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Radio Burst Flags Celestial Oddity

An odd radio burst that seems to signal a previously undiscovered astrophysical phenomenon is now on the scene. Culled out of archival data gathered from the Parkes radio telescope in Australia, the burst may signal something exotic indeed, the last stages of the evaporation of a black hole. Another candidate: A collision between two neutron stars.

Burst location

And while the data in question come from a survey that included 480 hours of observation of the Magellanic Clouds, some 200,000 light years from Earth, the phenomenon they’ve uncovered is far more distant. Drawing the attention of astronomers was the fact that no radio burst yet found shows the same characteristics. Despite its strength, the signal lasted less than five milliseconds. Dispersion effects caused by its passage through ionized gas in deep space caused higher frequencies to arrive at the telescope before lower frequencies.

Image: Visible-light (negative greyscale) and radio (contours) image of Small Magellanic Cloud and area where burst originated. CREDIT: Lorimer et al., NRAO/AUI/NSF.

Dispersion, it turns out, is a useful indicator, in this case helping to determine the distance of the event from Earth, about three billion light years. Maura McLaughlin (West Virginia University and NRAO) notes another potential benefit of unlocking the signal’s secret:

“We’re actively looking for more of these powerful, short bursts, in other archival pulsar surveys, and hope to resolve the mystery of their origin. In addition, if we can associate these events with galaxies of known distance, the radio dispersion we measure can be used as a powerful new way to determine the amount of material in intergalactic space.”

It’s an intriguing find, enough so that Matthew Bailes (Swinburne University, Australia) could say, “This burst represents an entirely new astronomical phenomenon.” Needless to say, follow-up studies are called for. They’ll involve a search for short, powerful bursts like this one in other archival survey data. Beyond that, the next generation of radio telescopes, more sensitive than today’s equipment, should be able to detect similar phenomena.

The paper is Lorimer, Bailes et al., “A Bright Millisecond Radio Burst of Extragalactic Origin,” ScienceXpress September 27, 2007 (abstract).

Comments on this entry are closed.

  • anon September 27, 2007, 18:10


  • ljk January 17, 2008, 11:47

    A Bright Millisecond Radio Burst of Extragalactic Origin

    D. R. Lorimer,1,2* M. Bailes,3 M. A. McLaughlin,1,2 D. J. Narkevic,1 F. Crawford4

    Pulsar surveys offer a rare opportunity to monitor the radio sky for impulsive burst-like events with millisecond durations. We analyzed archival survey data and found a 30-jansky dispersed burst, less than 5 milliseconds in duration, located 3° from the Small Magellanic Cloud. The burst properties argue against a physical association with our Galaxy or the Small Magellanic Cloud. Current models for the free electron content in the universe imply that the burst is less than 1 gigaparsec distant. No further bursts were seen in 90 hours of additional observations, which implies that it was a singular event such as a supernova or coalescence of relativistic objects. Hundreds of similar events could occur every day and, if detected, could serve as cosmological probes.

    1 Department of Physics, West Virginia University, Morgantown, WV 26506, USA.
    2 National Radio Astronomy Observatory, Green Bank, WV 24944, USA.
    3 Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia.
    4 Department of Physics and Astronomy, Franklin and Marshall College, Lancaster, PA 17604, USA.

    * To whom correspondence should be addressed. E-mail: duncan.lorimer@mail.wvu.edu

    Transient radio sources are difficult to detect, but they can potentially provide insights into a wide variety of astrophysical phenomena (1). Of particular interest is the detection of short radio bursts, no more than a few milliseconds in duration, that may be produced by exotic events at cosmological distances, such as merging neutron stars (2) or evaporating black holes (3). Pulsar surveys are currently among the few records of the sky with good sensitivity to radio bursts, and they have the necessary temporal and spectral resolution required to unambiguously discriminate between short-duration astrophysical bursts and terrestrial interference. Indeed, they have recently been successfully mined to detect a new galactic population of transients associated with rotating neutron stars (4). The burst we report here, however, has a substantially higher inferred energy output than this class and has not been observed to repeat. This burst therefore represents an entirely new phenomenon.

