The Stellar Halo of M104. I. A Survey for Planetary Nebulae and the Planetary Nebula Luminosity Function Distance

Ford, H. C.; Xue, Hui; Ciardullo, Robin; Jacoby, George H.; Freeman, K. C.

doi:10.1086/176828

Cited by 40 publications

(36 citation statements)

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“…Observations at optical wavelengths have identified globular clusters and planetary nebulae in M104 (VanDalfsen et al 2001;Larsen, Forbes, & Brodie 2001;Ford et al 1996). We searched for coincidences between these catalogs and our Chandra sources.…”

Section: Source Identificationmentioning

confidence: 99%

“…With two of 12 Magellanic Cloud SSSs associated with nebulae, and with $1000 SSSs predicted in galaxies such as M31, we might expect there to be dozens of such associations. The nebulae could be and would likely be included among PNe lists by surveys using the methodology that Ford et al (1996) used to identify PNe in M104 (Di Stefano, Paerels, & Rappaport 1995). Because only a small fraction of all SSSs can be detected, the number of observable PNe/very soft sources may be only 1%-10% of the number of physical associations.…”

Section: Relationship Between Very Soft Sources and Planetary Nebulaementioning

confidence: 99%

“…The results are remarkable because, in this relatively short observation of a galaxy located 8.9 Mpc from us (Ford et al 1996), Chandra detected 122 point X-ray sources, 22 of them identified as very soft by an algorithm (Di developed to search for luminous supersoft X-ray sources (SSSs) and quasisoft X-ray sources (QSSs). These observations provide the first glimpse of very soft sources located a measurable distance away from the plane of the galaxy in which they reside.…”

Section: Introductionmentioning

confidence: 97%

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X‐Ray Point Sources in the Sombrero Galaxy: Very Soft Sources, the Globular Cluster/Low‐Mass X‐Ray Binary Connection, and an Overview

Stefano¹,

Kong²,

VanDalfsen³

et al. 2003

ApJ

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We report on the population of point sources discovered during an 18.5 ks Chandra ACIS-S observation of the Sombrero galaxy. We present the luminosity function and the spectra of the six brightest sources, consider correlations with globular clusters (GCs) and with planetary nebulae, and study the galaxy's population of very soft sources. We detected 122 sources. Twenty-two sources are identified as very soft; of these, five appear to be classical luminous supersoft X-ray sources (SSSs), while 17 may belong to the slightly harder class referred to as quasi-soft (QSSs). There is an overdensity of very soft sources within 2 kpc of the nucleus, which is itself the brightest X-ray source. Very soft sources are also found in the disk and halo, with one QSS in a globular cluster (GC). This source is somewhat harder than most SSSs; the energy distribution of its photons is consistent with what is expected from an accreting intermediate-mass black hole. Several sources in the Sombrero's halo are good candidates for SSS models in which the accretor is a nuclear-burning white dwarf. In total, 32 X-ray sources are associated with GCs. The majority of sources with luminosity greater than 10 38 ergs s À1 are in GCs. These results for M104, an Sa galaxy, are similar to what has been found for elliptical galaxies and for the latetype spiral M31. We find that those optically bright GCs with X-ray sources house only the brightest X-ray sources. We find that, in common with other galaxies, there appears to be a positive connection between young (metal-rich) GCs and X-ray sources but that the brightest X-ray sources are equally likely to be in metal-poor GCs. The luminosity function of X-ray sources in GCs has a cut-off near the Eddington luminosity for a 1.4 M object. We propose a model that can explain the trends seen in the data sets from the Sombrero and other galaxies. Thermal timescale mass transfer can occur in some of the younger clusters in which the turnoff mass is slightly greater than 0.8 M ; multiplicity may play a role in some of the most massive clusters; accretion from giant stars may be the dominant mechanism in some older, less massive and less centrally concentrated clusters. Key elements of the model can be tested.

