- ID:
- ivo://CDS.VizieR/J/MNRAS/406/1318
- Title:
- Lensed-arc statistics of galaxy clusters
- Short Name:
- J/MNRAS/406/1318
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The statistics of strongly lensed arcs in samples of galaxy clusters provide information on cluster structure that is complementary to that from individual clusters. However, samples of clusters that have been analysed to date have been either small, heterogeneous or observed with limited angular resolution. We measure the lensed-arc statistics of 97 clusters imaged at high angular resolution with the Hubble Space Telescope, identifying lensed arcs using two automated arc-detection algorithms. The sample includes similar numbers of X-ray-selected [MAssive Cluster Survey (MACS)] and optically selected [Red-Sequence Cluster Survey (RCS)] clusters, and spans cluster redshifts in the range 0.2<z<1. We compile a catalogue of 42 arcs in the X-ray-selected subsample and seven arcs in the optical subsample. All but five of these arcs are reported here for the first time.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/462/2934
- Title:
- Lockman Hole North 3GHz catalogue
- Short Name:
- J/MNRAS/462/2934
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second of two papers describing the observations and source catalogues derived from sensitive $3$-GHz images of the Lockman Hole North using the Karl G. Jansky Very Large Array. We describe the reduction and cataloguing process, which yielded an image with 8-arcsec resolution and instrumental noise of {sigma}_n=1.01uJy/beam rms (before primary beam corrections) and a catalogue of 558 sources detected above 5{sigma}_n. We include details of how we estimate source spectral indices across the 2GHz VLA bandwidth, finding a median index of -0.76+/-0.04. Stacking of source spectra reveals a flattening of spectral index with decreasing flux density. We present a source count derived from the catalogue. We show a traditional count estimate compared with a completely independent estimate made via a P(D) confusion analysis, and find very good agreement. Cross-matches of the catalogue with X-ray, optical, infrared, radio, and redshift catalogues are also presented. The X-ray, optical and infrared data, as well as AGN selection criteria allow us to classify 10 per cent as radio-loud AGN, 28 percent as radio-quiet AGN, and 58 per cent as star-forming galaxies, with only 4 per cent unclassified.
- ID:
- ivo://CDS.VizieR/J/MNRAS/466/2570
- Title:
- Low ionization emission-line regions galaxies
- Short Name:
- J/MNRAS/466/2570
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using spatially resolved spectroscopy from SDSS-IV MaNGA we have demonstrated that low ionization emission-line regions (LIERs) in local galaxies result from photoionization by hot evolved stars, not active galactic nuclei, hence tracing galactic region hosting old stellar population where, despite the presence of ionized gas, star formation is no longer occurring. LIERs are ubiquitous in both quiescent galaxies and in the central regions of galaxies where star formation takes place at larger radii. We refer to these two classes of galaxies as extended LIER (eLIER) and central LIER (cLIER) galaxies, respectively. cLIERs are late-type galaxies primarily spread across the green valley, in the transition region between the star formation main sequence and quiescent galaxies. These galaxies display regular disc rotation in both stars and gas, although featuring a higher central stellar velocity dispersion than star-forming galaxies of the same mass. cLIERs are consistent with being slowly quenched inside-out; the transformation is associated with massive bulges, pointing towards the importance of bulge growth via secular evolution. eLIERs are morphologically early types and are indistinguishable from passive galaxies devoid of line emission in terms of their stellar populations, morphology and central stellar velocity dispersion. Ionized gas in eLIERs shows both disturbed and disc-like kinematics. When a large-scale flow/rotation is observed in the gas, it is often misaligned relative to the stellar component. These features indicate that eLIERs are passive galaxies harbouring a residual cold gas component, acquired mostly via external accretion. Importantly, quiescent galaxies devoid of line emission reside in denser environments and have significantly higher satellite fraction than eLIERs. Environmental effects thus represent the likely cause for the existence of line-less galaxies on the red sequence.
