Journal Club

Rules

1. This will be held on Mondays at 2 pm in room 3.30 from the 24th of January 2005.
2. Astrophysics postgraduate students are expected to be there. Permanent members of the teaching staff involved in graduate student supervision should NOT attend. Others are welcome to join as they wish. Journal Club is optional for 3rd and 4th (and beyond) years.
3. Usually two papers will be discussed and everyone should read both papers beforehand.
4. Presentations should be 20 minutes, including discussion.
5. The paper should have been published (preprint or journal) within the last two years.
6. The paper should not be about (or closely related to) your own research.
7. Please inform the organizer (Rhys Morris) which paper you will discuss at the latest by the Thursday before Journal Club, please send a URL or an Astro-ph number.

Schedule for 2005

Summer term

Some possible papers

Nature 433, 495 - 498 (03 February 2005); doi:10.1038/nature03245
The mass of the missing baryons in the X-ray forest of the warm hot intergalactic medium

FABRIZIO NICASTRO1, SMITA MATHUR2, MARTIN ELVIS1, JEREMY DRAKE1, TAOTAO FANG3, ANTONELLA FRUSCIONE1, YAIR KRONGOLD1,4, HERMAN MARSHALL5, RIK WILLIAMS2 & ANDREAS ZEZAS1

http://info.nature.com/cgi-bin24/DM/y/eR1O0BhW230Ch0ZeP0EL

_________________________________________________________________________

Paper (*cross-listing*): hep-ph/0307266
replaced with revised version Mon, 29 Mar 2004 14:29:43 GMT   (61kb)

Title: Homestake result, sterile neutrinos and low energy solar
neutrino experiments
Authors: P. C. de Holanda and A. Yu. Smirnov
Comments: Figures 5 and 6 modified, shorter version will be published
in PRD
\\ ( http://arXiv.org/abs/hep-ph/0307266 ,  61kb)


Period-luminosity relations for Galactic Cepheid variables with
independent distance measurements

Chow-Choong Ngeow, Shashi M. Kanbur
Monthly Notices of the Royal Astronomical Society; Volume 349, Issue
3, Page 1130

http://www.blackwell-synergy.com/links/doi/10.1111/j.1365-2966.2004.07595.x



Title: Cepheid distances from infrared long-baseline interferometry -
II.
  Calibration of the Period-Radius and Period-Luminosity relations
Authors: P. Kervella, D. Bersier, D. Mourard, N. Nardetto, V. Coude du
Foresto
Comments: 7 pages, 3 figures, submitted to Astronomy & Astrophysics
\\

Using our interferometric observations of seven classical Cepheids
reported in Kervella et al. (2003, Paper I), complemented by
previously existing measurements, we derive new calibrations of the
Cepheids Period-Radius (P-R) and Period-Luminosity (P-L) relations. We
obtain a P-R relation of log R = [0.767 +/- 0.009] log P + [1.091 +/-
0.011], only 1 sigma away from the relation obtained by Gieren et
al. (1998). We therefore confirm their P-R relation at a level of
Delta(log R) = +/- 0.02. We also derive an original calibration of the
P-L relation, assuming the slopes derived by Gieren et al.  (1998)
from LMC Cepheids, alpha_K = -3.267 +/- 0.042 and alpha_V = -2.769 +/-
0.073. With a P-L relation of the form M = alpha (log P - 1) + beta,
we obtain log P = 1 reference points of beta(K) = -5.904 +/- 0.063 and
beta(V) = -4.209 +/- 0.075. Our calibration in the V band is
statistically identical to the geometrical result of Lanoix et
al. (1999).  \\ ( http://arXiv.org/abs/astro-ph/0404179 , 90kb)


Updated pulsation models for anomalous Cepheids:
M. Marconi, G. Fiorentino and F. Caputo
A&A 417 (2004) 1101-1114 (Section 'Stellar structure and evolution')
http://publish.edpsciences.org/abstract/aa/v417/p1101


Gamma-Ray Bursts are Produced Predominately in the Early Universe
J. R. Lin, S. N. Zhang, and T. P. Li
Page 819  [ http://www.journals.uchicago.edu/cgi-bin/resolve?ApJ17944
]


