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Magnetic Massive Stars As Progenitors Of ‘Heavy’ Stellar-Mass Black Holes, V. Petit, Z. Keszthelyi, R. MacInnis, David H. Cohen, R. H. D. Townsend, G. A. Wade, S. L. Thomas, S. P. Owocki, J. Puls, A. Ud-Doula 2017 Swarthmore College

Magnetic Massive Stars As Progenitors Of ‘Heavy’ Stellar-Mass Black Holes, V. Petit, Z. Keszthelyi, R. Macinnis, David H. Cohen, R. H. D. Townsend, G. A. Wade, S. L. Thomas, S. P. Owocki, J. Puls, A. Ud-Doula

Physics & Astronomy Faculty Works

The groundbreaking detection of gravitational waves produced by the inspiralling and coalescence of the black hole (BH) binary GW150914 confirms the existence of ‘heavy’ stellar-mass BHs with masses >25 M⊙. Initial characterization of the system by Abbott et al. supposes that the formation of BHs with such large masses from the evolution of single massive stars is only feasible if the wind mass-loss rates of the progenitors were greatly reduced relative to the mass-loss rates of massive stars in the Galaxy, concluding that heavy BHs must form in low-metallicity (Z ≲ 0.25-0.5 Z⊙) environments. However, strong surface magnetic fields ...


Diverse Stellar Haloes In Nearby Milky Way Mass Disc Galaxies., Benjamin Harmsen, Antonela Monachesi, Eric F. Bell, Roelof S. de Jong, Jeremy Bailin, David J. Radburn-Smith, Benne W. Holwerda 2017 University of Michigan-Ann Arbor

Diverse Stellar Haloes In Nearby Milky Way Mass Disc Galaxies., Benjamin Harmsen, Antonela Monachesi, Eric F. Bell, Roelof S. De Jong, Jeremy Bailin, David J. Radburn-Smith, Benne W. Holwerda

Faculty Scholarship

We have examined the resolved stellar populations at large galactocentric distances along the minor axis (from 10 kpc up to between 40 and 75 kpc), with limited major axis coverage, of six nearby highly inclined MilkyWay (MW) mass disc galaxies using Hubble Space Telescope data from the Galaxy haloes, Outer discs, Substructure, Thick discs, and Star clusters (GHOSTS) survey. We select red giant branch stars to derive stellar halo density profiles. The projected minor axis density profiles can be approximated by power laws with projected slopes of −2 to −3.7 and a diversity of stellar halo masses of 1 ...


The Opacity Of Spiral Galaxy Disks. Iii. Automating The Synthetic Field Method., Benne W. Holwerda, R. A. Gonzalez, Ronald J. Allen, P. C. van der Kruit 2017 University of Louisville

The Opacity Of Spiral Galaxy Disks. Iii. Automating The Synthetic Field Method., Benne W. Holwerda, R. A. Gonzalez, Ronald J. Allen, P. C. Van Der Kruit

Benne Holwerda

Dust extinction in spiral disks can be estimated from the counts of background field galaxies, provided the deleterious effects of confusion introduced by structure in the image of the foreground spiral disk can be calibrated. Gonzalez et al. developed a method for this calibration, the Synthetic Field Method (SFM), and applied this concept to a Hubble Space Telescope (HST )/Wide Field Planetary Camera 2 image of NGC 4536. The SFM estimates the total extinction through the disk without requiring assumptions about the distribution of absorbers or disk light. The poor statistics, however, result in large errors in individual measurements. We ...


The Opacity Of Spiral Galaxy Disks. Vi. Extinction, Stellar Light And Color., Benne W. Holwerda, R. A. Gonzalez, P. C. van der Kruit, R. J. Allen 2017 University of Louisville

The Opacity Of Spiral Galaxy Disks. Vi. Extinction, Stellar Light And Color., Benne W. Holwerda, R. A. Gonzalez, P. C. Van Der Kruit, R. J. Allen

Benne Holwerda

In this paper we explore the relation between dust extinction and stellar light distribution in disks of spiral galaxies. Extinction influences our dynamical and photometric perception of disks, since it can distort our measurement of the contribution of the stellar component. To characterize the total extinction by a foreground disk, González et al. (1998, ApJ, 506, 152) proposed the "Synthetic Field Method" (SFM), which uses the calibrated number of distant galaxies seen through the foreground disk as a direct indication of extinction. The method is described in González et al. (1998, ApJ, 506, 152) and Holwerda et al. (2005a, AJ ...


