Werner Becker

• Professor
• Max Planck Society

Aims. G321.3–3.9 was first identified as a partial shell at radio frequencies a few decades ago. Although it continued to be observed, no additional studies were undertaken until recently. Methods. In this paper, we present results from a large selection of radio and X-ray data that cover the position of G321.3–3.9. We confirmed G321.3–3.9 as a new...

Aims. The Gemini-Monoceros X-ray enhancement is a rich field for studying diffuse X-ray emission and supernova remnants (SNRs). Most SNRs in this part of the sky are notoriously difficult to observe due to their large extent. With the launch of the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) on board the Spektrum-Röntgen-Gamm...

We report new radio timing solutions from a 3-yr observing campaign conducted with the MeerKAT and Murriyang telescopes for nine Small Magellanic Cloud pulsars, increasing the number of characterized rotation-powered extragalactic pulsars by 40 per cent. We can infer from our determined parameters that the pulsars are seemingly all isolated, that s...

We report new radio timing solutions from a three-year observing campaign conducted with the MeerKAT and Murriyang telescopes for nine Small Magellanic Cloud pulsars, increasing the number of characterised rotation-powered extragalactic pulsars by 40 per cent. We can infer from our determined parameters that the pulsars are seemingly all isolated,...

Hot plasma plays a crucial role in regulating the baryon cycle within the Milky Way, flowing from the energetic sources in the Galactic center and plane, to the corona and the halo. This hot plasma represents an important fraction of the Galactic baryons, plays a key role in galactic outflows and is an important ingredient in galaxy evolution model...

Supernova remnant (SNR) detection along the Galactic plane poses a number of challenges. The SNR G309.8+00.0 lies exactly on the Galactic plane, with its center coinciding with galactic latitude (b)=0 deg. In this paper we report the first detection of the SNR G309.8+00.0 in X-rays and $\gamma$ rays, using stacked data from the first four consecuti...

Supernova remnant (SNR) detection along the Galactic plane poses a number of challenges. A diffuse X-ray emission component emanating from unidentified sources on the Galactic plane further complicates such a detection in X-rays. Due to the presence of dense dust clouds along the Galactic plane, X-ray photons are also subject to high absorption. Si...

The Simeis 147 nebula (S147) is particularly well known for a spectacular net of $ H filaments. It is often considered one of the largest and oldest ($ yr $) cataloged supernova remnants in the Milky Way, although the kinematics of the pulsar PSR J0538+2817 suggests that this supernova remnant might be a factor of three younger. The former case is...

Simeis 147 (S147, G180.0-01.7, ``Spaghetti nebula'') is a supernova remnant (SNR) extensively studied across the entire electromagnetic spectrum, from radio to giga-electronvolt gamma -rays, except in X-rays. Here, we report the first detection of significant X-ray emission from the entire SNR using data of the extended ROentgen Survey Imaging Tele...

We present the serendipitous discovery of a low surface brightness Galactic supernova remnant candidate, Unicycle (G312.65+2.87). Unicycle was initially discovered in the Evolutionary Map of the Universe large-scale radio survey at 943.5 MHz. We measure a diffuse shell ( D = 288″ × 300″) and an integrated flux density of S I 944 MHz = 150 ± 20 mJy....

There are two contradictory views of the eROSITA bubbles: either a 10 ⁴ pc scale pair of giant bubbles blown by the Galactic center (GC), or a 10 ² pc scale local structure coincidentally located in the direction of GC. A key element of this controversy is the distance to the bubbles. Based on the 3D dust distribution in the Galactic plane, we foun...

The sensitivity of the MeerKAT radio interferometer is an opportunity to probe deeper into the population of rare and faint extragalactic pulsars. The TRAPUM (TRAnsients and PUlsars with MeerKAT) collaboration has conducted a radio-domain search for accelerated pulsars and transients in the Small Magellanic Cloud (SMC). This partially targeted surv...

We present the description and initial results of the TRAPUM (TRAnsients And PUlsars with MeerKAT) search for pulsars associated with supernova remnants (SNRs), pulsar wind nebulae and unidentified TeV emission. The list of sources to be targeted includes a large number of well-known candidate pulsar locations but also new candidate SNRs identified...

