Optical and near-infrared color distributions of the NGC 4874 globular cluster system

AbstractExamining both optical and optical-infrared color distributions of the globular cluster (GC) systems in large elliptical galaxies is the key to study how non-linearities in the color-metallicity relations of their GC systems are linked to bimodal optical color distributions. In order to do this for the core of the Coma cluster of galaxies (Abell 1656), centered on the giant elliptical galaxy NGC 4874, we have combined F160W (H160) near-infrared (NIR) imaging data acquired with the Wide Field Camera 3 IR Channel (WFC3/IR), installed on Hubble Space Telescope (HST) in 2009, with F475W (g475) and F814W (I814) optical imaging data from the HST Advanced Camera for Surveys (ACS). Since optical-NIR color distributions of extragalactic GC systems reflect the underlying features of the metallicity distributions, we have probed not only optical g475–I814 and optical-NIR I814–H160 color distributions but also the color-color relation for this GC system. The features of these color distributions have been quantitatively analyzed using the Gaussian Mixture Modeling code. We find that brighter GCs have a much redder mean color than fainter ones. The optical color distribution of the GC system in the Coma cluster core shows the typical bimodality, while the evidence for bimodality is significantly weaker in the optical-NIR color distribution.

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Cosmic distances from surface brightness fluctuations

Proceedings of the International Astronomical Union ◽

10.1017/s174392131202159x ◽

2012 ◽

Vol 8 (S289) ◽

pp. 304-311 ◽

Cited By ~ 2

Author(s):

John P. Blakeslee

Keyword(s):

Surface Brightness ◽

Near Infrared ◽

Hubble Space Telescope ◽

Stellar System ◽

Distance Scale ◽

Wide Field ◽

Coma Cluster ◽

Infrared Wavelength ◽

Surface Brightness Fluctuations ◽

Advanced Camera For Surveys

AbstractHigh spatial-resolution measurements of surface brightness fluctuations (SBFs) with the Hubble Space Telescope (HST) provide the most precise distances available to early-type galaxies beyond the Local Group. The observable SBF magnitude in a given bandpass is a basic property of any stellar system, corresponding to a ratio of the first and second moments of the stellar luminosity function. Calibration of the method has presented challenges, but we now have an excellent empirical determination of how the SBF observable varies with galaxy color in broad bandpasses at the red end of the optical spectrum, and we are working towards a similar calibration for HST's Wide-Field Camera 3 in the near-infrared wavelength range, where the SBF magnitudes are considerably brighter. From HST Advanced Camera for Surveys data, we have determined the relative distances of the Virgo and Fornax clusters to within a precision of 2%, and resolved their internal structures. More recent measurements allow us to tie the Coma cluster, the standard of comparison for distant cluster studies, to the same precise distance scale. The SBF method can be calibrated in an absolute sense either empirically using Cepheids or theoretically based on stellar population models. The agreement between model and empirical zero points provides an independent confirmation of the Cepheid distance scale.

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Hunting for brown dwarfs in the globular cluster M4: second epoch HST NIR observations

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz996 ◽

2019 ◽

Vol 486 (2) ◽

pp. 2254-2264 ◽

Cited By ~ 3

Author(s):

A Dieball ◽

L R Bedin ◽

C Knigge ◽

M Geffert ◽

R M Rich ◽

...

Keyword(s):

