arXiv subjects

John J. Feldmeier

Publications and source records attributed to John J. Feldmeier.

At least 37 records · Page 2Linked to original sources

arXiv2006

Calibrating Type Ia Supernovae using the Planetary Nebula Luminosity Function I. Initial Results

We report the results of an [O III] lambda 5007 survey for planetary nebulae (PN) in five galaxies that were hosts of well-observed Type Ia supernovae: NGC 524, NGC 1316, NGC 1380, NGC 1448 and NGC 4526. The goals of this survey are to better quantify the zero-point of the maximum magnitude versus decline rate relation for supernovae Type Ia and to validate the insensitivity of Type Ia luminosity to parent stellar population using the host galaxy Hubble type as a surrogate. We detected a total of 45 planetary nebulae candidates in NGC 1316, 44 candidates in NGC 1380, and 94 candidates in NGC 4526. From these data, and the empirical planetary nebula luminosity function (PNLF), we derive distances of 17.9 +0.8/-0.9 Mpc, 16.1 +0.8/-1.1 Mpc, and 13.6 +1.3/-1.2 Mpc respectively. Our derived distance to NGC 4526 has a lower precision due to the likely presence of Virgo intracluster planetary nebulae in the foreground of this galaxy. In NGC 524 and NGC 1448 we detected no planetary nebulae candidates down to the limiting magnitudes of our observations. We present a formalism for setting realistic distance limits in these two cases, and derive robust lower limits of 20.9 Mpc and 15.8 Mpc, respectively. After combining these results with other distances from the PNLF, Cepheid, and Surface Brightness Fluctuations distance indicators, we calibrate the optical and near-infrared relations for supernovae Type Ia and we find that the Hubble constants derived from each of the three methods are broadly consistent, implying that the properties of supernovae Type Ia do not vary drastically as a function of stellar population. We determine a preliminary Hubble constant of H_0 = 77 +/- 3 (random) +/- 5 (systematic) km/s/Mpc for the PNLF, though more nearby galaxies with high-quality observations are clearly needed.

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arXiv2006

The Resolved Stellar Populations of a Dwarf Spheroidal Galaxy in the Virgo Cluster

We report on the discovery of a faint (M_V ~ -10.6 +/- 0.2) dwarf spheroidal galaxy on deep F606W and F814W Hubble Space Telescope images of a Virgo intracluster field. The galaxy is easily resolved in our images, as our color magnitude diagram (CMD) extends > 1 magnitude beyond the tip of the red giant branch (RGB). Thus, it is the deepest CMD for a small dwarf galaxy inside a cluster environment. Using the colors of the RGB stars, we derive a metal abundance for the dwarf of [M/H]= -2.3 +/- 0.3, and show that the metallicity dispersion is less than 0.6 dex at 95% confidence. We also use the galaxy's lack of AGB stars and the absence of objects brighter than M_bol ~ -4.1 +/- 0.2 to show that the system is old (t >~10 Gyr). Finally, we derive the object's structural parameters, and show that the galaxy displays no obvious evidence of tidal threshing. Since the tip of the red giant branch distance ((m-M)_0 = 31.23 +/- 0.17 or D = 17.6 +/- 1.4 Mpc) puts the galaxy near the core of the Virgo cluster, one might expect the object to have undergone some tidal processing. Yet the chemical and morphological similarity between the dwarf and the dSph galaxies of the Local and M81 Group demonstrates that the object is indeed pristine, and not the shredded remains of a much larger galaxy. We discuss the possible origins of this galaxy, and suggest that it is just now falling into Virgo for the first time.

