arXiv subjects

Michael J. Longo

Publications and source records attributed to Michael J. Longo.

At least 19 recordsLinked to original sources

arXiv2022

Neutron size from high energy scattering data

Alvarado, Aranda, and Bonilla propose a sub-GeV U(1)R gauge boson model to explain the proton charge radius discrepancy. Their model assumes opposite sign U(1)R charge assignments for up and down quarks in the nucleon. I point out that might cause a difference between neutron and proton mass radii that contradicts existing p-p and n-p scattering data. Using existing neutron and proton scattering data I show that the neutron and proton mass radii are equal within about 2%. This constitutes a challenge to models that attempt to explain the discrepancy by modifying the quark couplings.

hep-ph↗

arXiv2014

Testing cosmic homogeneity and isotropy using galaxy correlations

Despite its fundamental importance in cosmology, there have been very few straight-forward tests of the cosmological principle. Such tests are especially timely because of the hemispherical asymmetry in the cosmic microwave background recently observed by the Planck collaboration. Most tests to date looked at the redshift dependence of cosmological parameters. These are subject to large systematic effects that require modeling and bias corrections. Unlike previous tests, the tests described here compare galaxy distributions in equal volumes at the same redshift z. This allows a straight-forward test and z-dependent biases are not a problem. Using ~10^6 galaxies from the SDSS DR7 survey, I show that re- gions of space separated by ~2 Gpc have the same average galaxy correlation radii, amplitudes, and number density to within approx. 5%, which is consistent with standard model expectations.

astro-ph.CO↗

arXiv2013

Testing Cosmic Homogeneity Using Galaxy Clusters

According to the cosmological principle, galaxy cluster sizes and cluster densities, when averaged over sufficiently large volumes of space, are expected to be constant everywhere, except for a slow variation with look-back time (redshift). Thus, average cluster sizes or correlation lengths provide a means of testing for homogeneity that is almost free of selection biases. Using ~10^6 galaxies from the SDSS DR7 survey, I show that regions of space separated by ~2 Gpc/h have the same average cluster size and density to 5 - 10 percent. I show that the average cluster size, averaged over many galaxies, remains constant to less than 10 percent from small redshifts out to redshifts of 0.25. The evolution of the cluster sizes with increasing redshift gives fair agreement when the same analysis is applied to the Millennium Simulation. However, the MS does not replicate the increase in cluster amplitudes with redshift seen in the SDSS data. This increase is shown to be caused by the changing composition of the SDSS sample with increasing redshifts. There is no evidence to support a model that attributes the SN Ia dimming to our happening to live in a large, nearly spherical void.

astro-ph.CO↗

arXiv2012

An Anomaly in the Angular Distribution of Quasar Magnitudes: Evidence for a Bubble Universe with a Mass ~10^21 M\odot

Quasars provide our farthest-reaching view of the Universe. The Sloan Survey now contains over 100,000 quasar candidates. A careful look at the angular distribution of quasar magnitudes shows a surprising intensity enhancement with a "bulls eye" pattern toward (alpha,delta) ~ (195°, 0°) for all wavelengths from UV through infrared. The angular pattern and size of the enhancement is very similar for all wavelengths, which is inconsistent with a Doppler shift due to a large peculiar velocity toward that direction. The shift is also too large to explain as a systematic error in the quasar magnitudes. The general features of the anomaly can be explained by the gravitational lensing of a massive bubble with Mlens ~ 10^21 M\odot, a lens radius ~350 Mpc, and with the lens subtending an angle of \pm15° on the sky. It is remarkable that the presence of such a massive bubble universe can explain not only the anomalies in the angular distribution of quasar intensities, but also anomalies in the distribution of luminous red galaxies, anomalies in the CMB, and bulk flow discrepancies, all of which appear in roughly the same direction.

astro-ph.CO↗

arXiv2012

More on the Evidence for a Bubble Universe with a Mass ~10^21 M_{\odot}

This is a very informal report that gives further details on the evidence for a bubble universe based on an anomaly in the angular distribution of quasar magnitudes that was presented in a short paper in arXiv:1202.4433. This report addresses some concerns of two reviewers. It is meant to be read in conjunction with 1202.4433. There is very little overlap between the two articles. This extended discussion is, by necessity, somewhat more technical in nature. I am grateful for the reviewers' comments that forced me to understand these issues more thoroughly.

