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An iced cosmic-ray macchiato
We know the Universe is filled with particles of extreme energies. The catch? We don’t know how they get their energy.
Baryonification – Dark matter N-body simulations and the impact of gas-trophysics
The effects of gas are complicated and challenging to simulate. Today’s paper explores a way to account for gas in cosmological simulations without actually including it!
Bosons in the Sky with Black Holes
Title: Discovering the QCD Axion with Black Holes and Gravitational WavesAuthors: Asimina Arvanitaki, Masha Baryakhtar, Xinlu HuangFirst Author’s Institution: Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5, CanadaStatus: : Published in Phys. Rev. D 91, 084011 (2015), open access on arXivThe success of the LIGO/VIRGO collaboration has opened a window into many previously gravitationally unprobed phenomena, from tiny dark matter candidates to supermassive black holes. One such example is black hole superradiance: when a wave is scattered off a rotating black hole, it can exit with a larger amplitude than it had before, carrying with it some of the angular momentum of the black hole. This effect is particularly interesting in the case of bosonic waves, whose quantum numbers are not suppressed by Pauli’s Exclusion Principle. This interaction leads to the formation of high occupation bound states around the black hole – creating, in essence, a gravitational atom, with the black hole as its nucleus.Thus, black hole superradiance can be used to detect signals of bosonic fields which cannot be observed in a detector. In this paper, Arvanitaki et al. consider in particular the QCD axion, a robust bosonic dark matter candidate, and the signatures it might produce through black hole superradiance. They estimate its gravitational signatures, both from transitions between “orbitals” of the gravitational atom and from annihilation, as well as its bounds from black hole spin measurements. Both of these criteria are measurable by advanced LIGO (aLIGO), and future observations will serve to constrain axion masses in the event of no detection. Gravitational AtomsJust like the familiar and beloved Hydrogen atom, the gravitational atom has a...
Pulling on Pulsars: Searching for Black Holes in Globular Clusters with Pulsars
What’s the best way to look for intermediate mass black holes? The authors of this paper think it’s to measure the change in the accelerations of pulsars in the center of globular clusters.
Compton-Thick or Thin? Classifying NGC 5347
Today’s paper examines the classification of NGC 5347 as a Compton-thick AGN.
Probing the Secrets of Gravity
How interstellar probes can make or break an alternative theory of gravity
Beyond astro-ph
Astronomy beyond the research
You should get Twitter…for science!
If you’ve been to a conference, you’ve probably seen a Twitter handle on someone’s poster. Come find out why that is, and learn about other ways we can use Twitter in astro!
Astrobites at AAS 235: Day 4
We report on Day 4 of the winter AAS meeting in Honolulu, HI.
Astrobites at AAS 235: Day 3
We report on Day 3 of the winter AAS meeting in Honolulu, HI. Highlights include
Navigating careers in astronomy
Career advice
You should get Twitter…for science!
If you’ve been to a conference, you’ve probably seen a Twitter handle on someone’s poster. Come find out why that is, and learn about other ways we can use Twitter in astro!
Meet the AAS Keynote Speakers: Dr. Daniel Kasen
Neutron star mergers are incredible events! Come hear Professor Daniel Kasen talk all about them on Monday, January 6th at 4:40 PM at #AAS235!
Meet the AAS Keynote Speakers: Dr. Robert Kennicutt
Professor Robert Kennicutt has been at the forefront of research on the star formation rate of galaxies for decade. Come here about his thoughts on the next decade of astronomy research at his talk on Tuesday, January 7th at 3:40 PM at #AAS235!