    The burst was discovered during a search of archival data from a 1.4-GHz survey of the Magellanic Clouds (5) using the multibeam receiver on the 64-m Parkes Radio Telescope (6) in Australia. The survey consisted of 209 telescope pointings, each lasting 2.3 hours. During each pointing, the multibeam receiver collected independent signals from 13 different positions (beams) on the sky. The data from each beam were one-bit sampled every millisecond over 96 frequency channels spanning a band 288 MHz wide.

    Radio signals from all celestial sources propagate through a cold ionized plasma of free electrons before reaching the telescope. The plasma, which exists within our Galaxy and in extragalactic space, has a refractive index that depends on frequency. As a result, any radio signal of astrophysical origin should exhibit a quadratic shift in its arrival time as a function of frequency, with the only unknown being the integrated column density of free electrons along the line of sight, known as the dispersion measure (DM). Full details of the data reduction procedure to account for this effect, and to search for individual dispersed bursts, are given in the supporting online material. In brief, for each beam, the effects of interstellar dispersion were minimized for 183 trial DMs in the range 0 to 500 cm–3 pc. The data were then searched for individual pulses with signal-to-noise (S/N) ratios greater than 4 with the use of a matched filtering technique (7) optimized for pulse widths in the range 1 to 1000 ms. The burst was detected in data taken on 24 August 2001 with DM = 375 cm–3 pc contemporaneously in three neighboring beams (Fig. 1) and was located ~3° south of the center of the Small Magellanic Cloud (SMC).

    Figure 1 Fig. 1. Multiwavelength image of the field surrounding the burst. The gray scale and contours respectively show H{alpha} and H I emission associated with the SMC (32, 33). Crosses mark the positions of the five known radio pulsars in the SMC and are annotated with their names and DMs in parentheses in units of cm–3 pc. The open circles show the positions of each of the 13 beams in the survey pointing of diameter equal to the half-power width. The strongest detection saturated the single-bit digitizers in the data acquisition system, indicating that its S/N >> 23. Its location is marked with a square at right ascension 01h 18m 06s and declination –75° 12′ 19” (J2000 coordinates). The other two detections (with S/Ns of 14 and 21) are marked with smaller circles. The saturation makes the true position difficult to localize accurately. The positional uncertainty is nominally ±7′ on the basis of the half-power width of the multibeam system. However, the true position is probably slightly (a few arcmin) northwest of this position, given the nondetection of the burst in the other beams. [View Larger Version of this Image (47K GIF file)]

    The pulse exhibited the characteristic quadratic delay as a function of radio frequency (Fig. 2) expected from dispersion by a cold ionized plasma along the line of sight (8). Also evident was a significant evolution of pulse width across the observing frequency band. The behavior we observed, where the pulse width W scales with frequency f as W {propto} f –4.8 ± 0.4, is consistent with pulse-width evolution due to interstellar scattering with a Kolmogorov power law [W {propto} f –4 (9)]. The filter-bank system has finite frequency and time resolution, which effectively sets an upper limit to the intrinsic pulse width Wint = 5 ms. We represent this below by the parameter W5 = Wint/5 ms. Note that it is entirely possible that the intrinsic width could be much smaller than observed (i.e., W5 < 10 in the analysis of data from almost 3000 separate positions. Sources with flux densities greater than ~1 Jy are typically detected in multiple receivers of the multibeam system. Although this is true for both terrestrial and astrophysical sources, the telescope had an elevation of ~ 60° at the time of the observation, making it virtually impossible for ground-based transmitters to be responsible for a source that was only detected in three adjacent beams of the pointing.