The Opacity Of Spiral Galaxy Disks Vii. The Accuracy Of Galaxy Counts As An Extinction Probe., Benne W. Holwerda, R. A. Gonzalez, Ronald J. Allen, P. C. van der Kruit 2017 University of Louisville

The Opacity Of Spiral Galaxy Disks Vii. The Accuracy Of Galaxy Counts As An Extinction Probe., Benne W. Holwerda, R. A. Gonzalez, Ronald J. Allen, P. C. Van Der Kruit

Benne Holwerda

The "Synthetic Field Method" (SFM) was introduced by González et al. (1998, ApJ, 506, 152) to calibrate numbers of distant galaxies as a probe of extinction in a foreground spiral disk. González et al. (2003, AJ, 125, 1182) studied the effect of the foreground disk on these numbers using simulations of current and future instruments for fields in the LMC, M 31 and NGC 4536, a galaxy in Virgo. They concluded that: (1) the brighter centers of disks were unsuitable; (2) the granularity of the disk at a fixed surface brightness is the limiting factor in the detection of distant ...


The Opacity Of Spiral Galaxy Disks. Iv. Radial Extinction Profiles From Counts Of Distant Galaxies Seen Through Foreground Disks., Benne W. Holwerda, R. A. Gonzalez, Ronald J. Allen, P. C. van der Kruit 2017 University of Louisville

The Opacity Of Spiral Galaxy Disks. Iv. Radial Extinction Profiles From Counts Of Distant Galaxies Seen Through Foreground Disks., Benne W. Holwerda, R. A. Gonzalez, Ronald J. Allen, P. C. Van Der Kruit

Benne Holwerda

Dust extinction can be determined from the number of distant field galaxies seen through a spiral disk. To calibrate this number for the crowding and confusion introduced by the foreground image, Gonzalez et al. and Holwerda et al. developed the Synthetic Field Method (SFM ), which analyzes synthetic fields constructed by adding various deep exposures of unobstructed background fields to the candidate foreground galaxy field. The advantage of the SFM is that it gives the average opacity for the area of a galaxy disk without making assumptions about either the distribution of absorbers or of the disk starlight. However, it is ...


The Opacity Of Spiral Galaxy Disks. V. Dust Opacity, Hi Distributions And Sub-Mm Emission., Benne W. Holwerda, R. A. Gonzalez, Ronald J. Allen, P. C. van der Kruit 2017 University of Louisville

The Opacity Of Spiral Galaxy Disks. V. Dust Opacity, Hi Distributions And Sub-Mm Emission., Benne W. Holwerda, R. A. Gonzalez, Ronald J. Allen, P. C. Van Der Kruit

Benne Holwerda

The opacity of spiral galaxy disks, from counts of distant galaxies, is compared to HI column densities. The opacity measurements are calibrated using the “Synthetic Field Method” from González et al. (1998, ApJ, 506, 152), Holwerda et al. (2005a, AJ, 129, 1381). When compared for individual disks, the HI column density and dust opacity do not seem to be correlated as HI and opacity follow different radial profiles. To improve statistics, an average radial opacity profile is compared to an average HI profile. Compared to dust-to-HI estimates from the literature, more extinction is found in this profile. This difference may ...


