- ID:
- ivo://CDS.VizieR/J/ApJS/93/211
- Title:
- IUE survey of H I Ly{alpha} absorption. I.
- Short Name:
- J/ApJS/93/211
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We measure Galactic interstellar neutral hydrogen column densities by analyzing archival interstellar Ly{alpha} absorption line data toward 554 B2 and hotter stars observed at high resolution with the IUE satellite. This study more than doubles the number of lines of sight with measures of N(H I) based on Ly{alpha}. We have included the scattered light background correction algorithm of Bianchi and Bohlin (1984A&A...134...31B) in our data reduction. We use the correlation between the Balmer discontinuity [c_1_] index and the stellar Ly{alpha} absorption in order to assess the effects of stellar Ly alpha contamination. Approximately 40% of the B stars with measured [c_1_] index, exhibit serious stellar Ly{alpha} contamination. Table 1 contains the derived values of the interstellar N(H I) for 393 stars with at most small amounts of stellar contamination. Table 2 lists the observed values of total N(H I) for 161 stars with suspected stellar Ly alpha contamination and/or uncertain stellar parameters.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/151/78
- Title:
- Jellyfish galaxy candidates in galaxy clusters
- Short Name:
- J/AJ/151/78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galaxies that are being stripped of their gas can sometimes be recognized from their optical appearance. Extreme examples of stripped galaxies are the so-called "jellyfish galaxies" that exhibit tentacles of debris material with a characteristic jellyfish morphology. We have conducted the first systematic search for galaxies that are being stripped of their gas at low-z (z=0.04-0.07) in different environments, selecting galaxies with varying degrees of morphological evidence for stripping. We have visually inspected B- and V-band images and identified 344 candidates in 71 galaxy clusters of the OMEGAWINGS+WINGS sample and 75 candidates in groups and lower mass structures in the PM2GC sample. We present the atlas of stripping candidates and a first analysis of their environment and their basic properties, such as morphologies, star formation rates and galaxy stellar masses. Candidates are found in all clusters and at all clustercentric radii, and their number does not correlate with the cluster velocity dispersion {sigma} or X-ray luminosity L_X_. Interestingly, convincing cases of candidates are also found in groups and lower mass halos (10^11^-10^14^M_{sun}_), although the physical mechanism at work needs to be securely identified. All the candidates are disky, have stellar masses ranging from log M/M_{sun}_<9 to >11.5 and the majority of them form stars at a rate that is on average a factor of 2 higher (2.5{sigma}) compared to non-stripped galaxies of similar mass. The few post-starburst and passive candidates have weak stripping evidence. We conclude that disturbed morphologies suggestive of stripping phenomena are ubiquitous in clusters and could be present even in groups and low mass halos. Further studies will reveal the physics of the gas stripping and clarify the mechanisms at work.
- ID:
- ivo://CDS.VizieR/J/ApJ/861/97
- Title:
- Jet power of blazars from the TGSS at 150MHz
- Short Name:
- J/ApJ/861/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The composition and energy dissipation in jets are two of the fundamental questions of jet physics that are not fully understood. In this paper, we attempt to constrain the composition, magnetization, and radiative efficiency for blazars with the recently released low-frequency radio catalog of the TIFR GMRT Sky Survey at 150MHz. The jet power estimated from the low-frequency radio emission is much lower than that derived from spectral energy distribution fitting assuming one proton per electron. Assuming the jet power estimated from low-frequency radio emission is physical, the fraction of electron/positron pairs can be constrained with n_pairs_/n_p_~10. By comparing the power carried by the magnetic field and radiation with the jet power estimated from the low-frequency radio emission, we find both the relatively high magnetization parameter of {sigma}~0.5 and the radiative efficiency of {eta}~0.4 in the dissipation region of blazars. These results suggest that magnetic reconnection processes may play an important role in the energy dissipation of blazars. We also explore the connection between these three parameters (n_pairs_/n_p_, {sigma}, and {eta}) and the black hole mass, disk luminosity, and Eddington ratio. No significant correlation is found, except that {sigma} shows a possible correlation with disk luminosity.
