- ID:
- ivo://CDS.VizieR/J/ApJS/149/53
- Title:
- Multicolor photometry of A2255 galaxies
- Short Name:
- J/ApJS/149/53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present our optical multicolor photometry for the nearby cluster of galaxies A2255 with 13 intermediate filters in the Beijing-Arizona-Taiwan-Connecticut (BATC) system (see Cat. II/262), which cover an optical wavelength range from 3000 to 10000{AA}. The spectral energy distributions (SEDs) in the optical band for more than 7000 sources are achieved down to V~20 in a field of 58'x58' entered on this rich cluster. A2255 has been observed by the Sloan Digital Sky Survey (SDSS) down to V~17.5 spectroscopically and r'~22.0 photometrically. A method of combining the SDSS photometric data in five broad bands and the BATC SEDs is then explored. A sample of 254 galaxies with known redshifts in the region of A2255 is constructed for testing the reliability of the method of combining SEDs. Our application of the technique of photometric redshift on this sample shows that the combined SEDs with higher resolution could lead to a more accurate estimate of photometric redshift. Based on 214 spectroscopically confirmed member galaxies, spatial and dynamical properties of this cluster are studied.
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- ID:
- ivo://CDS.VizieR/J/A+A/556/A55
- Title:
- Multi-color photometry of star-forming galaxies
- Short Name:
- J/A+A/556/A55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We estimate the galaxy stellar mass function and stellar mass density for star-forming and quiescent galaxies with 0.2<z<4. We construct a large, deep sample of galaxies selected using the new UltraVISTA DR1 data release (Cat. J/A+A/544/A156). Our analysis is based on precise 30-band photometric redshifts. By comparing these photometric redshifts with 10800 spectroscopic redshifts from the zCOSMOS bright (Cat. J/ApJS/172/70) and faint (Lilly et al. in prep) surveys, we find an accuracy of sigma(dz/(1+z))=0.008 at i<22.5 and sigma(dz/(1+z))=0.03 at 1.5<z<4.
- ID:
- ivo://CDS.VizieR/J/MNRAS/474/3324
- Title:
- Multicomponent matched filter test
- Short Name:
- J/MNRAS/474/3324
- Date:
- 02 Mar 2022 00:06:44
- Publisher:
- CDS
- Description:
- We describe a multicomponent matched filter (MCMF) cluster confirmation tool designed for the study of large X-ray source catalogues produced by the upcoming X-ray all-sky survey mission eROSITA. We apply the method to confirm a sample of 88 clusters with redshifts 0.05<z<0.8 in the recently published 2RXS catalogue from the ROSAT All-Sky Survey (RASS) over the 208 deg^2^ region overlapped by the Dark Energy Survey (DES) Science Verification (DES-SV) data set. In our pilot study, we examine all X-ray sources, regardless of their extent. Our method employs a multicolour red sequence (RS) algorithm that incorporates the X-ray count rate and peak position in determining the region of interest for follow-up and extracts the positionally and colour-weighted optical richness {lambda}_MCMF_ as a function of redshift for each source. Peaks in the {lambda}_MCMF_-redshift distribution are identified and used to extract photometric redshifts, richness and uncertainties. The significances of all optical counterparts are characterized using the distribution of richnesses defined along random lines of sight. These significances are used to extract cluster catalogues and to estimate the contamination by random superpositions of unassociated optical systems. The delivered photometric redshift accuracy is {delta}z/(1+z)=0.010. We find a well-defined X-ray luminosity-{lambda}_MCMF_ relation with an intrinsic scatter of {delta}ln({lambda}_MCMF_|Lx)=0.21. Matching our catalogue with the DES-SV redMaPPer catalogue yields good agreement in redshift and richness estimates; comparing our catalogue with the South Pole Telescope (SPT) selected clusters shows no inconsistencies. SPT clusters in our data set are consistent with the high-mass extension of the RASS-based {lambda}_MCMF_-mass relation.
