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471. ACS Fornax Cluster Survey. I.
ID:
ivo://CDS.VizieR/J/ApJS/169/213
Title:
ACS Fornax Cluster Survey. I.
Short Name:
J/ApJS/169/213
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Fornax Cluster is a conspicuous cluster of galaxies in the southern hemisphere and the second largest collection of early-type galaxies within 20Mpc after the Virgo Cluster. In this paper, we present a brief introduction to the ACS Fornax Cluster Survey - a program to image, in the F475W (g_475_) and F850LP (z_850_) bandpasses, 43 early-type galaxies in Fornax using the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. Combined with a companion survey of Virgo, the ACS Virgo Cluster Survey, this represents the most comprehensive imaging survey to date of early-type galaxies in cluster environments in terms of depth, spatial resolution, sample size, and homogeneity. We describe the selection of the program galaxies, their basic properties, and the main science objectives of the survey, which include the measurement of luminosities, colors, and structural parameters for globular clusters associated with these galaxies, an analysis of their isophotal properties and surface brightness profiles, and an accurate calibration of the surface brightness fluctuation distance indicator. Finally, we discuss the data reduction procedures adopted for the survey.
472. ACS Fornax Cluster Survey. XI. GC candidates
ID:
ivo://CDS.VizieR/J/ApJS/221/13
Title:
ACS Fornax Cluster Survey. XI. GC candidates
Short Name:
J/ApJS/221/13
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present catalogs of globular cluster (GC) candidates for 43 galaxies from the ACS Fornax Cluster survey, a program designed to carry out imaging of early-type members of the Fornax cluster using the Advanded Camera for Surveys (ACS) on board the Hubble Space Telescope. The procedure to select bona fide GC candidates from the full list of detections is based on model-based clustering methods, similar to those adopted for a survey of 100 galaxies in the Virgo cluster, the ACS Virgo Cluster Survey. For each detected source, we measure its position, magnitudes in the F475W (~Sloan g) and F850LP (~Sloan z) bandpasses, half-light radii obtained by fitting point-spread function-convolved King models to the observed light distribution, and an estimate of the probability {rho}_GC_ that each cataloged source is a GC. These measurements are presented for 9136 sources, of which 6275 have {rho}_GC_>=0.5, and are thus likely GCs.
473. ACS Galactic Globular Cluster Survey (ACSGGCT)
ID:
ivo://mast.stsci/acsggct
Title:
ACS Galactic Globular Cluster Survey (ACSGGCT)
Short Name:
HST.ACSGGCT
Date:
22 Jul 2020 22:26:50
Publisher:
Space Telescope Science Institute Archive
Description:
The ACSGGCT program used the HST ACS/WFC instrument to obtain uniform imaging of 65 of the nearest globular clusters to provide an extensive homogeneous dataset for a broad range of scientific investigations. An overview of the project was published by Sarajedini, A. et al. 2007, "The ACS Survey of Galactic Globular Clusters. I. Overview and Clusters Without Previous Hubble Space Telescope Photometry" AJ, 133, 1658.
474. ACS J1149.5+2223 LOFAR and VLA images
ID:
ivo://CDS.VizieR/J/A+A/650/A44
Title:
ACS J1149.5+2223 LOFAR and VLA images
Short Name:
J/A+A/650/A44
Date:
22 Feb 2022
Publisher:
CDS
Description:
Radio halos and relics are Mpc-scale diffuse radio sources in galaxy clusters, which have a steep spectral index {alpha}>1 (defined as S{prop.to}{nu}^-{alpha}^). It has been proposed that halos and relics arise from particle acceleration induced by turbulence and weak shocks that are injected into the intracluster medium (ICM) during mergers. MACS J1149.5+2223 is a high-redshift (z=0.544) galaxy cluster possibly hosting a radio halo and a relic. We analysed LOw Frequency Array (LOFAR), Giant Metrewave Radio Telescope, and Karl G. Jansky Very Large Array (JVLA) radio data at 144, 323, and 1500MHz, respectively. In addition, we analysed archival Chandra X-ray data to characterise the thermal and non-thermal properties of the cluster. We obtained radio images at different frequencies to investigate the spectral properties of the radio halo. We used Chandra X-ray images to constrain the thermal properties of the cluster and to search for discontinuities (due to cold fronts or shock fronts) in the surface brightness of the ICM. By combining radio and X-ray images, we carried out a point-to-point analysis to study the connection between the thermal and non-thermal emission. We measured a steep spectrum of the halo, which can be described by a power-law with {alpha}=1.49+/-0.12 between 144 and 1500MHz. The radio surface brightness distribution across the halo is found to correlate with the X-ray brightness of the ICM. The derived correlation shows a sub-linear slope in the range 0.4-0.6. We also report two possible cold fronts in north-east and north-west, but deeper X-ray observations are required to firmly constrain the properties of the upstream emission. We show that the combination of high-redshift, steep radio spectrum, and sub-linear radio-X scaling of the halo rules out hadronic models. An old (~1Gyr ago) major merger likely induced the formation of the halo through stochastic re-acceleration of relativistic electrons. We suggest that the two possible X-ray discontinuities may be part of the same cold front. In this case, the coolest gas pushed towards the north-west might be associated with the cool core of a sub-cluster involved in the major merger. The peculiar orientation of the south-east relic might indicate a different nature of this source and requires further investigation.