First Star Signature in Infrared Background Anisotropies
Asantha Cooray, James J. Bock, Brian Keatin, Andrew E. Lange, and
T. Matsumoto
Page 611  [ http://www.journals.uchicago.edu/cgi-bin/resolve?ApJ58833
]

Title: Discovery of a Transient U-band Dropout in a Lyman-Break
Survey: A
  Tidally-Disrupted Star at z = 3.3?
Authors: Daniel Stern (1), P.G. van Dokkum (2), Peter Nugent (3),
D.J. Sand
  (4), R.S. Ellis (4), Mark Sullivan (5), J.S. Bloom (6), D.A. Frail
  (7), J.-P.
  Kneib (4,8), L.V.E. Koopmans (9), Tommaso Treu (10) ((1)
  JPL/Caltech, (2)
  Yale University, (3) LBNL, (4) Caltech, (5) University of Durham,
  (6)
  Harvard/CfA, (7) NRAO, (8) OMP, (9) Kapteyn Astron. Inst., (10)
  UCLA)
Comments: 20 pages, 4 figures; to appear in the Astrophysical Journal;
  desparately seeking archival images of Abell 267 from Summer 2001
\\
  
We report the discovery of a transient source in the central regions
of galaxy cluster Abell 267. The object, which we call "PALS1", was
found in a survey aimed at identifying highly-magnified Lyman-break
galaxies in the fields of intervening rich clusters. At discovery, the
source had U>24.7 (2-sigma; AB), g=21.96, and very blue g-r and r-i
colors; i.e., PALS1 was a U-band drop-out, characteristic of
star-forming galaxies and quasars at z~3. However, three months later
the source had faded by more than three magnitudes. Further
observations showed a continued decline in luminosity, to R>26.4 seven
months after discovery. Though the apparent brightness is suggestive
of a supernova at roughly the cluster redshift, we show that the
photometry and light curve argue against any known type of supernova
at any redshift. The spectral energy distribution and location near
the center of a galaxy cluster are consistent with the hypothesis that
PALS1 is a gravitationally-lensed transient at z~3.3.  If this
interpretation is correct, the source is magnified by a factor of 4-7
and two counterimages are predicted. Our lens model predicts time
delays between the three images of 1-10 years and that we have
witnessed the final occurrence of the transient. The intense
luminosity (M(AB) ~ -23.5 after correcting for lensing) and blue UV
continuum (implying T>50,000 K) argue the source may have been a flare
resulting from the tidal disruption of a star by a 10^6-10^8
solar-mass black hole. Regardless of its physical nature, PALS1
highlights the importance of monitoring regions of high magnification
in galaxy clusters for distant, time-varying phenomena.  \\ (
http://arXiv.org/abs/astro-ph/0405482 , 238kb)


Paper: astro-ph/0406022
Date: Tue, 1 Jun 2004 13:15:11 GMT   (43kb)

Title: Confusion in the infrared: Spitzer and beyond
Authors: H. Dole, G. H. Rieke, G. Lagache, J-L. Puget,
A. Alonso-Herrero, L.
  Bai, M. Blaylock, E. Egami, C. W. Engelbracht, K. D. Gordon,
  D. C. Hines, D.
  M. Kelly, E. Le Floc'h, K. A. Misselt, J. E. Morrison, J. Muzerolle,
  C.
  Papovich, P. G. Perez-Gonzalez, M. J. Rieke, J. R. Rigby,
  G. Neugebauer, J.
  A. Stansberry, K. Y. L. Su, E. T. Young, C. A. Beichman,
  P. L. Richards
Comments: Accepted for Publication in ApJS Special Issue on Spitzer. 4
pages, 2
  B&W figures. emulateapj. Also available at
  http://ssc.spitzer.caltech.edu/pubs/journal2004.html
\\

