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2711. HST/NICMOS observations of bright IR galaxies
ID:
ivo://CDS.VizieR/J/ApJ/730/125
Title:
HST/NICMOS observations of bright IR galaxies
Short Name:
J/ApJ/730/125
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new results on the physical nature of infrared-luminous sources at 0.5<z<2.8 as revealed by HST/NICMOS imaging and Infrared Spectrograph mid-infrared spectroscopy. Our sample consists of 134 galaxies selected at 24um with a flux of S(24um)>0.9mJy. We find many (~60%) of our sources to possess an important bulge and/or central point source component, most of which reveal additional underlying structures after subtraction of a best-fit Sersic (or Sersic+PSF) profile. Based on visual inspection of the NIC2 images and their residuals, we estimate that ~80% of all our sources are mergers. We calculate lower and upper limits on the merger fraction to be 62% and 91%, respectively. At z<1.5, we observe objects in early (pre-coalescence) merging stages to be mostly disk and star formation dominated, while we find mergers to be mainly bulge dominated and active galactic nucleus (AGN)-starburst composites during coalescence and then AGN dominated in late stages. This is analogous to what is observed in local ULIRGs. Finally, we observe obscured ({tau}_9.7um_>3.36) quasars to live in faint and compact hosts and show that these are likely high-redshift analogs of local dense-core mergers. We find late-stage mergers to possess predominantly unobscured AGN spectra, but do not observe other morphological classes to carry any specific combination of {tau}_9.7um_ and polycyclic aromatic hydrocarbon (PAH) equivalent width.
2712. HST observations for LMC Cepheids
ID:
ivo://CDS.VizieR/J/ApJ/876/85
Title:
HST observations for LMC Cepheids
Short Name:
J/ApJ/876/85
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an improved determination of the Hubble constant from Hubble Space Telescope (HST) observations of 70 long-period Cepheids in the Large Magellanic Cloud (LMC). These were obtained with the same WFC3 photometric system used to measure extragalactic Cepheids in the hosts of SNe Ia. Gyroscopic control of HST was employed to reduce overheads while collecting a large sample of widely separated Cepheids. The Cepheid period-luminosity relation provides a zero-point-independent link with 0.4% precision between the new 1.2% geometric distance to the LMC from detached eclipsing binaries (DEBs) measured by Pietrzynski+ (2019Natur.567..200P) and the luminosity of SNe Ia. Measurements and analysis of the LMC Cepheids were completed prior to knowledge of the new DEB LMC distance. Combined with a refined calibration of the count-rate linearity of WFC3-IR with 0.1% precision, these three improved elements together reduce the overall uncertainty in the geometric calibration of the Cepheid distance ladder based on the LMC from 2.5% to 1.3%. Using only the LMC DEBs to calibrate the ladder, we find H_0_=74.22+/-1.82km/s/Mpc including systematic uncertainties, 3% higher than before for this particular anchor. Combining the LMC DEBs, masers in NGC 4258, and Milky Way parallaxes yields our best estimate: H_0_=74.03+/-1.42km/s/Mpc, including systematics, an uncertainty of 1.91%-15% lower than our best previous result. Removing any one of these anchors changes H0 by less than 0.7%. The difference between H0 measured locally and the value inferred from Planck CMB and {Lambda}CDM is 6.6+/-1.5km/s/Mpc or 4.4{sigma} (P=99.999% for Gaussian errors) in significance, raising the discrepancy beyond a plausible level of chance. We summarize independent tests showing that this discrepancy is not attributable to an error in any one source or measurement, increasing the odds that it results from a cosmological feature beyond {Lambda}CDM.
2713. HST Observations in inner region of M15
ID:
ivo://CDS.VizieR/J/AJ/106/154
Title:
HST Observations in inner region of M15
Short Name:
J/AJ/106/154
Date:
21 Oct 2021
Publisher:
CDS
Description:
A set of high resolution images of the core of the Galactic Globular Cluster M15 (NGC 7078) were obtained for the first time with the Faint Object Camera on Hubble Space Telescope through the f/48-F140W, f/48-F220W and f/96-F342W ultraviolet filters. Two UV-Color-Magnitude Diagrams are presented for the ~3000 objects measured in the 22"x22" field centered on the core covered by our observations. Out of these, 19 are variables discovered from the rms frame-to-frame scatter of the F220W images, 14 of which are probably RR Lyrae. The existence of the gap on the Horizontal Branch (HB) separating the bulk of the HB stars from the Blue Tail already known for the outer parts of the cluster, is confirmed for the core regions. The temperature and the mass distribution of the HB stars is derived from the ultraviolet color-color diagram. We also detect a well developed Blue Straggler sequence. At least two of the brighter blue stragglers reside within the sharp core.
2714. HST observations of clusters in NGC 3597
ID:
ivo://CDS.VizieR/J/AJ/117/1700
Title:
HST observations of clusters in NGC 3597
Short Name:
J/AJ/117/1700
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have analyzed HST/WFPC2 images of NGC 3597 and find {=~}700 compact objects surrounding the galaxy with an average (B-R)_0_ {=~}0.6. We propose that the majority of these objects are young globular clusters. They have a spread in colors that is consistent with that expected for a population of young clusters with a common age and spread induced by photometric errors and reddening within NGC 3597.