475. ACS Nearby Galaxy Survey Treasury
ID:
ivo://CDS.VizieR/J/ApJ/734/L22
Title:
ACS Nearby Galaxy Survey Treasury
Short Name:
J/ApJ/734/L22
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a measurement of the age distribution of stars residing in spiral disks and dwarf galaxies. We derive a complete star formation history of the ~140Mpc^3^ covered by the volume-limited sample of galaxies in the Advanced Camera for Surveys (ACS) Nearby Galaxy Survey Treasury (ANGST). The total star formation rate density history ({rho}_SFR_(t)) is dominated by the large spirals in the volume, although the sample consists mainly of dwarf galaxies. Our {rho}_SFR_(t) shows a factor of ~3 drop at z~2, in approximate agreement with results from other measurement techniques. While our results show that the overall {rho}_SFR_(t) has decreased since z~1, the measured rates during this epoch are higher than those obtained from other measurement techniques. This enhanced recent star formation rate appears to be largely due to an increase in the fraction of star formation contained in low-mass disks at recent times. Finally, our results indicate that despite the differences at recent times, the epoch of formation of ~50% of the stellar mass in dwarf galaxies was similar to that of ~50% of the stellar mass in large spiral galaxies (z>~2), despite the observed galaxy-to-galaxy diversity among the dwarfs.
476. ACS survey of galactic globular clusters
ID:
ivo://CDS.VizieR/J/AJ/133/1658
Title:
ACS survey of galactic globular clusters
Short Name:
J/AJ/133/1658
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first results of a large Advanced Camera for Surveys (ACS) survey of Galactic globular clusters. This Hubble Space Telescope (HST) Treasury project is designed to obtain photometry with S/N (signal-to-noise ratio) >~10 for main-sequence stars with masses >~0.2M_{sun}_ in a sample of globulars using the ACS Wide Field Channel. Here we focus on clusters without previous HST imaging data. These include NGC 5466, NGC 6779, NGC 5053, NGC 6144, Palomar 2, E3, Lynga 7, Palomar 1, and NGC 6366. Our color-magnitude diagrams (CMDs) extend reliably from the horizontal branch to as much as 7 mag fainter than the main-sequence turnoff and represent the deepest CMDs published to date for these clusters. Using fiducial sequences for three standard clusters (M92, NGC 6752, and 47 Tuc) with well-known metallicities and distances, we perform main-sequence fitting on the target clusters in order to obtain estimates of their distances and reddenings. These comparisons, along with fitting the cluster main sequences to theoretical isochrones, yield ages for the target clusters. We find that the majority of the clusters have ages that are consistent with the standard clusters at their metallicities. The exceptions are E3, which appears ~2Gyr younger than 47 Tuc, and Pal 1, which could be as much as 8Gyr younger than 47 Tuc.
477. A CS(2-1) survey of UC HII regions
ID:
ivo://CDS.VizieR/J/A+AS/115/81
Title:
A CS(2-1) survey of UC HII regions
Short Name:
J/A+AS/115/81
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have made a complete survey of the CS(2-1) emission toward IRAS point sources in the galactic plane. The sources observed were selected according to their far infrared (FIR) colors, which are characteristic of UC HII regions. They have 25{mu}m/12{mu}m flux ratios larger than 3.7 and 60{mu}m/12{mu}m flux ratios larger than 19.3. The survey covered a region from b=-2deg to b=2deg from l=300deg to l=0deg and from l=0deg to l=60deg, and from b=-4deg to b=4deg elsewhere. We detected 843 sources out of 1427 sources observed. The distributions of detected and undetected sources in a FIR color-color diagram show some differences, suggesting that more than one type of object is present in our observed sample.
478. ACS VI photometry of M31 halo RR Lyrea
ID:
ivo://CDS.VizieR/J/AJ/127/2738
Title:
ACS VI photometry of M31 halo RR Lyrea
Short Name:
J/AJ/127/2738
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a complete census of RR Lyrae stars in a halo field of the Andromeda galaxy. These deep observations, taken as part of a program to measure the star formation history in the halo, spanned a period of 41 days with sampling on a variety of timescales, enabling the identification of short- and long-period variables. Although the long-period variables cannot be fully characterized within the time span of this program, the enormous advance in sensitivity provided by the Advanced Camera for Surveys on the Hubble Space Telescope allows accurate characterization of the RR Lyrae population in this field. We find 29 RRab stars with a mean period of 0.594 days, 25 RRc stars with a mean period of 0.316 days, and one RRd star with a fundamental period of 0.473 days and a first-overtone period of 0.353 days. These 55 RR Lyrae stars imply a specific frequency S_RR_~5.6, which is large given the high mean metallicity of the halo, but not surprising given that these stars arise from the old, metal-poor tail of the distribution.
479. ACS Virgo Cluster Survey. I.
ID:
ivo://CDS.VizieR/J/ApJS/153/223
Title:
ACS Virgo Cluster Survey. I.
Short Name:
J/ApJS/153/223
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Virgo Cluster is the dominant mass concentration in the Local Supercluster and the largest collection of elliptical and lenticular galaxies in the nearby universe. In this paper, we present an introduction to the ACS (Advanced Camera for Surveys) Virgo Cluster Survey: a program to image, in the F475W and F850LP bandpasses (~Sloan g and z), 100 early-type galaxies in the Virgo Cluster using the Advanced Camera for Surveys on the Hubble Space Telescope.
480. ACS Virgo Cluster Survey. II.
ID:
ivo://CDS.VizieR/J/ApJS/154/509
Title:
ACS Virgo Cluster Survey. II.
Short Name:
J/ApJS/154/509
Date:
21 Oct 2021
Publisher:
CDS
Description:
The ACS Virgo Cluster Survey is a large program to carry out multicolor imaging of 100 early-type members of the Virgo Cluster using the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. Deep F475W and F850LP images (~SDSS g and z) are being used to study the central regions of the program galaxies, their globular cluster systems, and the three-dimensional structure of Virgo itself. In this paper, we describe in detail the data reduction procedures used for the survey, including image registration, drizzling strategies, the computation of weight images, object detection, the identification of globular cluster candidates, and the measurement of their photometric and structural parameters.

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