The AstroStat Slog » GRB http://hea-www.harvard.edu/AstroStat/slog Weaving together Astronomy+Statistics+Computer Science+Engineering+Intrumentation, far beyond the growing borders Fri, 09 Sep 2011 17:05:33 +0000 en-US hourly 1 http://wordpress.org/?v=3.4 [ArXiv] 1st week, May 2008 http://hea-www.harvard.edu/AstroStat/slog/2008/arxiv-1st-week-may-2008/ http://hea-www.harvard.edu/AstroStat/slog/2008/arxiv-1st-week-may-2008/#comments Mon, 12 May 2008 02:42:54 +0000 hlee http://hea-www.harvard.edu/AstroStat/slog/?p=298 I think I have to review spatial statistics in astronomy, focusing on tessellation (void structure), point process (expanding 2 (3) point correlation function), and marked point process (spatial distribution of hardness ratios of X-ray distant sources, different types of galaxies -not only morphological differences but other marks such as absolute magnitudes and existence of particular features). When? Someday…

In addition to Bayesian methodologies, like this week’s astro-ph, studies on characterizing empirical spatial distributions of voids and galaxies frequently appear, which I believe can be enriched further with the ideas from stochastic geometry and spatial statistics. Click for what was appeared in arXiv this week.

  • [astro-ph:0805.0156]R. D’Abrusco, G. Longo, N. A. Walton
    Quasar candidates selection in the Virtual Observatory era

  • [astro-ph:0805.0201] S. Vegetti& L.V.E. Koopmans
    Bayesian Strong Gravitational-Lens Modelling on Adaptive Grids: Objective Detection of Mass Substructure in Galaxies (many like to see this paper: nest sampling implemented, discusses penalty function and tessllation)

  • [astro-ph:0805.0238] J. A. Carter et al.
    Analytic Approximations for Transit Light Curve Observables, Uncertainties, and Covariances

  • [astro-ph:0805.0269] S.M.Leach et al.
    Component separation methods for the Planck mission

  • [astro-ph:0805.0276] M. Grossi et al.
    The mass density field in simulated non-Gaussian scenarios

  • [astro-ph:0805.0790] Ceccarelli, Padilla, & Lambas
    Large-scale modulation of star formation in void walls
    [astro-ph:0805.0797] Ceccarelli et al.
    Voids in the 2dFGRS and LCDM simulations: spatial and dynamical properties

  • [astro-ph:0805.0875] S. Basilakos and L. Perivolaropoulos
    Testing GRBs as Standard Candles

  • [astro-ph:0805.0968] A. A. Stanislavsky et al.
    Statistical Modeling of Solar Flare Activity from Empirical Time Series of Soft X-ray Solar Emission
]]> http://hea-www.harvard.edu/AstroStat/slog/2008/arxiv-1st-week-may-2008/feed/ 1 [ArXiv] 2nd week, Apr. 2008 http://hea-www.harvard.edu/AstroStat/slog/2008/arxiv-2nd-week-apr-2008/ http://hea-www.harvard.edu/AstroStat/slog/2008/arxiv-2nd-week-apr-2008/#comments Fri, 11 Apr 2008 06:21:41 +0000 hlee http://hea-www.harvard.edu/AstroStat/slog/?p=267 Markov chain Monte Carlo became the most frequent and stable statistical application in astronomy. It will be useful collecting tutorials from both professions.

  • [astro-ph:0804.0620] Q. Wu et al.
    Late transient acceleration of the universe in string theory on $S^{1}/Z_{2}$ (MCMC)

  • [astro-ph:0804.0692] Corless, Dobke & King
    The Hubble constant from galaxy lenses: impacts of triaxiality and model degeneracies (MCMC, Bayesian Modeling)

  • [astro-ph:0804.0788] Zamfir, Sulentic, & Marziani
    New Insights on the QSO Radio-Loud/Radio-Quiet Dichotomy: SDSS Spectra in the Context of the 4D Eigenvector1 Parameter Space

  • [astro-ph:0804.0965] Bloom, Butler, & Perley
    Gamma-ray Bursts, Classified Physically (instead of statistics, it relies on physics to grow a (classification) tree)

  • [astro-ph:0804.1089] G.K.Skinner
    The sensitivity of coded mask telescopes

  • [astro-ph:0804.1197] Bagla, Prasad and Khandai
    Effects of the size of cosmological N-Body simulations on physical quantities – III: Skewness

  • [astro-ph:0804.1447] Marsh, Ireland, & Kucera
    Bayesian Analysis of Solar Oscillations

  • [astro-ph:0804.1532] C. López-Sanjuan, C. E. García-Dabó, M. Balcells
    A maximum likelihood method for bidimensional experimental distributions, and its application to the galaxy merger fraction