We use the source counts measured with the Multiband Imaging
Photometer for Spitzer (MIPS) at 24, 70, and 160 microns to determine
the 5-sigma confusion limits due to extragalactic sources: 56
micro-Jy, 3.2 and 40 mJy at 24, 70 and 160 microns, respectively. We
also make predictions for confusion limits for a number of proposed
far infrared missions of larger aperture (3.5 to 10m diameter).  \\ (
http://arXiv.org/abs/astro-ph/0406022 , 43kb)


The Effect of Metallicity on Cepheid-based Distances
Shoko Sakai, Laura Ferrarese, Robert C. Kennicutt, Jr., and Abhijit
Saha
Page 42  [ http://www.journals.uchicago.edu/cgi-bin/resolve?ApJ59357 ]


Detecting Population III Stars through Observations of Near-Infrared
Cosmic
Infrared Background Anisotropies
A. Kashlinsky, R. Arendt, Jonathan P. Gardner, John C. Mather, and
S. Harvey
Moseley
Page 1  [ http://www.journals.uchicago.edu/cgi-bin/resolve?ApJ18028 ]


Paper: astro-ph/0308467
replaced with revised version Mon, 14 Jun 2004 13:46:31 GMT   (592kb)

Title: The Size Distribution of Trans-Neptunian Bodies
Authors: G. M. Bernstein, D. E. Trilling, R. L. Allen, M. E. Brown,
M. Holman,
  and R. Malhotra
Comments: Revised version accepted to the Astronomical
Journal. Numerical
  results are very slightly revised. Implications for the origins of
  short-period comets are substantially revised, and tedious material
  on
  statistical tests has been collected into a new Appendix
\\ ( http://arXiv.org/abs/astro-ph/0308467 ,  592kb)



The abundance of Galactic planets from OGLE-III 2002 microlensing data

Colin Snodgrass, Keith Horne, Yiannis Tsapras
Monthly Notices of the Royal Astronomical Society; Volume 351, Issue
3,
Page 967

http://www.blackwell-synergy.com/links/doi/10.1111/j.1365-2966.2004.07839.x


First sources in infrared light: stars, supernovae and miniquasars

Asantha Cooray, Naoki Yoshida
Monthly Notices of the Royal Astronomical Society; Volume 351, Issue
3,
Page L71

http://www.blackwell-synergy.com/links/doi/10.1111/j.1365-2966.2004.08047.x


Paper: astro-ph/0402659
Date: Fri, 27 Feb 2004 15:49:41 GMT   (161kb)

Title: 1E 1207.4-5209: a low-mass bare strange star?
Authors: R. X. Xu (PKU)
Comments: 26 pages, 5 figures, submitted
\\
  
Both rotation- and accretion-powered low-mass bare strange stars are
studied, the astrophysical appearances of which are especially
focused. It is suggested that low-mass bare strange stars, with weaker
ferromagnetic fields than that of normal pulsars, could result from
accretion-induced collapses (AIC) of white dwarfs. According to its
peculiar timing behavior, we propose that the radio-quiet object, 1E
1207.4-5209, could be a low-mass bare strange star with polar surface
magnetic field ~ 6 x 10^10 G and a few kilometers in radius. The
low-mass bare strange star ideal is helpful to distinguish neutron and
strange stars, and is testable by imaging pulsar-like stars with the
future Constellation-X telescope.  \\ (
http://arXiv.org/abs/astro-ph/0402659 , 161kb)

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\\

Title: Redshift-Independent Distances to Type Ia Supernovae
Authors: Brian J. Barris and John L. Tonry
Comments: 12 pages, 3 figures, accepted for publication in
Astrophysical
  Journal Letters
\\
  
We describe a procedure for accurately determining luminosity
distances to Type Ia supernovae (SNe Ia) without knowledge of
redshift. This procedure, which may be used as an extension of any of
the various distance determination methods currently in use, is based
on marginalizing over redshift, removing the requirement of knowing
$z$ a priori. We demonstrate that the Hubble diagram scatter of
distances measured with this technique is approximately equal to that
of distances derived from conventional redshift-specific methods for a
set of 60 nearby SNe Ia. This indicates that accurate distances for
cosmological SNe Ia may be determined without the requirement of
spectroscopic redshifts, which are typically the limiting factor for
the number of SNe that modern surveys can collect. Removing this
limitation would greatly increase the number of SNe for which current
and future SN surveys will be able to accurately measure distance. The
method may also be able to be used for high-$z$ SNe Ia to determine
cosmological density parameters without redshift information.  \\ (
http://arXiv.org/abs/astro-ph/0408097 , 75kb)
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\\

