Profile

Cover photo
Jay Cross
Works at Oracle Corporation
Attended Rensselaer Polytechnic Institute
Lived in Berlin, MA
17,515 followers|771,092 views
AboutPostsPhotosYouTube

Stream

 
Astronomy Papers That Caught My Eye In Today's arXiv

These are the Friday papers that caught Jerry Jensen 's eye.

Another slow day - 35 papers - It must be spring break; the shore birds are into their annual migratory run: Self lensing binaries, gamma ray guns and a gamma ray model meets reality.



KOI-3278: A Self-Lensing Binary Star System http://arxiv.org/abs/1404.4379 I think someone already started a thread on this topic, but it is worth mentioning here: A member of a binary pair the appears to brighten when it is in opposition.

Laboratory gamma-ray pulsar http://arxiv.org/abs/1404.4615 If this works, everybody will want one.

Spectral evolution in gamma-ray bursts: predictions of the internal shock model and comparison to observations http://arxiv.org/abs/1404.4577 As long as we are on gamma rays, it would be fun to come up with a working model. This one does appear to work - are we there yet?
1
Add a comment...
 
Astronomy Papers That Caught My Eye In Today's arXiv

These are the Thursday papers that caught Jerry Jensen 's eye.

Only thirty-three papers today, including cross listings, and the supernova community remains quiet: Mond, galactic boundaries, gamma ray origins, galactic stellar dynamics.


A census of the expected properties of classical Milky Way dwarfs in Milgromian dynamics http://arxiv.org/abs/1404.4049 "Milgromian Dynamics" are a simple calculation that match many 'dark matter' observations; but they imply a departure from Newtonian and relativistic gravitational theory. Dwarf galaxies are hot beds for this research, because the dynamics predict very different behavior from 'classical dark matter' This paper applies Milgromian solutions to five local clusters and finds that the 'Milgromian' model works well for two out of the five. So what about the other three? 'Classical' dark matter does not come even close to predicting the way these two dwarfs behave; so it leaves the question wide open.

As a side note, there have been attempts to weave Milgromian dynamics into a relativist version, but these have met with wide skepticism - the terms introduced to GR are unwieldy.

Where do galaxies end? A study of hydrodynamic-simulation galaxies and their integrated properties http://arxiv.org/abs/1404.4053 Well, who would have thought that something as straightforward as the physical size of galaxies could be so complex; but we have learned their are massive clouds of gases associated with galaxies that make any definition of galaxy size problematic.

Systematic search for high-energy gamma-ray emission from bow shocks of runaway stars http://arxiv.org/abs/1404.4059 What could be more fun that to discover that gamma rays are the bow shock waves of runaway stars. ...apparently not. Fun theory, though.

Bending and Breathing Modes of the Galactic Disk http://arxiv.org/abs/1404.4069 Rouge stars apparently effect galaxies the same way little moons pluck the rings of Saturn...which coincidentally are talked about here: The ballistic transport instability in Saturn's rings III: numerical simulations http://arxiv.org/abs/1404.4247
1
Add a comment...
 
Astronomy Papers That Caught My Eye In Today's arXiv

There are 52 papers today (Wednesday).

Topics: Superbubble N70, eLISA Expectations, Brown Dwarfs

Superbubble N70 http://arxiv.org/abs/1404.3823 N70 (LHA 120-N-70) is a spherical object in the LMC with a diameter of about 350 light years. The team behind this paper looked at it in x-rays, optical, and radio (both new and archival observations), in an effort to understand how this object formed and what it is doing now. The conclude that it was not formed from a solo supernova event, but rather several events at roughly the same time from the same star-forming region. Other details about the origin and evolution are discussed.

eLISA Expectations http://arxiv.org/abs/1404.3848 Te ESA's version of LISA (eLISA) is probably still a decade away from being launched, so while the team behind it makes the case for funding, the question is what will it be able to detect? The premise is that it should be good at detecting close-orbiting double compact objects. How many of these are close enough to be observed? Not many. For black holes (BH), neutron stars (NS), and white dwarfs (WD) orbiting with a period under 3 hours, our galaxy probably has 6 BH-BH, 3 BH-NS, 16 NS-NS, and 132 WD-NS pairs, and the WD-NS pairs might be fairly difficult for eLISA to tell from noise. This handful of signals will be very useful, but no one should expect a rich collection of sources from this early use of this new technology.

