E. C. Ferrara
Goddard Space Flight Center
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Featured researches published by E. C. Ferrara.
The Astrophysical Journal | 2010
P. M. Saz Parkinson; M. Dormody; M. Ziegler; Paul S. Ray; Aous A. Abdo; J. Ballet; Matthew G. Baring; A. Belfiore; T. H. Burnett; G. A. Caliandro; F. Camilo; Patrizia A. Caraveo; A. De Luca; E. C. Ferrara; P. C. C. Freire; J. E. Grove; C. Gwon; A. K. Harding; R. P. Johnson; T. J. Johnson; S. Johnston; M. J. Keith; M. Kerr; J. Knödlseder; A. Makeev; M. Marelli; P. F. Michelson; D. Parent; S. M. Ransom; O. Reimer
We report the discovery of eight gamma-ray pulsars in blind frequency searches using the LAT, onboard the Fermi Gamma-ray Space Telescope. Five of the eight pulsars are young (tau_c 10^36 erg/s), and located within the Galactic plane (|b|<3 deg). The remaining three are older, less energetic, and located off the plane. Five pulsars are associated with sources included in the LAT bright gamma-ray source list, but only one, PSR J1413-6205, is clearly associated with an EGRET source. PSR J1023-5746 has the smallest characteristic age (tau_c=4.6 kyr) and is the most energetic (Edot=1.1E37 erg/s) of all gamma-ray pulsars discovered so far in blind searches. PSRs J1957+5033 and J2055+25 have the largest characteristic ages (tau_c~1 Myr) and are the least energetic (Edot~5E33 erg/s) of the newly-discovered pulsars. We present the timing models, light curves, and detailed spectral parameters of the new pulsars. We used recent XMM observations to identify the counterpart of PSR J2055+25 as XMMU J205549.4+253959. In addition, publicly available archival Chandra X-ray data allowed us to identify the likely counterpart of PSR J1023-5746 as a faint, highly absorbed source, CXOU J102302.8-574606. The large X-ray absorption indicates that this could be among the most distant gamma-ray pulsars detected so far. PSR J1023-5746 is positionally coincident with the TeV source HESS J1023-575, located near the young stellar cluster Westerlund 2, while PSR J1954+2836 is coincident with a 4.3 sigma excess reported by Milagro at a median energy of 35 TeV. Deep radio follow-up observations of the eight pulsars resulted in no detections of pulsations and upper limits comparable to the faintest known radio pulsars, indicating that these can be included among the growing population of radio-quiet pulsars in our Galaxy being uncovered by the LAT, and currently numbering more than 20.
The Astrophysical Journal | 2011
Scott M. Ransom; Paul S. Ray; F. Camilo; Mallory Strider Ellison Roberts; Ö. Çelik; Michael T. Wolff; C. C. Cheung; M. Kerr; T. T. Pennucci; Megan E. DeCesar; I. Cognard; A. G. Lyne; B. W. Stappers; P. C. C. Freire; J. E. Grove; A. A. Abdo; G. Desvignes; Davide Donato; E. C. Ferrara; N. Gehrels; L. Guillemot; Chul Gwon; A. K. Harding; S. Johnston; M. J. Keith; M. Kramer; P. F. Michelson; D. Parent; P. M. Saz Parkinson; Roger W. Romani
We searched for radio pulsars in 25 of the non-variable, unassociated sources in the Fermi LAT Bright Source List with the Green Bank Telescope at 820 MHz. We report the discovery of three radio and γ-ray millisecond pulsars (MSPs) from a high Galactic latitude subset of these sources. All of the pulsars are in binary systems, which would have made them virtually impossible to detect in blind γ-ray pulsation searches. They seem to be relatively normal, nearby (≤2 kpc) MSPs. These observations, in combination with the Fermi detection of γ-rays from other known radio MSPs, imply that most, if not all, radio MSPs are efficient γ-ray producers. The γ-ray spectra of the pulsars are power law in nature with exponential cutoffs at a few GeV, as has been found with most other pulsars. The MSPs have all been detected as X-ray point sources. Their soft X-ray luminosities of ~1030-1031 erg s–1 are typical of the rare radio MSPs seen in X-rays.
Science | 2014
M. Ackermann; M. Ajello; A. Albert; L. Baldini; J. Ballet; D. Bastieri; R. Bellazzini; E. Bissaldi; R. D. Blandford; E. D. Bloom; E. Bottacini; T. J. Brandt; J. Bregeon; P. Bruel; R. Buehler; S. Buson; G. A. Caliandro; R. A. Cameron; M. Caragiulo; Patrizia A. Caraveo; E. C. Ferrara; A. K. Harding; E. Hays; J. S. Perkins; D. J. Thompson
Gamma-ray novas may be garden variety When astronomers detected gamma rays from the nova V407 Cyg, an explosive mass transfer from a red giant onto a white dwarf, they found it surprising enough. They blamed the rays on strong stellar winds enabling particle acceleration. Now, the Fermi-LAT Collaboration has observed gamma rays from three more novas, all lacking the strong winds. Although the three sources vary slightly in nature, none is particularly unusual. If all novas emit gamma rays, then astronomers would expect to see the same number of novas that they did in fact see within a 5-kpc distance over 5 years. Science, this issue p. 554 Three classical novae exhibit unexpected high-energy particle acceleration and may represent the norm for that object class. A classical nova results from runaway thermonuclear explosions on the surface of a white dwarf that accretes matter from a low-mass main-sequence stellar companion. In 2012 and 2013, three novae were detected in γ rays and stood in contrast to the first γ-ray–detected nova V407 Cygni 2010, which belongs to a rare class of symbiotic binary systems. Despite likely differences in the compositions and masses of their white dwarf progenitors, the three classical novae are similarly characterized as soft-spectrum transient γ-ray sources detected over 2- to 3-week durations. The γ-ray detections point to unexpected high-energy particle acceleration processes linked to the mass ejection from thermonuclear explosions in an unanticipated class of Galactic γ-ray sources.