    We have extensively searched for subsequent radio pulses from this enigmatic source. Including the original detection, there were a total of 27 beams in the survey data that pointed within 30 arcmin of the nominal burst position. These observations, which totaled 50 hours, were carried out between 19 June and 24 July 2001 and showed no significant bursts. In April 2007 we carried out 40 hours of follow-up observations with the Parkes telescope at 1.4 GHz with similar sensitivity to the original observation. No bursts were found in a search over the DM range 0 to 500 cm–3 pc. These dedicated follow-up observations implied that the event rate must be less than 0.025 hour–1 for bursts with S/N > 6 (i.e., a 1.4-GHz peak flux density greater than 300 mJy). The data were also searched for periodic radio signals using standard techniques (8) with null results.

    The galactic latitude (b = –41.8°) and high DM of the burst make it highly improbable for the source to be located within our Galaxy. The most recent model of the galactic distribution of free electrons (10) predicts a DM contribution of only 25 cm–3 pc for this line of sight. In fact, of more than 1700 pulsars currently known, none of the 730 with |b| > 3.5° has DM > 375 cm–3 pc. The DM is also far higher than any of the 18 known radio pulsars in the Magellanic Clouds (5), the largest of which is for PSR J0131-7310 in the SMC with DM = 205 cm–3 pc. The other four known radio pulsars in the SMC have DMs of 70, 76, 105, and 125 cm–3 pc. The high DM of PSR J0131-7310 is attributed (5) to its location in an H II region (Fig. 1). We have examined archival survey data to look for ionized structure such as H{alpha} filaments or H II regions that could similarly explain the anomalously large DM of the burst. No such features are apparent. The source lies 3° south from the center of the SMC, placing it outside all known contours of radio, infrared, optical, and high-energy emission from the SMC. This and the high DM strongly suggest that the source is well beyond the SMC, which lies 61 ± 3 kpc away (11).

    No published gamma-ray burst or supernova explosion is known at this epoch or position, and no significant gamma-ray events were detected by the Third Interplanetary Network (12, 13) around the time of the radio burst. The Principal Galaxy Catalog [PGC (14)] was searched for potential hosts to the burst source. The nearest candidate (PGC 246336) is located 5 arcmin south of the nominal burst position, but the nondetection of the burst in the beam south of the brightest detection appears to rule out an association. If the putative host galaxy were similar in type to the Milky Way, the nondetection in the PGC (limiting B magnitude of 18) implies a rough lower limit of ~600 Mpc on the distance to the source.

    We can place an upper bound on the likely distance to the burst from our DM measurement. Assuming a homogeneous intergalactic medium in which all baryons are fully ionized, the intergalactic DM is expected (15, 16) to scale with redshift, z, as DM ~ 1200 z cm–3 pc for z ≤ 2. Subtracting the expected contribution to the DM from our Galaxy, we infer z = 0.3, which corresponds to a distance of ~1 Gpc. This is likely an upper limit, because a host galaxy and local environment could both contribute to the observed DM. Using the electron density model for our Galaxy (10) as a guide, we estimate that there is a 25% probability that the DM contribution from a putative host galaxy is >100 cm–3 pc and hence z < 0.2. Obviously, the more distant the source, the more powerful it becomes as a potential cosmological probe. The sole event, however, offers little hope of a definitive answer at this stage. To enable some indicative calculations about potential source luminosity and event rates, we adopt a distance of 500 Mpc. This corresponds to z ~0.12 and a host galaxy DM of 200 cm–3 pc. In recognition of the considerable distance uncertainty, we parameterize this as D500 = D/500 Mpc. If this source is well beyond the local group, it would provide the first definitive limit on the ionized column density of the intracluster medium, which is currently poorly constrained (17).

    What is the nature of the burst source? From the observed burst duration, flux density, and distance, we estimate the brightness temperature and energy released to be ~1034 (D500/W5)2 K and ~1033W5D5002 J, respectively. These values, and light travel-time arguments that limit the source size to <1500 km for a nonrelativistic source, imply a coherent emission process from a compact region. Relativistic sources with bulk velocity v are larger by a factor of either {Gamma} (for a steady jet model) or {Gamma}2 (for an impulsive blast model), where the Lorentz factor {Gamma} =[1 – (v2/c2)]–1/2 and c is the speed of light.