- ID:
- ivo://CDS.VizieR/J/ApJS/235/39
- Title:
- Jet properties of {gamma}-ray-loud 3FGL AGNs
- Short Name:
- J/ApJS/235/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on broadband spectral energy distributions (SEDs), we estimate the jet physical parameters of 1392 {gamma}-ray-loud active galactic nuclei (AGNs), the largest sample so far. The (SED) jet power and magnetization parameter are derived for these AGNs. Out of these sources, the accretion disk luminosity of 232 sources and (extended) kinetic jet powers of 159 sources are compiled from archived papers. We find the following. (1) Flat-spectrum radio quasars (FSRQs) and BL Lacs are well separated by {Gamma}=-0.127logL_{gamma}_+8.18 in the {gamma}-ray luminosity versus photon index plane with a success rate of 88.6%. (2) Most FSRQs present a (SED) jet power larger than the accretion power, which suggests that the relativistic jet-launching mechanism is dominated by the Blandford-Znajek process. This result confirms previous findings. (3) There is a significant anticorrelation between jet magnetization and a ratio of the (SED) jet power to the (extended) kinetic jet power, which, for the first time, provides supporting evidence for the jet energy transportation theory: a high- magnetization jet may more easily transport energy to a large scale than a low-magnetization jet.
- ID:
- ivo://CDS.VizieR/J/A+A/568/A22
- Title:
- Joint analysis of the SDSS-II and SNLS SNe Ia
- Short Name:
- J/A+A/568/A22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We deliver luminosity-distance measurements from a joint analysis of 740 type-Ia supernovae from the SDSS and SNLS supernova surveys.
- ID:
- ivo://CDS.VizieR/J/ApJ/810/L9
- Title:
- 1.5Jy MOJAVE AGN sample and 3FGL data
- Short Name:
- J/ApJ/810/L9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the complete MOJAVE 1.5Jy sample of active galactic nuclei (AGNs) to examine the gamma-ray detection statistics of the brightest radio-loud blazars in the northern sky. We find that 23% of these AGNs were not detected above 0.1GeV by the Fermi-LAT during the four-year 3FGL catalog period partly because of an instrumental selection effect and partly due to their lower Doppler boosting factors. Blazars with synchrotron peaks in their spectral energy distributions located below 10^13.4^Hz also tend to have high-energy peaks that lie below the 0.1GeV threshold of the LAT, and are thus less likely to be detected by Fermi. The non-detected AGNs in the 1.5Jy sample also have significantly lower 15GHz radio modulation indices and apparent jet speeds, indicating that they have lower than average Doppler factors. Since the effective amount of relativistic Doppler boosting is enhanced in gamma-rays (particularly in the case of external inverse-Compton scattering), this makes them less likely to appear in the 3FGL catalog. Based on their observed properties, we have identified several bright radio-selected blazars that are strong candidates for future detection by Fermi.