The sensitivity of the MeerKAT radio interferometer is an opportunity to probe deeper into the population of rare and faint extragalactic pulsars. The TRAPUM (TRAnsients and PUlsars with MeerKAT) collaboration has conducted a radio-domain search for accelerated pulsars and transients in the Small Magellanic Cloud (SMC). This partially targeted surv...

We present the description and initial results of the TRAPUM (TRAnsients And PUlsars with MeerKAT) search for pulsars associated with supernova remnants (SNRs), pulsar wind nebulae and unidentified TeV emission. The list of sources to be targeted includes a large number of well-known candidate pulsar locations but also new candidate SNRs identified...

A thorough inspection of known Galactic supernova remnants (SNRs) along the Galactic plane with SRG/eROSITA yielded the detection of the X-ray counterpart of the SNR G279.0+01.1. The SNR is located just $1.5 above the Galactic plane. Its X-ray emission emerges as an incomplete, partial shell of $ angular extension. It is strongly correlated to the...

Context . The latest source catalog of the Fermi- LAT telescope contains more than 7000 γ -ray sources at giga-electronvolt energies, with the two dominant source classes thought to be blazars and rotation-powered pulsars. Despite continuous follow-up efforts, around 2600 sources have no known multiwavelength association. Aims . Our target is the i...

The eROSITA telescope array aboard the Spektrum Roentgen Gamma (SRG) satellite began surveying the sky in December 2019, with the aim of producing all-sky X-ray source lists and sky maps of an unprecedented depth. Here we present catalogues of both point-like and extended sources using the data acquired in the first six months of survey operations...

Context. Extended gamma-ray TeV emission (TeV halos) has been detected around middle-aged pulsars. A proposed model to explain these TeV halos is that electrons from a degree-wide pulsar wind nebula (PWN) get up-scattered by cosmic microwave background photons through inverse Compton processes. However, no X-ray degree-wide faint diffuse PWNe have...

Context. S 308 is an X-ray emitting bubble that surrounds the Wolf–Rayet star WR6. The structure shines in the optical as well and is thus known as the Dolphin Nebula. Due to its large angular extent, it has been covered at only 90% with past XMM-Newton observations. Aims. Thanks to the unique dataset provided by the all-sky survey performed in X-r...

By June of 2020, the extended ROentgen Survey with an Imaging Telescope Array ( ) on board the Spectrum Roentgen Gamma observatory had completed its first of the planned eight X-ray all-sky survey (eRASS1). The large effective area of the X-ray telescope makes it ideal for a survey of the faint X-ray diffuse emission over half of the sky with an un...

Context. G189.6+03.3 and IC443 are two examples of supernova remnants (SNRs) located in a region rich in gas and dust, and spatially close to the HII region S249. So far, the actual shape of IC443 is believed to be given by the past action of multiple supernova (SN) explosions, while a third unrelated SN might have originated G189.6+03.3. Aims. Alt...

We present the serendipitous detection of a new Galactic supernova remnant (SNR), G288.8–6.3, using data from the Australian Square Kilometre Array Pathfinder (ASKAP) Evolutionary Map of the Universe (EMU) survey. Using multifrequency analysis, we confirm this object as an evolved Galactic SNR at high Galactic latitude with low radio surface bright...

We present the serendipitous detection of a new Galactic Supernova Remnant (SNR), G288.8-6.3 using data from the Australian Square Kilometre Array Pathfinder (ASKAP)-Evolutionary Map of the Universe (EMU) survey. Using multi-frequency analysis, we confirm this object as an evolved Galactic SNR at high Galactic latitude with low radio surface bright...

We use data from the pilot observations of the EMU/POSSUM surveys to study the "missing supernova remnant (SNR) problem", the discrepancy between the number of Galactic SNRs that have been observed and the number that are estimated to exist. The Evolutionary Map of the Universe (EMU) and the Polarization Sky Survey of the Universe's Magnetism (POSS...

We use data from the pilot observations of the EMU/POSSUM surveys to study the ”missing supernova remnant (SNR) problem”, the discrepancy between the number of Galactic SNRs that have been observed and the number that are estimated to exist. The Evolutionary Map of the Universe (EMU) and the Polarization Sky Survey of the Universe’s Magnetism (POSS...