    The only two currently known radio sources capable of producing such bursts are the rotating radio transients (RRATs), thought to be produced by intermittent pulsars (4), and giant pulses from either a millisecond pulsar or a young energetic pulsar. A typical pulse from a RRAT would only be detectable out to ~ 6 kpc with our observing system. Even some of the brightest giant pulses from the Crab pulsar, with peak luminosities of 4 kJy kpc2 (18), would be observable out to ~100 kpc with the same system. In addition, both the RRAT bursts and giant pulses follow power-law distributions of pulse energies. The strength of this burst, which is some two orders of magnitude above our detection threshold, should have easily led to many events at lower pulse energies, either in the original survey data or follow-up observations. Hence, it appears to represent an entirely new class of radio source.

    To estimate the rate of similar events in the radio sky, we note that the survey we have analyzed was sensitive to bursts of this intensity over an area of about 5 square degrees (i.e., 1/8250 of the entire sky) at any given time over a 20-day period. Assuming the bursts to be distributed isotropically over the sky, we infer a nominal rate of 8250/20 {approx} 400 similar events per day. Given our observing system parameters, we estimate that a 1033-Jy radio burst would be detectable out to z ~ 0.3, or a distance of 1 Gpc. The corresponding cosmological rate for bursts of this energy is therefore ~90 day–1 Gpc–3. Although considerably uncertain, this is somewhat higher than the corresponding estimates of other astrophysical sources, such as binary neutron star inspirals [~3 day–1 Gpc–3 (19)] and gamma-ray bursts [~4 day–1 Gpc–3 (20)], but well below the rate of core-collapse supernovae [~1000 day–1 Gpc–3 (21)]. Although the implied rate is compatible with gamma-ray bursts, the brightness temperature and radio frequency we observed for this burst are higher than currently discussed mechanisms or limitations for the observation of prompt radio emission from these sources (22).

    Regardless of the physical origin of this burst, we predict that existing data from other pulsar surveys with the Parkes multibeam system (23–26) should contain several similar bursts. Their discovery would permit a more reliable estimate of the overall event rate. The only other published survey for radio transients on this time scale (27) did not have sufficient sensitivity to detect similar events at the rate predicted here. At lower frequencies (~400 MHz) where many pulsar surveys were conducted, although the steep spectral index of the source implies an even higher flux density, the predicted scattering time (~2 s) would make the bursts difficult to detect over the radiometer noise. At frequencies near 100 MHz, where low-frequency arrays currently under construction will operate (28), the predicted scattering time would be on the order of several minutes, and hence would be undetectable.

    Perhaps the most intriguing feature of this burst is its 30-Jy strength. Although this has allowed us to make a convincing case for its extraterrestrial nature, the fact that it is more than 100 times our detection threshold makes its uniqueness puzzling. Often, astronomical sources have a flux distribution that would naturally lead to many burst detections of lower significance; such events are not observed in our data. If, on the other hand, this burst was a rare standard candle, more distant sources would have such large DMs that they would be both red-shifted to lower radio frequencies and outside our attempted dispersion trials. If redshifts of their host galaxies are measurable, the potential of a population of radio bursts at cosmological distances to probe the ionized intergalactic medium (29) is very exciting, especially given the construction of wide-field instruments (30) in preparation for the Square Kilometre Array (31).

