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05-03-2006
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<br><a href="http://xxx.lanl.gov/pdf/astro-ph/0605038"> astro-ph/0605038</a>
<br> <b>Títol/<i>Title</i>:</b> The Mass of the Central Black Hole in the Seyfert Galaxy
<br> NGC 4151
<br> <b>Autors:</b> Kyle G. Metzroth (1, 2), Christopher A. Onken (1,3),
<br> Bradley M. Peterson (1) ((1) Department of Astronomy, The Ohio
<br> State University, (2) Department of Mechanical Engineering, The
<br> Ohio State University, (3) NRC Herzberg Institute of Astrophysics)
<br> <b>Comentaris/<i>Comments</i>:</b> 25 pages, 5 figures. Accepted for publication in The
<br> Astrophysical Journal
<br>
<br> In order to improve the reverberation-mapping based estimate of
<br> the mass of the central supermassive black hole in the Seyfert 1
<br> galaxy NGC 4151, we have reanalyzed archival ultraviolet
<br> monitoring spectra from two campaigns undertaken with the
<br> International Ultraviolet Explorer. We measure emission-line time
<br> delays for four lines, C IV 1549, He II 1640, C III] 1909, and Mg
<br> II 2798, from both campaigns. We combine these measurements with
<br> the dispersion of the variable part of each respective emission
<br> line to obtain the mass of the central object. Despite the
<br> problematic nature of some of the data, we are able to measure a
<br> mass of 41.1 (+/- 7.3) million solar masses, although this, like
<br> all reverberation-based masses, is probably systematically
<br> uncertain by a factor of 3-4.
<br>
<br>
<br>
<br><a href="http://xxx.lanl.gov/pdf/astro-ph/0605038"> astro-ph/0605038</a>
<br> <b>Títol/<i>Title</i>:</b> The Mass of the Central Black Hole in the Seyfert Galaxy
<br> NGC 4151
<br> <b>Autors:</b> Kyle G. Metzroth (1, 2), Christopher A. Onken (1,3),
<br> Bradley M. Peterson (1) ((1) Department of Astronomy, The Ohio
<br> State University, (2) Department of Mechanical Engineering, The
<br> Ohio State University, (3) NRC Herzberg Institute of Astrophysics)
<br> <b>Comentaris/<i>Comments</i>:</b> 25 pages, 5 figures. Accepted for publication in The
<br> Astrophysical Journal
<br>
<br> In order to improve the reverberation-mapping based estimate of
<br> the mass of the central supermassive black hole in the Seyfert 1
<br> galaxy NGC 4151, we have reanalyzed archival ultraviolet
<br> monitoring spectra from two campaigns undertaken with the
<br> International Ultraviolet Explorer. We measure emission-line time
<br> delays for four lines, C IV 1549, He II 1640, C III] 1909, and Mg
<br> II 2798, from both campaigns. We combine these measurements with
<br> the dispersion of the variable part of each respective emission
<br> line to obtain the mass of the central object. Despite the
<br> problematic nature of some of the data, we are able to measure a
<br> mass of 41.1 (+/- 7.3) million solar masses, although this, like
<br> all reverberation-based masses, is probably systematically
<br> uncertain by a factor of 3-4.
<br>
<br>
<br>
<br><a href="http://xxx.lanl.gov/pdf/astro-ph/0605046"> astro-ph/0605046</a>
<br> <b>Títol/<i>Title</i>:</b> On the viability of holistic cosmic-ray source models
<br> <b>Autors:</b> J. Aublin, E. Parizot
<br> <b>Comentaris/<i>Comments</i>:</b> 5 pages, 1 figure, Accepted for publication in Astronomy
<br> and Astrophysics
<br>
<br> We consider the energy spectrum of cosmic-rays (CRs) from a purely
<br> phenomenological point of view and investigate the possibility
<br> that they all be produced by the same type of sources with a
<br> single power-law spectrum, in E^{-x}, from thermal to ultra-high
<br> energies. We show that the relative fluxes of the Galactic (GCR)
<br> and extra-galactic (EGCR) components are compatible with such a
<br> holistic model, provided that the index of the source spectrum be
<br> x \simeq 2.23\pm 0.07. This is compatible with the best-fit
<br> indices for both GCRs and EGCRs, assuming that their source
<br> composition is the same, which is indeed the case in a holistic
<br> model. It is also compatible with theoretical expectations for
<br> particle acceleration at relativistic shocks.
