- ID:
- ivo://CDS.VizieR/J/ApJS/123/377
- Title:
- u*g*r*i*z* Photometry of stars, galaxies, QSOs
- Short Name:
- J/ApJS/123/377
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog (table 5 of the paper) contains the measurements of 2262 sources, including 334 extended sources, 1915 point sources, and 13 known QSOs, in five passbands close to the u'g'r'i'z' passbands of SDSS (see the definition of the photometric system in Richards et al., 1997PASP..109...39R). Of these objects, over 1600 are measured in 15 fields covering 0.5deg^2^, with a limiting magnitude of r*<19.5, similar to the photometric limit of the SDSS spectroscopic survey.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/563/A142
- Title:
- UGR photometry of LBG candidates at z~3
- Short Name:
- J/A+A/563/A142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a deep multi wavelength imaging survey (UGR) in 3 different fields, Q0933, Q1623 and COSMOS, for a total area of ~1500arcmin^2^ The data were obtained with the Large Binocular Camera on the Large Binocular Telescope. To select our LBG candidates we adopt the well established and widely used color selection criterion (U-G vs. G-R). One of the main advantages of our survey is that it has a wider dynamic color range for U drop-out selection compared to previous studies. This allows us to fully exploit the depth of our R band images, obtaining a robust sample with few interlopers. In addition, for 2 of our fields we have spectroscopic redshift information that is necessary to better estimate the completeness of our sample and interloper fraction. Our limiting magnitudes reach 27.0(AB) in the R band (5{sigma}) and 28.6(AB) in the U band (1{sigma}). This dataset was used to derive Lyman Break Galaxy candidates at z~3. We obtained a catalog with a total of 12264 sources down to the 50% completeness magnitude limit in the R band for each field. We find a surface density of ~3 LBG candidates arcmin^-2^ down to R=25.5, where completeness is >=95% for all 3 fields. This number is higher than the original studies, but consistent with more recent samples.
- ID:
- ivo://CDS.VizieR/J/A+A/531/A4
- Title:
- Ultra compact dwarfs and globulars in Hya I
- Short Name:
- J/A+A/531/A4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We performed a large spectroscopic survey of compact, unresolved objects in the core of the Hydra I galaxy cluster (Abell 1060), with the aim of identifying ultra-compact dwarf galaxies (UCDs) and investigating the properties of the globular cluster (GC) system around the central cD galaxy NGC 3311. We obtained VIMOS medium-resolution spectra of about 1200 candidate objects with apparent magnitudes 18.5<V<24.0mag, covering both the bright end of the GC luminosity function and the luminosity range of all known UCDs.
- ID:
- ivo://CDS.VizieR/J/ApJ/923/257
- Title:
- Ultra-diffuse galaxies with spectroscopic obs.
- Short Name:
- J/ApJ/923/257
- Date:
- 14 Mar 2022 07:42:35
- Publisher:
- CDS
- Description:
- We present new redshift measurements for 19 candidate ultra-diffuse galaxies (UDGs) from the Systematically Measuring Ultra-Diffuse Galaxies (SMUDGes) survey after conducting a long-slit spectroscopic follow-up campaign on 23 candidates with the Large Binocular Telescope. We combine these results with redshift measurements from other sources for 29 SMUDGes and 20 non-SMUDGes candidate UDGs. Together, this sample yields 44 spectroscopically confirmed UDGs (r_e_>=1.5kpc and {mu}_g_(0)>=24mag/arcsec^2^ within uncertainties) and spans cluster and field environments, with all but one projected on the Coma cluster and environs. We find no statistically significant differences in the structural parameters of cluster and noncluster confirmed UDGs, although there are hints of differences among the axis ratio distributions. Similarly, we find no significant structural differences among those in locally dense or sparse environments. However, we observe a significant difference in color with respect to projected clustercentric radius, confirming trends observed previously in statistical UDG samples. This trend strengthens further when considering whether UDGs reside in either cluster or locally dense environments, suggesting starkly different star formation histories for UDGs residing in high- and low-density environments. Of the 16 large (r_e_>=3.5kpc) UDGs in our sample, only one is a field galaxy that falls near the early-type galaxy red sequence. No other field UDGs found in low-density environments fall near the red sequence. This finding, in combination with our detection of Galaxy Evolution Explorer NUV flux in nearly half of the UDGs in sparse environments, suggests that field UDGs are a population of slowly evolving galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/894/75