- ID:
- ivo://CDS.VizieR/J/ApJ/853/68
- Title:
- Multi-epoch VLBA imaging of 20 Tev blazars
- Short Name:
- J/ApJ/853/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 88 multi-epoch Very Long Baseline Array (VLBA) images (most at an observing frequency of 8GHz) of 20TeV blazars, all of the high-frequency-peaked BL Lac (HBL) class, that have not been previously studied at multiple epochs on the parsec scale. From these 20 sources, we analyze the apparent speeds of 43 jet components that are all detected at four or more epochs. As has been found for other TeV HBLs, the apparent speeds of these components are relatively slow. About two-thirds of the components have an apparent speed that is consistent (within 2{sigma}) with no motion, and some of these components may be stationary patterns whose apparent speed does not relate to the underlying bulk flow speed. In addition, a superluminal tail to the apparent speed distribution of the TeV HBLs is detected for the first time, with eight components in seven sources having a 2{sigma} lower limit on the apparent speed exceeding 1c. We combine the data from these 20 sources with an additional 18 sources from the literature to analyze the complete apparent speed distribution of all 38 TeV HBLs that have been studied with very long baseline interferometry at multiple epochs. The highest 2{sigma} apparent speed lower limit considering all sources is 3.6c. This suggests that bulk Lorentz factors of up to about 4, but probably not much higher, exist in the parsec-scale radio-emitting regions of these sources, consistent with estimates obtained in the radio by other means such as brightness temperatures. This can be reconciled with the high Lorentz factors estimated from the high-energy data if the jet has velocity structures consisting of different emission regions with different Lorentz factors. In particular, we analyze the current apparent speed data for the TeV HBLs in the context of a model with a fast central spine and a slower outer layer.
- ID:
- ivo://CDS.VizieR/J/A+A/495/691
- Title:
- Multifrequency catalogue of blazars, Roma-BZCAT
- Short Name:
- J/A+A/495/691
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalogue of blazars based on multifrequency surveys and on an extensive review of the literature. Blazars are classified as BL Lacertae objects, as flat spectrum radio quasars or as blazars of uncertain/transitional type. Each object is identified by a root name, coded as BZB, BZQ and BZU for these three subclasses respectively, and by its coordinates. This catalogue is being built as a tool useful for the identification of the extragalactic sources that will be detected by present and future experiments for X and gamma-ray astronomy, like Swift, AGILE, Fermi-GLAST and Simbol-X. An electronic version is available from the ASI Science Data Center web site at http://www.asdc.asi.it/bzcat.
- ID:
- ivo://CDS.VizieR/J/ApJ/749/97
- Title:
- Multiple lensed images in MCS J1206.2-0847
- Short Name:
- J/ApJ/749/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a strong-lensing analysis of the galaxy cluster MACS J1206.2-0847 (z=0.44) using UV, Optical, and IR, HST/ACS/WFC3 data taken as part of the CLASH multi-cycle treasury program, with VLT/VIMOS spectroscopy for some of the multiply lensed arcs. The CLASH observations, combined with our mass model, allow us to identify 47 new multiply lensed images of 12 distant sources. These images, along with the previously known arc, span the redshift range 1<~z<~5.5, and thus enable us to derive a detailed mass distribution and to accurately constrain, for the first time, the inner mass profile of this cluster. We find an inner profile slope of dlog{Sigma}/dlog{theta}=~-0.55+/-0.1 (in the range [1",53"], or 5kpc<~r<~300kpc), as commonly found for relaxed and well-concentrated clusters. Using the many systems uncovered here we derive credible critical curves and Einstein radii for different source redshifts. For a source at z_s_=~2.5, the critical curve encloses a large area with an effective Einstein radius of {theta}_E_=28"+/-3", and a projected mass of (1.34+/-0.15)x10^14^M_{sun}_. From the current understanding of structure formation in concordance cosmology, these values are relatively high for clusters at z~0.5, so that detailed studies of the inner mass distribution of clusters such as MACS J1206.2-0847 can provide stringent tests of the {Lambda}CDM paradigm.