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Section: Source Identificationmentioning

confidence: 99%

Section: Relationship Between Very Soft Sources and Planetary Nebulaementioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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X‐Ray Point Sources in the Sombrero Galaxy: Very Soft Sources, the Globular Cluster/Low‐Mass X‐Ray Binary Connection, and an Overview

Stefano¹,

Kong²,

VanDalfsen³

et al. 2003

ApJ

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“…Figure 1 shows the location of the M104 clusters from the 3 studies; it can be seen that our 2dF data extend out to ∼20 arcmin radius (50 kpc for a distance of 9 Mpc; [4]), much further out than previous studies. ; Crosses: Keck GCs [7].…”

Section: Observationsmentioning

confidence: 62%

2dF Spectroscopy of M104 Globular Clusters

Bridges

Freeman

Rhode

et al.

Eso Astrophysics Symposia

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Abstract. We present preliminary results of 2dF spectroscopy of globular clusters in The Sombrero (M104). We find 56 new clusters, and compile a total sample of 103 velocities combined with previous data. Our 2dF data extend out to 20 arcmin radius (∼50 kpc), much further than previous studies. In the combined sample, we tentatively find a steep drop in the velocity dispersion with radius, which might possibly indicate a truncated halo. There is no obvious solid-body rotation over all radii, but separate fits for those clusters inside and outside 25 kpc radius show tantalizing evidence for counter-rotation. The projected mass estimator with isotropic orbits yields an M104 mass of 1.2×1012 M inside 50 kpc, and a (M/L)B = 30: solid evidence for a dark matter halo in this galaxy.

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“…DF thanks the ARC for financial support. 8.9 ± 0.6 LF (PNLF) (Ford et al 1996) Adopted distance 29.77 ± 0.03 9.0 ± 0.1 Weighted average of to Sombrero SBF & PNLF …”

Section: Acknowledgmentsmentioning

confidence: 99%

HST ACS Wide-Field Photometry of the Sombrero Galaxy Globular Cluster System

Spitler

Globular Clusters - Guides to Galaxies

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A detailed imaging analysis of the globular cluster (GC) system of the Sombrero galaxy (NGC 4594) has been accomplished using a six-image mosaic from the Hubble Space Telescope Advanced Camera for Surveys. The quality of the data is such that contamination by foreground stars and background galaxies is negligible for all but the faintest 5% of the GC luminosity function (GCLF). This enables the study of an effectively pure sample of 659 GCs until ∼ 2 mags fainter than the turnover magnitude, which occurs at M T OM V = −7.60 ± 0.06 for an assumed m−M= 29.77. Two GC metallicity subpopulations are easily distinguishable, with the metal-poor subpopulation exhibiting a smaller intrinsic dispersion in color compared to the metal-rich subpopulation.Three new discoveries include: (1) A metal-poor GC color-magnitude trend. (2) Confirmation that the metal-rich GCs are ∼ 17% smaller than the metal-poor ones for small projected galactocentric radii (less than ∼ 2 arcmin). However, the median half-light radii of the two subpopulations become identical at ∼ 3 arcmin from the center. This is most easily explained if the size difference is the result of projection effects. (3) The brightest (M V < −9.0) members of the GC system show a size-magnitude upturn where the average GC size increases with increasing luminosity. Evidence is presented that supports an intrinsic origin for this feature rather than a being result from accreted dwarf elliptical nuclei. In addition, the metal-rich GCs show a shallower positive size-magnitude trend, similar to what is found in previous studies of young star clusters.

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The Stellar Halo of M104. I. A Survey for Planetary Nebulae and the Planetary Nebula Luminosity Function Distance

Cited by 40 publications

References 0 publications

X‐Ray Point Sources in the Sombrero Galaxy: Very Soft Sources, the Globular Cluster/Low‐Mass X‐Ray Binary Connection, and an Overview

X‐Ray Point Sources in the Sombrero Galaxy: Very Soft Sources, the Globular Cluster/Low‐Mass X‐Ray Binary Connection, and an Overview

2dF Spectroscopy of M104 Globular Clusters

HST ACS Wide-Field Photometry of the Sombrero Galaxy Globular Cluster System

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