- ID:
- ivo://CDS.VizieR/J/ApJ/860/83
- Title:
- 22 extreme [OIII] emitters at z~0.5 from SDSS-DR14
- Short Name:
- J/ApJ/860/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have found a sample of extreme emission-line galaxies (EELGs) with strong [OIII]{lambda}5007 emission at z~0.5. Using broadband photometric selection and requiring small uncertainties in photometry, we searched the 14th Data Release of the Sloan Digital Sky Survey (SDSS) and found 2658 candidates with strong i-band excess (i-z<=r-i-0.7). We further obtained 649 SDSS spectra of these objects, and visually identified 22 [OIII] emitters lying at 0.40<z<0.63. Having constructed their ultraviolet-infrared spectral energy distributions, we found that they have fairly blue r-W2 and red W1-W4 colors, indicative of strong, warm dust emission. Their rest-frame [OIII]{lambda}5007 equivalent widths are mostly 200-600{AA}, and their high [OIII]{lambda}5007/H{beta} ratios put them at the boundary of star-forming galaxies and active galactic nuclei on line ratio classification diagrams. The typical E(B-V) and electron temperature of [OIII] emitters are ~0.1-0.3mag and ~104K, respectively. The lowest metallicity of our [OIII] emitters with S/N[OIII]{lambda}4363>3 is 12+log(O/H)=7.98_-0.02_^+0.12^, with a median value of 8.24_-0.04_^+0.05^. Our [OIII] emitters exhibit remarkably high line luminosity-18/22 have L[OIII]{lambda}5007>5x10^42^erg/s and 5/22 have L[OIII]{lambda}5007>10^43^erg/s. Their estimated volume number density at z~0.5 is ~2x10^-8^Mpc^-3^, with L[OIII]{lambda}5007 down to ~3x10^42^erg/s. The cumulative number distribution of EELGs across different redshifts is indicative of a strong redshift evolution at the bright end of the [OIII] luminosity function.
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- ID:
- ivo://CDS.VizieR/J/MNRAS/297/885
- Title:
- Faint galaxies KIc photometry
- Short Name:
- J/MNRAS/297/885
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The excess number of blue galaxies at faint magnitudes is a subject of much controversy. Recent Hubble Space Telescope results have revealed a plethora of galaxies with peculiar morphologies tentatively identified as the evolving population. We report the results of optical spectroscopy and near-infrared photometry of a sample of faint HST galaxies from the Medium Deep Survey to ascertain the physical properties of the faint morphological populations. We find four principal results. First, the population of objects classified as 'peculiar' are intrinsically luminous in the optical (M_B_~-19). Secondly these systems tend to be strong sources of [OII] line luminosity. Thirdly the optical-infrared colours of the faint population (a) confirm the presence of a population of compact blue galaxies and (b) show the stellar populations of irregular/peculiar galaxies encompass a wide range in age. Finally a surface-brightness comparison with the local galaxy sample of Freiz et al. (1996AJ....111..174F) shows that these objects are not of anomalously low surface brightness, rather we find that all morphological classes have evolved to a higher surface brightness at higher redshifts (z>0.3).
- ID:
- ivo://CDS.VizieR/J/MNRAS/470/1512
- Title:
- Faint LSB galaxy cand. in Perseus cluster
- Short Name:
- J/MNRAS/470/1512
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the detection of 89 low surface brightness (LSB), and thus low stellar density galaxy candidates in the Perseus cluster core, of the kind named 'ultra-diffuse galaxies', with mean effective V-band surface brightnesses 24.8-27.1mag/arcsec^2^, total V-band magnitudes -11.8 to -15.5mag, and half-light radii 0.7-4.1kpc. The candidates have been identified in a deep mosaic covering 0.3deg^2^, based on wide-field imaging data obtained with the William Herschel Telescope. We find that the LSB galaxy population is depleted in the cluster centre and only very few LSB candidates have half-light radii larger than 3kpc. This appears consistent with an estimate of their tidal radius, which does not reach beyond the stellar extent even if we assume a high dark matter content (M/L=100). In fact, three of our candidates seem to be associated with tidal streams, which points to their current disruption. Given that published data on faint LSB candidates in the Coma cluster --with its comparable central density to Perseus-- show the same dearth of large objects in the core region, we conclude that these cannot survive the strong tides in the centres of massive clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/418/445
- Title:
- FCOS Ultra Compact Dwarf galaxies radial vel.