The Astrophysical Journal | 2011
I. Cognard; L. Guillemot; T. J. Johnson; D. A. Smith; C. Venter; A. K. Harding; Michael T. Wolff; C. C. Cheung; Davide Donato; A. A. Abdo; J. Ballet; F. Camilo; G. Desvignes; D. Dumora; E. C. Ferrara; P. C. C. Freire; J. E. Grove; S. Johnston; M. J. Keith; M. Kramer; A. G. Lyne; P. F. Michelson; D. Parent; S. M. Ransom; Paul S. Ray; Roger W. Romani; P. M. Saz Parkinson; B. W. Stappers; G. Theureau; D. J. Thompson
We report the discovery of two millisecond pulsars in a search for radio pulsations at the positions of \emph{Fermi Large Area Telescope} sources with no previously known counterparts, using the Nancay radio telescope. The two millisecond pulsars, PSRs J2017+0603 and J2302+4442, have rotational periods of 2.896 and 5.192 ms and are both in binary systems with low-eccentricity orbits and orbital periods of 2.2 and 125.9 days respectively, suggesting long recycling processes. Gamma-ray pulsations were subsequently detected for both objects, indicating that they power the associated \emph{Fermi} sources in which they were found. The gamma-ray light curves and spectral properties are similar to those of previously-detected gamma-ray millisecond pulsars. Detailed modeling of the observed radio and gamma-ray light curves shows that the gamma-ray emission seems to originate at high altitudes in their magnetospheres. Additionally, X-ray observations revealed the presence of an X-ray source at the position of PSR J2302+4442, consistent with thermal emission from a neutron star. These discoveries along with the numerous detections of radio-loud millisecond pulsars in gamma rays suggest that many \emph{Fermi} sources with no known counterpart could be unknown millisecond pulsars.
The Astrophysical Journal | 2012
M. Kerr; F. Camilo; T. J. Johnson; E. C. Ferrara; L. Guillemot; A. K. Harding; J. W. T. Hessels; S. Johnston; M. J. Keith; M. Kramer; Scott M. Ransom; Paul S. Ray; J. E. Reynolds; J. Sarkissian; K. S. Wood
We have discovered five millisecond pulsars (MSPs) in a survey of 14unidentified Fermi Large Area Telescope sources in the southern skyusing the Parkes radio telescope. PSRs J0101-6422, J1514-4946, andJ1902-5105 reside in binaries, while PSRs J1658-5324 and J1747-4036 areisolated. Using an ephemeris derived from timing observations of PSRJ0101-6422 (P = 2.57 ms, DM = 12 pc cm
The Astrophysical Journal | 2012
M. Ackermann; M. Ajello; A. Allafort; L. Baldini; J. Ballet; G. Barbiellini; D. Bastieri; K. Bechtol; R. Bellazzini; B. Berenji; R. D. Blandford; Elliott D. Bloom; E. Bonamente; A. W. Borgland; E. Bottacini; T. J. Brandt; J. Bregeon; M. Brigida; P. Bruel; R. Buehler; G. Busetto; S. Buson; G. A. Caliandro; R. A. Cameron; P. A. Caraveo; E. C. Ferrara; A. K. Harding; R. Nemmen; D. J. Thompson; Eleonora Troja
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Astrophysical Journal Supplement Series | 2014
T. J. Johnson; C. Venter; A. K. Harding; L. Guillemot; D. A. Smith; M. Kramer; Ö. Çelik; P. R. den Hartog; E. C. Ferrara; X. Hou; J. Lande; Paul S. Ray
), we have detected{
Monthly Notices of the Royal Astronomical Society | 2012
L. Guillemot; P. C. C. Freire; I. Cognard; T. J. Johnson; Y. Takahashi; J. Kataoka; G. Desvignes; F. Camilo; E. C. Ferrara; A. K. Harding; G. H. Janssen; M. J. Keith; M. Kerr; M. Kramer; D. Parent; Scott M. Ransom; Paul S. Ray; P. M. Saz Parkinson; D. A. Smith; B. W. Stappers; G. Theureau
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The Astrophysical Journal | 2013
Tracey Johnson; L. Guillemot; M. Kerr; I. Cognard; Paul S. Ray; Michael T. Wolff; S. Begin; G. H. Janssen; Roger W. Romani; C. Venter; J. E. Grove; P. C. C. Freire; M. Wood; C. C. Cheung; J. M. Casandjian; I. H. Stairs; F. Camilo; C. Espinoza; E. C. Ferrara; Alice K. Harding; S. Johnston; M. Kramer; A. G. Lyne; P. F. Michelson; Scott M. Ransom; R. M. Shannon; David Stanley Smith; B. W. Stappers; G. Theureau; S. E. Thorsett
}-ray pulsations and measured its proper motion. Its {
The Astrophysical Journal | 2013
Paul S. Ray; Scott M. Ransom; C. C. Cheung; M. Giroletti; I. Cognard; F. Camilo; Bhaswati Bhattacharyya; J. Roy; Roger W. Romani; E. C. Ferrara; L. Guillemot; S. Johnston; M. J. Keith; M. Kerr; M. Kramer; H. J. Pletsch; P. M. Saz Parkinson; K. S. Wood
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