- Title:
- Ultra-diffuse & LSB dwarf galaxies in A370 from HFF
- Short Name:
- J/ApJ/894/75
- Date:
- 19 Jan 2022 13:03:46
- Publisher:
- CDS
- Description:
- We report the discovery of ultra-diffuse galaxies (UDGs) in Abell 370 (A370; z=0.375). We find 46 UDGs in A370 from the images of the Hubble Frontier Fields. Most UDGs are low-luminosity red sequence galaxies, while a few of them are blue UDGs. We estimate the abundance of UDGs in A370, N(UDG)=644+/-104. Combining these results with those of Abell S1063 (z=0.348) and Abell 2744 (z=0.308), we derive a mean radial number density profile of UDGs in the three clusters. The number density profiles of UDGs and bright galaxies show a discrepancy in the central region of the clusters: the profile of UDGs shows a flattening as clustercentric distance decreases, while that of bright galaxies shows a continuous increase. This implies that UDGs are prone to disruption in the central region of the clusters. The relation between the abundance of UDGs and virial masses of their host systems is described by a power law with an index of nearly one: N(UDG){propto}M_200_^0.99+/-0.05^ for M_200_>10^13^M_{sun}_. We estimate approximately dynamical masses of UDGs using the fundamental manifold method and find that most UDGs have dwarf-like masses (M_200_<10^11^M_{sun}_). This implies that most UDGs have a dwarf-like origin and a small number of them could be failed L* galaxies. These results suggest that multiple origins may contribute to the formation and evolution of UDGs in massive galaxy clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/436/457
- Title:
- Ultra-steep spectrum radio sources
- Short Name:
- J/A+A/436/457
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of radio (VLA) and optical (ESO/La Silla) imaging of a sample of 52 radio sources having an ultra-steep radio spectrum with {alpha} mostly steeper than -1.1 at decimetre wavelengths (median {alpha}=-1.22). Radio-optical overlays are presented to an astrometric accuracy of ~1". For 41 of the sources, radio spectral indices are newly determined using unpublished observations made with the 100-m Effelsberg radio telescope. For 14 of the sources identified with relatively brighter optical counterparts, spectroscopic observations were also carried out at La Silla and their redshifts are found to lie in the range 0.4 to 2.6.
- ID:
- ivo://CDS.VizieR/J/AJ/90/2221
- Title:
- UMi dwarf galaxy BV photometry
- Short Name:
- J/AJ/90/2221
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have constructed a color-magnitude diagram of the Ursa Minor dwarf spheroidal to m_V_=24.8mag from charged-coupled device (CCD) observations with the Kitt Peak 4 m telescope. The main-sequence turnoff is easily visible. Fits to evolutionary isochrones and the globular M92 indicate that Ursa Minor has an age and metal abundance very similar to that of the latter cluster. No evidence for stars younger than about 16 billion years is seen, with the possible exception of approximately 20 stars believed to be blue stragglers. Ursa Minor is therefore an extreme-age galaxy, unlike superficially similar objects such as the Carina dwarf. Indeed, Ursa Minor may be the only outer-halo spheroidal whose stellar content lives up to the classical ideals of a Population II system. A distance modulus of (m-M)_0_=19.0mag is derived from a sliding fit to the M92 ridge lines. However, this modulus is uncertain by ~0.1mag, for the horizontal branch in our color-magnitude diagram is poorly populated. The ratio of blue stragglers to anomalous Cepheids in Ursa Minor is estimated to be ~100, a number that may provide an important constraint on binary models for the origin of these stars. A surprising result of our study is the discovery of clumpiness in the distribution of stars. This finding may give more weight to the idea that dwarf spheroidal galaxies were previously dwarf irregular galaxies, although clearly, if so, Ursa Minor must have lost its gaseous content very soon after formation.