    References and Notes

    * 1. J. M. Cordes, T. J. W. Lazio, M. A. McLaughlin, N. Astron. Rev. 48, 1459 (2004). [CrossRef]
    * 2. B. M. S. Hansen, M. Lyutikov, Mon. Not. R. Astron. Soc. 322, 695 (2001). [CrossRef] [ISI]
    * 3. M. J. Rees, Nature 266, 333 (1977). [CrossRef]
    * 4. M. A. McLaughlin et al., Nature 439, 817 (2006). [CrossRef] [Medline]
    * 5. R. N. Manchester, G. Fan, A. G. Lyne, V. M. Kaspi, F. Crawford, Astrophys. J. 649, 235 (2006). [CrossRef] [ISI]
    * 6. L. Staveley-Smith et al., Proc. Astron. Soc. Pac. 13, 243 (1996).
    * 7. J. M. Cordes, M. A. McLaughlin, Astrophys. J. 596, 1142 (2003). [CrossRef] [ISI]
    * 8. D. R. Lorimer, M. Kramer, Handbook of Pulsar Astronomy (Cambridge Univ. Press, Cambridge, 2005).
    * 9. L. C. Lee, J. R. Jokipii, Astrophys. J. 206, 735 (1976). [CrossRef] [ISI]
    * 10. J. M. Cordes, T. J. W. Lazio, http://arxiv.org/abs/astro-ph/0207156 (2002).
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    * 12. K. Hurley et al., Astrophys. J. Suppl. Ser. 164, 124 (2006). [CrossRef] [ISI]
    * 13. K. Hurley, personal communication.
    * 14. G. Paturel et al., Astron. Astrophys. 412, 45 (2003). [CrossRef] [ISI]
    * 15. K. Ioka, Astrophys. J. 598, L79 (2003). [CrossRef] [ISI]
    * 16. S. Inoue, Mon. Not. R. Astron. Soc. 348, 999 (2004). [CrossRef] [ISI]
    * 17. P. R. Maloney, J. Bland-Hawthorn, Astrophys. J. 522, L81 (1999). [CrossRef] [ISI]
    * 18. J. M. Cordes, N. D. R. Bhat, T. H. Hankins, M. A. McLaughlin, J. Kern, Astrophys. J. 612, 375 (2004). [CrossRef] [ISI]
    * 19. V. Kalogera et al., Astrophys. J. 601, L179 (2004). [CrossRef] [ISI]
    * 20. D. Guetta, M. Della Valle, Astrophys. J. 657, L73 (2007). [CrossRef] [ISI]
    * 21. P. Madau, M. Della Valle, N. Panagia, Mon. Not. R. Astron. Soc. 297, L17 (1998). [CrossRef] [ISI]
    * 22. J.-P. Macquart, Astrophys. J. 658, L1 (2007). [CrossRef] [ISI]
    * 23. R. N. Manchester et al., Mon. Not. R. Astron. Soc. 328, 17 (2001). [CrossRef] [ISI]
    * 24. R. T. Edwards, M. Bailes, W. van Straten, M. C. Britton, Mon. Not. R. Astron. Soc. 326, 358 (2001). [CrossRef] [ISI]
    * 25. M. Burgay et al., Mon. Not. R. Astron. Soc. 368, 283 (2006). [ISI]
    * 26. B. A. Jacoby, M. Bailes, S. M. Ord, H. S. Knight, A. W. Hotan, Astrophys. J. 656, 408 (2007). [CrossRef] [ISI]
    * 27. S. W. Amy, M. I. Large, A. E. Vaughan, Proc. Astron. Soc. Aust. 8, 172 (1989).
    * 28. B. W. Stappers, A. G. J. van Leeuwen, M. Kramer, D. Stinebring, J. Hessels, in Proceedings of the 363. Heraeus Seminar on Neutron Stars and Pulsars, W. Becker, H. H. Huang, Eds. (Physikzentrum, Bad Honnef, Germany, 2006), pp. 101–103.
    * 29. V. L. Ginzburg, Nature 246, 415 (1973). [CrossRef]
    * 30. S. Johnston et al., ATNF SKA Memo 13 (Australia Telescope National Facility, 2007).
    * 31. P. N. Wilkinson, K. I. Kellermann, R. D. Ekers, J. M. Cordes, T. J. W. Lazio, N. Astron. Rev. 48, 1551 (2004). [CrossRef]
    * 32. J. E. Gaustad, P. R. McCullough, W. Rosing, D. Van Buren, Proc. Astron. Soc. Pac. 113, 1326 (2001). [CrossRef]
    * 33. S. Stanimirovic, L. Staveley-Smith, J. M. Dickey, R. J. Sault, S. L. Snowden, Mon. Not. R. Astron. Soc. 302, 417 (1999). [CrossRef] [ISI]
    * 34. The Parkes Radio Telescope is part of the Australia Telescope, which is funded by the Commonwealth of Australia for operation as a National Facility managed by the Commonwealth Scientific and Industrial Research Organisation. We thank R. Manchester for making the archival data available to us. This research has made use of data obtained from the High Energy Astrophysics Science Archive Research Center, provided by NASA’s Goddard Space Flight Center. We thank K. Hurley for providing access to the GCN network archive, and V. Kondratiev, S. Tingay, S. Johnston, F. Camilo, and J. Bland-Hawthorn for useful comments on the manuscript. We acknowledge the prompt awarding of follow-up time by the ATNF Director and thank L. Toomey and P. Sullivan for observing assistance.

