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This is an auxiliary blog to Science and Reason for the more timely posting of shorter science news items, explanations of important concepts, and pointers to interesting posts on other science blogs.

Charles Daney
22 posts

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  • March 6, 2012
  • 01:28 AM

Puzzle remains around dark core in cosmic collision

by Charles Daney in Today's Science

Galaxy clusters, like the universe as a whole, are composed of both baryonic (“ordinary”) matter and dark matter, with about 1 part in 6 of the former, and five parts in 6 of the latter. A curious thing happens – usually – when two clusters collide. Both the visible baryonic matter, consisting mainly of luminous [...]... Read more »

Jee, M., Mahdavi, A., Hoekstra, H., Babul, A., Dalcanton, J., Carroll, P., & Capak, P. (2012) A STUDY OF THE DARK CORE IN A520 WITH THE HUBBLE SPACE TELESCOPE: THE MYSTERY DEEPENS . The Astrophysical Journal, 747(2), 96. DOI: 10.1088/0004-637X/747/2/96  

  • February 27, 2012
  • 07:11 PM

The dwarf satellite galaxy problem

by Charles Daney in Today's Science

Simulations of galaxy formation based on the Lambda-Cold Dark Matter (ΛCDM) cosmological model predict that a large galaxy such as the Milky Way should have many dwarf satellite galaxies, perhaps thousands. However, only about 20 or 30 have been identified. Where are the rest? Are they really there? That question alludes to the “dwarf galaxy [...]... Read more »

Vegetti, S., Lagattuta, D., McKean, J., Auger, M., Fassnacht, C., & Koopmans, L. (2012) Gravitational detection of a low-mass dark satellite galaxy at cosmological distance. Nature, 481(7381), 341-343. DOI: 10.1038/nature10669  

  • February 18, 2012
  • 09:42 PM

An Alzheimer’s disease protein seems to spread via synapses

by Charles Daney in Today's Science

For what seems like forever, medical scientists have been trying to figure out the relative disease-causing importance of two types of protein often found in the brains of Alzheimer’s disease (AD) victims: tau and amyloid-beta (Aβ). While the larger question is still unresolved, recent research may have made a significant discovery about the tau protein. [...]... Read more »

Liu, L., Drouet, V., Wu, J., Witter, M., Small, S., Clelland, C., & Duff, K. (2012) Trans-Synaptic Spread of Tau Pathology In Vivo. PLoS ONE, 7(2). DOI: 10.1371/journal.pone.0031302  

  • February 8, 2012
  • 10:00 PM

How did some early black holes get so big so fast?

by Charles Daney in Today's Science

The supermassive black holes (SMBHs) found in the centers of large galaxies can be astonishingly large. The closest example to us is in the giant elliptical galaxy M87, and it’s estimated to be 6.6 billion solar masses (M⊙). More distant examples can be even larger, more than 10 billion M⊙ (at distances ~300 million light-years). [...]... Read more »

Di Matteo, T., Khandai, N., DeGraf, C., Feng, Y., Croft, R., Lopez, J., & Springel, V. (2012) COLD FLOWS AND THE FIRST QUASARS. The Astrophysical Journal, 745(2). DOI: 10.1088/2041-8205/745/2/L29  

  • January 30, 2012
  • 02:30 AM

How large were the first stars in the universe?

by Charles Daney in Today's Science

Since it is currently, and for the foreseeable future, not possible to actually observe what the first stars in the universe were like when they formed, the only way to answer this question is by detailed calculations from first principles. In other words, by computer simulations. Until very recently, such simulations couldn’t be very conclusive, [...]... Read more »

  • January 7, 2012
  • 08:45 PM

A hyperactive young galaxy

by Charles Daney in Today's Science

Active galaxies contain a supermassive black hole (SMBH) that causes vigorous radiation of electromagnetic energy as a result of rapid accretion of gas and dust. While almost all galaxies except dwarfs contain an SMBH in the center, active galaxies are rare – fewer that 1% of galaxies in the present universe. A very few active [...]... Read more »

  • January 5, 2012
  • 01:30 AM

Some supermassive black holes are much more super than others

by Charles Daney in Today's Science

Supermassive black holes (SMBHs) can get to be pretty large. Astrophysicists don’t really know what the upper limit is, if any. But before some recent research, the mass of the largest SMBH yet determined was 6.3×109 M⊙ (solar masses). That value is known fairly precisely, since the SMBH is in the nearby giant elliptical galaxy [...]... Read more »

McConnell, N., Ma, C., Gebhardt, K., Wright, S., Murphy, J., Lauer, T., Graham, J., & Richstone, D. (2011) Two ten-billion-solar-mass black holes at the centres of giant elliptical galaxies. Nature, 480(7376), 215-218. DOI: 10.1038/nature10636  