<br>
<br>
<br>
<br><a href="http://xxx.lanl.gov/pdf/astro-ph/0605049"> astro-ph/0605049</a>
<br> <b>Títol/<i>Title</i>:</b> X-rays from the Globular Cluster G1: Intermediate Mass
<br> Black Hole or Low Mass X-ray Binary?
<br> <b>Autors:</b> David Pooley (UC Berkeley), Saul Rappaport (MIT)
<br> <b>Comentaris/<i>Comments</i>:</b> accepted to ApJL
<br>
<br> The globular cluster G1 (Mayall II) in M31 is the most massive
<br> (~10^7 M_sun) stellar cluster in the Local Group, and it has the
<br> highest central velocity dispersion (~28 km/s). It has been
<br> claimed to host a central ~20,000 M_sun black hole, but these
<br> claims have been controversial. We report here the XMM-Newton
<br> detection of X-ray emission from G1 at a level of Lx ~ 2x10^{36}
<br> erg/s. This emission could be the result of Bondi-Hoyle accretion
<br> of ionized cluster gas by a central black hole, or it could be
<br> produced by a conventional low-mass X-ray binary. A precise
<br> localization of the X-ray emission, which is not possible with the
<br> current XMM data, could distinguish between these possibilities.
<br> While such a measurement may be difficult, it is of sufficient
<br> potential importance to pursue.
<br>
<br>
<br>
<br><a href="http://xxx.lanl.gov/pdf/astro-ph/0605049"> astro-ph/0605049</a>
<br> <b>Títol/<i>Title</i>:</b> X-rays from the Globular Cluster G1: Intermediate Mass
<br> Black Hole or Low Mass X-ray Binary?
<br> <b>Autors:</b> David Pooley (UC Berkeley), Saul Rappaport (MIT)
<br> <b>Comentaris/<i>Comments</i>:</b> accepted to ApJL
<br>
<br> The globular cluster G1 (Mayall II) in M31 is the most massive
<br> (~10^7 M_sun) stellar cluster in the Local Group, and it has the
<br> highest central velocity dispersion (~28 km/s). It has been
<br> claimed to host a central ~20,000 M_sun black hole, but these
<br> claims have been controversial. We report here the XMM-Newton
<br> detection of X-ray emission from G1 at a level of Lx ~ 2x10^{36}
<br> erg/s. This emission could be the result of Bondi-Hoyle accretion
<br> of ionized cluster gas by a central black hole, or it could be
<br> produced by a conventional low-mass X-ray binary. A precise
<br> localization of the X-ray emission, which is not possible with the
<br> current XMM data, could distinguish between these possibilities.
<br> While such a measurement may be difficult, it is of sufficient
<br> potential importance to pursue.
<br>
<br>
<br>
<br><a href="http://xxx.lanl.gov/pdf/astro-ph/0605049"> astro-ph/0605049</a>
<br> <b>Títol/<i>Title</i>:</b> X-rays from the Globular Cluster G1: Intermediate Mass
<br> Black Hole or Low Mass X-ray Binary?
<br> <b>Autors:</b> David Pooley (UC Berkeley), Saul Rappaport (MIT)
<br> <b>Comentaris/<i>Comments</i>:</b> accepted to ApJL
<br>
<br> The globular cluster G1 (Mayall II) in M31 is the most massive
<br> (~10^7 M_sun) stellar cluster in the Local Group, and it has the
<br> highest central velocity dispersion (~28 km/s). It has been
<br> claimed to host a central ~20,000 M_sun black hole, but these
<br> claims have been controversial. We report here the XMM-Newton
<br> detection of X-ray emission from G1 at a level of Lx ~ 2x10^{36}
<br> erg/s. This emission could be the result of Bondi-Hoyle accretion
<br> of ionized cluster gas by a central black hole, or it could be
<br> produced by a conventional low-mass X-ray binary. A precise
<br> localization of the X-ray emission, which is not possible with the
<br> current XMM data, could distinguish between these possibilities.
<br> While such a measurement may be difficult, it is of sufficient
<br> potential importance to pursue.
<br>
<br>
<br>
<br><a href="http://xxx.lanl.gov/pdf/astro-ph/0605049"> astro-ph/0605049</a>
<br> <b>Títol/<i>Title</i>:</b> X-rays from the Globular Cluster G1: Intermediate Mass
<br> Black Hole or Low Mass X-ray Binary?