Context. The Vela supernova remnant (SNR) is one of the most nearby and extended objects in the X-ray sky. It constitutes a unique laboratory for studying the thermal and nonthermal X-ray emission from an evolved SNR and its central plerion at an unprecedented level of detail. Aims. Our goal is to characterize the hot ejecta and shocked interstella...

Aims. Our goal is the characterization of the hot ejecta and shocked interstellar medium (ISM) associated to the Vela supernova remnant (SNR), as well as the relativistic electrons injected into the ambient medium by its central pulsar. To achieve this, we analyze the X-ray data set of Vela acquired by SRG/eROSITA during its first four all-sky surv...

Context . The Vela supernova remnant (SNR) complex is a region containing at least three SNRs: Vela, Puppis A, and Vela Jr. With the launch of the spectro-imaging X-ray telescope eROSITA on board the Spectrum-Röntgen-Gamma (SRG) mission, it became possible to observe the one degree wide Vela Jr in its entirety. Although several previous pointed Cha...

The Vela supernova remnant complex is a region containing at least three supernova remnants: Vela, Puppis A, and Vela Jr. With the launch of the spectro-imaging X-ray telescope eROSITA on board the Spectrum Roentgen Gamma (SRG) mission, it became possible to observe the one degree wide Vela Jr in its entirety. Although several previous pointed Chan...

More than 100 millisecond pulsars (MSPs) have been discovered in radio observations of gamma-ray sources detected by the Fermi Large Area Telescope (LAT), but hundreds of pulsar-like sources remain unidentified. Here we present the first results from the targeted survey of Fermi-LAT sources being performed by the Transients and Pulsars with MeerKAT...

More than 100 millisecond pulsars (MSPs) have been discovered in radio observations of gamma-ray sources detected by the Fermi Large Area Telescope (LAT), but hundreds of pulsar-like sources remain unidentified. Here we present the first results from the targeted survey of Fermi-LAT sources being performed by the Transients and Pulsars with MeerKAT...

We report the results of follow-up investigations of a possible new thermally emitting isolated neutron star (INS), 4XMM J 022141.5−735632 , using observations from XMM-Newton and Spectrum Roentgen Gamma (SRG) eROSITA. The analysis is complemented by Legacy Survey imaging in the optical and near-infrared wavelengths. The X-ray source, the first to...

We report the results of follow-up investigations of a possible new thermally emitting isolated neutron star (INS), 4XMM J022141.5-735632, using observations from XMM-Newton and Spectrum Roentgen Gamma (SRG) eROSITA. The analysis is complemented by Legacy Survey imaging in the optical and near-infrared wavelengths. The X-ray source, the first to be...

The curious Galactic features near G357.2−0.2 were observed with the MeerKAT radio interferometer array in the UHF and L bands (0.56–1.68 GHz). There are two possibly related features: a newly identified faint heart-shaped partial shell (the “heart”), and a series of previously known but now much better imaged narrow, curved features (the “worm”) i...

The curious Galactic features near G357.2$-$0.2 were observed with the MeerKAT radio interferometer array in the UHF and L bands (0.56--1.68 GHz). There are two possibly related features: a newly identified faint heart-shaped partial shell (the "Heart"), and a series of previously known but now much better imaged narrow, curved features (the "Worm"...

Context. Puppis A is a medium-age supernova remnant (SNR), which is visible as a very bright extended X-ray source. While numerous studies have investigated individual features of the SNR, at this time, no comprehensive study of the entirety of its X-ray emission exists. Aims. Using field-scan data acquired by the SRG/eROSITA telescope during its c...

Aims. We present the results of the analysis of five observations of the globular clutser 47 Tucanae (47 Tuc) with the extended Roentgen Survey with an Imaging Telescope Array (eROSITA) on board the Spektrum-Roentgen-Gamma (Spektr-RG, SRG). We study the X-ray population in the field of one of the most massive globular clusters in our Milky Way. We...

Context. Puppis A is a medium-age supernova remnant (SNR), which is visible as a very bright extended X-ray source. While numerous studies have investigated individual features of the SNR, at this time, no comprehensive study of the entirety of its X-ray emission exists. Aims. Using field-scan data acquired by the SRG/eROSITA telescope during its c...