  • December 23, 2011
  • 07:04 PM

Cosmic rays from stellar superbubbles

by Charles Daney in Today's Science

Cosmic rays were discovered almost 100 years ago (1912), yet astrophysicists are still uncertain about where they come from or how they acquire their extremely high energies. Research recently published gives strong evidence that the Cygnus X region, which contains hundreds of very hot, massive, young stars, is a source of cosmic rays and has [...]... Read more »

Ackermann, M., Ajello, M., Allafort, A., Baldini, L., Ballet, J., Barbiellini, G., Bastieri, D., Belfiore, A., Bellazzini, R., Berenji, B.... (2011) A Cocoon of Freshly Accelerated Cosmic Rays Detected by Fermi in the Cygnus Superbubble. Science, 334(6059), 1103-1107. DOI: 10.1126/science.1210311  

  • December 19, 2011
  • 06:30 PM

Possible constraints on dark matter particle mass

by Charles Daney in Today's Science

Although there is very good indirect evidence for the existence of dark matter, it’s an understatement to say that actual detection of dark matter particles has not been easy. Recent research results from two different teams that both studied gamma rays from dwarf galaxy neighbors of the Milky Way provide an illustration of the difficulty. [...]... Read more »

  • December 11, 2011
  • 11:55 PM

Active star-forming galaxies have substantial halos

by Charles Daney in Today's Science

Detailed new research shows that there is a distinct correlation between galaxies with large, oxygen-rich gas halos and active ongoing star formation. Although active star formation requires large amounts of available gas, what is surprising is that much, or perhaps even most, of the gas may be in the halo region outside of where most [...]... Read more »

Tumlinson, J., Thom, C., Werk, J., Prochaska, J., Tripp, T., Weinberg, D., Peeples, M., O'Meara, J., Oppenheimer, B., Meiring, J.... (2011) The Large, Oxygen-Rich Halos of Star-Forming Galaxies Are a Major Reservoir of Galactic Metals. Science, 334(6058), 948-952. DOI: 10.1126/science.1209840  

  • December 4, 2011
  • 11:30 PM

Cygnus X-1 mass and spin determined

by Charles Daney in Today's Science

Cygnus X-1 was a very puzzling object when it was discovered in 1964, because (as the name suggests) it was an extremely powerful X-ray source. Since X-rays are (fortunately) blocked by the Earth’s atmosphere, the exceptional nature of the object was only recognized when it became possible to do astronomy from above the atmosphere, in [...]... Read more »

Reid, M., McClintock, J., Narayan, R., Gou, L., Remillard, R., & Orosz, J. (2011) THE TRIGONOMETRIC PARALLAX OF CYGNUS X-1. The Astrophysical Journal, 742(2), 83. DOI: 10.1088/0004-637X/742/2/83  

Orosz, J., McClintock, J., Aufdenberg, J., Remillard, R., Reid, M., Narayan, R., & Gou, L. (2011) THE MASS OF THE BLACK HOLE IN CYGNUS X-1. The Astrophysical Journal, 742(2), 84. DOI: 10.1088/0004-637X/742/2/84  

Gou, L., McClintock, J., Reid, M., Orosz, J., Steiner, J., Narayan, R., Xiang, J., Remillard, R., Arnaud, K., & Davis, S. (2011) THE EXTREME SPIN OF THE BLACK HOLE IN CYGNUS X-1. The Astrophysical Journal, 742(2), 85. DOI: 10.1088/0004-637X/742/2/85  

  • December 3, 2011
  • 01:37 AM

Star formation and molecular clouds in the Large Magellanic Cloud

by Charles Daney in Today's Science

The Large Magellanic Cloud (LMC) is the largest close neighbor of our own galaxy, at a distance of only 160,000 light-years – less than twice the diameter of the Milky Way itself. Its proximity makes it a very useful object to study in connection with the process of star formation, which is generally assumed to [...]... Read more »

Wong, T., Hughes, A., Ott, J., Muller, E., Pineda, J., Bernard, J., Chu, Y., Fukui, Y., Gruendl, R., Henkel, C.... (2011) THE MAGELLANIC MOPRA ASSESSMENT (MAGMA). I. THE MOLECULAR CLOUD POPULATION OF THE LARGE MAGELLANIC CLOUD. The Astrophysical Journal Supplement Series, 197(2), 16. DOI: 10.1088/0067-0049/197/2/16  

  • December 1, 2011
  • 11:19 PM

Magnetic fields may set the stage for birth of new stars

by Charles Daney in Today's Science

Star formation does not happen as easily as one might suppose from the abundance of stars in a galaxy like the Milky Way, in which more than 100 billion times the mass of the Sun (M⊙) exists in the form of stars. Stars condense out of interstellar gas within the galaxy, but the process is [...]... Read more »