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arXiv2006

The Metallicity Distribution of Intracluster Stars in Virgo

We have used the Hubble Space Telescope's Advanced Camera for Surveys (ACS) to detect and measure ~5300 stars in a single intracluster field in the Virgo Cluster. By performing F606W and F814W photometry on these stars, we have determined their metallicity distribution function, and constrained the types of stars present in this portion of Virgo's intracluster space. Based on the small number of stars detected brighter than the red giant branch (RGB) tip, we suggest that in this region, Virgo's intracluster stars are mostly old (>~10 Gyr). Through analysis of the RGB stars themselves, we determine that the population contains the full range of metallicities probed (-2.3<[M/H]<0.0). We also present evidence that the younger (<10 Gyr) component of the population is more metal-rich, with [M/H]>-0.5. The spatial distribution of the most metal-poor stars in the field shows significantly more structure than that of the metal-rich stars, indicating that the intracluster population is not well-mixed. We discuss the implications these observations have for the production of intracluster stars and the dynamical evolution of the Virgo Cluster.

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arXiv2006

Virgo's Intracluster Globular Clusters as Seen by the Advanced Camera for Surveys

We report the discovery of 4 candidate intracluster globular clusters (IGCs) in a single deep HST ACS field of the Virgo Cluster. We show that each cluster is roughly spherical, has a magnitude near the peak of the Virgo globular cluster luminosity function, has a radial profile that is best-fit by a King model, and is surrounded by an excess of point sources which have the colors and magnitudes of cluster red giant stars. Despite the fact that two of our IGC candidates have integrated colors redder than the mean of the M87 globular cluster system, we propose that all of the objects are metal-poor with [M/H] < -1. We show that the tidal radii of our intracluster globulars are all larger than the mean for Milky Way clusters, and suggest that the clusters have undergone less tidal stress than their Galactic counterparts. Finally, we normalize our globular cluster observations to the luminosity of intracluster stars, and derive a value of S_N ~ 6 for the specific frequency of Virgo intracluster globular clusters. We use these data to constrain the origins of Virgo's intracluster population, and suggest that globular clusters in our intracluster field have a different origin than globular clusters in the vicinity of M87. In particular, we argue that dwarf elliptical galaxies may be an important source of intracluster stars.

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arXiv2006

Intracluster Planetary Nebulae

I review the progress in research on intracluster planetary nebulae over the last five years. Hundreds more intracluster planetary nebulae have been detected in the nearby Virgo and Fornax galaxy clusters, searches of several galaxy groups have been made, and intracluster planetary candidates have been detected in the distant Coma cluster. The first theoretical studies of intracluster planetaries have also been completed, studying their utility as tracers of the intracluster light as a whole, and also as individual objects. From the results to date, it appears that intracluster planetaries are common in galaxy clusters (10-20% of the total amount of starlight), but thus far, none have been detected in galaxy groups, a result which currently is not well understood. Limited spectroscopic follow-up of intracluster planetaries in Virgo indicate that they have a complex velocity structure, in agreement with numerical models of intracluster light. Hydrodynamic simulations of individual intracluster planetaries predict that their morphology is significantly altered by their intracluster environment, but their emission-line properties appear to be unaffected.

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arXiv2005

Hypervelocity intracluster stars ejected by supermassive black hole binaries

Hypervelocity stars have been recently discovered in the outskirts of galaxies, such as the unbound star in the Milky Way halo, or the three anomalously fast intracluster planetary nebulae (ICPNe) in the Virgo Cluster. These may have been ejected by close 3-body interactions with a binary supermassive black hole (SMBBH), where a star which passes within the semimajor axis of the SMBBH can receive enough energy to eject it from the system. Stars ejected by SMBBHs may form a significant sub-population with very different kinematics and mean metallicity than the bulk of the intracluster stars. The number, kinematics, and orientation of the ejected stars may constrain the mass ratio, semimajor axis, and even the orbital plane of the SMBBH. We investigate the evolution of the ejected debris from a SMBBH within a clumpy and time-dependent cluster potential using a high resolution, self-consistent cosmological N-body simulation of a galaxy cluster. We show that the predicted number and kinematic signature of the fast Virgo ICPNe is consistent with 3-body scattering by a SMBBH with a mass ratio $10:1$ at the center of M87.