Subgalactic Clumps at High Redshift: A Fragmentation Origin?
Andreas Immeli, Markus Samland, Pieter Westera, and Ortwin Gerhard
Page 20  [ http://www.journals.uchicago.edu/cgi-bin/resolve?ApJ17082 ]

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\\
A Luminous Ly alpha -emitting Galaxy at Redshift z = 6.535: Discovery
and
Spectroscopic Confirmation
James E. Rhoads, Chun Xu, Steve Dawson, Arjun Dey, Sangeeta Malhotra,
JunXian
Wang, Buell T. Jannuzi, Hyron Spinrad, and Daniel Stern
Page 59  [ http://www.journals.uchicago.edu/cgi-bin/resolve?ApJ59984 ]

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\\

The Glow of Primordial Remnants
G. Chabrier
Page 315  [ http://www.journals.uchicago.edu/cgi-bin/resolve?ApJ59536
]


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The Cosmic Energy Inventory
Masataka Fukugita and P. J. E. Peebles
Page 643  [ http://www.journals.uchicago.edu/cgi-bin/resolve?ApJ60693 ]

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Paper: astro-ph/0412031
Date: Wed, 1 Dec 2004 19:26:34 GMT   (326kb)

Title: Millimeter Wavelength Brightness Fluctuations of the Atmosphere Above
  the South Pole
Authors: R. S. Bussmann, W. L. Holzapfel, C. L. Kuo
Comments: 13 pages, 15 figures, submitted to ApJ
\\
  We report measurements of the millimeter wavelength brightness fluctuations
produced by the atmosphere above the South Pole made with the Arcminute
Cosmology Bolometer Array Receiver (ACBAR). The data span the 2002 Austral
winter during which ACBAR was mounted on the Viper telescope at the South Pole.
We recover the atmospheric signal in the presence of instrument noise by
calculating the correlation between signals from distinct elements of the ACBAR
bolometer array. With this method, it is possible to measure atmospheric
brightness fluctuations with high SNR even under the most stable atmospheric
conditions. The observed atmospheric signal is characterized by the parameters
of the Komolgorov-Taylor (KT) model, which are the amplitude and power law
exponent describing the atmospheric power spectrum, and the two components of
the wind angular velocity at the time of the observation. The KT model is
typically a good description of the observed fluctuations, and fits to the data
produce values of the Komolgorov exponent that are consistent with theoretical
expectations. By combining the wind angular velocity results with measurements
of the wind linear velocity, we find that the altitude of the observed
atmospheric fluctuations is consistent with the distribution of water vapor
determined from radiosonde data. For data corresponding to frequency passbands
centered on 150, 219, and 274 GHz, we obtain median fluctuation power
amplitudes of [10, 38, 74] mK^{2} rad^{-5/3} in Rayleigh-Jeans temperature
units. Comparing with previous work, we find that these median amplitudes are
approximately an order of magnitude smaller than those found at the South Pole
during the Austral summer and at least 30 times lower than found at the ALMA
site in the Atacama desert.
\\ ( http://arXiv.org/abs/astro-ph/0412031 ,  326kb)
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Paper: astro-ph/0411034
replaced with revised version Thu, 2 Dec 2004 09:19:29 GMT   (2kb)

Title: Has Dark Energy really been discovered in the Lab?
Authors: Philippe Jetzer and Norbert Straumann
Comments: The paper is accepted for publication in Physics Letters B;
added
  equation 4

\\ ( http://arXiv.org/abs/astro-ph/0411034 , 2kb)
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Cosmological Parameters sigma 8, the Baryon Density
Omega b, the Vacuum Energy Density Omega  Lamda
, the Hubble Constant and the UV Background Intensity from a
Calibrated Measurement of H I Ly alpha Absorption at z = 1.9