Globular Cluster ◽

White Dwarf ◽

Near Infrared ◽

Magnitude Estimate ◽

Cluster Member ◽

Imaging Data ◽

Brown Dwarf ◽

Data Set ◽

Bona Fide ◽

Low Mass

ABSTRACT We present an analysis of the second epoch Hubble Space TelescopeWide Field Camera 3 F110W near-infrared (NIR) imaging data of the globular cluster M 4. The new data set suggests that one of the previously suggested four brown dwarf candidates in this cluster is indeed a high-probability cluster member. The position of this object in the NIR colour–magnitude diagrams (CMDs) is in the white dwarf/brown dwarf area. The source is too faint to be a low-mass main-sequence (MS) star, but, according to theoretical considerations, also most likely somewhat too bright to be a bona-fide brown dwarf. Since we know that the source is a cluster member, we determined a new optical magnitude estimate at the position the source should have in the optical image. This new estimate places the source closer to the white dwarf sequence in the optical–NIR CMD and suggests that it might be a very cool (Teff ≤ 4500 K) white dwarf at the bottom of the white dwarf cooling sequence in M 4, or a white dwarf/brown dwarf binary. We cannot entirely exclude the possibility that the source is a very massive, bright brown dwarf, or a very low-mass MS star, however, we conclude that we still have not convincingly detected a brown dwarf in a globular cluster, but we expect to be very close to the start of the brown dwarf cooling sequence in this cluster. We also note that the MS ends at F110W ≈ 22.5 mag in the proper-motion cleaned CMDs, where completeness is still high.

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Structural and Morphological Properties of Ultraluminous Infrared Galaxies at 1 < z < 3

Open Astronomy ◽

10.1515/astro-2017-0224 ◽

2015 ◽

Vol 24 (3) ◽

Author(s):

Guanwen Fang ◽

Zhongyang Ma ◽

Yang Chen ◽

Xu Kong

Keyword(s):

High Resolution ◽

Near Infrared ◽

Hubble Space Telescope ◽

Morphological Properties ◽

Wide Field ◽

High Resolution Imaging ◽

Infrared Galaxies ◽

Morphology And Structure ◽

Ultraluminous Infrared Galaxies ◽

Resolution Imaging

AbstractUsing the Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) near-infrared high-resolution imaging from the 3D-HST survey, we analyze the morphology and structure of 502 ultraluminous infrared galaxies (ULIRGs;

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How Massive is the Black Hole in M87?

Highlights of Astronomy ◽

10.1017/s1539299600011977 ◽

1995 ◽

Vol 10 ◽

pp. 535-538

Author(s):

S.K. Chakrabarti

Keyword(s):

Black Hole ◽

Dwarf Galaxy ◽

Hubble Space Telescope ◽

Elliptical Galaxy ◽

Wide Field ◽

Line Profiles ◽

Present Contribution ◽

Doppler Shifts ◽

Spiral Structures ◽

Armed Spiral

Using the Faint Object Spectrograph (FOS) on Hubble Space Telescope (HST), Harms et al. (1994, H94) have recently reported the spectroscopy of central region of the elliptical galaxy M87. Ford et al. 1994 (hereafter F94), using Wide Field Planetary Camera-2 have imaged the region around the nucleus in Hα+[NII] and find an ionized disk with spiral structures of mainly two arms. From the kinematical argument, based on the Doppler shifts of several lines emitted from the disk, and assuming a Keplerian motion of the emitting gas, they conclude that the mass of the disk plus the nucleus: Mc(R < 18pc) = (2.4± 0.7)× 109M⊙ and the inclination angle of the disk with the line of sight is i = (42±5)°. However, if the bright spiral structures are real, and represent shocked region in the disk, we expect that the disk is strongly non-Keplerian and therefore the mass of the black hole must be higher than above estimation.In the present contribution, we provide a complete description of the velocity field of the ionized disk and compute the shape of typical line profiles expected from various parts of the disk. Our analysis is based on the solution of a non-axisymmetric disk which includes two armed spiral density waves. We find a very good agreement between the theoretical and observed line profiles as regards to the Doppler shifts, line widths and the intensity ratios and estimate the mass of the black hole to be (4 ± 0.2) × 109M⊙. Details of this work will be published elsewhere (Chakrabarti, 1995).In a binary system with a thin accretion disk, the binary companion can induce two armed spiral shocks in the disk (e.g., Matsuda et al. 1987, Spruit 1987, Chakrabarti & Matsuda, 1992). In the case of active galaxies, a passing companion (or a globular cluster or a dwarf galaxy) which is more massive than the disk can induce the same effect.