We present a detailed spectroscopic and timing analysis of X-ray observations of the bright pulsar PSR B0656+14. The observations were obtained simultaneously with eROSITA and XMM-Newton during the calibration and performance verification phase of the Spektrum-Roentgen-Gamma mission (SRG). The analysis of the 100 ks deep observation of eROSITA is s...

(abridged version) We present a detailed spectroscopic and timing analysis of X-ray observations of the bright radio-to-gamma-ray emitting pulsar PSR B0656+14, which were obtained simultaneously with eROSITA and XMM-Newton during the Calibration and Performance Verification phase of the Spektrum-Roentgen-Gamma mission (SRG) for 100 ks. Using XMM-Ne...

We present the results of the analysis of five observations of the globular clutser 47 Tucanae (47 Tuc) with eROSITA (extended Roentgen Survey with an Imaging Telescope Array) on board Spektrum-Roentgen-Gamma (Spektr-RG, SRG). The aim of the work is the study of the X-ray population in the field of one of the most massive globular clusters in our M...

Context. Central compact objects (CCOs) are a peculiar class of neutron stars, primarily encountered close to the center of young supernova remnants (SNRs) and characterized by thermal X-ray emission. Measurements of their proper motion and the expansion of the parent SNR are powerful tools for constraining explosion kinematics and the age of the s...

Context. Central compact objects (CCOs) are a peculiar class of neutron stars, primarily encountered close to the center of young supernova remnants (SNRs) and characterized by thermal X-ray emission. Aims. Our goal is to perform a systematic study of the proper motion of all known CCOs with appropriate data available. In addition, we aim to measur...

Supernova remnants (SNRs) are observable for about 6-15x10^4 years before they fade into the Galactic interstellar medium. With a Galactic supernova rate of approximately two per century, we can expect to have of the order of 1200 SNRs in our Galaxy. However, only about 300 of them are known to date, with the majority having been discovered in Gala...

Supernova remnants (SNRs) are observable for about (6−15) × 10 ⁴ yr before they fade into the Galactic interstellar medium. With a Galactic supernova rate of approximately two per century, we can expect to have of the order of 1200 SNRs in our Galaxy. However, only about 300 of them are known to date, with the majority having been discovered in Gal...

The halo of the Milky Way provides a laboratory to study the properties of the shocked hot gas that is predicted by models of galaxy formation. There is observational evidence of energy injection into the halo from past activity in the nucleus of the Milky Way1–4; however, the origin of this energy (star formation or supermassive-black-hole activit...

The halo of the Milky Way provides a laboratory to study the properties of the shocked hot gas that is predicted by models of galaxy formation. There is observational evidence of energy injection into the halo from past activity in the nucleus of the Milky Way; however, the origin of this energy (star formation or supermassive-black-hole activity)...

eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the primary instrument on the Spectrum-Roentgen-Gamma (SRG) mission, which was successfully launched on July 13, 2019, from the Baikonour cosmodrome. After the commissioning of the instrument and a subsequent calibration and performance verification phase, eROSITA started a surve...

eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the primary instrument on the Spectrum-Roentgen-Gamma (SRG) mission, which was successfully launched on July 13, 2019, from the Baikonour cosmodrome. After the commissioning of the instrument and a subsequent calibration and performance verification phase, eROSITA started a surve...

We present an improved proper-motion measurement of the central compact object RX J0822–4300, located in the supernova remnant Puppis A. By employing a new data set taken in 2019 February by the High Resolution Camera on board the Chandra X-ray Observatory, we approximately double the available temporal baseline for our analysis to slightly more th...

We present an improved proper motion measurement of the central compact object RX J0822-4300, located in the supernova remnant Puppis A. By employing a new data set taken in February 2019 by the High Resolution Camera aboard the Chandra X-ray Observatory, we approximately double the available temporal baseline for our analysis to slightly more than...

The X-ray source CXO J085201.4−461753 in the few kyr-old Vela Jr. supernova remnant (SNR, G266.2−1.2) belongs to the peculiar class of isolated neutron stars dubbed ‘Central Compact Objects’ (CCOs). At variance with the other CCOs, which are only detected in the X-rays, CXO J085201.4−461753 has been possibly detected also at other wavelengths. In p...