- ID:
- ivo://CDS.VizieR/J/A+A/561/A49
- Title:
- 867um image of SBS 0335-052 with ALMA
- Short Name:
- J/A+A/561/A49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 0 Band 7 observations of an extremely metal-poor dwarf starburst galaxy in the Local Universe, SBS 0335-052 (12+log(O/H)~7.2). With these observations, dust is detected at 870um (ALMA Band 7), but 87% of the flux in this band is due to free-free emission from the starburst.
- ID:
- ivo://CDS.VizieR/J/ApJ/801/127
- Title:
- 3.6um, 4.5um, B and V light curves of NGC 6418
- Short Name:
- J/ApJ/801/127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a 15 month campaign of high-cadence (~3 days) mid-infrared Spitzer and optical (B and V) monitoring of the Seyfert 1 galaxy NGC 6418, with the objective of determining the characteristic size of the dusty torus in this active galactic nucleus (AGN). We find that the 3.6 and 4.5{mu}m flux variations lag behind those of the optical continuum by 37.2_-2.2_^+2.4^-days and 47.1_-3.1_^+3.1^-days, respectively. We report a cross-correlation time lag between the 4.5 and 3.6{mu}m flux of 13.9_-0.1_^+0.5^ days. The lags indicate that the dust emitting at 3.6 and 4.5{mu}m is located at a distance ~1-light-month (~0.03pc) from the source of the AGN UV-optical continuum. The reverberation radii are consistent with the inferred lower limit to the sublimation radius for pure graphite grains at 1800K, but smaller by a factor of ~2 than the corresponding lower limit for silicate grains; this is similar to what has been found for near-infrared (K-band) lags in other AGNs. The 3.6 and 4.5{mu}m reverberation radii fall above the K-band {tau}{propto}L^0.5^ size-luminosity relationship by factors <~2.8 and <~3.4, respectively, while the 4.5{mu}m reverberation radius is only 27% larger than the 3.6{mu}m radius. This is broadly consistent with clumpy torus models, in which individual optically thick clouds emit strongly over a broad wavelength range.
- ID:
- ivo://CDS.VizieR/J/ApJ/798/54
- Title:
- "Under-massive" black hole candidates
- Short Name:
- J/ApJ/798/54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Several recent papers have reported on the occurrence of active galactic nuclei (AGNs) containing undermassive black holes relative to a linear scaling relation between black hole mass (M_bh_) and host spheroid stellar mass (M_sph,*_). However, dramatic revisions to the M_bh_-M_sph,*_ and M_bh_-L_sph_ relations, based on samples containing predominantly inactive galaxies, have recently identified a new steeper relation at M_bh_<~(2-10)x10^8^M_{sun}_, roughly corresponding to M_sph,*_<~(0.3-1)x10^11^M_{sun}_. We show that this steeper, quadratic-like M_bh_-M_sph,*_ relation defined by the Sersic galaxies, i.e., galaxies without partially depleted cores, roughly tracks the apparent offset of the AGN having 10^5^<~M_bh_/M_{sun}_<~0.5x10^8^. That is, these AGNs are not randomly offset with low black hole masses, but also follow a steeper (nonlinear) relation. As noted by Busch et al. (2014, J/A+A/561/A140), confirmation or rejection of a possible AGN offset from the steeper M_bh_-M _sph,*_ relation defined by the Sersic galaxies will benefit from improved stellar mass-to-light ratios for the spheroids hosting these AGNs. Several implications for formation theories are noted. Furthermore, reasons for possible under- and overmassive black holes, the potential existence of intermediate mass black holes (<10^5^M_{sun}_), and the new steep (black hole)-(nuclear star cluster) relation, M_bh_{propto}M_nc_^2.7+/-0.7^, are also discussed.