- ID:
- ivo://CDS.VizieR/J/MNRAS/451/2723
- Title:
- Low-redshift clusters in the SAMI Pilot Survey
- Short Name:
- J/MNRAS/451/2723
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using new integral field observations of 106 galaxies in three nearby clusters, we investigate how the intrinsic scatter of the Fundamental Plane depends on the way in which the velocity dispersion and effective radius are measured. Our spatially resolved spectroscopy, combined with a cluster sample with negligible relative distance errors, allows us to derive a Fundamental Plane with minimal systematic uncertainties. From the apertures we tested, we find that velocity dispersions measured within a circular aperture with radius equal to one effective radius minimizes the intrinsic scatter of the Fundamental Plane. Using simple yet powerful Jeans dynamical models, we determine dynamical masses for our galaxies. Replacing luminosity in the Fundamental Plane with dynamical mass, we demonstrate that the resulting Mass Plane has further reduced scatter, consistent with zero intrinsic scatter. Using these dynamical models, we also find evidence for a possibly non-linear relationship between dynamical mass-to-light ratio and velocity dispersion.
- ID:
- ivo://CDS.VizieR/J/MNRAS/441/1802
- Title:
- Low-redshift QSOs in SDSS Stripe 82
- Short Name:
- J/MNRAS/441/1802
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the environments of low-redshift (z<0.5) quasars based on a large and homogeneous data set from the Stripe 82 region of the Sloan Digital Sky Survey (SDSS). We have compared the <1Mpc scale environments of 302 quasars that were resolved in our recent study to those of 288 inactive galaxies with closely matched redshifts. Crucially, the luminosities of the inactive galaxies and the quasar host galaxies are also closely matched, unlike in most previous studies. The environmental overdensities were studied by measuring the number density of galaxies within a projected distance of 200kpc to 1Mpc. The galaxy number density of the quasar environments is comparable to that of the inactive galaxies with similar luminosities, both classes of objects showing significant excess compared to the background galaxy density for distances <400kpc. There is no significant dependence of the galaxy number density on redshift, quasar or host galaxy luminosity, black hole mass or radio loudness. This suggests that the fuelling and triggering of the nuclear activity is only weakly dependent on the local environment of quasars, and the quasar phase may be a short-lived common phase in the life cycle of all massive galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/440/476
- Title:
- Low-redshift quasars in SDSS Stripe 82
- Short Name:
- J/MNRAS/440/476
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a photometrical and morphological study of the properties of low-redshift (z<0.5) quasars based on a large and homogeneous data set of objects derived from the Sloan Digital Sky Survey Data Release 7. This study over number by a factor of ~5 any other previous study of quasi-stellar object (QSO) host galaxies at low redshift undertaken either on ground or on space surveys. We used ~400 quasars that were imaged in the SDSS Stripe 82 that is up to 2mag deeper than standard Sloan images. For these quasars we undertake a study of the host galaxies and of their environments. In this paper we report the results for the quasar hosts. We are able to detect the host galaxy for more than 3/4 of the whole data set and characterize the properties of their hosts. We found that QSO hosts are dominated by luminous galaxies of absolute magnitude M*-3<M(R)<M*. For the unresolved objects we computed an upper limit to the host luminosity. For each well-resolved quasar we are also able to characterize the morphology of the host galaxy that turn out to be more complex than what found in previous studies. QSOs are hosted in a variety of galaxies from pure ellipticals to complex/composite morphologies that combine spheroids, disc, lens and halo. The black hole (BH) mass of the quasar, estimated from the spectral properties of the nuclei, is poorly correlated with the total luminosity of the host galaxy. However, taking into account only the bulge component we found a significant correlation between the BH mass and the bulge luminosity of the host.