- ID:
- ivo://CDS.VizieR/J/ApJS/237/14
- Title:
- KASI-Yonsei Deep Imaging Survey of Clusters (KYDISC)
- Short Name:
- J/ApJS/237/14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the KASI-Yonsei Deep Imaging Survey of Clusters targeting 14 clusters at 0.015<~z<~0.144 using the Inamori Magellan Areal Camera and Spectrograph on the 6.5m Magellan Baade telescope and the MegaCam on the 3.6m Canada-France-Hawaii Telescope. We provide a catalog of cluster galaxies that lists magnitudes, redshifts, morphologies, bulge-to-total ratios, and local density. Based on the 1409 spectroscopically confirmed cluster galaxies brighter than -19.8 in the r band, we study galaxy morphology, color, and visual features generated by galaxy mergers. We see a clear trend between morphological content and cluster velocity dispersion, which was not presented by previous studies using local clusters. Passive spirals are preferentially found in a highly dense region (i.e., cluster center), indicating that they have gone through environmental quenching. In deep images ({mu}_r'_~27mag/arcsec^2^), 20% of our sample shows signatures of recent mergers, which is not expected from theoretical predictions and a low frequency of ongoing mergers in our sample (~4%). Such a high fraction of recent mergers in the cluster environment supports a scenario that the merger events that made the features have preceded the galaxy accretion into the cluster environment. We conclude that mergers affect a cluster population mainly through the preprocessing of recently accreted galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/560/566
- Title:
- K-band galaxy luminosity function from 2MASS
- Short Name:
- J/ApJ/560/566
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We measured the K-band luminosity function using a complete sample of 4192 morphologically typed 2MASS galaxies with {mu}_Ks_=20mag/arcsec^2^ isophotal magnitudes 7<K_20_<11.25mag spread over 2.12sr.
- ID:
- ivo://CDS.VizieR/J/ApJ/748/56
- Title:
- K2-detected clusters in the CFHTLS-W1 field
- Short Name:
- J/ApJ/748/56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first weak gravitational lensing analysis of the completed Canada-France-Hawaii Telescope Legacy Survey (CFHTLS). We study the 64 deg^2^ W1 field, the largest of the CFHTLS-Wide survey fields, and present the largest contiguous weak lensing convergence "mass map" yet made. 2.66 million galaxy shapes are measured, using the Kaiser Squires and Broadhurst Method (KSB) pipeline verified against high-resolution Hubble Space Telescope imaging that covers part of the CFHTLS. Our i'-band measurements are also consistent with an analysis of independent r'-band imaging. The reconstructed lensing convergence map contains 301 peaks with signal-to-noise ratio {nu}>3.5, consistent with predictions of a {Lambda}CDM model. Of these peaks, 126 lie within 3.0' of a brightest central galaxy identified from multicolor optical imaging in an independent, red sequence survey. We also identify seven counterparts for massive clusters previously seen in X-ray emission within 6 deg^2^ XMM-LSS survey. With photometric redshift estimates for the source galaxies, we use a tomographic lensing method to fit the redshift and mass of each convergence peak. Matching these to the optical observations, we confirm 85 groups/clusters with {chi}^2^_reduced_<3.0, at a mean redshift <z_c_>=0.36 and velocity dispersion <{sigma}_c_>=658.8km/s. Future surveys, such as DES, LSST, KDUST, and EUCLID, will be able to apply these techniques to map clusters in much larger volumes and thus tightly constrain cosmological models.
- ID:
- ivo://CDS.VizieR/J/ApJS/173/471
- Title:
- Keck DEIMOS spectroscopy of GALEX sources
- Short Name:
- J/ApJS/173/471
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report results from a pilot program to obtain spectroscopy for objects detected in the Galaxy Evolution Explorer (GALEX) Medium Imaging Survey (MIS). Our study examines the properties of galaxies detected by GALEX fainter than the Sloan Digital Sky Survey (SDSS) spectroscopic survey. This is the first study to extend the techniques of Salim and coworkers to estimate stellar masses, star formation rates (SFRs), and the b (star formation history) parameter for star-forming galaxies out to z~0.7. We obtain redshifts for 50 GALEX MIS sources reaching NUV=23.9 (AB mag) having counterparts in the SDSS Data Release 4 (DR4). Of our sample, 43 are star-forming galaxies with z<0.7, 3 have emission-line ratios indicative of active galactic nuclei with z<0.7, and 4 objects with z>1 are QSOs, 3 of which are not previously cataloged. We compare our sample to a much larger sample of ~50000 matched GALEX/SDSS galaxies with SDSS spectroscopy; while our survey is shallow, the optical counterparts to our sources reach ~3mag fainter in SDSS r than the SDSS spectroscopic sample. We use emission-line diagnostics for the galaxies to determine that the sample contains mostly star-forming galaxies.