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arXiv2005

Close Binaries as the Progenitors of the Brightest Planetary Nebulae

We investigate the possible progenitors of the planetary nebulae (PNs) which populate the top 0.5 mag of the [O III] 5007 planetary nebula luminosity function (PNLF). We show that the absolute luminosity of the PNLF cutoff demands that the central stars of these most luminous planetaries be greater than 0.6 Msun, and that such high-mass PN cores must exist in every galaxy. We also use the bolometric-luminosity specific PN number density to show that in early-type galaxies, [O III]-bright planetaries are relatively rare, with only about 10% of stars evolving to these bright magnitudes. We demonstrate that the combination of these two facts implies that either all early-type systems contain a small, smoothly distributed component of young (< 1 Gyr old) stars, or another mechanism exists for creating high-core mass planetaries. We argue that binary-star evolution is this second mechanism, and demonstrate that blue stragglers have the appropriate core properties and number density to explain the observations. We discuss the implications of this alternative mode of stellar evolution, and speculate on how coalesced binaries might affect the use of PNs for measuring a galaxy's star-formation history and chemical evolution.

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arXiv2004

Intracluster Planetary Nebulae as Probes of Intracluster Starlight

I review the progress in research on Intracluster Planetary Nebulae (IPN). Hundreds of IPN candidates have now been found in the Virgo and Fornax galaxy clusters, and searches of two nearby galaxy groups have made. From the results thus far, approximately 10 - 20% of all stars in Virgo and Fornax are in an intracluster component, but there are few such stars in galaxy groups. From the spatial distribution of IPN, it appears that the intracluster stars are clustered, in agreement with tidal-stripping scenarios. In Virgo, the IPN have a large line-of-sight depth, which implies that the bulk of intracluster stars in this cluster derive from late-type galaxies and dwarfs. I also discuss other important developments in IPN research such as the detection of intracluster H II regions, a possible detection of IPN in the Coma Cluster, and future observational and theoretical developments.

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arXiv2004

The Planetary Nebula System of M33

We report the results of a photometric and spectroscopic survey for planetary nebulae (PNe) in the Local Group spiral galaxy M33. We use our sample of 152 PNe to derive an [O III] planetary nebula luminosity function (PNLF) distance of (m-M)_0 = 24.86^+0.07-0.11 (0.94^+0.03-0.05 Mpc). Although this value is ~ 15% larger than the galaxy's Cepheid distance, the discrepancy likely arises from differing assumptions about the system's internal extinction. Our photometry (which extends >3 mag down the PNLF), also reveals that the faint-end of M33's PN luminosity function is non-monotonic, with an inflection point ~2 mag below the PNLF cutoff. We argue that this feature is due to the galaxy's large population of high core-mass planetaries, and that its amplitude may eventually be useful as a diagnostic for studies of stellar populations. Fiber-coupled spectroscopy of 140 of the PN candidates confirms that M33's PN population rotates along with the old disk, with a small asymmetric drift of \~ 10km/s. Remarkably, the population's line-of-sight velocity dispersion varies little over ~4 optical disk scale lengths, with sigma_{rad}~20km/s. We show that this is due to a combination of factors, including a decline in the radial component of the velocity ellipsoid at small galactocentric radii, and a gradient in the ratio of the vertical to radial velocity dispersion. We use our data to show that the mass scale length of M33's disk is ~2.3 times larger than that of the system's IR luminosity and that the disk's V-band mass-to-light ratio changes from M/L_V ~0.3 in the galaxy's inner regions to M/L_V ~2.0 at ~9 kpc. Models in which the dark matter is distributed in the plane of the galaxy are excluded by our data. (abridged)

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arXiv2004

Deep CCD Surface Photometry of Galaxy Clusters II: Searching for Intracluster Starlight in non-cD clusters