The Megasecond Chandra X-Ray Visionary Project Observation Of Ngc 3115. Iii. Luminosity Functions Of Lmxbs And Dependence On Stellar Environments, Dacheng Lin, Jimmy A. Irwin, Ka-Wah Wong, Zachary G. Jennings, Jeroen Homan, Aaron J. Romanowsky, Jay Strader, Jean P. Brodie, Gregory R. Sivakoff, Ronald A. Remillard 2017 University of New Hampshire, Durham

The Megasecond Chandra X-Ray Visionary Project Observation Of Ngc 3115. Iii. Luminosity Functions Of Lmxbs And Dependence On Stellar Environments, Dacheng Lin, Jimmy A. Irwin, Ka-Wah Wong, Zachary G. Jennings, Jeroen Homan, Aaron J. Romanowsky, Jay Strader, Jean P. Brodie, Gregory R. Sivakoff, Ronald A. Remillard

Aaron J. Romanowsky

We studied the X-ray luminosity function (XLF) of low-mass X-ray binaries (LMXBs) in the nearby lenticular galaxy NGC 3115, using the Megasecond Chandra X-ray Visionary Project Observation. With a total exposure time of ~1.1 Ms, we constructed the XLF down to a limiting luminosity of ~1036 erg s−1, which is much deeper than that typically reached for other early-type galaxies. We found significant flattening of the overall LMXB XLF from dN/dLL−2.2±0.4 above 5.5 × 1037 erg s−1 to dN/dLL−1.0±0.1 below it, although we ...


The Sluggs Survey: Hst/Acs Mosaic Imaging Of The Ngc 3115 Globular Cluster System, Zachary G. Jennings, Jay Strader, Aaron J. Romanowsky, Jean P. Brodie, Jacob A. Arnold, Dacheng Lin, Jimmy A. Irwin, Gregory R. Sivakoff, Ka-Wah Wong 2017 University of California Observatories

The Sluggs Survey: Hst/Acs Mosaic Imaging Of The Ngc 3115 Globular Cluster System, Zachary G. Jennings, Jay Strader, Aaron J. Romanowsky, Jean P. Brodie, Jacob A. Arnold, Dacheng Lin, Jimmy A. Irwin, Gregory R. Sivakoff, Ka-Wah Wong

Aaron J. Romanowsky

We present Hubble Space Telescope/Advanced Camera for Surveys (HST/ACS) g and z photometry and half-light radii R h measurements of 360 globular cluster (GC) candidates around the nearby S0 galaxy NGC 3115. We also include Subaru/Suprime-Cam g, r, and i photometry of 421 additional candidates. The well-established color bimodality of the GC system is obvious in the HST/ACS photometry. We find evidence for a "blue tilt" in the blue GC subpopulation, wherein the GCs in the blue subpopulation get redder as luminosity increases, indicative of a mass-metallicity relationship. We find a color gradient in both the ...


The Megasecond Chandra X-Ray Visionary Project Observation Of Ngc 3115. Ii. Properties Of Point Sources, Dacheng Lin, Jimmy A. Irwin, Ka-Wah Wong, Zachary G. Jennings, Jeroen Homan, Aaron J. Romanowsky, Jay Strader, Gregory R. Sivakoff, Jean P. Brodie, Ronald A. Remillard 2017 University of New Hampshire, Durham

The Megasecond Chandra X-Ray Visionary Project Observation Of Ngc 3115. Ii. Properties Of Point Sources, Dacheng Lin, Jimmy A. Irwin, Ka-Wah Wong, Zachary G. Jennings, Jeroen Homan, Aaron J. Romanowsky, Jay Strader, Gregory R. Sivakoff, Jean P. Brodie, Ronald A. Remillard

Aaron J. Romanowsky

We carried out an in-depth study of low-mass X-ray binaries (LMXBs) detected in the nearby lenticular galaxy NGC 3115 using the Megasecond Chandra X-ray Visionary Project observation (total exposure time 1.1 Ms). In total we found 136 candidate LMXBs in the field and 49 in globular clusters (GCs) above 2σ detection, with 0.3–8 keV luminosity LX ~ 1036–1039 erg s−1. Other than 13 transient candidates, the sources overall have less long-term variability at higher luminosity, at least at erg s−1. In order to identify the nature and spectral state of our sources, we compared their ...