astro-ph.CO↗

arXiv2011

An Anomaly in the Angular Distribution of Quasar Spectra

Quasars provide our farthest-reaching view of the Universe. The Sloan Survey now contains over 100,000 quasar candidates. A careful look at the angular distribution of quasar spectra shows a surprising "bullseye" pattern on the sky toward (RA, Dec) ~ (190°, 0°) for all wavelengths from UV through infrared. The angular distribution of the shift in the UV suggests a large peculiar velocity vp toward that direction. However, the size of the shift would indicate a vp ~0.2 c, which is two orders of magnitude larger than measures of our peculiar velocity from nearby galaxies and cosmic microwave background (CMB) measurements. The angular pattern and size of the shift is very similar for all wavelengths, which is inconsistent with a Doppler shift. The shift is also too large to explain as a systematic error in the quasar magnitudes. The anomaly appears to be a very large hotspot in the Universe. Its direction is close to that of the reported anomalies in the CMB, the so-called "axis of evil". The angular pattern of the shift and its redshift dependence are consistent with the existence of an expanding bubble universe in that direction, which could also explain the CMB anomalies.

astro-ph.CO↗

arXiv2011

Time Variation of GeV Gammas from the Galactic Center with a Period ~4 yr

An analysis of data from the Fermi LAT on long time scales shows strong evidence that the flux of GeV gammas from Sgr A* has a significant component that varies with a period \gtrsim4 yr. The flux varied about 15% over the 3-years of LAT observations. Orbits of over 100 stars in the innermost arcsecond of our Galaxy have been tracked around the massive black hole that resides there. Of these, the star S2 has the shortest orbital period 15.8 yr. This suggests that the GeV gamma flux is being modulated by accretion flow of matter accompanying the orbiting stars into the black hole.

astro-ph.GA↗

arXiv2011

Detection of a Dipole in the Handedness of Spiral Galaxies with Redshifts z ~ 0.04

A preference for spiral galaxies in one sector of the sky to be left-handed or right-handed spirals would indicate a parity violating asymmetry in the overall universe and a preferred axis. This study uses 15158 spiral galaxies with redshifts <0.085 from the Sloan Digital Sky Survey. An unbinned analysis for a dipole component that made no prior assumptions for the dipole axis gives a dipole asymmetry of -0.0408\pm0.011 with a probability of occurring by chance of 7.9 x 10-4. A similar asymmetry is seen in the Southern Galaxy spin catalog of Iye and Sugai. The axis of the dipole asymmetry lies at approx. (l, b) =(52°, 68.5°), roughly along that of our Galaxy and close to alignments observed in the WMAP cosmic microwave background distributions. The observed spin correlation extends out to separations ~210 Mpc/h, while spirals with separations < 20 Mpc/h have smaller spin correlations.

astro-ph.CO↗

arXiv2009

The Alignment of Galaxy Clusters: Conclusive Evidence for a Cosmic Axis

This paper has been withdrawn. I belatedly found that the alignment I saw in galaxy cluster axes was bogus. It turns out that it is due to a well-known effect called the "Fingers of God" that stretches out the redshifts of galaxies in a cluster due to their motion within the cluster. This would not cause an overall bias if the SDSS survey were complete, but there is no coverage toward right ascensions near 90 degrees or 270 deg. Thus the apparent alignment appears along 0 -- 180 deg.

astro-ph.CO↗

arXiv2009

Evidence for a Preferred Handedness of Spiral Galaxies

In this article I extend an earlier study of spiral galaxies in the Sloan Digital Sky Survey (SDSS) to investigate whether the universe has an overall handedness. A preference for spiral galaxies in one sector of the sky to be left-handed or right-handed spirals would indicate a parity-violating asymmetry in the overall universe and a preferred axis. The previous study used 2616 spiral galaxies with redshifts <0.04 and identified handedness. The new study uses 15158 with redshifts <0.085 and obtains very similar results to the first with a signal exceeding 5 sigma, corresponding to a probability ~2.5x10-7 for occurring by chance. A similar asymmetry is seen in the Southern Galaxy spin catalog of Iye and Sugai. The axis of the dipole asymmetry lies at approx. (l, b) =(52 d, 68.5 d), roughly along that of our Galaxy and close to alignments observed in the WMAP cosmic microwave background distributions.

astro-ph.CO↗

arXiv2009

Comparing Correlation Lengths of Red and Blue Galaxies: A New Standard Length for Testing Cosmic Isotropy

I introduce a simple empirical measure of average galaxy cluster sizes based on a comparison of the correlation lengths of red galaxies with blue that can provide a more accurate and bias-free measure of the average size and number density of galaxy clusters. Using 269,000 galaxies from the SDSS DR6 survey, I show that this 3D correlation length, averaged over many clusters, remains very nearly constant at L0= 4.797 +/- 0.024 Mpc/h from small redshifts out to redshifts of 0.5. This serves as a new measure of cosmic length scales and provides a means of testing the standard cosmological model that is almost free of selection biases. The unprecedented accuracy of the technique allows the possibility of sensitive searches for large-scale inhomogeneities. Applying the same technique to the Millennium Simulation galaxies I find very good agreement between it and the SDSS galaxies.

astro-ph.CO↗

arXiv2008

Does the Universe Have a Handedness?