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Galaxy build-up at cosmic dawn: Insights from deep observations with Hubble, Spitzer, and ALMA

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320001064 ◽

2019 ◽

Vol 15 (S352) ◽

pp. 12-12

Author(s):

Pascal Oesch

Keyword(s):

Rest Frame ◽

Near Infrared ◽

Infrared Imaging ◽

Hubble Space Telescope ◽

Uv Light ◽

Big Bang ◽

Limited Information ◽

Imaging Data ◽

Early Galaxies ◽

Stellar Masses

AbstractOver the last few years, great progress has been made in understanding the build-up of the first generations of galaxies based on deep optical and near-infrared imaging from the Hubble Space Telescope. However, HST only samples the rest-frame UV light of galaxies at z …4, providing only limited information on the dust obscuration and on stellar masses of these sources. Fortunately, several Spitzer/IRAC programs have complemented the extragalactic HST fields with ultra-deep imaging data, allowing for a rest-frame optical view on early galaxies. Together with first ALMA/ NOEMA (sub)mm observations on distant galaxies, we are starting to gain a more and more complete picture of galaxy star-formation and mass build-up in the early universe. In this talk, I will present an overview of our current understanding of normal star-forming galaxies at z > 3 based the combination of HST+Spitzer+ALMA/NOEMA data. In particular, I will show how HST as already pushed into JWST territory with the discovery and spectroscopic confirmation of a galaxy at z = 11.1 ± 0.1, only : 400 Myr after the Big Bang. I will also highlight some of the exciting possibilities that lie ahead with JWST to push the spectroscopic frontier to the cosmic dawn and to finally probe the physics of early galaxies.

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Near-infrared surface brightness fluctuation measurements with the Hubble Space Telescope's WFC3/IR channel

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312021734 ◽

2012 ◽

Vol 8 (S289) ◽

pp. 371-374

Author(s):

Hyejeon Cho ◽

Joseph B. Jensen ◽

John P. Blakeslee ◽

Brigham S. French ◽

Hyun-chul Lee ◽

...

Keyword(s):

Surface Brightness ◽

Near Infrared ◽

Hubble Space Telescope ◽

Wide Field ◽

Population Synthesis ◽

Early Type ◽

Distance Method ◽

Brightness Fluctuation ◽

Advanced Camera For Surveys ◽

Fornax Cluster

AbstractThe surface brightness fluctuation (SBF) method at near-infrared (NIR) wavelengths is a powerful tool for estimating distances to unresolved stellar systems with high precision. The IR channel of the Wide Field Camera 3 (WFC3), installed on board the Hubble Space Telescope (HST) in 2009, has a greater sensitivity and a wider field of view than the previous generation of HST IR instruments, making it much more efficient for measuring distances to early-type galaxies in the Local Volume. To take full advantage of its capabilities, we need to empirically calibrate the SBF distance method for WFC3's NIR passbands. We present the SBF measurements for the WFC3/IR F160W bandpass filter using observations of 16 early-type galaxies in the Fornax and Virgo Clusters. These have been combined with existing (g475–z850) color measurements from the Advanced Camera for Surveys Virgo and Fornax Cluster Surveys to derive a space-based H160-band SBF relation as a function of color. We have also compared the absolute SBF magnitudes to those predicted by evolutionary population synthesis models in order to study stellar population properties in the target galaxies.

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Spectroscopically Identified Emission Line Galaxy Pairs in the WISP Survey*

The Astrophysical Journal ◽

10.3847/1538-4357/ac2f96 ◽

2021 ◽

Vol 923 (2) ◽

pp. 156

Author(s):

Y. Sophia Dai ◽

Matthew M. Malkan ◽

Harry I. Teplitz ◽

Claudia Scarlata ◽

Anahita Alavi ◽

...

