A. Fruscione

University of Exeter, Exeter, England, United Kingdom

Are you A. Fruscione?

Claim your profile

Publications (135)377.48 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The Cygnus OB2 association is the largest concentration of young and massive stars within 2 kpc of the Sun, including an estimated 65 O-type stars and hundreds of OB stars. The Chandra Cygnus OB2 Legacy Survey is a large imaging program undertaken with the Advanced CCD Imaging Spectrometer onboard the Chandra X-ray Observatory. The survey has imaged the central 0.5 deg^2 of the Cyg OB2 association with an effective exposure of 120ks and an outer 0.35 deg^2 area with an exposure of 60ks. Here we describe the survey design and observations, the data reduction and source detection, and present a catalog of 8,000 X-ray point sources. The survey design employs a grid of 36 heavily (~50%) overlapping pointings, a method that overcomes Chandra's low off-axis sensitivity and produces a highly uniform exposure over the inner 0.5 deg^2. The full X-ray catalog is described here and is made available online.
    08/2014;
  • [Show abstract] [Hide abstract]
    ABSTRACT: We studied a peculiar X-ray source detected in the Chandra-COSMOS survey at z=0.359. CID-42 is the only source in the survey which clearly shows two optical sources (in the HST/ACS image) embedded in the same galaxy. Civano et al. 2010 and 2012 showed that one source is a bright active galactic nucleus (AGN) recoiling from the center of the galaxy, while the other is most likely a star-forming region in the center of the galaxy. CID-42 was imaged in the X-rays using both XMM-Newton and Chandra satellites. The X-ray spectra show a rare Kalpha line inverted P-Cygni profile, i.e. a redshifted absorption component and an emission component. Redshifted absorption lines are usually explained as high velocity inflows of ionized material very close to the active black hole. CID-42 absorption feature showed a considerable variability in the line energy peak, implying rapid changes of velocity and ionization state of the infalling material. We present the results of a new XMM-Newton single long (130 ks) observation obtained to perform an accurate modeling of the absorption line. The results show that the highly significant (3 sigma) absorption feature observed between 2003 and 2007 with XMM and Chandra is not present in the new observation. We performed a detailed statistical analysis to understand if this result is due to a physical change in the absorber rather than to an instrumental effect. We also studied the connection between the presence of high velocity inflows and recoiling supermassive black hole.
    01/2014;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present a detailed spectral analysis of new XMM-Newton data of the source CXOC J100043.1+020637, also known as CID-42, detected in the COSMOS survey at z = 0.359. Previous works suggested that CID-42 is a candidate recoiling supermassive black holes showing also an inverted P-Cygni profile in the X- ray spectra at ~6 keV (rest) with an iron emission line plus a redshifted absorption line (detected at 3sigma in previous XMM-Newton and Chandra observations). Detailed analysis of the absorption line suggested the presence of ionized material inflowing into the black hole at high velocity. In the new long XMM-Newton observation, while the overall spectral shape remains constant, the continuum 2-10 keV flux decreased of ~20% with respect to previous observation and the absorption line is undetected. The upper limit on the intensity of the absorption line is EW<162 keV. Extensive Monte Carlo simulations show that the non detection of the line is solely due to variation in the properties of the inflowing material, in agreement with the transient nature of these features, and that the intensity of the line is lower than the previously measured with a probability of 98.8%. In the scenario of CID-42 as recoiling SMBH, the absorption line can be interpreted as due to inflow of gas with variable density and located in the proximity of the SMBH and recoiling with it. New monitoring observations will be requested to further characterize this line.