- Short Name:
- J/A+A/418/445
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The relation between the Ultra Compact Dwarf galaxies (hereafter UCDs) recently discovered in the Fornax cluster (Drinkwater et al., 2003Natur.423..519D; Mieske et al., 2002, Cat. <J/A+A/383/823>) and the brightest globular clusters associated with the central galaxy NGC 1399 has been investigated in the spectroscopic Fornax Compact Object Survey FCOS. FCOS was carried out with the 2.5m du Pont telescope at Las Campanas, in the three nights of 2002/12/04 to 2002/12/06. Mieske et al. (2002, Cat. <J/A+A/383/823>) deals with the first part FCOS-1, this paper deals with the larger FCOS-2. The spectral resolution of FCOS was approx. 4{AA}. In the FCOS, 280 unresolved objects with 0<(V-I)<1.5mag in the magnitude space covering UCDs and bright globular clusters (18<V<21mag) were observed spectroscopically, among them 185 in FCOS-2. In the entire FCOS-sample there are five already known UCDs and 54 new Fornax members, 12 from FCOS-1 and 42 from FCOS-2.
- ID:
- ivo://CDS.VizieR/J/ApJ/895/78
- Title:
- [Fe/H] and [{alpha}/Fe] in M31 dwarf galaxies
- Short Name:
- J/ApJ/895/78
- Date:
- 15 Mar 2022 06:34:41
- Publisher:
- CDS
- Description:
- We present chemical abundances of red giant branch (RGB) stars in the dwarf spheroidal (dSph) satellite system of Andromeda (M31), using spectral synthesis of medium-resolution (R~6000) spectra obtained with the KeckII telescope and Deep Imaging Multi-Object Spectrometer spectrograph via the Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo survey. We coadd stars according to their similarity in photometric metallicity or effective temperature to obtain a signal-to-noise ratio (S/N) high enough to measure average [Fe/H] and [{alpha}/Fe] abundances. We validate our method using high S/N spectra of RGB stars in Milky Way globular clusters, as well as deep observations for a subset of the M31 dSphs in our sample. For this set of validation coadds, we compare the weighted average abundance of the individual stars with the abundance determined from the coadd. We present individual and coadded measurements of [Fe/H] and [{alpha}/Fe] for stars in 10 M31 dSphs, including the first [{alpha}/Fe] measurements for And IX, XIV, XV, and XVIII. These fainter, less massive dSphs show declining [{alpha}/Fe] relative to [Fe/H], implying an extended star formation history (SFH). In addition, these dSphs also follow the same mass-metallicity relation found in other Local Group satellites. The conclusions we infer from coadded spectra agree with those from previous measurements in brighter M31 dSphs with individual abundance measurements, as well as conclusions from photometric studies. These abundances greatly increase the number of spectroscopic measurements of the chemical composition of M31's less massive dwarf satellites, which are crucial to understanding their SFH and interaction with the M31 system.