In this article I extend an earlier study of spiral galaxies in the Sloan Digital Sky Survey (SDSS) to investigate whether the universe has an overall handedness. A preference for spiral galaxies in one sector of the sky to be left-handed or right-handed spirals would indicate a parity-violating asymmetry in the overall universe and a preferred axis. The previous study used 2616 spiral galaxies with redshifts <0.04 and identified handedness. The new study uses 15872 with redshifts <0.085 and obtains very similar results to the first with a signal exceeding 5 sigma, corresponding to a probability of 2.5x10-7 for occurring by chance. The axis of the dipole asymmetry lies at approx. (l, b) =(32d,69d), roughly along that of our Galaxy and close to the so-called "Axis of Evil".

astro-ph↗

arXiv2008

Correlation Lengths of Red and Blue Galaxies: A New Cosmic Ruler

A comparison of the correlation lengths of red galaxies with blue can provide a new cosmic ruler. Using 269,000 galaxies from the SDSS DR6 survey, I show that the 3D correlation length averaged over many clusters remains very nearly constant at Lo=4.797+/-0.024 Mpc/h from small redshifts out to redshifts of 0.5. This serves as a new measure of cosmic length scales as well as a means of testing the standard cosmological model that is almost free of selection biases. The cluster number density also appears to remain constant over this redshift range.

astro-ph↗

arXiv2007

The Axis of Opportunity: The Large-Scale Correlation of Elliptical Galaxies

This paper has been withdrawn by the author due to the discovery of a serious bias resulting from the systematic dimming of galaxies with larger ellipticities away from the North Galactic Pole. Thus the conclusion that there is a special axis along which the elliptical galaxies tend to be aligned is incorrect.

astro-ph↗

arXiv2007

Does the Universe Have a Handedness?

In this article I study the distribution of spiral galaxies in the Sloan Digital Sky Survey (SDSS) to investigate whether the universe has an overall handedness. A preference for spiral galaxies in one sector of the sky to be left-handed or right-handed spirals would indicate a preferred handedness. The SDSS data show a strong signal for such an asymmetry with a probability of occurring by chance ~3.0 x 10-4. The asymmetry axis is at (RA,Dec) ~(202d,25d) with an uncertainty ~15d. The axis appears to be correlated with that of the quadrupole and octopole moments in the WMAP microwave sky survey, an unlikely alignment that has been dubbed "the axis of evil". Our Galaxy is aligned with its spin axis within 8.4d of this spiral axis.

astro-ph↗

arXiv2007

Evidence for a Preferred Handedness of Spiral Galaxies

In this article I study the distribution of spiral galaxies in the Sloan Digital Sky Survey (SDSS) to investigate whether the universe has an overall handedness. A preference for spiral galaxies in one sector of the sky to be left-handed or right-handed spirals would indicate a preferred handedness. The SDSS data show a strong signal for such an asymmetry with a probability <0.2%. The asymmetry axis is at (RA,dec) ~(202 deg,25 deg) with an uncertainty ~15 deg. The axis appears to be correlated with that of the quadrupole and octopole moments in the WMAP microwave sky survey, an unlikely alignment that has been dubbed "the axis of evil". Our Galaxy is aligned with its spin axis along the same direction as the majority of the spirals.

astro-ph↗

arXiv2007

Is the Cosmic "Axis of Evil" due to a Large-Scale Magnetic Field

I propose a mechanism that would explain the near alignment of the low order multipoles of the cosmic microwave background (CMB). This mechanism supposes a large-scale cosmic magnetic field that tends to align the cyclotron orbit axes of electrons in hot plasmas along the same direction. Inverse Compton scattering of the CMB photons then imprints this pattern on the CMB, thus causing the low- multipoles to be generally aligned. The spins of the majority of spiral galaxies and that of our own Galaxy appear to be aligned along the cosmic magnetic field.

astro-ph↗

arXiv2003

Charge Conjugation and Parity Violations as a Signature for Black Hole Formation or Other New Physics in Hadron Collisions

I point out that there have been essentially no tests of discrete symmetries, such as baryon number, charge conjugation (C), parity (P), strangeness, isospin, etc., in high energy, high pT hadron collisions. If, for example, black hole formation (BHF) occurs, we might expect large violations of C, P, >... I propose new tests of C and P that can be adapted to a variety of new physics scenarios by selecting events with appropriate topologies. Large effects, such as ~10% longitudinal polarizations of outgoing particles, might be expected in events involving BHF. These tests may provide more sensitive searches for new physics at existing colliders.

hep-ex↗