- ID:
- ivo://CDS.VizieR/J/ApJ/745/31
- Title:
- HST Cluster Supernova Survey. VI. SNIa rate
- Short Name:
- J/ApJ/745/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a measurement of the volumetric Type Ia supernova (SN Ia) rate out to z=~1.6 from the Hubble Space Telescope Cluster Supernova Survey. In observations spanning 189 orbits with the Advanced Camera for Surveys we discovered 29 SNe, of which approximately 20 are SNe Ia. Twelve of these SNe Ia are located in the foregrounds and backgrounds of the clusters targeted in the survey. Using these new data, we derive the volumetric SN Ia rate in four broad redshift bins, finding results consistent with previous measurements at z>~1 and strengthening the case for an SN Ia rate that is >~0.6x10^-4^h^3^_70_/yr/Mpc3 at z~1 and flattening out at higher redshift. We provide SN candidates and efficiency calculations in a form that makes it easy to rebin and combine these results with other measurements for increased statistics. Finally, we compare the assumptions about host-galaxy dust extinction used in different high-redshift rate measurements, finding that different assumptions may induce significant systematic differences between measurements.
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- ID:
- ivo://CDS.VizieR/J/ApJ/817/111
- Title:
- HST/COS survey of z<0.9 AGNs. I.
- Short Name:
- J/ApJ/817/111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use high-quality, medium-resolution Hubble Space Telescope/Cosmic Origins Spectrograph (HST/COS) observations of 82 UV-bright active galactic nuclei (AGNs) at redshifts z_AGN_<0.85 to construct the largest survey of the low-redshift intergalactic medium (IGM) to date: 5138 individual extragalactic absorption lines in HI and 25 different metal-ion species grouped into 2611 distinct redshift systems at z_abs_<0.75 covering total redshift pathlengths {Delta}z_HI_=21.7 and {Delta}z_OVI_=14.5. Our semi-automated line-finding and measurement technique renders the catalog as objectively defined as possible. The cumulative column density distribution of HI systems can be parametrized d N(>N)/dz=C_14_(N/10^14^/cm2)^-({beta}-1)^, with C_14_=25+/-1 and {beta}=1.65+/-0.02. This distribution is seen to evolve both in amplitude, C_14_{propto}(1+z)^2.3+/-0.1^, and slope {beta}(z)=1.75-0.31 z for z<=0.47. We observe metal lines in 418 systems, and find that the fraction of IGM absorbers detected in metals is strongly dependent on N_H1_. The distribution of OVI absorbers appears to evolve in the same sense as the Ly{alpha} forest. We calculate contributions to {Omega}_b_ from different components of the low-z IGM and determine the Ly{alpha} decrement as a function of redshift. IGM absorbers are analyzed via a two-point correlation function in velocity space. We find substantial clustering of HI absorbers on scales of {Delta}v=50-300km/s with no significant clustering at {Delta}v>~1000km/s. Splitting the sample into strong and weak absorbers, we see that most of the clustering occurs in strong, N_HI_>~10^13.5^/cm2, metal-bearing IGM systems.
- ID:
- ivo://CDS.VizieR/J/AJ/159/119
- Title:
- HST emission line survey of Andromeda. I. Be stars
- Short Name:
- J/AJ/159/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a two epoch Hubble Space Telescope H{alpha} emission line survey of the Andromeda galaxy that overlaps the footprint of the Panchromatic Hubble Andromeda Treasury (PHAT) survey. We found 552 (542) classical Be stars and 8429 (8556) normal B-type stars in epoch 1 (epoch 2), yielding an overall fractional Be content of 6.15%{+/-}0.26% (5.96%{+/-}0.25%). The fractional Be content decreased with spectral subtype from ~23.6%{+/-}2.0% (~23.9%{+/-}2.0%) for B0-type stars to ~3.1%{+/-}0.34% (~3.4%{+/-}0.35%) for B8-type stars in epoch 1 (epoch 2). We observed a clear population of cluster Be stars at early fractional main-sequence lifetimes, indicating that a subset of Be stars emerge onto the zero-age main sequence as rapid rotators. Be stars are 2.8x rarer in M31 for the earliest subtypes compared to the Small Magellanic Cloud, confirming that the fractional Be content decreases in significantly more metal-rich environments (like the Milky Way and M31). However, M31 does not follow a clear trend of Be fraction decreasing with metallicity compared to the Milky Way, which may reflect that the Be phenomenon is enhanced with evolutionary age. The rate of disk-loss or disk-regeneration episodes we observed, 22%{+/-}2%/yr, is similar to that observed for seven other Galactic clusters reported in the literature, assuming these latter transient fractions scale by a linear rate. The similar number of disk-loss events (57) as disk-renewal events (43) was unexpected since disk dissipation timescales can be ~2x the typical timescales for disk build-up phases.