<br> <b>Autors:</b> David Pooley (UC Berkeley), Saul Rappaport (MIT)
<br> <b>Comentaris/<i>Comments</i>:</b> accepted to ApJL
<br>
<br> The globular cluster G1 (Mayall II) in M31 is the most massive
<br> (~10^7 M_sun) stellar cluster in the Local Group, and it has the
<br> highest central velocity dispersion (~28 km/s). It has been
<br> claimed to host a central ~20,000 M_sun black hole, but these
<br> claims have been controversial. We report here the XMM-Newton
<br> detection of X-ray emission from G1 at a level of Lx ~ 2x10^{36}
<br> erg/s. This emission could be the result of Bondi-Hoyle accretion
<br> of ionized cluster gas by a central black hole, or it could be
<br> produced by a conventional low-mass X-ray binary. A precise
<br> localization of the X-ray emission, which is not possible with the
<br> current XMM data, could distinguish between these possibilities.
<br> While such a measurement may be difficult, it is of sufficient
<br> potential importance to pursue.
<br>
<br>
<br>
<br><a href="http://xxx.lanl.gov/pdf/astro-ph/0605051"> astro-ph/0605051</a>
<br> <b>Títol/<i>Title</i>:</b> Spitzer Reveals Infrared Optically-Thin Synchrotron
<br> Emission from the Compact Jet of the Neutron Star X-Ray Binary 4U
<br> 0614+091
<br> <b>Autors:</b> S. Migliari (UCSD), J.A. Tomsick (UCSD), T.J. Maccarone
<br> (Southampton), E. Gallo (UCSB), R.P. Fender (Southampton), G.
<br> Nelemans (Nijmegen), D.M. Russell (Southampton)
<br> <b>Comentaris/<i>Comments</i>:</b> Accepted for publication in ApJ Letters
<br>
<br> Spitzer observations of the neutron star (ultra-compact) X-ray
<br> binary (XRB) 4U 0614+091 with the Infrared Array Camera reveal
<br> emission of non-thermal origin in the range 3.5-8 um. The
<br> mid-infrared spectrum is well fit by a power law with spectral
<br> index of alpha=-0.57+/-0.04 (where the flux density is F_nu
<br> \propto nu^(alpha)). Given the ultra-compact nature of the binary
<br> system, we exclude the possibility that either the companion star
<br> or the accretion disk can be the origin of the observed emission.
<br> These observations represent the first spectral evidence for a
<br> compact jet in a low-luminosity neutron star XRB and furthermore
<br> of the presence, already observed in two black hole (BH) XRBs, of
<br> a `break' in the synchrotron spectrum of such compact jets. We can
<br> derive a firm upper limit on the break frequency of the spectrum
<br> of nu_thin=3.7x10^(13) Hz, which is lower than that observed in BH
<br> XRBs by at least a factor of 10. Assuming a high-energy cooling
<br> cutoff at ~1 keV, we estimate a total (integrated up to X-rays)
<br> jet power to X-ray bolometric luminosity ratio of \~5%, much lower
<br> than that inferred in BHs.
<br>
<br>
<br>
<br><a href="http://xxx.lanl.gov/pdf/astro-ph/0605059"> astro-ph/0605059</a>
<br> <b>Títol/<i>Title</i>:</b> The Abundances of Light Neutron-Capture Elements in
<br> Planetary Nebulae
<br> <b>Autors:</b> N. C. Sterling, Harriet L. Dinerstein (University of
<br> Texas at Austin)
<br> <b>Comentaris/<i>Comments</i>:</b> 4 pages, 1 figure, to appear in IAU Symp. 234,
<br> "Planetary Nebulae in our Galaxy and Beyond", eds. M. J. Barlow
<br> and R. H. Mendez
<br>
<br> We present preliminary results from a large-scale survey of the
<br> neutron(n)-capture elements Se and Kr in Galactic planetary
<br> nebulae (PNe). These elements may be produced in PN progenitors by
<br> s-process nucleosynthesis, and brought to the stellar envelope by
<br> third dredge-up (TDU). We have searched for [Kr III] 2.199 and [Se
<br> IV] 2.287 $\mu$m in 120 PNe, and detected one or both lines in 79
<br> objects, for a detection rate of 66%. In order to determine
<br> abundances of Se and Kr, we have added these elements to the
<br> atomic database of the photoionization code CLOUDY, and
<br> constructed a large grid of models to derive corrections for
<br> unobserved ionization stages. Se and Kr are enriched in 73% of the
<br> PNe in which they have been detected, and exhibit a wide range of
<br> abundances, from roughly solar to enriched by a factor of 10 or
<br> more. These enrichments are interpreted as evidence for the
<br> operation of the s-process and TDU in the progenitor stars. In
<br> line with theoretical expectations, Kr is more strongly enhanced
<br> than Se, and the abundances of both elements are correlated with
<br> the carbon abundance. Kr and Se are strongly enhanced in Type I
<br> PNe, which may be evidence for the operation of the $^{22}$Ne
<br> neutron source in intermediate-mass AGB stars. These results
<br> constitute the first broad characterization of s-process
<br> enrichments in PNe as a population, and reveal the impact of low-
<br> and intermediate-mass stars on the chemical evolution of
<br> trans-iron elements in the Galaxy.
