Older research-related news, events and ideas
Primary Tags: research
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What Every Scientist Needs to Know
ideas research amir_shahmoradi teaching
Reference:
– BEACON Researchers at Work: What Every Scientist Needs to KnowI recently wrote a guest blog post for the Bio-computational Evolution in Action Consortium (BEACON) on the importance of teaching, or at least introducing all STEM graduate students with cognitive sciences and cognitive flaws that can affect human mind and reasoning. The full post can found here. The following is a summary of the post:
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Beyond Univariate Luminosity Functions for Long Gamma-Ray Bursts
astrophysics physics research
Reference:
– A Multivariate Fit Luminosity Function and World Model for Long Gamma-Ray BurstsAvailable Downloads:
– BATSE Catalog trigger numbers for 1366 events classified as Long GRBs in this analysis can be found here.
– Spectral data for these triggers are available from BATSE Current & 4B GRB Catalogs.
– The spectral peak energy EP,obs estimates for all LGRBs can be found here.
– Full MCMC samples of the model parameters for different cosmic rates can be found in the project’s repository.A Brief (incomplete) Introduction to the Story:
The Luminosity Function (LF) of Long-duration Gamma-Ray Bursts (LGRBs) has been subject of many researches in GRB community. Early attempts to constrain the LF of LGRBs in the BATSE era were primarily aimed at finding the true origin of LGRBs: Cosmological vs. Galactic. Back in the 90’ there was a great debate and suspicion about the cosmological origin of LGRBs with some scientists arguing that a cosmological origin for GRBs would imply an enormous output of energy on the order of. 1051 [erg] in a matter of a few seconds. Nevertheless, observations of the GRB afterglows in the late 90’ and the first measurement of a GRB redshift, ruled out the galactic models as a potential candidate for GRBs, or at best, for many classes of Gamma-Ray events. Now with GRB distance puzzle being solved, researchers turned into other interesting aspects of these bursts, such as the studies of GRB energetics and the correlations among the spectral parameters of the prompt gamma-ray emission from (mostly) LGRBs. Most prominently, some observational astronomers reported strong correlations between the total isotropic emission of the gamma-ray energies (Eiso), or the isotropic peak luminosity (Liso) and the spectral peak energies (EP,z) of LGRBs. Such correlations were later criticized by some other researchers for the lack of significance and sample incompleteness. The culprit here turns out to be the unknown complex selection effects in the GRB detection mechanism, spectral analysis, and redshift measurement which modify the observed sample of LGRBs from the true underlying population without leaving a clear trace. Nevertheless, the debate still goes on to this date among GRB researchers (c.f. Shahmoradi & Nemiroff 2011 for a complete review).
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Human Perception and Instrumental Bias
astrophysics cognitive_science physics research
References:
– The Possible Impact of Gamma-Ray Burst Detector Thresholds on Cosmological Standard Candles
– How Real Detector Thresholds Create False Standard CandlesThe psychological literature is full of studies that demonstrate how the humans’ limited senses can result in cognitive flaws and biases in our understanding of the universe. In fact, psychologists have pinpointed many specific biases that affect not only the way we see but how we think about and perceive the world. Confirmation bias, for example, is the tendency to notice, accept, and remember data that confirms what we already believe, and to ignore, forget, or explain away data that is contradictory to our beliefs. To make things worse, add the (unknown) limitations of instruments by which human probes the universe. The combined effects of human and instrument biases can result in erroneous conclusions and predictions.
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Hardness as a proxy for the spectral peak energy of Gamma-Ray Bursts
astrophysics physics research
Reference:
– Hardness as a Spectral Peak Estimator for Gamma-Ray BurstsAvailable Downloads:
– The spectral peak energy (EP,obs) estimates for 2130 BATSE GRBs can be downloaded from here.
– Conditional EP,obs probability density functions for all bursts can be downloaded collectively as a zip file.One of the most widely used spectral parameters in the studies of Gamma-Ray Bursts (GRBs) is the time-integrated νFν spectrum peak energy of these cosmic events. Since the early 1990s, there has been a growing trend in the research community to plot GRBs’s spectra in the form of E2 dE or νFν versus energy, (E), where Fν is the spectral flux at the frequency ν. This has the advantage of making it easy to discern the energy of the peak power from the burst. The νFν plot of many of the bursts’ spectra shows a peak which is denoted by EP,obs where the subscript “P,obs” stands for OBServer-frame spectral Peak energy (in contrast to the Comoving-frame Peak energy).
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BSc project: Cygnus X-3 and the Muon Excess Puzzle
astrophysics high_energy_physics physics research
After months of research and article reading, my undergraduate degree project is complete and available to view here (it’s all in Persian language).
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