Fermi pulsar revolution

📝 Abstract

2009 has been an extraordinary year for gamma-ray pulsar astronomy and 2010 promises to be equally good. Not only have we registered an extraordinary increase in the number of pulsars detected in gamma rays, but we have also witnessed the birth of new sub-families: first of all, the radio-quiet gamma pulsars and later an ever growing number of millisecond pulsars, a real surprise. We started with a sample of 7 gamma-ray emitting neutron stars (6 radio pulsars and Geminga) and now the Fermi-LAT harvest encompasses 24 “Geminga-like” new gamma-ray pulsars, a dozen millisecond pulsars and about thirty radio pulsars. Moreover, radio searches targeted to LAT unidentified sources yielded 18 new radio millisecond pulsars, several of which have been already detected also in gamma rays. Thus, currently the family of gamma-ray emitting neutron stars seems to be evenly divided between classical radio pulsars, millisecond pulsars and radio quiet neutron stars.

💡 Analysis

2009 has been an extraordinary year for gamma-ray pulsar astronomy and 2010 promises to be equally good. Not only have we registered an extraordinary increase in the number of pulsars detected in gamma rays, but we have also witnessed the birth of new sub-families: first of all, the radio-quiet gamma pulsars and later an ever growing number of millisecond pulsars, a real surprise. We started with a sample of 7 gamma-ray emitting neutron stars (6 radio pulsars and Geminga) and now the Fermi-LAT harvest encompasses 24 “Geminga-like” new gamma-ray pulsars, a dozen millisecond pulsars and about thirty radio pulsars. Moreover, radio searches targeted to LAT unidentified sources yielded 18 new radio millisecond pulsars, several of which have been already detected also in gamma rays. Thus, currently the family of gamma-ray emitting neutron stars seems to be evenly divided between classical radio pulsars, millisecond pulsars and radio quiet neutron stars.

📄 Content

 Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. http://pos.sissa.it

Fermi Pulsar Revolution Patrizia A. Caraveo Affiliation IASF-INAF Address, Via Bassini, 15 -20133 Milano ITALY E-mail: pat@iasf-milano.inaf.it 2009 has been an extraordinary year for gamma-ray pulsar astronomy and 2010 promises to be equally good. Not only have we registered an extraordinary increase in the number of pulsars detected in gamma rays, but we have also witnessed the birth of new sub-families: first of all, the radio-quiet gamma pulsars and later an ever growing number of millisecond pulsars, a real surprise. We started with a sample of 7 gamma-ray emitting neutron stars (6 radio pulsars and Geminga) and now the Fermi-LAT harvest encompasses 24 “Geminga-like” new gamma-ray pulsars, a dozen millisecond pulsars and about thirty radio pulsars. Moreover, radio searches targeted to LAT unidentified sources yielded 18 new radio millisecond pulsars, several of which have been already detected also in gamma rays. Thus, currently the family of gamma-ray emitting neutron stars seems to be evenly divided between classical radio pulsars, millisecond pulsars and radio quiet neutron stars.

High Time Resolution Astrophysics IV - The Era of Extremely Large Telescopes-HTRA-IV Agios Nikolaos, Crete, Greece May 5-7 2010 Short title Speaker Name

 2 

1. Introduction With the demise of the CGRO mission in 2000, gamma-ray pulsar astronomy entered a long hiatus with the family of gamma-ray pulsars being frozen to 7 objects, namely the radio pulsars Crab, Vela, PSRB1055-52, PSRB1706-44, PSRB1951+32, PSRB1509-58 (only detected at low energy) and the radio quiet Geminga [1,2]. While radio observers discovered several new pulsars within the unidentified EGRET sources error boxes[e.g.3], the lack of contemporary gamma-ray data made the search for gamma pulsed signal a frustrating exercise, leading, at most, to tantalizing results [4]. Despite the small number of confirmed gamma-ray pulsars, they are one of just two classes of objects identified as gamma ray sources. With about 70 Unidentified low latitude EGRET sources, it was clear that pulsars were to play a major role in future, more sensitive, gamma-ray experiments [e.g.5]. To improve our ability to find gamma- ray pulsars deeply imbedded in the noisy galactic plane the EGRET lesson pointed to two major avenues
   In view of the paramount importance of the availability of contemporary radio and gamma observations, monitoring programmes were arranged for hundreds of promising radio pulsars, selected on the basis of their rotational energy loss weighted by the distance square [6,7].
   Meanwhile, the expectation of a significant contribution from radio-quiet, Geminga- like, gamma ray pulsars lead to the development of new codes tailored to the search for pulsation in the sparse photon harvest typical of gamma-ray observations [8]. Both avenues are now bringing fruits, with some unexpected findings leading to the Fermi pulsar Revolution

2. Results beyond expectations

A preview of the Fermi ability to spot gamma-ray pulsars without any outside help came soon after the launch of the mission, when PSR J0007+7303 was detected within the CTA 1 supernova remnant[9,10]. Actually the gamma-ray source was known since EGRET times and had been extensively (yet inconclusively) studied in X-rays [11]. A faint X-ray source surrounded by diffuse emission pointed to a neutron star embedded in a PWN, but the timing signature was missing, partly owing to the source faintness.
Taking advantage of the X-ray source coordinates to barycentrize the Fermi Lat photon arrival times, the application of the newly designed codes devoted to blind searches yielded the source periodicity.
The pulsar timing parameters unveiled a radio quiet neutron star with a kinetic age of 10.000 y (comparable with the CTA 1 SNR age) and a rotational energy loss intermediate between Vela and Geminga. Such a quick discovery of the first LAT radio quiet pulsar heralded a new era on gamma-ray pulsar astronomy.
Applying the blind search techniques to all unidentified gamma-ray sources (most of which dated back to EGRET and even COS-B times) 15 more gamma ray pulsars were found, establishing the radio quiet pulsars as a major fraction of the pulsar family[12].
Short title Speaker Name

 3 

13 of the 16 newly found pulsars are indeed unidentified EGRET sources, many of which had been already studied at X-ray wavelengths thus providing promising candidates whose positions could be injected in the data analysis, establishing a new synergy between X and gamma-ray astronomies [13] Meanwhile, the radio monitoring campaigns, which had requested a lot of organizational efforts, started to pay back yielding the detection in gamma rays of 16 new radio pulsars, b

This content is AI-processed based on ArXiv data.