An Extended Dust Disk In A Spiral Galaxy : An Occulting Galaxy Pair In The Acs Nearby Galaxy Survey Treasury., Benne W. Holwerda, W. C. Keel, B. Williams, J. J. Dalcanton, R. S. de Jong 2017 University of Louisville

An Extended Dust Disk In A Spiral Galaxy : An Occulting Galaxy Pair In The Acs Nearby Galaxy Survey Treasury., Benne W. Holwerda, W. C. Keel, B. Williams, J. J. Dalcanton, R. S. De Jong

Benne Holwerda

We present an analysis of an occulting galaxy pair, serendipitously discovered in the ACS Nearby Galaxy Survey Treasury observations of NGC 253 taken with the Hubble Space Telescope’s (HST) Advanced Camera for Surveys in F475W, F606W, and F814W (SDSS − g, broad V, and I). The foreground disk system (at z 0.06) shows a dusty disk much more extended than the starlight, with spiral lanes seen in extinction out to 1.5 R25, approximately 6 half-light radii. This pair is the first where extinction can be mapped reliably out to this distance from the center. The spiral arms of ...


Gaps In The Cloud Cover? : Comparing Extinction Measures In Spiral Disks., Benne W. Holwerda, M. Meyer, M. W. Regan, D. Calzetti, K. D. Gordon, J. D. Smith, D. Dale, C. W. Engelbracht, T. Jarrett, M. Thornley, C. Bot, B. Buckalew, R. C. Kennicutt, R. A. Gonzalez 2017 University of Louisville

Gaps In The Cloud Cover? : Comparing Extinction Measures In Spiral Disks., Benne W. Holwerda, M. Meyer, M. W. Regan, D. Calzetti, K. D. Gordon, J. D. Smith, D. Dale, C. W. Engelbracht, T. Jarrett, M. Thornley, C. Bot, B. Buckalew, R. C. Kennicutt, R. A. Gonzalez

Benne Holwerda

Dust in galaxies can be mapped either by the FIR/submillimeter emission, the optical or infrared reddening of starlight, or the extinction of a known background source. We compare two dust extinction measurements for a set of 15 sections in 13 nearby galaxies to determine the scale of the dusty interstellar medium ( ISM ) responsible for disk opacity: one using stellar reddening and the other a known background source. In our earlier papers, we presented extinction measurements of 29 galaxies, based on calibrated counts of distant background objects identified though foreground disks in Hubble Space Telescope WFPC2 images. For the 13 ...


Host Galaxy Extinction Of Type Ia Supernovae : Co-Evolution Of Interstellar Medium Structure And The Extinction Law With Star Formation., Benne W. Holwerda 2017 University of Louisville

Host Galaxy Extinction Of Type Ia Supernovae : Co-Evolution Of Interstellar Medium Structure And The Extinction Law With Star Formation., Benne W. Holwerda

Benne Holwerda

This paper presents a mechanism that may modify the extinction law for Type Ia supernovae (SNeIa) observed at higher redshift. Starting from the observations that (i) SNeIa occur predominantly in spiral galaxies, (ii) star formation ejects interstellar medium (ISM) out of the plane of spirals, (iii) star formation alters the extinction properties of the dust in the ISM, and (iv) there is substantially more star formation at higher redshift, I propose that spiral galaxies have a dustier halo in the past than they do now. The ejected material’s lower value of RV will lead to a lower average value ...


A Dust Component ~2 Kpc Above The Plane In Ngc 891., P. Kamphuis, Benne W. Holwerda, R. J. Allen, R. F. Peletier, P. C. van der Kruit 2017 University of Groningen

A Dust Component ~2 Kpc Above The Plane In Ngc 891., P. Kamphuis, Benne W. Holwerda, R. J. Allen, R. F. Peletier, P. C. Van Der Kruit

Benne Holwerda

Context.The halo of NGC 891 has been the subject of studies for more than a decade. One of its most striking features is the large asymmetry in H emission. In this letter, we will take a quantitative look at this asymmetry at different wavelengths for the first time.
Aims.We suggest that NGC 891 is intrinsically almost symmetric and the large asymmetry in H emission is mostly due to dust attenuation. We will quantify the additional optical depth needed to cause the observed asymmetry in this model.
Methods.By comparing large strips on the North East side of the ...