  • November 22, 2011
  • 01:00 AM

Neutron star research points to different classes of supernovae

by Charles Daney in Today's Science

Classifying things is the starting point for almost all scientific fields – from flowers to fundamental particles. Once one has classes the next step is to find subclasses, and then sub-subclasses. Finding correlations between different classification schemes, then, often leads to significant understandings. Neutron stars are not stars in the normal sense. They are remnants [...]... Read more »

  • November 11, 2011
  • 11:00 PM

Galaxy interactions accelerate the growth of supermassive black holes

by Charles Daney in Today's Science

It’s now well-known that there’s a rough correlation between a galaxy’s size and the size of its central supermassive black hole (SMBH). The correlation is even better (for spiral galaxies) between the black hole size and the size of the central bulge of the galaxy. It’s been found that the mass of a SMBH is [...]... Read more »

J. D. Silverman, P. Kampczyk, K. Jahnke, R. Andrae, S. Lilly, M. Elvis, F. Civano, V. Mainieri, C. Vignali, G. Zamorani.... (2011) The impact of galaxy interactions on AGN activity in zCOSMOS. Astrophysical Journal. arXiv: 1109.1292v1

  • November 8, 2011
  • 11:30 PM

Hubble directly observes the disk around a black hole

by Charles Daney in Today's Science

Quasars are the brightest persistent objects in the universe. They represent the brightest examples of a somewhat more common object: an active galactic nucleus (AGN). As the name implies, an AGN exists at the center of some galaxies. Most quasars, and even most AGN, are not found in the nearby universe, since they are especially [...]... Read more »

Muñoz, J., Mediavilla, E., Kochanek, C., Falco, E., & Mosquera, A. (2011) A STUDY OF GRAVITATIONAL LENS CHROMATICITY WITH THE HUBBLE SPACE TELESCOPE . The Astrophysical Journal, 742(2), 67. DOI: 10.1088/0004-637X/742/2/67  

  • November 5, 2011
  • 12:43 AM

Record-breaking gamma-ray emissions from a millisecond pulsar

by Charles Daney in Today's Science

Breaking old records for some statistic or another generally makes for catchy headlines, at least. If nothing else, the fact that the statistic is being tracked (whether or not by Guinness) suggests it’s a matter of more than passing interest. Now astrophysicists have come up with a new find that breaks three records at the [...]... Read more »

, ., Freire, P., Abdo, A., Ajello, M., Allafort, A., Ballet, J., Barbiellini, G., Bastieri, D., Bechtol, K., Bellazzini, R.... (2011) Fermi Detection of a Luminous γ-Ray Pulsar in a Globular Cluster. Science. DOI: 10.1126/science.1207141  

  • October 30, 2011
  • 04:39 AM

Astronomers Pin Down Galaxy Collision Rate

by Charles Daney in Today's Science

Galaxies have been growing over most of the 13.7 billion year history of the universe. Some of the growth is due to intergalactic gas gradually swept up by an existing galaxy and then driving star formation in the galaxy. But another growth mechanism is the merger of two (and sometimes more) existing galaxies into one. [...]... Read more »

Jennifer M. Lotz, Patrik Jonsson, T. J. Cox, Darren Croton, Joel R. Primack, Rachel S. Somerville, & Kyle Stewart. (2011) The Major and Minor Galaxy Merger Rates at z . Astrophysical Journal. arXiv: 1108.2508v1

  • October 20, 2011
  • 06:30 PM

Distant Galaxies Reveal The Clearing of the Cosmic Fog

by Charles Daney in Today's Science

The first billion years after the big bang (out of about 13.7 billion years total since then) were among the most interesting in terms of giving birth to the kind of objects that still dominate the scene today. Mostly that means stars and galaxies, plus a few exotica such as quasars. Unfortunately, it’s very difficult [...]... Read more »

L. Pentericci, A. Fontana, E. Vanzella, M. Castellano, A. Grazian, M. Dijkstra, K. Boutsia, S. Cristiani, M. Dickinson, E. Giallongo.... (2011) Spectroscopic confirmation of z~7 LBGs: probing the earliest galaxies and the epoch of reionization. Astrophysical Journal. arXiv: 1107.1376v1

  • October 17, 2011
  • 05:25 PM

Universe’s “Standard Candles” Are White Dwarf Mergers

by Charles Daney in Today's Science

Supernovae are spectacular but fairly rare events, at least on the human time scale. In our own galaxy, only 5 have been seen (necessarily by the naked eye, before telescopes were invented in 1608) in the last 2000 years. Since there have been none in our galaxy when any telescopes were available to study them, [...]... Read more »

Graur, O., Poznanski, D., Maoz, D., Yasuda, N., Totani, T., Fukugita, M., Filippenko, A., Foley, R., Silverman, J., Gal-Yam, A.... (2011) Supernovae in the Subaru Deep Field: the rate and delay-time distribution of Type Ia supernovae out to redshift 2. Monthly Notices of the Royal Astronomical Society, 417(2), 916-940. DOI: 10.1111/j.1365-2966.2011.19287.x  

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