  • [astro-ph:0804.1536] V.J.Martinez (One of my favorite astronomers who brings in mathematics and statistics)
    The Large Scale Structure in the Universe: From Power-Laws to Acoustic Peaks
]]> http://hea-www.harvard.edu/AstroStat/slog/2008/arxiv-2nd-week-apr-2008/feed/ 3 [ArXiv] 5th week, Jan. 2008 http://hea-www.harvard.edu/AstroStat/slog/2008/arxiv-5th-week-jan-2008/ http://hea-www.harvard.edu/AstroStat/slog/2008/arxiv-5th-week-jan-2008/#comments Fri, 01 Feb 2008 18:01:03 +0000 hlee http://hea-www.harvard.edu/AstroStat/slog/2008/arxiv-5th-week-jan-2008/ Some statistics papers were listed at the top, of which topics would interest some slog subscribers.

From statistics arxiv:

  • [stat.CO:0801.3387] Contemplating Evidence: properties, extensions of, and alternatives to Nested Sampling N. Chopin &C. Robert
  • [math.ST:0801.4329] Estimators of Long-Memory: Fourier versus Wavelets G. Fay et.al. (not comprehensible but the title is more than interesting)

From astro-ph:

  • [astro-ph:0801.4041] Quantifying parameter errors due to the peculiar velocities of type Ia supernovae R. Ali Vanderveld
  • [astro-ph:0801.4233] Effects of the interaction between dark energy and dark matter on cosmological parameters J. He & B. Wang
  • [astro-ph:0801.4889] Temporal variability and statistics of the Strehl ratio in adaptive-optics images S. Gladysz
  • [astro-ph:0801.4751] Low-Luminosity Gamma-Ray Bursts as a Distinct GRB Population:A Monte Carlo Analysis F Virgili, E Liang, &B Zhang
  • [astro-ph:0801.4759] Optical afterglow luminosities in the Swift epoch: confirming clustering and bimodality M. Nardini, G. Ghisellini & G. Ghirlanda

(The last two papers mentioned Kolmogorov-Smirnov test and probability)

]]> http://hea-www.harvard.edu/AstroStat/slog/2008/arxiv-5th-week-jan-2008/feed/ 0 [ArXiv] 2nd week, Jan. 2007 http://hea-www.harvard.edu/AstroStat/slog/2008/arxiv-2nd-week-jan-2007/ http://hea-www.harvard.edu/AstroStat/slog/2008/arxiv-2nd-week-jan-2007/#comments Fri, 11 Jan 2008 19:44:44 +0000 hlee http://hea-www.harvard.edu/AstroStat/slog/2008/arxiv-2nd-week-jan-2007/ It is notable that there’s an astronomy paper contains AIC, BIC, and Bayesian evidence in the title. The topic of the paper, unexceptionally, is cosmology like other astronomy papers discussed these (statistical) information criteria (I only found a couple of papers on model selection applied to astronomical data analysis without articulating CMB stuffs. Note that I exclude Bayes factor for the model selection purpose).

To find the paper or other interesting ones, click

  • [astro-ph:0801.0638]
    AIC, BIC, Bayesian evidence and a notion on simplicity of cosmological model M Szydlowski & A. Kurek

  • [astro-ph:0801.0642]
    Correlation of CMB with large-scale structure: I. ISW Tomography and Cosmological Implications S. Ho et.al.

  • [astro-ph:0801.0780]
    The Distance of GRB is Independent from the Redshift F. Song

  • [astro-ph:0801.1081]
    A robust statistical estimation of the basic parameters of single stellar populations. I. Method X. Hernandez and D. Valls–Gabaud

  • [astro-ph:0801.1106]
    A Catalog of Local E+A(post-starburst) Galaxies selected from the Sloan Digital Sky Survey Data Release 5 T. Goto (Carefully built catalogs are wonderful sources for classification/supervised learning, or semi-supervised learning)

  • [astro-ph:0801.1358]
    A test of the Poincare dodecahedral space topology hypothesis with the WMAP CMB data B.S. Lew & B.F. Roukema

In cosmology, a few candidate models to be chosen, are generally nested. A larger model usually is with extra terms than smaller ones. How to define the penalty for the extra terms will lead to a different choice of model selection criteria. However, astronomy papers in general never discuss the consistency or statistical optimality of these selection criteria; most likely Monte Carlo simulations and extensive comparison across those criteria. Nonetheless, my personal thought is that the field of model selection should be encouraged to astronomers to prevent fallacies of blindly fitting models which might be irrelevant to the information that the data set contains. Physics tells a correct model but data do the same.