Vacuum.Doc, Vildyan Yanbikov 2017 Yanbikov Vildyan Shavkyatovich

Vacuum.Doc, Vildyan Yanbikov

Vildyan Yanbikov

The calculated density of the physical vacuum. The high density of physical vacuum.              


The Onset Of Warps In Spitzer Observations Of Edge-On Spiral Galaxies., Kanak Saha, Roelof de Jong, Benne W. Holwerda 2017 Indian Institute of Science, Bangalore

The Onset Of Warps In Spitzer Observations Of Edge-On Spiral Galaxies., Kanak Saha, Roelof De Jong, Benne W. Holwerda

Benne Holwerda

We analyse warps in the nearby edge-on spiral galaxies observed in the Spitzer/Infrared Array Camera (IRAC )4.5-μm band. In our sample of 24 galaxies, we find evidence of warp in 14 galaxies. We estimate the observed onset radii for the warps in a subsample of 10 galaxies. The dark matter distribution in each of these galaxies are calculated using the mass distribution derived from the observed light distribution and the observed rotation curves. The theoretical predictions of the onset radii for the warps are then derived by applying a self-consistent linear response theory to the obtained mass models ...


The Thick Disk In The Galaxy Ngc 4244 From S4g Imaging., Sebastien Comeron, Johan H. Knapen, Kartik Sheth, Michael Regan, Joannah L. Hinz, Armando Gil de Paz, Karin Menendez-Delmestre, Juan Carlos Munoz-Mateos, Mark Seibert, Taehyun Kim, E. Athanassoula, Albert Bosma, Ronald J. Buta, Bruce G. Elmegreen, Luis C. Ho, Benne W. Holwerda, Eija Laurikainen, Heikki Salo, Eva Schinnerer 2017 Korea Astronomy and Space Science Institute

The Thick Disk In The Galaxy Ngc 4244 From S4g Imaging., Sebastien Comeron, Johan H. Knapen, Kartik Sheth, Michael Regan, Joannah L. Hinz, Armando Gil De Paz, Karin Menendez-Delmestre, Juan Carlos Munoz-Mateos, Mark Seibert, Taehyun Kim, E. Athanassoula, Albert Bosma, Ronald J. Buta, Bruce G. Elmegreen, Luis C. Ho, Benne W. Holwerda, Eija Laurikainen, Heikki Salo, Eva Schinnerer

Benne Holwerda

If thick disks are ubiquitous and a natural product of disk galaxy formation and/or evolution processes, all undisturbed galaxies that have evolved during a significant fraction of a Hubble time should have a thick disk. The late-type spiral galaxy NGC 4244 has been reported as the only nearby edge-on galaxy without a confirmed thick disk. Using data from the Spitzer Survey of Stellar Structure in Galaxies (S4G) we have identified signs of two disk components in this galaxy. The asymmetries between the light profiles on both sides of the mid-plane of NGC 4244 can be explained by a combination ...


The Ghosts Survey. I. Hubble Space Telescope Advanced Camera For Surveys Data., D. J. Radburn-Smith, R. S. de Jong, A. C. Seth, J. Bailin, E. F. Bell, T. M. Brown, J. S. Bullock, S. Courteau, J. J. Dalcanton, H. C. Ferguson, P. Goudfrooij, S. Holfeltz, Benne W. Holwerda, C. Purcell, J. Sick, D. Streich, M. Vlajic, D. B. Zucker 2017 University of Washington - Seattle Campus

The Ghosts Survey. I. Hubble Space Telescope Advanced Camera For Surveys Data., D. J. Radburn-Smith, R. S. De Jong, A. C. Seth, J. Bailin, E. F. Bell, T. M. Brown, J. S. Bullock, S. Courteau, J. J. Dalcanton, H. C. Ferguson, P. Goudfrooij, S. Holfeltz, Benne W. Holwerda, C. Purcell, J. Sick, D. Streich, M. Vlajic, D. B. Zucker