197. LRG catalog
- ID:
- ivo://CDS.VizieR/J/MNRAS/380/1608
- Title:
- LRG catalog
- Short Name:
- J/MNRAS/380/1608
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work I discuss the necessary steps for deriving photometric redshifts for luminous red galaxies (LRGs) and galaxy clusters through simple empirical methods. The data used are from the Sloan Digital Sky Survey (SDSS). I show that with three bands only (gri) it is possible to achieve results as accurate as the ones obtained by other techniques, generally based on more filters. In particular, the use of the (g-i) colour helps improving the final redshifts (especially for clusters), as this colour monotonically increases up to z~0.8. For the LRGs I generate a catalogue of ~1.5 million objects at z<0.70. The accuracy of this catalogue is sigma=0.027 for z<=0.55 and sigma=0.049 for 0.55<z<=0.70. The photometric redshift technique employed for clusters is independent of a cluster selection algorithm. Thus, it can be applied to systems selected by any method or wavelength, as long as the proper optical photometry is available. When comparing the redshift listed in literature to the photometric estimate, the accuracy achieved for clusters is sigma=0.024 for z<=0.30 and sigma=0.037 for 0.30<z<=0.55. However, when considering the spectroscopic redshift as the mean value of SDSS galaxies on each cluster region, the accuracy is at the same level as found by other authors: sigma=0.011 for z<=0.30 and sigma=0.016 for 0.30<z<=0.55. The photometric redshift relation derived here is applied to thousands of cluster candidates selected elsewhere. I have also used galaxy photometric redshifts available in SDSS to identify groups in redshift space and then compare the redshift peak of the nearest group to each cluster redshift. This procedure provides an alternative approach for cluster selection, especially at high redshifts, as the cluster red sequence may be poorly defined.
- ID:
- ivo://CDS.VizieR/J/MNRAS/424/2086
- Title:
- LX-T relation in galaxy clusters
- Short Name:
- J/MNRAS/424/2086
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We measure the evolution of the X-ray luminosity-temperature (L_X_-T) relation since z~1.5 using a sample of 211 serendipitously detected galaxy clusters with spectroscopic redshifts drawn from the XMM Cluster Survey first data release (XCS-DR1). This is the first study spanning this redshift range using a single, large, homogeneous cluster sample. We compare our results to numerical simulations, where we fit simulated cluster samples using the same methods used on the XCS data.
- ID:
- ivo://CDS.VizieR/J/PASJ/58/313
- Title:
- Ly{alpha} emitters in the SUBARU Deep Field
- Short Name:
- J/PASJ/58/313
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the properties of Ly{alpha} emitters (LAEs) at z=5.7 in the Subaru Deep Field. A photometric sample of 89 LAE candidates was constructed from narrow-band data down to NB816=26.0 (AB) in a continuous 725arcmin^2^ area. Spectra of 39 objects satisfying the photometric selection criteria for LAEs were obtained with Subaru and Keck II Telescopes, among which 28 were confirmed LAEs, one was a nearby galaxy, and eight were unclassified. We also obtained spectra of another 24 NB816-excess objects in the field, identifying six additional LAEs.
- ID:
- ivo://CDS.VizieR/J/PASJ/57/165
- Title:
- Ly{alpha} emitters in the SUBARU Deep Field
- Short Name:
- J/PASJ/57/165
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new results of a deep optical imaging survey using a narrow band filter (NB921) centered at {lambda}=9196{AA} together with B, V, R, i', and z' broadband filters in the sky area of the Subaru Deep Field, which has been promoted as one of legacy programs of the 8.2m Subaru Telescope. We obtained a photometric sample of 58 Ly{alpha} emitter candidates at z~6.5-6.6 among ~180 strong NB921-excess (z'-NB921>1.0) objects together with a color criterion of i'-z'>1.3. We then obtained optical spectra of 20 objects in our NB921-excess sample, and identified at least nine Ly{alpha} emitters at z~6.5-6.6, including the two emitters reported by Kodaira et al. (2003PASJ...55L..17K). Since our Ly{alpha}-emitter candidates are free from strong amplification of gravitational lensing, we are able to discuss their observational properties from a statistical point of view. Based on these new results, we obtained a lower limit of the star-formation rate density of rho_SFR_~5.7x10^-4^h_0.7_M_{sun}/yr/Mpc^3^ at z~6.6, being consistent with our previous estimate. We discuss the nature of star-formation activity in galaxies beyond z=6.