Brown Dwarfs http://arxiv.org/abs/1404.3970 & http://arxiv.org/abs/1404.3896 There are maybe a hundred brown dwarfs which have been observed well enough to be able to use them to construct models of low-mass star behavior. One of these papers looks at the impact that Gaia will have on identifying thousands of nearby brown dwarfs, and the other looks at some recent discoveries of brown dwarfs in the Hyades and Coma Berenices. Both of these will contribute to better determining more precisely the mass/metalicity relationships for determining when an object fuses Hydrogen and when it doesn't.
1
Add a comment...

Jay Cross

Shared publicly  - 
 
Astronomy Papers That Caught My Eye In Today's arXiv

There are 52 papers today (Wednesday).

Topics: Superbubble N70, eLISA Expectations, Brown Dwarfs

Superbubble N70 http://arxiv.org/abs/1404.3823 N70 (LHA 120-N-70) is a spherical object in the LMC with a diameter of about 350 light years. The team behind this paper looked at it in x-rays, optical, and radio (both new and archival observations), in an effort to understand how this object formed and what it is doing now. The conclude that it was not formed from a solo supernova event, but rather several events at roughly the same time from the same star-forming region. Other details about the origin and evolution are discussed.

eLISA Expectations http://arxiv.org/abs/1404.3848 Te ESA's version of LISA (eLISA) is probably still a decade away from being launched, so while the team behind it makes the case for funding, the question is what will it be able to detect? The premise is that it should be good at detecting close-orbiting double compact objects. How many of these are close enough to be observed? Not many. For black holes (BH), neutron stars (NS), and white dwarfs (WD) orbiting with a period under 3 hours, our galaxy probably has 6 BH-BH, 3 BH-NS, 16 NS-NS, and 132 WD-NS pairs, and the WD-NS pairs might be fairly difficult for eLISA to tell from noise. This handful of signals will be very useful, but no one should expect a rich collection of sources from this early use of this new technology.

Brown Dwarfs http://arxiv.org/abs/1404.3970 & http://arxiv.org/abs/1404.3896 There are maybe a hundred brown dwarfs which have been observed well enough to be able to use them to construct models of low-mass star behavior. One of these papers looks at the impact that Gaia will have on identifying thousands of nearby brown dwarfs, and the other looks at some recent discoveries of brown dwarfs in the Hyades and Coma Berenices. Both of these will contribute to better determining more precisely the mass/metalicity relationships for determining when an object fuses Hydrogen and when it doesn't.
7
1
Phillip Ressler's profile photo
Add a comment...

Jay Cross

Shared publicly  - 
 
Astronomy Papers That Caught My Eye In Today's arXiv

There are 73 papers today (Tuesday). Many more about BICEP2.

Topics: Brown Dwarf Weather, VHE Gamma Source, SFR in LBGs

Brown Dwarf Weather http://arxiv.org/abs/1404.3247 Brown dwarfs radiate strongly in the infrared, and the particular wavelengths depend on how high up the clouds are. This team spent time studying 62 dwarfs from L4 down to T9, and found a subset of them have variable amounts of cloud cover. The most variable ones were near the L-T transition.

VHE Gamma Source http://arxiv.org/abs/1404.3583 Gamma Rays above 100 GeV aren't all that common, but they do get detected now and again... but from where? They are much too high energy to be connected to nuclear transitions. The Fermi-LAT has detected them from the BL Lac object RBS 0970, but strangely does not find them correlated to peaks in lower energy photons. This object is one to watch more closely going forward.

SFR in LBGs http://arxiv.org/abs/1404.3624 Sorry for the obtuse short title. Star formation Rate in Lyman Break Galaxies. This study looks at faint LBGs at about z=4 to look at the extinction levels that hide the formation of stars in those galaxies so that we can get a better sense of how rapidly stars formed in different types of galaxies in the early days of galaxy formation.
5
Add a comment...

Jay Cross

Shared publicly  - 
 
Astronomy Papers That Caught My Eye In Today's arXiv

There are 41 papers today (Monday). 

Topics: Massive WIMPs?, CMB Dipole, eLISA etc.