Benne Holwerda

We present an overview of the GHOSTS survey, the largest study to date of the resolved stellar populations in the outskirts of disk galaxies. The sample consists of 14 disk galaxies within 17 Mpc, whose outer disks and halos are imaged with the Hubble Space Telescope Advanced Camera for Surveys (ACS). In the first paper of this series, we describe the sample, explore the benefits of using resolved stellar populations, and discuss our ACS F606W and F814W photometry. We use artificial star tests to assess completeness and use overlapping regions to estimate photometric uncertainties. The median depth of the survey ...


Spectrophotometrically Identified Stars In The Pears-N And Pears-S Fields., N. Pirzkal, A. J. Burgasser, S. Malhotra, Benne W. Holwerda, K. C. Sahu, J. E. Rhoads, C. Xu, J. J. Bochanski, J. R. Walsh, R. A. Windhorst, N. P. Hathi, S. H. Cohen 2017 Space Telescope Science Institute

Spectrophotometrically Identified Stars In The Pears-N And Pears-S Fields., N. Pirzkal, A. J. Burgasser, S. Malhotra, Benne W. Holwerda, K. C. Sahu, J. E. Rhoads, C. Xu, J. J. Bochanski, J. R. Walsh, R. A. Windhorst, N. P. Hathi, S. H. Cohen

Benne Holwerda

Deep ACS slitless grism observations and identification of stellar sources are presented within the Great Observatories Origins Deep Survey North and South fields which were obtained in the Probing Evolution And Reionization Spectroscopically (PEARS) program. It is demonstrated that even low-resolution spectra can be a very powerful means of identifying stars in the field, especially low-mass stars with stellar types M0 and later. The PEARS fields lay within the larger GOODS fields, and we used new, deeper images to further refine the selection of stars in the PEARS field, down to a magnitude of z850 = 25 using a newly developed ...


The Unusual Vertical Mass Distribution Of Ngc 4013 Seen Through The Spitzer Survey Of Stellar Structure In Galaxies (S4g)., Sebastien Comeron, Bruce G. Elmegreen, Johan H. Knapen, Kartik Sheth, Joannah L. Hinz, Michael W. Regan, Armando Gil de Paz, Juan Carlos Munoz-Mateos, Karin Menendez-Delmestre, Mark Seibert, Taehyun Kim, Trisha Mizusawa, Eija Laurikainen, Heikki Salo, Jarkko Laine, E. Athanassoula, Albert Bosma, Ronald J. Buta, Dimitri A. Gadotti, Luis C. Ho, Benne W. Holwerda, Eva Schinnerer, Dennis Zaritsky 2017 Korea Astronomy and Space Science Institute

The Unusual Vertical Mass Distribution Of Ngc 4013 Seen Through The Spitzer Survey Of Stellar Structure In Galaxies (S4g)., Sebastien Comeron, Bruce G. Elmegreen, Johan H. Knapen, Kartik Sheth, Joannah L. Hinz, Michael W. Regan, Armando Gil De Paz, Juan Carlos Munoz-Mateos, Karin Menendez-Delmestre, Mark Seibert, Taehyun Kim, Trisha Mizusawa, Eija Laurikainen, Heikki Salo, Jarkko Laine, E. Athanassoula, Albert Bosma, Ronald J. Buta, Dimitri A. Gadotti, Luis C. Ho, Benne W. Holwerda, Eva Schinnerer, Dennis Zaritsky

Benne Holwerda

NGC 4013 is a nearby Sb edge-on galaxy known for its “prodigious” H i warp and its “giant” tidal stream. Previous work on this unusual object shows that it cannot be fitted satisfactorily by a canonical thin+thick disk structure. We have produced a new decomposition of NGC 4013, considering three stellar flattened components (thin+thick disk plus an extra and more extended component) and one gaseous disk. All four components are considered to be gravitationally coupled and isothermal. To do so, we have used the 3.6μm images from the Spitzer Survey of Stellar Structure in Galaxies. We find ...


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