<br>
<br>
<br>
<br><a href="http://xxx.lanl.gov/pdf/astro-ph/0605059"> astro-ph/0605059</a>
<br> <b>Títol/<i>Title</i>:</b> The Abundances of Light Neutron-Capture Elements in
<br> Planetary Nebulae
<br> <b>Autors:</b> N. C. Sterling, Harriet L. Dinerstein (University of
<br> Texas at Austin)
<br> <b>Comentaris/<i>Comments</i>:</b> 4 pages, 1 figure, to appear in IAU Symp. 234,
<br> "Planetary Nebulae in our Galaxy and Beyond", eds. M. J. Barlow
<br> and R. H. Mendez
<br>
<br> We present preliminary results from a large-scale survey of the
<br> neutron(n)-capture elements Se and Kr in Galactic planetary
<br> nebulae (PNe). These elements may be produced in PN progenitors by
<br> s-process nucleosynthesis, and brought to the stellar envelope by
<br> third dredge-up (TDU). We have searched for [Kr III] 2.199 and [Se
<br> IV] 2.287 $\mu$m in 120 PNe, and detected one or both lines in 79
<br> objects, for a detection rate of 66%. In order to determine
<br> abundances of Se and Kr, we have added these elements to the
<br> atomic database of the photoionization code CLOUDY, and
<br> constructed a large grid of models to derive corrections for
<br> unobserved ionization stages. Se and Kr are enriched in 73% of the
<br> PNe in which they have been detected, and exhibit a wide range of
<br> abundances, from roughly solar to enriched by a factor of 10 or
<br> more. These enrichments are interpreted as evidence for the
<br> operation of the s-process and TDU in the progenitor stars. In
<br> line with theoretical expectations, Kr is more strongly enhanced
<br> than Se, and the abundances of both elements are correlated with
<br> the carbon abundance. Kr and Se are strongly enhanced in Type I
<br> PNe, which may be evidence for the operation of the $^{22}$Ne
<br> neutron source in intermediate-mass AGB stars. These results
<br> constitute the first broad characterization of s-process
<br> enrichments in PNe as a population, and reveal the impact of low-
<br> and intermediate-mass stars on the chemical evolution of
<br> trans-iron elements in the Galaxy.
<br>
<br>
<br>
<br><a href="http://xxx.lanl.gov/pdf/astro-ph/0605066"> astro-ph/0605066</a>
<br> <b>Títol/<i>Title</i>:</b> Galactic Abundance Patterns via Peimbert Types I & II
<br> Planetary Nebulae
<br> <b>Autors:</b> J.B. Milingo (Franklin & Marshall College), K.B. Kwitter
<br> (Williams College), R.B.C. Henry (University of Oklahoma), S.P.
<br> Souza (Williams College)
<br>
<br> Planetary Nebulae (PNe) abundance patterns have long been used to
<br> note signatures of nuclear processing and to trace the
<br> distribution of metals throughout galaxies. We present abundance
<br> gradients and heavy element ratios based upon newly acquired
<br> spectrophotometry of a sample of >120 Galactic PNe. This new data
<br> set is extracted from spectra that extend from 3600 - 9600 A,
<br> allowing the use of [S III] features at 9069 and 9532 A. Since a
<br> significant portion of S in PNe resides in S+2 and higher
<br> ionization stages, including these strong features should improve
<br> the extrapolation from observed ion abundances to total element
<br> abundance. S is believed to be precluded from enhancement and
<br> depletion across the range of PNe progenitor masses, making it an
<br> alternate metallicity tracer to the canonical oxygen. If S can be
<br> reliably determined in PNe, its stability in intermediate mass
<br> stars makes it a valuable tool to probe the natal conditions as
<br> well as the evolution of PNe progenitors. This is a continuation
<br> of our Type II PNe work, the impetus being to compile a relatively
<br> large set of line strengths and abundances with internally
<br> consistent observation, reduction, measurement, and abundance
<br> determination, minimizing systematic effects that come from
<br> compiling various data sets. This research is supported by the AAS
<br> Small Research Grants program, the Franklin & Marshall Committee
<br> on Grants, and NSF grant AST- 0307118.