- ID:
- ivo://CDS.VizieR/J/ApJ/859/38
- Title:
- HST grism obs. of CARLA galaxy cluster candidates
- Short Name:
- J/ApJ/859/38
- Date:
- 08 Mar 2022 13:56:29
- Publisher:
- CDS
- Description:
- We report spectroscopic results from our 40-orbit Hubble Space Telescope slitless grism spectroscopy program observing the 20 densest Clusters Around Radio-Loud AGN (CARLA) candidate galaxy clusters at 1.4<z<2.8. These candidate rich structures, among the richest and most distant known, were identified on the basis of [3.6]-[4.5] color from a 408hr multi-cycle Spitzer program targeting 420 distant radio-loud AGN. We report the spectroscopic confirmation of 16 distant structures at 1.4<z<2.8 associated with the targeted powerful high-redshift radio-loud AGN. We also report the serendipitous discovery and spectroscopic confirmation of seven additional structures at 0.87<z<2.12 not associated with the targeted radio-loud AGN. We find that 10^10^-10^11^M_{sun}_ member galaxies of our confirmed CARLA structures form significantly fewer stars than their field counterparts at all redshifts within 1.4<=z<=2. We also observe higher star-forming activity in the structure cores up to z=2, finding similar trends as cluster surveys at slightly lower redshifts (1.0<z<1.5). By design, our efficient strategy of obtaining just two grism orbits per field only obtains spectroscopic confirmation of emission line galaxies. Deeper spectroscopy will be required to study the population of evolved, massive galaxies in these (forming) clusters. Lacking multi-band coverage of the fields, we adopt a very conservative approach of calling all confirmations "structures," although we note that a number of features are consistent with some of them being bona fide galaxy clusters. Together this survey represents a unique and large homogenous sample of spectroscopically confirmed structures at high redshifts, potentially more than doubling the census of confirmed, massive clusters at z>1.4.
- ID:
- ivo://CDS.VizieR/J/ApJ/595/685
- Title:
- HST imaging in Chandra Deep Field-South
- Short Name:
- J/ApJ/595/685
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present quantitative morphological analyses of 37 Hubble Space Telescope (HST)/WFPC2 counterparts of X-ray sources in the 1Ms Chandra Deep Field South (CDFS, Cat. <J/ApJS/139/369>). We investigate (1) one-dimensional surface brightness profiles via isophotal ellipse fitting; (2) two-dimensional, point-spread function convolved, bulge+disk+nucleus profile fitting; (3) asymmetry and concentration indices compared with all ~3000 sources in our three WFPC2 fields; and (4) near-neighbor analyses comparing local environments of X-ray sources versus the field control sample. Significant nuclear point-source optical components appear in roughly half of the resolved HST/WFPC2 counterparts, showing a narrow range of FX/Fopt, nuc consistent with the several HST-unresolved X-ray sources (putative type 1 active galactic nuclei [AGNs]) in our fields.
- ID:
- ivo://CDS.VizieR/J/MNRAS/417/114
- Title:
- HST/NICMOS Galactic Center survey catalogue
- Short Name:
- J/MNRAS/417/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our Hubble Space Telescope/Near-Infrared Camera and Multi-Object Spectrometer (HST/NICMOS) Paschen {alpha} survey of the Galactic Centre, first introduced by Wang et al. (2010MNRAS.402..895W), provides a uniform, panoramic, high-resolution map of stars and an ionized diffuse gas in the central 416arcmin^2^ of the Galaxy. This survey was carried out with 144 HST orbits using two narrow-band filters at 1.87 and 1.90um in NICMOS Camera 3. In this paper, we describe in detail the data reduction and mosaicking procedures followed, including background level matching and astrometric corrections. We have detected ~570000 near-infrared (near-IR) sources using the 'starfinder' software and are able to quantify photometric uncertainties of the detections.
- ID:
- ivo://CDS.VizieR/J/ApJS/195/16
- Title:
- HST survey for Lyman limit systems. I.
- Short Name:
- J/ApJS/195/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a set of 71 quasars observed in the near ultraviolet with the PR200L prism on the Advanced Camera for Surveys and the G280 grism on the Wide Field Camera 3 (WFC3) on board the Hubble Space Telescope. The quasars were selected from the Sloan Digital Sky Survey data to search for intervening Lyman limit system (LLS) absorption. The sample was subjected to the constraints that the quasars have AB magnitude g'<18.5, quasar emission redshift 2.3<z_em_<2.6, and lack strong BAL or z~z_em_ absorption. The median emission redshift of the sample is {bar}z=2.403. The data were all processed using custom data reduction pipelines, and the one-dimensional spectra have sufficient signal-to-noise ratio and resolution to easily identify absorption from LLS over the redshift range 1.2<z<2.5. The WFC3 data presented here are the first non-calibration spectra from the G280 grism.