We report the search for intracluster light in four Abell Type II/III (non-cD) galaxy clusters: Abell 801, 1234, 1553, & 1914. We find on average that these clusters contain $\sim$ 10% of their detected stellar luminosity in a diffuse component. We show that for two of the clusters the intracluster light closely follows the galaxy distribution, but in the other two cases, there are noticeable differences between the spatial distribution of the galaxies and the intracluster light. We report the results of a search for intracluster tidal debris in each cluster, and note that Abell 1914 in particular has a number of strong tidal features likely due to its status as a recent cluster merger. One of the Abell 1914 features appears to be spatially coincident with an extension seen in weak lensing maps, implying the feature traces a large amount of mass. We compare these results to numerical simulations of hierarchically-formed galaxy clusters, and find good general agreement between the observed and simulated images, although we also find that our observations sample only the brightest features of the intracluster light. Together, these results suggest that intracluster light can be a valuable tool in determining the evolutionary state of galaxy clusters.

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arXiv2003

A CFH12K Survey of Red Giant Stars in the M81 Group

We present the preliminary results of a wide-field photometric survey of individual red giant branch (RGB) and asymptotic giant branch (AGB) stars in the M81 group, performed with the CFH12K mosaic camera of the CFHT. We use deep VI images of 0.65 sq. deg. of sky to map out the two-dimensional distribution of intragroup stars and to search for stars associated with the many HI tidal tails in the group. We place an upper limit on the presence of metal-poor RGB stars in a field located 50-80 kpc from M81, and derive an `intragroup' fraction of <2%. In a field sampling the M81-NGC3077 HI tidal tail, we find blue stars associated with some of the tidal features, including 2 clumps which we tentatively describe as tidal dwarf candidates. These objects are ~1 kpc in size, and, based on their color-magnitude diagrams, have formed stars as recently as ~30-70 Myr ago, long after the group's most recent interactions.

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arXiv2003

Intracluster Planetary Nebulae in Clusters and Groups

We present the results from multiple surveys for intracluster planetary nebulae (IPNe) in nearby galaxy clusters and groups. We find that in the case of clusters, our observations imply: 1) the amount of intracluster starlight is significant, up to 20% of the total starlight, 2) the Virgo Cluster is elongated along our line of sight, and 3) the intracluster light is clustered on the sky, implying ongoing tidal stripping. In contrast, searches for IPNe in groups have found little or no intra-group population, implying there may be something in the cluster environment that significantly enhances intracluster star production. From high-resolution N-body simulations, we find that the IPNe should create observable features in position-velocity space, and that these features may eventually allow us to place limits on the dynamics of galaxy clusters.

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arXiv2003

Results from a diffuse intracluster light survey

We give an update of our ongoing survey for intracluster light (ICL), in a sample of distant Abell clusters. We find that the amount of intracluster starlight is comparable to that seen in nearby clusters, and that tidal debris appears to be common.

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arXiv2003

Using Intracluster Light to Study Cluster Evolution

We present some early results from our deep imaging survey of galaxy clusters intended to detect and study intracluster light (ICL). From our observations to date, we find that ICL is common in galaxy clusters, and that substructure in the ICL also appears to be common as well. We also discuss some initial comparisons of our imaging results to high-resolution numerical simulations of galaxy clusters, and give avenues for future research.

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arXiv2002

Kinematics of Planetary Nebulae in M51's Tidal Debris

We report the results of a radial velocity survey of planetary nebulae (PNe) located in the tidal features of the well-known interacting system NGC 5194/95 (M51). We find clear kinematic evidence that M51's northwestern tidal debris consists of two discrete structures which overlap in projection -- NGC 5195's own tidal tail, and diffuse material stripped from NGC 5194. We compare these kinematic data to a new numerical simulation of the M51 system, and show that the data are consistent with the classic ``single passage'' model for the encounter, with a parabolic satellite trajectory and a 2:1 mass ratio. We also comment on the spectra of two unusual objects: a high-velocity PN which may be associated with NGC 5194's halo, and a possible interloping high-redshift galaxy.