]]> http://hea-www.harvard.edu/AstroStat/slog/2008/arxiv-2nd-week-jan-2007/feed/ 0 [ArXiv] GRB host galaxies, Aug. 10, 2007 http://hea-www.harvard.edu/AstroStat/slog/2007/arxiv-grb-host-galaxies/ http://hea-www.harvard.edu/AstroStat/slog/2007/arxiv-grb-host-galaxies/#comments Tue, 14 Aug 2007 16:47:04 +0000 hlee http://hea-www.harvard.edu/AstroStat/slog/2007/arxiv-grb-host-galaxies-aug-10-2007/ From arxiv/astro-ph:0708.1510v1
Connecting GRBs and galaxies: the probability of chance coincidence by Cobb and Bailyn

Without an optical afterglow, a galaxy within the 2 arc second error region of a GRB x-ray afterglow is identified as a host galaxy; however confusion can rise due to the facts that 1. the edge of a galaxy is diffused, 2. multiple sources could exist within 2 arc second error region, 3.the distance between the galaxy and the x-ray afterglow is measured by projection, and 4. lensing causes increase of brightness and position shifts. In this paper, the authors “investigated the fields of 72 GRBs in order to examine the general issue of associations between GRBs and host galaxies.”

The authors added some statistical issues on this matching GRBs and host galaxies but current knowledge and techniques seem short to tackle the problem. Yet, to prevent false discovery, the authors proposed strategic studies for the followings:

  • Gamma-ray luminosity indicators
  • Detection (or non-detection ) SNe (Supernova) for long-duration bursts
  • Classification of associated galaxy : long-duration and short-duration bursts are associated with late-type and early-type galaxies, respectively
  • Optical afterglow spectral absorption features
  • Visual detection of true host galaxy as happened with GRB 060912a
  • X-ray afterglow spectral emission lines, and
  • Strong lensing of x-ray afterglows

As multi-wavelength studies become popular nowadays, this source matching issue across bands continuously arises where statistics can contribute the validity of source matching methods. So far, those methods are incomprehensible to statisticians.

]]> http://hea-www.harvard.edu/AstroStat/slog/2007/arxiv-grb-host-galaxies/feed/ 0 [ArXiv] Three Classes of GRBs, July 21, 2007 http://hea-www.harvard.edu/AstroStat/slog/2007/arxiv-three-classes-of-grbs/ http://hea-www.harvard.edu/AstroStat/slog/2007/arxiv-three-classes-of-grbs/#comments Wed, 25 Jul 2007 07:22:52 +0000 hlee http://hea-www.harvard.edu/AstroStat/slog/2007/arxiv-three-classes-of-grbs-july-21-2007/ From arxiv/astro-ph:0705.4020v2
Statistical Evidence for Three classes of Gamma-ray Bursts by T. Chattopadhyay et. al.

In general, gamma-ray bursts (GRBs) are classified into two groups: long (>2 sec) and short (<2 sec) duration bursts. Nonetheless, there have been some studies including arxiv/astro-ph:0705.4020v2 that statistically proved the optimal existence of 3 clusters. The pioneer work of GRB clusterings was based on hierarchical clustering methods by Mukerjee et. al.(Three Types of Gamma-Ray Bursts)

The new feature of this article is that Chattopadhyay et. al. applied the k-means and the Dirichlet process model based clustering method to confirm three classes of GRBs. In addition, they investigated classes among 21 GRBs with known red shifts (Click for those GRBs).

]]> http://hea-www.harvard.edu/AstroStat/slog/2007/arxiv-three-classes-of-grbs/feed/ 0 [ArXiv] Complete Catalog of GRBs from BeppoSAX, July 13, 2007 http://hea-www.harvard.edu/AstroStat/slog/2007/arxiv-complete-catalog-of-grbs-from-bepposax/ http://hea-www.harvard.edu/AstroStat/slog/2007/arxiv-complete-catalog-of-grbs-from-bepposax/#comments Mon, 16 Jul 2007 16:15:52 +0000 hlee http://hea-www.harvard.edu/AstroStat/slog/2007/arxiv-complete-catalog-of-grbs-from-bepposax-july-13-2007/ From arxiv/astro-ph:0707.1900v1
The complete catalogue of gamma-ray bursts observed by the Wide Field Cameras on board BeppoSAX by Vetere, et.al.

This paper intend to publicize the largest data set of Gamma Ray Burst (GRB) X-ray afterglows (right curves after the event), which is available from http://www.asdc.asi.it. It is claimed to be a complete on-line catalog of GRB observed by two wide-Field Cameras on board BeppoSAX (Click for its Wiki) in the period of 1996-2002. It is comprised with 77 bursts and 56 GRBs with Xray light curves, covering the energy range 40-700keV. A brief introduction to the instrument, data reduction, and catalog description is given.

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