- ID:
- ivo://CDS.VizieR/J/AJ/133/2846
- Title:
- Photometric decomposition of barred galaxies
- Short Name:
- J/AJ/133/2846
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a nonparametric method for decomposition of the light of disk galaxies into disk, bulge, and bar components. We have developed and tested the method on a sample of 68 disk galaxies for which we have acquired I-band photometry. The separation of disk and bar light relies on the single assumption that the bar is a straight feature with a different ellipticity and position angle from that of the projected disk. Here we present the basic method, but we recognize that it can be significantly refined.
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- ID:
- ivo://CDS.VizieR/J/ApJ/684/1026
- Title:
- Photometric profiles from GOODS data
- Short Name:
- J/ApJ/684/1026
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted the largest systematic search so far for stellar disk truncations in disklike galaxies at intermediate redshift (z<1.1), using the Great Observatories Origins Deep Survey-South (GOODS-S) data from the Hubble Space Telescope ACS. Focusing on type II galaxies (i.e., downbending profiles), we explore whether the position of the break in the rest-frame B-band radial surface brightness profile (a direct estimator of the extent of the disk where most of the massive star formation is taking place) evolves with time. The number of galaxies under analysis (238 of a total of 505) is an order of magnitude larger than in previous studies. For the first time, we probe the evolution of the break radius for a given stellar mass (a parameter well suited to address evolutionary studies). We have explored the distribution of the scale lengths of the disks in the region inside the break and how this parameter relates to the break radius. We also present results of the statistical analysis of profiles of artificial galaxies, to assess the reliability of our results.
- ID:
- ivo://CDS.VizieR/J/ApJ/704/548
- Title:
- Photometric properties of galaxies at z=4-6
- Short Name:
- J/ApJ/704/548
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new information on galaxies in the vicinity of luminous radio galaxies (RGs) and quasars at z~4, 5, and 6. These fields were previously found to contain overdensities of Lyman Break Galaxies (LBGs) or spectroscopic Ly{alpha} emitters (LAEs), which were interpreted as evidence for clusters-in-formation ("protoclusters"). We use Hubble Space Telescope and Spitzer data to infer stellar masses from stellar synthesis models calibrated against the Millennium Run simulations, and contrast our results with large samples of LBGs in more average environments as probed by the Great Observatories Origins Deep Survey (GOODS).
- ID:
- ivo://CDS.VizieR/J/ApJS/158/161
- Title:
- Photometric redshift catalog from the RCS
- Short Name:
- J/ApJS/158/161
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Red-Sequence Cluster Survey (RCS, Cat. <J/ApJS/157/1>) provides a large and deep photometric catalog of galaxies in the z' and R_c_ bands for 90{deg}^2^ of sky, and supplemental V and B data have been obtained for 33.6{deg}^2^. We compile a photometric redshift catalog from these four-band data by utilizing the empirical quadratic polynomial photometric redshift fitting technique in combination with CNOC2 and GOODS/HDF-N redshift data. The training set includes 4924 spectral redshifts. The resulting catalog contains more than one million galaxies with photometric redshifts <1.5 and R_c_<24, giving an rms scatter {sigma}({Delta}z)<0.06 within the redshift range 0.2<z<0.5 and {sigma}({Delta}z)<0.11 for galaxies at 0.0<z<1.5.
- ID:
- ivo://CDS.VizieR/J/ApJ/862/12
- Title:
- Photometric Redshift Catalog (SCUSS, SDSS, WISE)
- Short Name:
- J/ApJ/862/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We publish a photometric redshift catalog based on imaging data of the South Galactic Cap u-band Sky Survey, Sloan Digital Sky Survey (SDSS), and Wide-field Infrared Survey Explorer (WISE). A total of 7 photometric bands are used, ranging from near ultraviolet to near infrared. A local linear regression method is adopted to estimate the photometric redshift with a dedicated spectroscopic training set. The photometric redshift catalog contains about 23.1 million galaxies classified by SDSS. Using the training set with redshift up to 0.8 and r-band magnitude down to 22mag, we achieve an average bias of {Delta}z_norm_=0.000228, standard deviation of {sigma}({Delta}z_norm_)=0.019, and 3{sigma} outlier rate of about 4.2%. The bias is less than 0.01 at z<0.6 and goes up to about 0.05 at z~0.8. Compared with SDSS photometric redshifts, our redshift estimations are more accurate and have less bias.