- ID:
- ivo://CDS.VizieR/J/A+A/399/813
- Title:
- Multiple merging events in Abell 521
- Short Name:
- J/A+A/399/813
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed spatial and dynamical analysis of the central ~2.2Mpc(Ho=75km/s/Mpc) region of the galaxy cluster Abell 521 (z=0.247), based on 238 spectra (of which 191 new measurements) obtained at the 3.6m Telescope of the European Southern Observatory and at the Canada-France-Hawaii Telescope. From the analysis of the 125 galaxies that are confirmed members of the cluster, we derive a location ("mean" velocity) of C_BI_=74019^{+112}^_{-125}_km/s and detect a complex velocity distribution with high velocity scale ("dispersion", S_BI_=1325^{+145}^_{-100}_km/s), but clear departure from a single Gaussian component. When excluding a possible background group of four galaxies, the velocity dispersion remains still large (~1200 km/s).
- ID:
- ivo://CDS.VizieR/J/ApJ/668/643
- Title:
- Multiply imaged gravitational lens systems
- Short Name:
- J/ApJ/668/643
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a reconstruction of the mass distribution of galaxy cluster Abell 1689 at z=0.18 using detected strong lensing features from deep ACS observations and extensive ground based spectroscopy. Earlier analyses have reported up to 32 multiply imaged systems in this cluster, of which only 3 were spectroscopically confirmed. In this work, we present a parametric strong lensing mass reconstruction using 34 multiply imaged systems of which 24 have newly determined spectroscopic redshifts, which is a major step forward in building a robust mass model. In turn, the new spectroscopic data allows a more secure identification of multiply imaged systems.
- ID:
- ivo://CDS.VizieR/J/ApJ/817/60
- Title:
- Multiply imaged supernova Refsdal
- Short Name:
- J/ApJ/817/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Supernova "Refsdal", multiply imaged by cluster MACS1149.5+2223, represents a rare opportunity to make a true blind test of model predictions in extragalactic astronomy, on a timescale that is short compared to a human lifetime. In order to take advantage of this event, we produced seven gravitational lens models with five independent methods, based on Hubble Space Telescope (HST) Hubble Frontier Field images, along with extensive spectroscopic follow-up observations by HST, the Very Large and the Keck Telescopes. We compare the model predictions and show that they agree reasonably well with the measured time delays and magnification ratios between the known images, even though these quantities were not used as input. This agreement is encouraging, considering that the models only provide statistical uncertainties, and do not include additional sources of uncertainties such as structure along the line of sight, cosmology, and the mass sheet degeneracy. We then present the model predictions for the other appearances of supernova "Refsdal". A future image will reach its peak in the first half of 2016, while another image appeared between 1994 and 2004. The past image would have been too faint to be detected in existing archival images. The future image should be approximately one-third as bright as the brightest known image (i.e., H_AB_~25.7mag at peak and H_AB_~26.7mag six months before peak), and thus detectable in single-orbit HST images. We will find out soon whether our predictions are correct.
- ID:
- ivo://CDS.VizieR/J/ApJ/851/33
- Title:
- Multi-wavelength analysis of CGRaBS blazars
- Short Name:
- J/ApJ/851/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a multi-frequency, time-averaged analysis of blazars included in the Candidate Gamma-ray Blazar Survey catalog. Our sample consists of 324 {gamma}-ray detected ({gamma}-ray loud) and 191 {gamma}-ray undetected ({gamma}-ray quiet) blazars; we consider all the data up to 2016 April 1. We find that both the {gamma}-ray loud and {gamma}-ray quiet blazar populations occupy similar regions in the WISE color-color diagram, and {gamma}-ray loud sources are brighter in the radio and X-ray bands. A simple one-zone synchrotron inverse-Compton emission model is applied to derive the physical properties of both populations. We find that the central black hole mass and accretion disk luminosity (L_disk_) computed from the modeling of the optical-UV emission with a Shakura-Sunyaev disk reasonably matches that estimated from the optical spectroscopic emission-line information. A significantly larger Doppler boosting in the {gamma}-ray loud blazars is noted, and their jets are more radiatively efficient. On the other hand, the {gamma}-ray quiet objects are more MeV-peaked and thus could be potential targets for next-generation MeV missions. Our results confirm earlier findings about the accretion-jet connection in blazars; however, many of the {gamma}-ray quiet blazars tend to deviate from the recent claim that the jet power exceeds L_disk_ in blazars. A broadband study, considering a larger set of {gamma}-ray quiet objects and also including BL Lacs, will be needed to confirm/reject this hypothesis as well as to verify the evolution of the powerful high-redshift blazars into their low-power nearby counterparts.