The X-ray source CXO\, J085201.4$-$461753in the few kyr-old Vela Jr. supernova remnant (G266.2-1.2) belongs to the peculiar class of isolated neutron stars dubbed "Central Compact Objects" (CCOs). At variance with the other CCOs, which are only detected in the X-rays, \cxo\ has been possibly detected also at other wavelengths. In particular, a cand...

Pulsars are natural cosmic clocks. On long timescales they rival the precision of terrestrial atomic clocks. Using a technique called pulsar timing, the exact measurement of pulse arrival times allows a number of applications, ranging from testing theories of gravity to detecting gravitational waves. Also an external reference system suitable for a...

Pulsars are natural cosmic clocks. On long timescales they rival the precision of terrestrial atomic clocks. Using a technique called pulsar timing, the exact measurement of pulse arrival times allows a number of applications, ranging from testing theories of gravity to detecting gravitational waves. Also an external reference system suitable for a...

About one third of the 3033 gamma-ray sources in the Third Fermi-LAT Gamma-ray Source Catalogue (3FGL) are unidentified and have not even a tentative association with a known object, hence they are defined as unassociated. Among Galactic gamma-ray sources, pulsars represent the largest class, with over 200 identifications to date. About one third o...

About one third of the 3033 $\gamma$-ray sources in the Third Fermi-LAT Gamma-ray Source Catalogue (3FGL) are unidentified and do not have even a tentative association with a known object, hence they are defined as unassociated. Among Galactic $\gamma$-ray sources, pulsars represent the largest class, with over 200 identifications to date. About on...

eROSITA (extended ROentgen Survey with an Imaging Telescope Array) is the core instrument on the Russian/German Spektrum-Roentgen-Gamma (SRG) mission which is now officially scheduled for launch on September 2017, eROSITA will perform a deep survey of the entire X-ray sky. Within the first 4 years of the mission the sky will be scanned 8 times. In...

We describe a systematic search for X-ray counterparts of radio pulsars. The search was accomplished by cross-correlating the radio timing positions of all radio pulsars from the ATNF pulsar database (version 1.54) with archival XMM-Newton and Chandra observations publicly released by August 1st 2015. In total, 171 of the archival XMM-Newton observ...

An external reference system suitable for deep space navigation can be defined by fast spinning and strongly magnetized neutron stars, called pulsars. Their beamed periodic signals have timing stabilities comparable to atomic clocks and provide characteristic temporal signatures that can be used as natural navigation beacons, quite similar to the u...

We present multi-wavelength observations of the unassociated gamma-ray source 3FGL J2039.6-5618 detected by the Fermi Large Area Telescope. The source gamma-ray properties suggest that it is a pulsar, most likely a millisecond pulsar, for which neither radio nor $\gamma$-ray pulsations have been detected yet. We observed 3FGL J2039.6-5618 with XMM-...

This White Paper, submitted to the recent ESA call for science themes to define its future large missions, advocates the need for a transformational leap in our understanding of two key questions in astrophysics: 1) How does ordinary matter assemble into the large scale structures that we see today? 2) How do black holes grow and shape the Universe...

White dwarfs, neutron stars and stellar mass black holes are key laboratories to study matter in most extreme conditions of gravity and magnetic field. The unprecedented effective area of Athena+ will allow us to advance our understanding of emission mechanisms and accretion physics over a wide range of mass accretion rates, starting from lower and...

An external reference system suitable for deep space navigation can be defined by fast spinning and strongly magnetized neutron stars, called pulsars. Their beamed periodic signals have timing stabilities comparable to atomic clocks and provide characteristic temporal signatures that can be used as natural navigation beacons, quite similar to the u...

An external reference system suitable for deep space navigation can be defined by fast spinning and strongly magnetized neutron stars, called pulsars. Their beamed periodic signals have timing stabilities comparable to atomic clocks and provide characteristic temporal signatures that can be used as natural navigation beacons, quite similar to the u...