- ID:
- ivo://CDS.VizieR/J/AJ/157/99
- Title:
- Photometric redshifts of emission-line galaxies
- Short Name:
- J/AJ/157/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Broadband photometric redshifts are routinely obtained for galaxies to estimate their distances. While effective for many uses, the common resolution in z of 0.01-0.02 is too coarse for detailed large-scale structure mapping, particularly in low-density volumes where the galaxy distribution is least understood. To map galaxies in these low-density volumes, and noting that the percentage of galaxies having emission tends to rise as number density decreases, we have designed a filter system to photometrically measure the redshifts of galaxies with emission. The system consists of two "ramp" filters that cover a common wavelength range with transmission curves sloping from blue to red and from red to blue respectively. This causes the intensity of the image through either filter to be a function of the wavelength of the emission line. A third filter with a bandpass to the side is used to measure and remove the continuum. We have obtained a set of such filters that are tuned for isolating H{alpha} in the redshift range of 3000-9000 km/s. Simulated photometry, applied to spectra of 197 emission-line galaxies from the SDSS, shows the accuracy of the method to be between 250 and 620 km/s, depending on line strength. Actual photometry of a sample of 16 active galaxies measured their redshifts with an accuracy of 573 km/s. This is approximately an order of magnitude more accurate than broadband photometric redshifts. We discuss the errors inherent in this method and present ways to modify the filter set to further improve accuracy.
- ID:
- ivo://CDS.VizieR/J/MNRAS/405/1089
- Title:
- Photometric scaling for L/S0 galaxies
- Short Name:
- J/MNRAS/405/1089
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometric scaling relations are studied for S0 galaxies and compared with those obtained for spirals. New two-dimensional multi-component decompositions are presented for 122 early-type disc galaxies, using deep Ks-band images. Combining them with our previous decompositions, the final sample consists of 175 galaxies (Near-Infrared Survey of S0s, NIRS0S: 117 S0s + 22 S0/a and 36 Sa galaxies). As a comparison sample we use the Ohio State University Bright Spiral Galaxy Survey (OSUBSGS) of nearly 200 spirals, for which similar multi-component decompositions have previously been made by us.
- ID:
- ivo://CDS.VizieR/J/MNRAS/486/1377
- Title:
- Photometric SFR using machine learning
- Short Name:
- J/MNRAS/486/1377
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Star formation rates (SFRs) are crucial to constrain theories of galaxy formation and evolution. SFRs are usually estimated via spectroscopic observations requiring large amounts of telescope time. We explore an alternative approach based on the photometric estimation of global SFRs for large samples of galaxies, by using methods such as automatic parameter space optimisation, and supervised machine learning models. We demonstrate that, with such approach, accurate multiband photometry allows to estimate reliable SFRs. We also investigate how the use of photometric rather than spectroscopic redshifts, affects the accuracy of derived global SFRs. Finally, we provide a publicly available catalogue of SFRs for more than 27 million galaxies extracted from the Sloan Digital Sky Survey Data Release 7. The catalogue will be made available through the Vizier facility.
- ID:
- ivo://CDS.VizieR/J/AJ/158/175
- Title:
- Photometric & spectroscopic study of AF And in M31
- Short Name:
- J/AJ/158/175
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a photometric and spectroscopic analysis of the Hubble-Sandage variable star AF And in M31. The data have been taken under the Nainital Microlensing Survey during 1998-2002, and follow-up observations were carried out until 2011. During this period, photometric observations in Cousins R and I bands were obtained for 169 nights spanning about 5000 days. AF And showed a prominent outburst around 1999 mid-January, followed by a gradual decrease in brightness of about 1.5 mag in the next 3 yr with a declining rate of ~0.0015 mag/day, leading to a quiescent phase at the end of 2001. After lying low for about 9 yr, AF And again went through a secondary outburst phase in late 2010 with an amplitude of 0.44 mag, where it lasted for one year before fading back to its quiescent phase. Spectroscopic observations of AF And show prominent Balmer and He I emission lines along with the comparatively weaker Fe II and [Fe II] emissions. Asymmetric emission line profiles in its spectrum imply a mass-loss rate of about 2.2x10^-4^ M_{sun}_/yr through the stellar winds in the photosphere. Using spectral energy distribution fitting, we find a photospheric temperature of 33000+/-3000 K during the visual minimum. Using a weak P Cygni profile of the He I emission line, the wind terminal velocity for AF And is found to be around 280-300 km/s.
- ID:
- ivo://CDS.VizieR/J/AcA/58/23
- Title:
- Photometric survey for M33 stellar clusters
- Short Name:
- J/AcA/58/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 4780 extended sources from the outer field of M33. The catalog includes 73 previously identified clusters or planetary nebulae, 1153 likely background galaxies, and 3554 new candidate stellar clusters. The survey is based on deep ground-based images obtained with the MegaCam instrument on the CFHT telescope. We provide g'r'i' photometry for detected objects as well as estimates of the FWHM and ellipticity of their profiles. The sample includes 122 new, relatively bright, likely globular clusters. Follow-up observations of fainter candidates from our list may extend the faint-end of the observed luminosity function of globular clusters in M33 by up to 3 magnitudes. The catalog includes several cluster candidates located in the outskirts of the galaxy. These objects are promising targets for deep photometry with the HST. We present a color-magnitude diagram for one detected object, showing that it is an extended and low-surface-brightness old cluster located at an angular distance of 27' from the center of M33.