David Tytler, David Kirkman, John M. O'Meara, Nao Suzuki, Adam Orin,
Dan Lubin, Pascal Paschos, Tridivesh Jena, Wen-Ching Lin, Michael
L. Norman, and Avery Meiksin

Page 1  [ http://www.journals.uchicago.edu/cgi-bin/resolve?ApJ60257 ]

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Studying the Star Formation Histories of Galaxies in Clusters from Composite
Spectra
Alan Dressler, Augustus Oemler, Jr., Bianca M. Poggianti, Ian Smail, Scott
Trager, Stephen A. Shectman, Warrick J. Couch, and Richard S. Ellis
Page 867  [ http://www.journals.uchicago.edu/cgi-bin/resolve?ApJ60042 ]

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Paper: astro-ph/0412566
Date: Tue, 21 Dec 2004 16:03:03 GMT   (219kb)

Title: Tracing the Warm Hot Intergalactic Medium in the local Universe
Authors: M. Viel, E. Branchini, R. Cen, J.P. Ostriker, S. Matarrese, P.
  Mazzotta, B. Tully
Comments: 15 pages 11 Figures. Submitted to MNRAS
\\
  We present a simple method for tracing the spatial distribution and
predicting the physical properties of the Warm-Hot Intergalactic Medium (WHIM),
from the map of galaxy light in the local universe. Under the assumption that
biasing is local and monotonic we map the ~ 2 Mpc/h smoothed density field of
galaxy light into the mass density field from which we infer the spatial
distribution of the WHIM in the local supercluster. Taking into account the
scatter in the WHIM density-temperature and density-metallicity relation,
extracted from the z=0 outputs of high-resolution and large box size
hydro-dynamical cosmological simulations, we are able to quantify the
probability of detecting WHIM signatures in the form of absorption features in
the X-ray spectra, along arbitrary directions in the sky. To illustrate the
usefulness of this semi-analytical method we focus on the WHIM properties in
the Virgo Cluster region.
\\ ( http://arXiv.org/abs/astro-ph/0412566 ,  219kb)
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\\
Paper: astro-ph/0501088
Date: Thu, 6 Jan 2005 01:19:55 GMT   (482kb)

Title: The Assembly of Diversity in the Morphologies and Stellar Populations of
  High-Redshift Galaxies
Authors: Casey Papovich (1), Mark Dickinson (2,3,4), Mauro Giavalisco (3),
  Christopher J. Conselice (5), Henry C. Ferguson (3,4) ((1) Steward Obs., (2)
  NOAO, (3) STScI, (4) Johns Hopkins, (5) Caltech)
Comments: Accepted for publication in the Astrophysical Journal. 20 pages, in
  emulateapj format
\\
  We have studied the evolution in the morphologies, sizes, stellar-masses,
colors, and internal color dispersion (ICD) of galaxies at z=1 and 2.3, using a
near-IR, flux-limited catalog for the HDF-N. At z=1 most luminous galaxies have
morphologies of early-to-mid Hubble-types, and many show transformations
between their rest-frame UV-optical morphologies. Galaxies at z=2.3 have
compact and irregular morphologies with no clearly evident Hubble-sequence
candidates. The mean galaxy size grows from z=2.3 to 1 by 40%, and the density
of galaxies larger than 3 kpc increases by 7 times. At z=1, the size-luminosity
distribution is broadly consistent with that of local galaxies, with passive
evolution. However, galaxies at z=2.3 are smaller than the large present-day
galaxies, and must continue to grow in size and stellar mass. We have measured
the galaxies' UV-optical ICD, which quantifies differences in morphology and
the relative amount of on-going star-formation. The mean and scatter in
galaxies' total colors and ICD increase from z=2.3 to 1. At z=1 many galaxies
with large ICD are spirals, with a few irregular systems. Few z=2.3 galaxies
have high ICD, and those that do are actively merging. We interpret this as
evidence for the presence of older and more diverse stellar populations at z=1
that are not generally present at z>2. We conclude that the star-formation
histories of galaxies at z>2 are dominated by discrete, recurrent bursts, which
quickly homogenize the galaxies' stellar content, and are possibly associated
with mergers. The increase in the stellar-population diversification by z<1.4
implies that merger-induced starbursts occur less frequently than at higher
redshifts, and more quiescent star-forming modes dominate. This transition
coincides with the emergence of Hubble-sequence galaxies. [Abridged]
\\ ( http://arXiv.org/abs/astro-ph/0501088 ,  482kb)
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\\