    The Astrophysical Journal 10/2013; 778(1). · 6.73 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The formation of stars in massive clusters is one of the main modes of the star formation process. However, the study of massive star forming regions is hampered by their typically large distances to the Sun. One exception to this is the massive star forming region Cygnus OB2 in the Cygnus X region, at the distance of about 1400 pc. Cygnus OB2 hosts very rich populations of massive and low-mass stars, being the best target in our Galaxy to study the formation of stars, circumstellar disks, and planets in presence of massive stars. In this paper we combine a wide and deep set of photometric data, from the r band to 24 micron, in order to select the disk bearing population of stars in Cygnus OB2 and identify the class I, class II, and stars with transition and pre-transition disks. We selected 1843 sources with infrared excesses in an area of 1 degree x 1 degree centered on Cyg OB2 in several evolutionary stages: 8.4% class I, 13.1% flat-spectrum sources, 72.9% class II, 2.3% pre-transition disks, and 3.3% transition disks. The spatial distribution of these sources shows a central cluster surrounded by a annular overdensity and some clumps of recent star formation in the outer region. Several candidate subclusters are identified, both along the overdensity and in the rest of the association.
    The Astrophysical Journal 06/2013; 773(2). · 6.73 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The young massive cluster Cyg OB2 is the closest massive star forming region to the Sun, with hundreds of OB members, and then the best target in the Milky Way to study the feedback of massive stars on the star formation process. To study in detail the stellar population of such a unique target, Cyg OB2 has been observed with GTC/OSIRIS and Chandra/ACIS-I. We present the OSIRIS observations, the catalog and the preliminary scientific results.
    05/2013;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present the X-ray spectral analysis of the 390 brightest extragalactic sources in the Chandra-COSMOS catalog, showing at least 70 net counts in the 0.5-7 keV band. This sample has a 100% completeness in optical-IR identification, with 75% of the sample having a spectroscopic redshift and 25% a photometric redshift. Our analysis allows us to accurately determine the intrinsic absorption, the broad band continuum shape ({\Gamma}) and intrinsic L(2-10) distributions, with an accuracy better than 30% on the spectral parameters for 95% of the sample. The sample is equally divided in type-1 (49.7%) and type-2 AGN (48.7%) plus few passive galaxies at low z. We found a significant difference in the distribution of {\Gamma} of type-1 and type-2, with small intrinsic dispersion, a weak correlation of {\Gamma} with L(2-10) and a large population (15% of the sample) of high luminosity, highly obscured (QSO2) sources. The distribution of the X ray/Optical flux ratio (Log(FX /Fi)) for type-1 is narrow (0 < X/O < 1), while type-2 are spread up to X/O = 2. The X/O correlates well with the amount of X-ray obscuration. Finally, a small sample of Compton thick candidates and peculiar sources is presented. In the appendix we discuss the comparison between Chandra and XMM-Newton spectra for 280 sources in common. We found a small systematic difference, with XMM-Newton spectra that tend to have softer power-laws and lower obscuration.
    Monthly Notices of the Royal Astronomical Society 02/2013; 431(1). · 5.52 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The equatorial 2 deg2 COSMOS area is the only large field for which a complete, deep, pan-chromatic data set exists, from an outstanding survey effort, and that all large telescopes can observe. Now, this pioneering and ambitious COSMOS survey is undergoing major extension, pushing its frontiers via the newly approved Chandra COSMOS Legacy Survey, the second largest Chandra proposal ever approved.'COSMOS-Legacy' will uniformly cover the 1.7 deg2 COSMOS/HST field with 2.8 Ms of Chandra ACIS-I imaging at ~160 ksec depth. This project expands the current deep C-COSMOS area by a factor of ~3 at ~3e-16 (1.45 vs 0.44 deg2). This will be achieved with 56x50 ks tiles covering a total area of 2.2 deg2, which will be observed during Chandra Cycle 14. The area and depth of COSMOS Legacy are designed to detect ~{40 zgt4, and ~}4 zgt5 Large Scale Structures on gt15 arcmin scales. These structures have proven to connect luminous AGN (over 200 at zgt3 will be detected) and sub-mm galaxies. COSMOS Legacy will also probe mini-quasars at zgt7, using anistotropies of the unresolved X-ray Background, and the masses of the Dark Matter halos hosting X-ray AGN up to 3, via autocorrelation functions on ~30arcmin scales. To fully achieve these goals, COSMOS Legacy is complemented by spectroscopic follow-up with DEIMOS and MOSFIRE at Keck and KMOS at the VLT and FMOS at Subaru, just approved observations with Spitzer and JVLA, and with harder (5-80 keV) X-ray imaging with NuSTAR. In the near future, observations with Subaru HyperSuprimeCam (grizY) to r(AB)=28.2 are planned.