The Square Kilometre Array (SKA) is the most ambitious radio telescope ever planned. With a collecting area of about a square kilometre, the SKA will be far superior in sensitivity and observing speed to all current radio facilities. The scientific capability promised by the SKA and its technological challenges provide an ideal base for interdiscip...

Mobile ad hoc networks (MANETs) are gaining increasing significance with computing devices becoming ubiquitous and equipped with wireless communication modules. Many applications for such networks require the devices to know their position within the network or their distance to other devices. Precise determination of these parameters often fails d...

eROSITA is the primary instrument on the Russian SRG mission. In the first four years of scientific operation after its launch, foreseen for 2014, it will perform a deep survey of the entire X-ray sky. In the soft X-ray band (0.5-2 keV), this will be about 20 times more sensitive than the ROSAT all sky survey, while in the hard band (2-10 keV) it w...

Aims: We present a detailed study of the supernova remnant (SNR) G296.7-0.9 in the 0.2-12 keV X-ray band. Methods: Using data from XMM-Newton we performed a spectro-imaging analysis of G296.7-0.9 in order to deduce the basic parameters of the remnant and to search for evidence of a young neutron star associated with it. Results: In X-rays the remna...

Aims: We have observed two newly detected γ-ray pulsars, PSR J1459-6053 and PSR J1614-2230, in the X-ray domain with XMM-Newton to try to enlarge the sample of pulsars for which multi-wavelength data exist. We use these data with the aim of understanding the pulsar emission mechanisms of these pulsars. Methods: We analysed the X-ray spectra to dete...

Using the High Resolution Camera (HRC) aboard the Chandra X-ray Observatory, we have re-examined the proper motion of the central compact object RX J0822-4300 in the supernova remnant Puppis A. New data from 2010 August, combined with three archival data sets from as early as 1999 December, provide a baseline of 3886 days (more than 10 1/2 years) t...

Aims: We present a detailed X-ray and radio wavelength study of G308.4-1.4, a candidate supernova remnant (SNR) in the ROSAT All Sky Survey and the MOST supernova remnant catalogue, in order to identify it as a SNR. Methods: The SNR candidate and its central sources were studied using observations from the Chandra X-ray Observatory, SWIFT, the Aust...

We discuss the possibility of an autonomous navigation system for spacecraft that is based on pulsar timing data. Pulsars are rapidly rotating neutron stars that are observable as variable celestial sources of electromagnetic radiation. Their periodic signals have timing stabilities comparable to atomic clocks and provide characteristic temporal si...

We report the likely identification of the X-ray counterpart to the gamma-ray pulsar LAT PSR J2021+4026, using images from the Chandra X-Ray Observatory's Advanced CCD Imaging Spectrometer (ACIS) and timing data from the Fermi Gamma-ray Space Telescope's Large-Area Telescope (LAT). The X-ray source that lies closest (10 arcsec) to the position dete...

We report the probable identification of the X-ray counterpart to the γ-ray pulsar PSR J2021+4026 using imaging with the Chandra X-ray Observatory Advanced CCD Imaging Spectrometer and timing analysis with the Fermi satellite. Given the statistical and systematic errors, the positions determined by both satellites are coincident. The X-ray source...

EMU is a wide-field radio continuum survey planned for the new Australian Square Kilometre Array Pathfinder (ASKAP) telescope. The primary goal of EMU is to make a deep (rms ~ 10 microJy/beam) radio continuum survey of the entire Southern Sky at 1.3 GHz, extending as far North as +30 degrees declination, with a resolution of 10 arcsec. EMU is expec...

We present a new study of the X-ray spectral properties of the Crab Pulsar. The superb angular resolution of the Chandra X-Ray Observatory enables distinguishing the pulsar from the surrounding nebulosity. Analysis of the spectrum as a function of pulse phase allows the least-biased measure of interstellar X-ray extinction due primarily to photoel...

We present a Chandra X-ray Observatory investigation of the millisecond pulsars in the globular cluster M28 (NGC 6626). In what is one of the deepest X-ray observations of a globular cluster, we firmly detect seven and possibly detect two of the 12 known M28 pulsars. With the exception of PSRs B1821-24 and J1824-2452H, the detected pulsars have rel...

