%+/-8% of the cases. Ram-pressure stripping appears significantly less prominent in the field (2%+/-2%), where the most common morphology/mechanism appears to be consistent with minor gas-rich mergers or clump accretion. This work demonstrates that while environment-specific mechanisms affect galaxy evolution at this redshift, they are diverse and their effects are subtle. A full understanding of this complexity requires larger samples and detailed and spatially resolved physical models.
- ID:
- ivo://CDS.VizieR/J/A+A/620/A119
- Title:
- GRB 161023A light curves and EW
- Short Name:
- J/A+A/620/A119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Long gamma-ray bursts (GRBs) are produced during the dramatic deaths of massive stars with very short lifetimes, meaning that they explode close to the birth place of their progenitors. Over a short period they become the most luminous objects observable in the Universe, being perfect beacons to study high-redshift star-forming regions. We aim to use the afterglow of GRB161023A at a redshift z=2.710 as a background source to study the environment of the explosion and the intervening systems along its line of sight. For the first time, we complement ultraviolet (UV), optical and near-infrared (NIR) spectroscopy with millimetre spectroscopy using the Atacama Large Millimeter Array (ALMA), which allows us to probe the molecular content of the host galaxy. The X-shooter spectrum shows a plethora of absorption features including fine-structure and metastable transitions of Fe, Ni, Si, C, and O. We present photometry ranging from 43s to over 500 days after the burst
- ID:
- ivo://CDS.VizieR/J/A+A/586/A120
- Title:
- Grid of 1D models for Mg line formation
- Short Name:
- J/A+A/586/A120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mg is the alpha element of choice for Galactic population and chemical evolution studies as it is easily detectable in all late-type stars. Such studies require precise elemental abundances, and thus departures from LTE need to be accounted for.
- ID:
- ivo://CDS.VizieR/J/A+A/550/A79
- Title:
- H{alpha} and H{beta} lines of northern Be stars
- Short Name:
- J/A+A/550/A79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Be stars are fast rotating early-type emission line stars. It is generally assumed that observed emission is generated in a rotating disk- like envelope, as supported by the observed correlation between the stellar projected rotational velocity v sin i and the width of the emission lines. Then, high resolution spectroscopic observations of Balmer lines profiles play an important role in putting constrains on Be stars modeling. We present Balmer lines spectroscopy for a sample of 48 Be stars. For most of them, H{alpha} and H{beta} have been observed more than two times, in a total period spanning almost two years between 2008 and 2009. Spectral synthesis of the H{alpha} profile has been performed following two steps: photospheric contribution has been computed by using Kurucz's code ATLAS9 and SYNTHE, and disk emission have been derived by the approach of Hummel & Vrancken (1995A&A...302..751H). For 26 out of 48 stars, a modeling of the total H{alpha} emission, i.e. photospheric absorption plus disk net emission, has been attempted. By this modeling we derived an estimation of the disk radius, as well as the inclination angle between rotational axis and line of sight and the base density at the stellar equator. We also discussed, for the stars observed more than once, the variability of H{alpha} and H{beta} for what concerns both the equivalent width and the spectral profile. We found 16 stars with variable equivalent width and 7 stars with clear sign of profile variations. For all the stars of our sample we derive all the fundamental astrophysical quantities, such as: effective temperature, gravity, and projected rotational velocity. We found 13 stars which equivalent width is variable with a confidence level greater than 80% and 7 object for which spectral profiles show change with time. According to the classification scheme commonly used in literature, we classified 16 stars as belonging to class 1, 13 to class 2, 11 are shell stars, 6 objects do not show net emission, and 2 stars display transition from class 1 and 2. For the class 1 stars, we confirm the correlation between vsini and peak separation. concerning the geometry of the disk, we derived the inclination angle between rotational axis and line of sight, the base density at the stellar equator, and the radius. The maximum concentration of stars occur for disk dimensions ranging in the interval of 6 to 8 stellar radii and for inclination angles going from 23{deg} to 35{deg}.
- ID:
- ivo://CDS.VizieR/J/ApJS/178/247
- Title:
- H{alpha} and [NII] survey in local 11 Mpc
- Short Name:
- J/ApJS/178/247
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of a broader effort to characterize the population of star-forming galaxies in the local universe, we have carried out an H{alpha}+[NII] imaging survey for an essentially volume-limited sample of galaxies within 11Mpc of the Milky Way. This first paper describes the design of the survey, the observation, data processing, and calibration procedures, and the characteristics of the galaxy sample. The main product of the paper is a catalog of integrated H{alpha} fluxes, luminosities, and equivalent widths for the galaxies in the sample. We briefly discuss the completeness properties of the survey and compare the distribution of the sample and its star formation properties to other large H{alpha} imaging surveys. These data form the foundation for a series of follow-up studies of the star formation properties of the local volume, and the properties and duty cycles of star formation bursts in dwarf galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/545/A16
- Title:
- Halpha3. Catalog and SFR in Virgo cluster
- Short Name:
- J/A+A/545/A16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present H{alpha}3 (acronym for H{alpha}-{alpha}{alpha}), an H{alpha} narrow-band imaging survey of ~400 galaxies selected from the HI Arecibo Legacy Fast ALFA Survey (ALFALFA) in the Local Supercluster, including the Virgo cluster. By using hydrogen recombination lines as a tracer of recent star formation, we aim to investigate the relationships between atomic neutral gas and newly formed stars in different environments (cluster and field), morphological types (spirals and dwarfs), and over a wide range of stellar masses (~10^7.5^-10^11.5^M_{sun}_). We image in H{alpha}+[NII] all the galaxies that contain more than 10^7^M_{sun}_ of neutral atomic hydrogen in the sky region 11h<R.A.<16h ; 4{deg}<Dec.<16{deg}; 350<cz<2000km/s using the San Pedro Martir 2m telescope. This survey provides a complete census of the star formation in HI rich galaxies of the local universe. We present the properties of the galaxy sample, together with H{alpha} fluxes and equivalent widths. We find an excellent agreement between the fluxes determined from our images in apertures of 3-arcsec diameter and the fluxes derived from the SDSS spectral database. From the H{alpha} fluxes corrected for galactic and internal extinction and for [NII] contamination we derive the global star formation rates (SFRs).