  • ljk January 31, 2008, 12:15

    Binary recycled pulsars, as a most precise physical laboratory

    Authors: G.S. Bisnovatyi-Kogan

    (Submitted on 30 Jan 2008)

    Abstract: The following problems are discussed. 1. Pulsars and close binaries. 2. Hulse-Taylor pulsar. 3. Disrupted pulsar pairs. 4. RP statistics. 5. Enhanced evaporation: formation of single RP. 6. General relativity effects: NS+NS. 7. A Double pulsar system. 8. Checking general relativity. 9. Variability of the gravitational constant. 10. Space Watch.

    Comments: Invited talk in The Fourth scientific conference in honor of Bohdan Babiy “Selected Issues of Astronomy and Astrophysics”, 19-21 October 2006 in Lviv (Ukraine)

    Subjects: Astrophysics (astro-ph)

    Journal reference: Journal of Physical Studies, v.11, No.4 (2007)

    Cite as: arXiv:0801.4738v1 [astro-ph]

    Submission history

    From: G. S. Bisnovatyi-Kogan [view email]

    [v1] Wed, 30 Jan 2008 19:01:33 GMT (375kb)


  • ljk February 1, 2008, 22:47

    Radio giants come into focus

    New observations could shed light on galaxies that have
    radio lobes spanning hundreds of millions of light-years


  • ljk May 19, 2008, 11:23

    An Eccentric Binary Millisecond Pulsar in the Galactic Plane

    Authors: D. J. Champion, S. M. Ransom, P. Lazarus, F. Camilo, C. Bassa, V. M. Kaspi, D. J. Nice, P. C. C. Freire, I. H. Stairs, J. van Leeuwen, B. W. Stappers, J. M. Cordes, J. W. T. Hessels, D. R. Lorimer, Z. Arzoumanian, D. C. Backer, N. D. R. Bhat, S. Chatterjee, I. Cognard, J. S. Deneva, C.-A. Faucher-Giguere, B. M. Gaensler, J. L. Han, F. A. Jenet, L. Kasian, V. I. Kondratiev, M. Kramer, J. Lazio, M. A. McLaughlin, A. Venkataraman, W. Vlemmings

    (Submitted on 15 May 2008)

    Abstract: Binary pulsar systems are superb probes of stellar and binary evolution and the physics of extreme environments. In a survey with the Arecibo telescope, we have found PSR J1903+0327, a radio pulsar with a rotational period of 2.15 ms in a highly eccentric (e = 0.44) 95-day orbit around a solar mass companion.

    Infrared observations identify a possible main-sequence companion star. Conventional binary stellar evolution models predict neither large orbital eccentricities nor main-sequence companions around millisecond pulsars.

    Alternative formation scenarios involve recycling a neutron star in a globular cluster then ejecting it into the Galactic disk or membership in a hierarchical triple system. A relativistic analysis of timing observations of the pulsar finds its mass to be 1.74+/-0.04 Msun, an unusually high value.