- ID:
- ivo://CDS.VizieR/J/ApJ/736/86
- Title:
- FeII emission in SDSS type 1 AGNs
- Short Name:
- J/ApJ/736/86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used a large, homogeneous sample of 4178 z<=0.8 Seyfert 1 galaxies and QSOs selected from the Sloan Digital Sky Survey to investigate the strength of FeII emission and its correlation with other emission lines and physical parameters of active galactic nuclei. We find that the strongest correlations of almost all the emission-line intensity ratios and equivalent widths (EWs) are with the Eddington ratio (L/L_Edd_), rather than with the continuum luminosity at 5100{AA} (L_5100_) or black hole mass (M_BH_); the only exception is the EW of ultraviolet FeII emission, which does not correlate at all with broad-line width, L_5100_, M_BH_, or L/L_Edd_. By contrast, the intensity ratios of both the ultraviolet and optical FeII emission to MgII{lambda}2800 correlate quite strongly with L/L_Edd_. Interestingly, among all the emission lines in the near-UV and optical studied in this paper (including MgII{lambda}2800, H{beta}, and [OIII]{lambda}5007), the EW of narrow optical FeII emission has the strongest correlation with L/L_Edd_. We hypothesize that the variation of the emission-line strength in active galaxies is regulated by L/L_Edd_ because it governs the global distribution of the hydrogen column density of the clouds gravitationally bound in the line-emitting region, as well as its overall gas supply. The systematic dependence on L/L_Edd_ must be corrected when using the FeII/MgII intensity ratio as a measure of the Fe/Mg abundance ratio to study the history of chemical evolution in QSO environments.
- ID:
- ivo://CDS.VizieR/J/ApJ/835/L38
- Title:
- Fermi blazars with Doppler factors
- Short Name:
- J/ApJ/835/L38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Blazars are an extreme subclass of active galactic nuclei. Their rapid variability, luminous brightness, superluminal motion, and high and variable polarization are probably due to a beaming effect. However, this beaming factor (or Doppler factor) is very difficult to measure. Currently, a good way to estimate it is to use the timescale of their radio flares. In this Letter, we use multiwavelength data and Doppler factors reported in the literature for a sample of 86 flaring blazars detected by Fermi to compute their intrinsic multiwavelength data and intrinsic spectral energy distributions and investigate the correlations among observed and intrinsic data. Quite interestingly, intrinsic data show a positive correlation between luminosity and peak frequency, in contrast with the behavior of observed data, and a tighter correlation between {gamma}-ray luminosity and the lower-energy ones. For flaring blazars detected by Fermi, we conclude that (1) observed emissions are strongly beamed; (2) the anti-correlation between luminosity and peak frequency from the observed data is an apparent result, the correlation between intrinsic data being positive; and (3) intrinsic {gamma}-ray luminosity is strongly correlated with other intrinsic luminosities.
- ID:
- ivo://CDS.VizieR/J/MNRAS/393/1467
- Title:
- Field early-type galaxies at 0.2<z<0.8
- Short Name:
- J/MNRAS/393/1467
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the properties of 24 field early-type galaxies in the redshift range 0.20<z<0.75 down to M_B<=-19.30 in a sample extracted from the FORS Deep Field and the William Herschel Deep Field. Target galaxies were selected on the basis of a combination of luminosity, spectrophotometric type, morphology and photometric redshift or broad-band colours. High signal-to-noise intermediate-resolution spectroscopy has been acquired at the Very Large Telescope, complemented by deep high-resolution imaging with the Advanced Camera for Surveys onboard the HST and additional ground-based multi-band photometry. All galaxy spectra were observed under sub-arcsecond conditions and allow to derive accurate kinematics and stellar population properties of the galaxies. To clarify the low level of star formation detected in some galaxies, we identify the amount of active galactic nuclei (AGN) activity in our sample using archive data of Chandra and XMM-Newton X-ray surveys. None of the galaxies in our sample were identified as secure AGN sources based on their X-ray emission. The rest-frame B and K-band scaling relations of the Faber-Jackson relation and the Fundamental Plane display a moderate evolution for the field early-type galaxies. Lenticular (S0) galaxies feature on average a stronger luminosity evolution and bluer rest-frame colours which can be explained that they comprise more diverse stellar populations compared to elliptical galaxies. The evolution of the FP can be interpreted as an average change in the dynamical (effective) mass-to-light ratio of our galaxies as <{Delta}log(M/L_B_)/z>=-0.74+/-0.08. The M/L evolution of these field galaxies suggests a continuous mass assembly of field early-type galaxies during the last 5Gyr, that gets support by recent studies of field galaxies up to z~1. Independent evidence for recent star formation activity is provided by spectroscopic (OII emission, Hdelta) and photometric (rest-frame broad-band colors) diagnostics. Based on the Hdelta absorption feature we detect a weak residual star formation for galaxies that accounts for 5%-10% in the total stellar mass of these galaxies. The co-evolution in the luminosity and mass of our galaxies favours a downsizing formation process. We find some evidence that our galaxies experienced a period of star formation quenching, possible triggered by AGN activity that is in good agreement with recent results on both observational and theoretical side.