*Massive WIMPs?, * http://arxiv.org/abs/1404.2932 There have been 28 very energetic neutrinos detected by IceCube so far. Seven of them came from roughly the direction of the Milky Way's center. Five more came from the direction of Milky Way satellite galaxies. This paper looks at the possibility that the source is from PeV mass Dark Matter particles (a million times the mass of a Proton). 

CMB Dipole http://arxiv.org/abs/1404.2936 One curiosity of the WMAP and Planck data is that the low multipoles (dipole, quadrupole, octopole) have an unexpected alignment. Is this a consequence of foreground badly subtracted or some other systematic issue? This paper revisits this curiosity with some new methods and finds the alignment is still there.

eLISA etc. http://arxiv.org/abs/1404.3136 There are (so far) three general scales where plans are in the works to try and detect gravitational waves, including 1. LIGO and Virgo here on the ground, which are looking for short wavelength events, 2. Pulsar Timing Arrays which look for waves with lengths of tens or hundreds of light years, and 3. Space-based probes, such as LISA, eLISA, and LISA-pathfinder (this last one will be launched next year). This paper looks at the prospects for what this missions will look for.
7
Add a comment...
In his circles
3,307 people
Have him in circles
17,515 people
Jari Sundell's profile photo
Sean Veale's profile photo
John Geiger's profile photo

Jay Cross

Shared publicly  - 
 
Astronomy Papers That Caught My Eye In Today's arXiv

These are the Friday papers that caught Jerry Jensen 's eye.

Another slow day - 35 papers - It must be spring break; the shore birds are into their annual migratory run: Self lensing binaries, gamma ray guns and a gamma ray model meets reality.



KOI-3278: A Self-Lensing Binary Star System http://arxiv.org/abs/1404.4379 I think someone already started a thread on this topic, but it is worth mentioning here: A member of a binary pair the appears to brighten when it is in opposition.

Laboratory gamma-ray pulsar http://arxiv.org/abs/1404.4615 If this works, everybody will want one.

Spectral evolution in gamma-ray bursts: predictions of the internal shock model and comparison to observations http://arxiv.org/abs/1404.4577 As long as we are on gamma rays, it would be fun to come up with a working model. This one does appear to work - are we there yet?
3
Add a comment...
 
Astronomy Papers That Caught My Eye In Today's arXiv

These are the Thursday papers that caught Jerry Jensen 's eye.

Only thirty-three papers today, including cross listings, and the supernova community remains quiet: Mond, galactic boundaries, gamma ray origins, galactic stellar dynamics.


A census of the expected properties of classical Milky Way dwarfs in Milgromian dynamics http://arxiv.org/abs/1404.4049 "Milgromian Dynamics" are a simple calculation that match many 'dark matter' observations; but they imply a departure from Newtonian and relativistic gravitational theory. Dwarf galaxies are hot beds for this research, because the dynamics predict very different behavior from 'classical dark matter' This paper applies Milgromian solutions to five local clusters and finds that the 'Milgromian' model works well for two out of the five. So what about the other three? 'Classical' dark matter does not come even close to predicting the way these two dwarfs behave; so it leaves the question wide open.

As a side note, there have been attempts to weave Milgromian dynamics into a relativist version, but these have met with wide skepticism - the terms introduced to GR are unwieldy.

Where do galaxies end? A study of hydrodynamic-simulation galaxies and their integrated properties http://arxiv.org/abs/1404.4053 Well, who would have thought that something as straightforward as the physical size of galaxies could be so complex; but we have learned their are massive clouds of gases associated with galaxies that make any definition of galaxy size problematic.

Systematic search for high-energy gamma-ray emission from bow shocks of runaway stars http://arxiv.org/abs/1404.4059 What could be more fun that to discover that gamma rays are the bow shock waves of runaway stars. ...apparently not. Fun theory, though.

Bending and Breathing Modes of the Galactic Disk http://arxiv.org/abs/1404.4069 Rouge stars apparently effect galaxies the same way little moons pluck the rings of Saturn...which coincidentally are talked about here: The ballistic transport instability in Saturn's rings III: numerical simulations http://arxiv.org/abs/1404.4247
6
1
Jay Cross's profile photoR K's profile photo
5 comments
R K
 
Thanks for responding. - My book has become a celebration for everyone to finally understand cosmology and astronomy for the first time.
Add a comment...