    Comments: 28 pages, 4 figures inc Supplementary On-Line Material. Accepted for publication in Science, published on Science Express: 10.1126/science.1157580

    Subjects: Astrophysics (astro-ph)

    Cite as: arXiv:0805.2396v1 [astro-ph]

    Submission history

    From: David Champion [view email]

    [v1] Thu, 15 May 2008 20:11:29 GMT (152kb)


  • ljk September 14, 2009, 13:14

    Sources of the Radio Background Considered

    Authors: J. Singal, L. Stawarz, A. Lawrence, V. Petrosian

    (Submitted on 10 Sep 2009)

    Abstract: We investigate possible origins of the extragalactic radio background reported by the ARCADE 2 collaboration. The surface brightness of the background is several times higher than that which would result from currently observed radio sources.

    We consider contributions to the background from diffuse synchrotron emission from clusters and the intergalactic medium, previously unrecognized flux from low surface brightness regions of radio sources, and faint point sources below the flux limit of existing surveys.

    By examining radio source counts available in the literature, we conclude that most of the radio background is produced by radio point sources that dominate at sub microJy fluxes.

    We show that a truly diffuse background produced by electrons far from galaxes is ruled out because such energetic electrons would overproduce the obserevd X-ray/gamma-ray background through inverse Compton scattering of the other photon fields. Unrecognized flux from low surface brightness regions of extended radio sources, or moderate flux sources missed entirely by radio source count surveys, cannot explain the bulk of the observed background, but may contribute as much as 10%.

    We consider both radio supernovae and radio quiet quasars as candidate sources for the background, and show that both fail to produce it at the observed level because of insufficient number of objects and total flux, although radio quiet quasars contribute at the level of at least a few percent.

    We conclude that the most important population for production of the background is likely ordinary starforming galaxies above redshift 1 characterized by an evolving radio far-infrared correlation, which increases toward the radio loud with redshift.

    Comments: 11 pages, 3 figures, 1 table; ApJ submitted

    Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO)

    Cite as: arXiv:0909.1997v1 [astro-ph.CO]

    Submission history

    From: Jack Singal [view email]

    [v1] Thu, 10 Sep 2009 19:44:44 GMT (171kb,D)


  • ljk September 18, 2010, 4:28

    September 17, 2010

    From the X Files Dept: Mystery of Radio Waves Emitted From Nearby Galaxy Still Unsolved

    “Could it be black hole dragging material from one universe into yet another universe?” – Tom Muxlow of Jodrell Bank Centre for Astrophysics

    There is something strange in the cosmic neighborhood. An unknown object in the nearby galaxy M82 has started sending out radio waves, and the emission does not look like anything seen anywhere in the universe before.

    “We don’t know what it is,” says co-discoverer Tom Muxlow of Jodrell Bank Centre for Astrophysics near Macclesfield, UK.

    Full artice here:


  • ljk September 28, 2011, 0:18

    Radio Continuum Emission from FS CMa Stars

    L.F. Rodriguez, A. Baez-Rubio, A. S. Miroshnichenko

    (Submitted on 27 Sep 2011)

    The FS CMa stars exhibit bright optical emission-line spectra and strong IR excesses. Very little is known of their radio characteristics. We analyzed archive Very Large Array data to search for radio continuum emission in a sample of them. There are good quality data for seven of the $\sim$40 known FS CMa stars.

    Of these seven stars, five turn out to have associated radio emission. Two of these stars, CI Cam and MWC 300, have been previously reported in the literature as radio emitters.

    We present and briefly discuss the radio detection of the other three sources: FS CMa (the prototype of the class), AS 381, and MWC 922. The radio emission is most probably of a free-free nature but additional observations are required to better characterize it.


    7 pages, 5 figures


    Solar and Stellar Astrophysics (astro-ph.SR)

    Cite as:

    arXiv:1109.5939v1 [astro-ph.SR]

    Submission history

    From: Luis F. Rodriguez [view email]

    [v1] Tue, 27 Sep 2011 15:45:49 GMT (51kb)