- ID:
- ivo://CDS.VizieR/J/A+A/601/A81
- Title:
- FIRST catalog of FR II radio galaxies
- Short Name:
- J/A+A/601/A81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We built a catalog of 122 FR II radio galaxies, called FRIICAT, selected from a published sample obtained by combining observations from the NVSS, FIRST, and SDSS surveys. The catalog includes sources with redshift <=0.15, an edge-brightened radio morphology, and those with at least one of the emission peaks located at radius r larger than 30 kpc from the center of the host. The radio luminosity at 1.4GHz of the FRIICAT sources covers the range L1.4~10^39.5^-10^42.5^erg/s. The FRIICAT catalog has 90% of low and 10% of high excitation galaxies (LEGs and HEGs), respectively. The properties of these two classes are significantly different. The FRIICAT LEGs are mostly luminous (-20>~Mr>~-24), red early-type galaxies with black hole masses in the range 10^8^<~M_BH_<~10^9^M_{sun}_; they are essentially indistinguishable from the FR Is belonging to the FRICAT. The HEG FR IIs are associated with optically bluer and mid-IR redder hosts than the LEG FR IIs and to galaxies and black holes that are smaller, on average, by a factor ~2. FR IIs have a factor ~3higher average radio luminosity than FR Is. Nonetheless, most (~90%) of the selected FR IIs have a radio power that is lower, by as much as a factor of ~100, than the transition value between FR Is and FR IIs found in the 3C sample. The correspondence between the morphological classification of FR I and FR II and the separation in radio power disappears when including sources selected at low radio flux thresholds, which is in line with previous results. In conclusion, a radio source produced by a low power jet can be edge brightened or edge darkened, and the outcome is not related to differences in the optical properties of the host galaxy.
- ID:
- ivo://CDS.VizieR/J/ApJ/883/175
- Title:
- First release of the MaNGA Stellar Library (MaStar)
- Short Name:
- J/ApJ/883/175
- Date:
- 29 Nov 2021 07:46:33
- Publisher:
- CDS
- Description:
- We present the first release of the MaNGA Stellar Library (MaStar), which is a large, well-calibrated, high-quality empirical library covering the wavelength range 3622-10354{AA} at a resolving power of R~1800. The spectra were obtained using the same instrument as used by the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) project, by piggybacking on the Sloan Digital Sky Survey (SDSS-IV)/Apache Point Observatory Galaxy Evolution Experiment 2-N (APOGEE-2N) observations. Compared to previous empirical libraries, the MaStar library will have a higher number of stars and a more comprehensive stellar-parameter coverage, especially of cool dwarfs, low-metallicity stars, and stars with different [{alpha}/Fe], achieved by a sophisticated target-selection strategy that takes advantage of stellar-parameter catalogs from the literature. This empirical library will provide a new basis for stellar-population synthesis and is particularly well suited for stellar-population analysis of MaNGA galaxies. The first version of the library contains 8646 high-quality per-visit spectra for 3321 unique stars. Compared to photometry, the relative flux calibration of the library is accurate to 3.9% in g-r, 2.7% in r-i, and 2.2% in i-z. The data are released as part of SDSS Data Release 15. We expect the final release of the library to contain more than 10000 stars.