Jay Cross

Astronomy  - 
 
Astronomy Papers That Caught My Eye In Today's arXiv

There are 73 papers today (Tuesday). Many more about BICEP2.

Topics: Brown Dwarf Weather, VHE Gamma Source, SFR in LBGs

Brown Dwarf Weather http://arxiv.org/abs/1404.3247 Brown dwarfs radiate strongly in the infrared, and the particular wavelengths depend on how high up the clouds are. This team spent time studying 62 dwarfs from L4 down to T9, and found a subset of them have variable amounts of cloud cover. The most variable ones were near the L-T transition.

VHE Gamma Source http://arxiv.org/abs/1404.3583 Gamma Rays above 100 GeV aren't all that common, but they do get detected now and again... but from where? They are much too high energy to be connected to nuclear transitions. The Fermi-LAT has detected them from the BL Lac object RBS 0970, but strangely does not find them correlated to peaks in lower energy photons. This object is one to watch more closely going forward.

SFR in LBGs http://arxiv.org/abs/1404.3624 Sorry for the obtuse short title. Star formation Rate in Lyman Break Galaxies. This study looks at faint LBGs at about z=4 to look at the extinction levels that hide the formation of stars in those galaxies so that we can get a better sense of how rapidly stars formed in different types of galaxies in the early days of galaxy formation.
1
Add a comment...
 
Astronomy Papers That Caught My Eye In Today's arXiv

There are 41 papers today (Monday). 

Topics: Massive WIMPs?, CMB Dipole, eLISA etc.

*Massive WIMPs?, * http://arxiv.org/abs/1404.2932 There have been 28 very energetic neutrinos detected by IceCube so far. Seven of them came from roughly the direction of the Milky Way's center. Five more came from the direction of Milky Way satellite galaxies. This paper looks at the possibility that the source is from PeV mass Dark Matter particles (a million times the mass of a Proton). 

CMB Dipole http://arxiv.org/abs/1404.2936 One curiosity of the WMAP and Planck data is that the low multipoles (dipole, quadrupole, octopole) have an unexpected alignment. Is this a consequence of foreground badly subtracted or some other systematic issue? This paper revisits this curiosity with some new methods and finds the alignment is still there.

eLISA etc. http://arxiv.org/abs/1404.3136 There are (so far) three general scales where plans are in the works to try and detect gravitational waves, including 1. LIGO and Virgo here on the ground, which are looking for short wavelength events, 2. Pulsar Timing Arrays which look for waves with lengths of tens or hundreds of light years, and 3. Space-based probes, such as LISA, eLISA, and LISA-pathfinder (this last one will be launched next year). This paper looks at the prospects for what this missions will look for.
1
Add a comment...
People
In his circles
3,307 people
Have him in circles
17,515 people
Jari Sundell's profile photo
Sean Veale's profile photo
John Geiger's profile photo
Work
Occupation
I'm a technical trainer for enterprise software systems
Employment
  • Oracle Corporation
    Technical Trainer, 2011 - present
  • Art Technology Group
    Technical Trainer, 2007 - 2011
  • Sterling Commerce
    Technical Trainer, 2004 - 2007
Places
Map of the places this user has livedMap of the places this user has livedMap of the places this user has lived
Previously
Berlin, MA - Chelmsford, MA - Littleton, MA - Arlington, MA - Framingham, MA - Waltham, MA - Secaucus, NJ - New York, NY - Austin, TX - Spring Valley, NY - Katonah, NY - Troy, NY - Watertown, CT - Hebron, CT - Lincoln, RI -
Links
YouTube
Contributor to
Story
Tagline
One of a long line of Renaissance Men
Introduction
Publicly, I post a lot of astronomy stuff. I also post about politics, my life, the future, and links to my photo journal to people in specific circles.

Bragging rights
It seems impolite for me to say all the great stuff I've been lucky enough to do.
Education
  • Rensselaer Polytechnic Institute
    Physics, 1973 - 1979
Basic Information
Gender
Male
Other names
I've gone by "antoniseb" on the web, and in the Society for Creative Anachronism, I'm called "Anton of Winteroak"