The Australian Square Kilometre Array Pathfinder (ASKAP) is a 36-element array with a 30-square-degree field of view being built at the proposed SKA site in Western Australia. We are conducting a Design Study for pulsar observations with ASKAP, planning both timing and search observations. We provide an overview of the ASKAP telescope and an update...

Usually, positions of spacecraft on interplanetary or deep space missions are determined by radar tracking from ground stations, a method by which uncertainty increases with distance from Earth. As an alternative, a spacecraft equipped with e.g. an X-ray telescope could determine its position autonomoulsy via onboard analysis of X-ray pulsar signal...

We report on archival Hubble Space Telescope (HST) observations of the globular cluster M71 (NGC 6838). These observations, covering the core of the globular cluster, were performed by the Advanced Camera for Surveys (ACS) and the Wide Field Planetary Camera 2 (WFPC2). Inside the half-mass radius (r_h = 1.65') of M71, we find 33 candidate optical c...

We have systematically studied the X-ray emission properties of globular cluster millisecond pulsars in order to evaluate their spectral properties and luminosities in a uniform way. Cross-correlating the radio timing positions of the cluster pulsars with the high resolution Chandra images revealed 31 X-ray counterparts identified in nine different...

PSR J0537-6910 is the fastest rotating young pulsar. It has a period of about 16 ms and a spin-down age of 5 kyrs. The pulsar is located in the Large Magellanic Cloud and is surrounded by a bright X-ray emitting nebula. We present the results of a Chandra ACIS-S and XMM-Newton PN observation which were taken in order to explore the physical details...

We present a phase-resolved study of the X-ray spectrum of the Crab Pulsar, using data obtained in a special mode with the Chandra X-ray Observatory. The superb angular resolution easily enables discerning the Pulsar from the surrounding nebulosity, even at pulse minimum. We find that the Pulsar's X-ray spectral index varies sinusoidally with phase...

The millisecond pulsar PSR J1740-5340 in the globular cluster NGC 6397 shows radio eclipses over ~40% of its binary orbit. A first Chandra observation revealed indications for the X-ray flux being orbit dependent as well. In this work we analysed five data sets of archival Chandra data taken between 2000 and 2007 in order to investigate the emissio...

A recent Chandra observation has shown that the X-ray morphology of the supernova remnant G67.7+1.8 is well-correlated with the the double-arc structure in radio. The X-ray spectra of the northern and southern rims of G67.7+1.8 exhibit emission line features of highly ionized metals which suggests most of the observed X-rays originated from a therm...

Thanks to extensive radio surveys, about 140 radio millisecond pulsars have been uncovered in globular clusters. However, less than 20% of them have identified X-ray counterparts. Therefore, our current understanding of the high energy emission nature of the cluster pulsars is seriously biased. In this paper, we present the most recent results of o...

The idea of neutron stars can be traced back to the early 1930s, when Subrahmanyan Chandrasekhar discovered that there is no way for a collapsed stellar core with a mass more than 1.4 times the solar mass, M, to hold itself up against gravity once its nuclear fuel is exhausted. This implies that a star left with M › 1.4 M (the Chandrasekhar limit)...

Radio Pulsar Statistics.- Radio Emission Properties of Pulsars.- Rotating Radio Transients.- Intermittent Pulsars.- The Double Pulsar: A Unique Lab for Relativistic Plasma Physics and Tests of General Relativity.- X-Ray Emission from Pulsars and Neutron Stars.- Isolated Neutron Stars: The Challenge of Simplicity.- Millisecond Pulsars in Globular Cl...

We present spectral and long-timescale variability analyses of Chandra X-Ray Observatory ACIS-S observations of the 19 millisecond pulsars (MSPs) with precisely known positions in the globular cluster 47 Tucanae. The X-ray emission of the majority of these MSPs is well described by a thermal (blackbody or neutron star hydrogen atmosphere) spectrum...

We present precise localizations of AXP 1E1841-045 and SGR 1627-41 with Chandra. We obtained new infrared observations of SGR 1627-41 and reanalyzed archival observations of AXP 1E1841-045 in order to refine their positions and search for infrared counterparts. A faint source is detected inside the error circle of AXP 1E1841-045. In the case of SGR...