Keyword(s):

Emission Line ◽

Near Infrared ◽

Hubble Space Telescope ◽

Galactic Nuclei ◽

Wide Field ◽

Isolated Galaxies ◽

Parallel Mode ◽

Power Law Index ◽

Attenuation Corrected ◽

Line Galaxy

Abstract We identify a sample of spectroscopically measured emission line galaxy (ELG) Pairs up to z = 1.6 from the Wide Field Camera 3 (WFC3) Infrared Spectroscopic Parallels (WISP) survey. WISP obtained slitless, near-infrared grism spectroscopy along with direct imaging in the J and H bands by observing in the pure-parallel mode with the WFC3 on board the Hubble Space Telescope. From our search of 419 WISP fields covering an area of ∼0.5 deg2, we find 413 ELG pair systems, mostly H α emitters. We then derive reliable star formation rates (SFRs) based on the attenuation-corrected H α fluxes. Compared to isolated galaxies, we find an average SFR enhancement of 40%–65%, which is stronger for major Pairs and Pairs with smaller velocity separations (Δ v < 300 km s−1). Based on the stacked spectra from various subsamples, we study the trends of emission line ratios in pairs, and find a general consistency with enhanced lower ionization lines. We study the pair fraction among ELGs, and find a marginally significant increase with redshift f ∝ (1 + z) α , where the power-law index α = 0.58 ± 0.17 from z ∼ 0.2 to ∼1.6. The fraction of active galactic nuclei is found to be the same in the ELG Pairs as compared to the isolated ELGs.

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AstroSat Study of the Globular Cluster NGC 2298: Probable Evolutionary Scenarios of Hot Horizontal Branch Stars

The Astrophysical Journal ◽

10.3847/1538-4357/ac2eb6 ◽

2021 ◽

Vol 923 (2) ◽

pp. 162

Author(s):

Sharmila Rani ◽

Gajendra Pandey ◽

Annapurni Subramaniam ◽

Chul Chung ◽

Snehalata Sahu ◽

...

Keyword(s):

Globular Cluster ◽

Hubble Space Telescope ◽

Spectral Energy Distribution ◽

Outer Region ◽

Spectral Energy ◽

Horizontal Branch ◽

Horizontal Branch Stars ◽

Cooling Phase ◽

Ehb Stars ◽

Optical Color

Abstract We present the far-UV (FUV) photometry of images acquired with UVIT on AstroSat to probe the horizontal branch (HB) population of the Galactic globular cluster NGC 2298. UV-optical color–magnitude diagrams (CMDs) are constructed for member stars in combination with Hubble Space Telescope UV Globular Cluster Survey data for the central region and Gaia and ground-based photometric data for the outer region. A blue HB (BHB) sequence with a spread and four hot HB stars are detected in all FUV-optical CMDs and are compared with theoretical updated BaSTI isochrones and synthetic HB models with a range in helium abundance, suggesting that the hot HB stars are helium enhanced when compared to the BHB. The estimated effective temperature, radius, and luminosity of HB stars, using the best spectral energy distribution fits, were compared with various HB models. BHB stars span a temperature range from 7500 to 12,250 K. Three hot HB stars have 35,000–40,000 K, whereas one star has around ∼100,000 K. We suggest the following evolutionary scenarios: two stars are likely to be the progeny of extreme HB (EHB) stars formed through an early hot-flasher scenario, one is likely to be an EHB star with probable helium enrichment, and the hottest HB star, which is about to enter the white dwarf cooling phase, could have evolved from the BHB phase. Nevertheless, these are interesting spectroscopic targets to understand the late stages of evolution.

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Discovery of Likely Globular Clusters in Maffei 1

Symposium - International Astronomical Union ◽

10.1017/s0074180900223905 ◽

2002 ◽

Vol 207 ◽

pp. 306-308

Author(s):

R. Buta ◽

M. L. McCall

Keyword(s):

High Resolution ◽

Preliminary Data ◽

Globular Clusters ◽

Hubble Space Telescope ◽

Elliptical Galaxy ◽

Core Region ◽

Wide Field ◽

Space Telescope ◽

The Core

The Hubble Space Telescope Wide Field and Planetary Camera 2 was used to image at high resolution the core region of the nearby, heavily obscured massive elliptical galaxy Maffei 1. We report on the discovery of 19 diffuse objects in the WFPC2 field that are likely to be globular clusters associated with Maffei 1. We present some preliminary data on the luminosities, colors, and sizes of these candidates.

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