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arXiv2002

Planetary Nebulae as Standard Candles. XII. Connecting the Population I and Population II Distance Scales

We report the results of [OIII] lambda 5007 surveys for planetary nebulae (PNe) in NGC 2403, 3115, 3351, 3627, 4258, and 5866. Using on-band/off-band [OIII] and H-alpha images, we identify samples of PNe in these galaxies and derive distances using the planetary nebula luminosity function (PNLF). We then combine these measurements with previous data to compare the PNLF, Cepheid, and surface brightness fluctuation (SBF) distance scales. We use a sample of 13 galaxies to show that the absolute magnitude of the PNLF cutoff is fainter in small, low-metallicity systems, but the trend is well modelled theoretically. When this dependence is removed, the scatter between the Cepheid and PNLF distances becomes consistent with the internal errors of the methods and independent of any obvious galaxy parameter. We then use the data to recalibrate the zero point of the PNLF distance scale. We use a sample of 28 galaxies to show that the scatter between the PNLF and SBF distance measurements agrees with that predicted from the techniques' internal errors, and that no systematic trend exists between the distance residuals and stellar population. However, we find the PNLF and SBF methods have a significant scale offset: Cepheid-calibrated PNLF distances are, on average, ~0.3 mag smaller than Cepheid-calibrated SBF distances. We discuss the possible causes of this offset, and suggest that internal extinction in the bulges of the SBF calibration galaxies is the principle cause of the discrepancy. If this is correct, the SBF-based Hubble Constant must be increased by ~7%. We use our distance to NGC 4258 to argue that the short distance scale to the LMC is correct, and that the global Hubble Constant inferred from the HST Key Project should be increased by 8 +/- 3% to H_0 = 78 +/- 7 km/s/Mpc. (abridged)

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arXiv2002

Deep CCD Surface Photometry of Galaxy Clusters I: Methods and Initial Studies of Intracluster Starlight

We report the initial results of a deep imaging survey of galaxy clusters. The primary goals of this survey are to quantify the amount of intracluster light as a function of cluster properties, and to quantify the frequency of tidal debris. We outline the techniques needed to perform such a survey, and we report findings for the first two galaxy clusters in the survey: Abell 1413, and MKW 7 . These clusters vary greatly in richness and structure. We show that our surface photometry reliably reaches to a surface brightness of μ_v = 26.5 mags per arcsec. We find that both clusters show clear excesses over a best-fitting r^{1/4} profile: this was expected for Abell 1413, but not for MKW 7. Both clusters also show evidence of tidal debris in the form of plumes and arc-like structures, but no long tidal arcs were detected. We also find that the central cD galaxy in Abell 1413 is flattened at large radii, with an ellipticity of $\approx 0.8$, the largest measured ellipticity of any cD galaxy to date.

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arXiv2002

Intracluster Planetary Nebulae

We review the progress of research on intracluster planetary nebulae (IPN). In the past five years, hundreds of IPN candidates have been detected in the Virgo and Fornax galaxy clusters and searches are also underway in poorer galaxy groups. From the observations to date, and applying the known properties of extragalactic planetary nebulae, the intracluster light in Virgo and Fornax: 1) is significant, at least 20% of the total cluster stellar luminosity, 2) is elongated in Virgo along our line of sight, and 3) may derive from lower-luminosity galaxies, consistent with some models of intracluster star production. A fraction of IPN candidates are not true IPN, but emission-line sources of very large observed equivalent width (> 200 A). The most likely source for these contaminating objects are Lyman-alpha galaxies at z ~ 3.1. Follow-up spectroscopy of the IPN candidates will be crucial to discriminate against high redshift galaxies and to derive the velocity field of the intracluster stellar population.

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