<br>
<br>
<br>
<br><a href="http://xxx.lanl.gov/pdf/astro-ph/0605069"> astro-ph/0605069</a>
<br> <b>Títol/<i>Title</i>:</b> A Fresh Look at the Binary Characteristics Among Massive
<br> Stars with Implications for Supernova and X-Ray Binary Rates
<br> <b>Autors:</b> Henry A. Kobulnicky (1), Chris L. Fryer (2), Daniel C.
<br> Kiminki (1) ((1) University of Wyoming, (2) Los Alamos National
<br> Laboratory)
<br> <b>Comentaris/<i>Comments</i>:</b> 40 pages, 18 figures; Submitted to ApJ; comments welcome
<br>
<br> We use a radial velocity survey of 141 early-type stars in the
<br> Cygnus OB2 Association over a 6-year time baseline to
<br> statistically describe the binary properties among massive stars.
<br> The observed radial velocity variations permit an estimate of the
<br> binary fraction, f, the power law index of the distribution of
<br> companion masses, alpha, and the power law index of orbital
<br> separations, beta. We constrain f to be >0.6 and in the probable
<br> range 0.7 - 1.0. Comparison of the data to populations of binary
<br> systems simulated by Monte-Carlo methods indicates a firm lower
<br> limit of alpha>-0.8 regardless of assumptions about the true
<br> binary frequency. If f>0.9, then the data require mass ratios
<br> peaked toward unity with alpha>0.0. These data indicate that the
<br> mass ratios in O and early B type systems are approximately flat
<br> or peaked toward unity, broadly consistent with Garmany, Conti, &
<br> Massey (1980). Our analysis rules out the possibility that the
<br> companions to massive stars are drawn from the field star mass
<br> distribution with alpha<-2. Assuming the lowest reasonable value
<br> of alpha, the classic low-mass X-ray binary formation scenario
<br> falls short from producing enough of these binaries. Alternate
<br> scenarios, such as those invoking intermediate mass primaries,
<br> must be the dominate formation scenarios for low-mass X-ray
<br> binaries. The large binary fraction poses a problem for
<br> single-star progenitors for type Ib/c supernovae and strengthens
<br> the case for binaries dominating the progenitors of this class of
<br> supernovae. (Abridged)
<br>
<br>
<br>
<br><a href="http://xxx.lanl.gov/pdf/astro-ph/0605070"> astro-ph/0605070</a>
<br> <b>Títol/<i>Title</i>:</b> Dynamics of galaxy cores and supermassive black holes
<br> <b>Autors:</b> David Merritt
<br> <b>Comentaris/<i>Comments</i>:</b> 75 pages, 28 figures. To appear in Reports on Progress
<br> in Physics
<br>
<br> Recent work on the dynamical evolution of galactic nuclei
<br> containing supermassive black holes is reviewed. Topics include
<br> galaxy structural properties; collisionless and collisional
<br> equilibria; loss-cone dynamics; and dynamics of binary and
<br> multiple supermassive black holes.
<br>
<br>
<br>
<br><a href="http://xxx.lanl.gov/pdf/astro-ph/0605070"> astro-ph/0605070</a>
<br> <b>Títol/<i>Title</i>:</b> Dynamics of galaxy cores and supermassive black holes
<br> <b>Autors:</b> David Merritt
<br> <b>Comentaris/<i>Comments</i>:</b> 75 pages, 28 figures. To appear in Reports on Progress
<br> in Physics
<br>
<br> Recent work on the dynamical evolution of galactic nuclei
<br> containing supermassive black holes is reviewed. Topics include
<br> galaxy structural properties; collisionless and collisional
<br> equilibria; loss-cone dynamics; and dynamics of binary and
<br> multiple supermassive black holes.
<br>
<br>
<br>
<br><a href="http://xxx.lanl.gov/pdf/astro-ph/0605070"> astro-ph/0605070</a>
<br> <b>Títol/<i>Title</i>:</b> Dynamics of galaxy cores and supermassive black holes
<br> <b>Autors:</b> David Merritt
<br> <b>Comentaris/<i>Comments</i>:</b> 75 pages, 28 figures. To appear in Reports on Progress
<br> in Physics
<br>
<br> Recent work on the dynamical evolution of galactic nuclei
<br> containing supermassive black holes is reviewed. Topics include
<br> galaxy structural properties; collisionless and collisional
<br> equilibria; loss-cone dynamics; and dynamics of binary and
<br> multiple supermassive black holes.
<br>
<br>
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