Paper (*cross-listing*): gr-qc/0211052
replaced with revised version Wed, 25 Jun 2003 17:25:12 GMT   (11kb)

Title: The Pioneer riddle, the quantum vacuum and the acceleration of light
Authors: Antonio F. Ranada
Comments: 11 pages, no figures
\\ ( http://arXiv.org/abs/gr-qc/0211052 ,  11kb)
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\\
Paper (*cross-listing*): gr-qc/0310088
From: Jean-Paul Mbelek 
Date: Fri, 17 Oct 2003 08:53:24 GMT   (6kb)

Title: Can conventional forces really explain the anomalous acceleration of
  Pioneer 10/11 ?
Authors: J. P. Mbelek (1), M. Michalski (2) ((1) Service d'Astrophysique, CEA
  Saclay, (2) Abt. Quanteninformationsverarbeitung, Universit\"at Ulm)
Comments: 9 pages, no figure
\\
  A conventional explanation of the correlation between the Pioneer 10/11
anomalous acceleration and spin-rate change is given. First, the rotational
Doppler shift analysis is improved. Finally, a relation between the radio beam
reaction force and the spin-rate change is established. Computations are found
in good agreement with observational data. The relevance of our result to the
main Pioneer 10/11 anomalous acceleration is emphasized. Our analysis leads us
to conclude that the latter may not be merely artificial.
\\ ( http://arXiv.org/abs/gr-qc/0310088 ,  6kb)
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\\
Paper: astro-ph/0402384
Date: Mon, 16 Feb 2004 20:20:33 GMT   (3kb)

Title: Modified Newtonian dynamics from acceleration fluctuations
Authors: Thomas F. Jordan
Comments: 5 Pages
\\
  A speculative mathematical model is used to generate the modified Newtonian
dynamics called MOND from fluctuations of the number of quanta of quantized
acceleration. The one new parameter can be chosen either to make the transition
to modification comparable to that obtained from the functions used to fit data
with MOND, or to make the modification at larger accelerations comparable in
magnitude to the unexplained accelerations of Pioneer 10 and 11.
\\ ( http://arXiv.org/abs/astro-ph/0402384 ,  3kb)
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The Discovery of a High-Redshift X-Ray-Emitting QSO Very Close to the
Nucleus of NGC 7319

Pasquale Galianni, E. M. Burbidge, H. Arp, V. Junkkarinen,
G. Burbidge, and Stefano Zibetti

Page 88  [ http://www.journals.uchicago.edu/cgi-bin/resolve?ApJ60493 ]

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Paper: astro-ph/0503306
Date: Mon, 14 Mar 2005 23:21:24 GMT   (106kb)

Title: Ice Age Epochs and the Sun's Path Through the Galaxy
Authors: D. R. Gies and J. W. Helsel
Comments: 14 pages, 3 figures, accepted for publication in ApJ

We present a calculation of the Sun's motion through the Milky Way
Galaxy over the last 500 million years. The integration is based upon
estimates of the Sun's current position and speed from measurements
with Hipparcos and upon a realistic model for the Galactic
gravitational potential. We estimate the times of the Sun's past
spiral arm crossings for a range in assumed values of the spiral
pattern angular speed. We find that for a difference between the mean
solar and pattern speed of Omega_Sun - Omega_p = 11.9 +/- 0.7 km/s/kpc
the Sun has traversed four spiral arms at times that appear to
correspond well with long duration cold periods on Earth. This
supports the idea that extended exposure to the higher cosmic ray flux
associated with spiral arms can lead to increased cloud cover and long
ice age epochs on Earth.

\\ ( http://arXiv.org/abs/astro-ph/0503306 ,  106kb)
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Journal Club is organised by Rhys Morris.