- ID:
- ivo://CDS.VizieR/J/ApJ/765/137
- Title:
- HST survey for Lyman limit systems. II.
- Short Name:
- J/ApJ/765/137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first science results from our Hubble Space Telescope survey for Lyman limit absorption systems (LLS) using the low dispersion spectroscopic modes of the Advanced Camera for Surveys and the Wide Field Camera 3. Through an analysis of 71 quasars, we determine the incidence frequency of LLS per unit redshift and per unit path length, l(z) and l(X), respectively, over the redshift range 1<z<2.6, and find a weighted mean of l(X)=0.29+/-0.05 for 2.0<z<2.5 through a joint analysis of our sample and that of Ribaudo et al. (2011, J/ApJ/736/42). Through stacked spectrum analysis, we determine a median (mean) value of the mean free path to ionizing radiation at z=2.4 of {lambda}^912^_mfp_=243(252)h^-1^_72_Mpc, with an error on the mean value of +/-43h^-1^_72_Mpc. We also re-evaluate the estimates of {lambda}^912^_mfp_ from Prochaska et al. (2010, J/ApJ/718/392) and place constraints on the evolution of {lambda}^912^_mfp_ with redshift, including an estimate of the "breakthrough" redshift of z=1.6. Consistent with results at higher z, we find that a significant fraction of the opacity for absorption of ionizing photons comes from systems with N_HI_<=10^17.5^cm^-2^ with a value for the total Lyman opacity of {tau}^Lyman^_eff_=0.40+/-0.15. Finally, we determine that at minimum, a 5-parameter (4 power law) model is needed to describe the column density distribution function f(N_HI_,X) at z~2.4, find that f(N_HI_,X) undergoes no significant change in shape between z~2.4 and z~3.7, and provide our best fit model for f(N_HI_,X).
- ID:
- ivo://CDS.VizieR/J/ApJS/227/1
- Title:
- HST survey for novae in M87. I. VI LCs
- Short Name:
- J/ApJS/227/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Hubble Space Telescope has imaged the central part of M87 over a 10 week span, leading to the discovery of 32 classical novae (CNe) and nine fainter, likely very slow, and/or symbiotic novae. In this first paper of a series, we present the M87 nova finder charts, and the light and color curves of the novae. We demonstrate that the rise and decline times, and the colors of M87 novae are uncorrelated with each other and with position in the galaxy. The spatial distribution of the M87 novae follows the light of the galaxy, suggesting that novae accreted by M87 during cannibalistic episodes are well-mixed. Conservatively using only the 32 brightest CNe we derive a nova rate for M87: 363_-45_^+33^ novae yr^-1^. We also derive the luminosity-specific classical nova rate for this galaxy, which is 7.88_-2.6_^+2.3^yr^-1^/10^10^L_{sun},K_. Both rates are 3-4 times higher than those reported for M87 in the past, and similarly higher than those reported for all other galaxies. We suggest that most previous ground-based surveys for novae in external galaxies, including M87, miss most faint, fast novae, and almost all slow novae near the centers of galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/788/55
- Title:
- HST/WFC3 SNR discoveries in M83 (NGC5236)
- Short Name:
- J/ApJ/788/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an optical/NIR imaging survey of the face-on spiral galaxy M83, using data from the Hubble Space Telescope Wide Field Camera 3 (WFC3). Seven fields are used to cover a large fraction of the inner disk, with observations in nine broadband and narrowband filters. In conjunction with a deep Chandra survey and other new radio and optical ground-based work, these data enable a broad range of science projects to be pursued. We provide an overview of the WFC3 data and processing and then delve into one topic, the population of young supernova remnants (SNRs). We used a search method targeted toward soft X-ray sources to identify 26 new SNRs. Many compact emission nebulae detected in [FeII]1.644{mu}m align with known remnants and this diagnostic has also been used to identify many new remnants, some of which are hard to find with optical images. We include 37 previously identified SNRs that the data reveal to be <0.5" in angular size and thus are difficult to characterize from ground-based data. The emission line ratios seen in most of these objects are consistent with shocks in dense interstellar material rather than showing evidence of ejecta. We suggest that the overall high elemental abundances in combination with high interstellar medium pressures in M83 are responsible for this result.