2715. HST Observations of core of 47 Tuc
ID:
ivo://CDS.VizieR/J/ApJS/85/293
Title:
HST Observations of core of 47 Tuc
Short Name:
J/ApJS/85/293
Date:
21 Oct 2021
Publisher:
CDS
Description:
(no description available)
2716. HST observations of Extremely Red Objects
ID:
ivo://CDS.VizieR/J/MNRAS/330/1
Title:
HST observations of Extremely Red Objects
Short Name:
J/MNRAS/330/1
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a survey for extremely red objects (EROs) undertaken in the fields of 10 massive galaxy cluster lenses at z~0.2, combining sensitive, high-resolution Hubble Space Telescope imaging with deep, half-arcsecond K-band imaging from UKIRT. We detect 60 EROs with (R-K)>=5.3, of which 26 have (R-K)>=6.0 in a total image-plane survey area of 49arcmin2 down to K=20.6, including one multiply imaged ERO.
2717. HST observations of GCs in NGC 1399
ID:
ivo://CDS.VizieR/J/ApJ/746/88
Title:
HST observations of GCs in NGC 1399
Short Name:
J/ApJ/746/88
Date:
21 Oct 2021
Publisher:
CDS
Description:
We combine new Wide Field Camera 3 IR Channel (WFC3/IR) F160W (H_160_) imaging data for NGC 1399, the central galaxy in the Fornax cluster, with archival F475W (g_475_), F606W (V_606_), F814W (I_814_), and F850LP (z _850_) optical data from the Advanced Camera for Surveys (ACS). The purely optical g_475_-I_814_, V_606_-I_814_, and g_475_-z_850_colors of NGC 1399's rich globular cluster (GC) system exhibit clear bimodality, at least for magnitudes I_814_>21.5. The optical-IR I_814_-H_160_ color distribution appears unimodal, and this impression is confirmed by mixture modeling analysis. The V_606_-H_160_ colors show marginal evidence for bimodality, consistent with bimodality in V_606_-I_814_ and unimodality in I_814_-H_160_.
2718. HST Observations of 2 high-z clusters
ID:
ivo://CDS.VizieR/J/ApJ/644/30
Title:
HST Observations of 2 high-z clusters
Short Name:
J/ApJ/644/30
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study the photometric and structural properties of spectroscopically confirmed members in the two massive X-ray-selected z~0.83 galaxy clusters MS 105403 and RX J0152.7-1357 using three-band mosaic imaging with the Hubble Space Telescope Advanced Camera for Surveys. The samples include 105 and 140 members of RX J0152.7-1357 and MS 105403, respectively, to i_775_<24.0. A quantitative classification scheme using Sersic indices and "bumpiness" (the ratio of the rms residuals to the model mean) was found to correlate well with visual morphological type. The color-magnitude residuals correlate well with the local density, as measured from both galaxy numbers and weak lensing. Weaker correlations are found with cluster radius (the fundamental dependence is on local density).
2719. HST observations of low-mass BH host galaxies
ID:
ivo://CDS.VizieR/J/ApJ/742/68
Title:
HST observations of low-mass BH host galaxies
Short Name:
J/ApJ/742/68
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using Hubble Space Telescope observations of 147 host galaxies of low-mass black holes (BHs), we systematically study the structures and scaling relations of these active galaxies. Our sample is selected to have central BHs with virial masses of ~10^5^-10^6^M_{sun}_. The host galaxies have total I-band magnitudes of -23.2<M_I_<-18.8mag and bulge magnitudes of -22.9<M_I_<-16.1mag. Detailed bulge-disk-bar decompositions with GALFIT show that 93% of the galaxies have extended disks, 39% have bars, and 5% have no bulges at all at the limits of our observations. Based on the Sersic index and bulge-to-total ratio, we conclude that the majority of the galaxies with disks are likely to contain pseudobulges and very few of these low-mass BHs live in classical bulges. The fundamental plane of our sample is offset from classical bulges and ellipticals in a way that is consistent with the scaling relations of pseudobulges. The sample has smaller velocity dispersion at fixed luminosity in the Faber-Jackson plane compared with classical bulges and elliptical galaxies. The galaxies without disks are structurally more similar to spheroidals than to classical bulges according to their positions in the fundamental plane, especially the Faber-Jackson projection. Overall, we suggest that BHs with mass <~10^6^M_{sun}_ live in galaxies that have evolved secularly over the majority of their history. A classical bulge is not a prerequisite to host a BH.
2720. HST observations of low-mass stars in IC 348
ID:
ivo://CDS.VizieR/J/ApJ/541/977
Title:
HST observations of low-mass stars in IC 348
Short Name:
J/ApJ/541/977
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the low-mass population of the young cluster IC 348 down to the deuterium-burning limit, a fiducial boundary between brown dwarf and planetary mass objects, using a new and innovative method for the spectral classification of late-type objects. Using photometric indices, constructed from HST/NICMOS narrowband imaging, that measure the strength of the 1.9{mu}m water band, we determine the spectral type and reddening for every M-type star in the field, thereby separating cluster members from the interloper population. Due to the efficiency of our spectral classification technique, our study is complete from ~0.7 to 0.015M_{sun}_. The mass function derived for the cluster in this interval, dN/dlogM{prop.to}M^0.5^, is similar to that obtained for the Pleiades, but appears significantly more abundant in brown dwarfs than the mass function for companions to nearby Sunlike stars. This provides compelling observational evidence for different formation and evolutionary histories for substellar objects formed in isolation versus as companions. Because our determination of the IMF is complete to very low masses, we can place interesting constraints on the role of physical processes such as fragmentation in the star and planet formation process and the fraction of dark matter in the Galactic halo that resides in substellar objects.