    American Astronomical Society Meeting Abstracts; 01/2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: The coalescence of two SMBHs in galaxy major merger gives rise to the strongest Gravitational Wave (GW) events in the universe. Typically, the GW emission is asymmetric and causes the newly merged single SMBH to displace from the galaxy center of few parsecs. Under particular condition of BH spin and mass ratio, the SMBH can gain a significant velocity (up to ~5000km/s) and it may be displaced by several kpc. If the SMBH is ejected from the galaxy, or even if wanders through the halo for several Gyrs, it will continue to shine for 10^6-10^7 yr, until it exhausts the fuel and is no longer recognizable as an active SMBH. The partial or total absence of the SMBH from the galaxy center has strong implications on the SF history of the galaxy. Despite predicted by theoretical models of structure formation, GW recoiling SMBHs are very hard to detect. The recoils with high probability have a very small velocity resulting in undetectable offsets, those with low probability can escape easily from the galaxy and not been recognized as such. We discovered in the COSMOS survey CID-42 (z=0.359), the best candidate recoiling SMBH to date, just caught when still active. CID-42 clearly shows both the presence of two compact sources, ~2.5 kpc embedded in the same galaxy in HST imaging, and a ~1100km/s velocity offset between the narrow and broad components of Hα, in 3 optical spectra. High resolution Chandra data were crucial to resolve the X-ray emission from the two optical sources and determines the AGN activity level of each. The results clearly favor the recoiling scenario for this source. Models & simulations have been developed to explain the observed properties of CID-42.
    09/2012;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present Chandra High Resolution Camera observations of CID-42, a candidate recoiling supermassive black hole (SMBH) at z = 0.359 in the COSMOS survey. CID-42 shows two optical compact sources resolved in the HST/ACS image embedded in the same galaxy structure and a velocity offset of ~1300 km s–1 between the Hβ broad and narrow emission line, as presented by Civano et al. Two scenarios have been proposed to explain the properties of CID-42: a gravitational wave (GW) recoiling SMBH and a double Type 1/Type 2 active galactic nucleus (AGN) system, where one of the two is recoiling because of slingshot effect. In both scenarios, one of the optical nuclei hosts an unobscured AGN, while the other one, either an obscured AGN or a star-forming compact region. The X-ray Chandra data allow us to unambiguously resolve the X-ray emission and unveil the nature of the two optical sources in CID-42. We find that only one of the optical nuclei is responsible for the whole X-ray unobscured emission observed and a 3σ upper limit on the flux of the second optical nucleus is measured. The upper limit on the X-ray luminosity plus the analysis of the multiwavelength spectral energy distribution indicate the presence of a star-forming region in the second source rather than an obscured SMBH, thus favoring the GW recoil scenario. However, the presence of a very obscured SMBH cannot be fully ruled out. A new X-ray feature, in a SW direction with respect to the main source, is discovered and discussed.
    The Astrophysical Journal 05/2012; 752(1):49. · 6.73 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8 Ms, Chandra program that has imaged the central 0.9 deg^2 of the COSMOS field down to limiting depths of 1.9 10^-16 erg cm^-2 s-1 in the 0.5-2 keV band, 7.3 10^-16 erg cm^-2 s^-1 in the 2-10 keV band, and 5.7 10^-16 erg cm^-2 s-1 in the 0.5-10 keV band. In this paper we report the i, K and 3.6micron identifications of the 1761 X-ray point sources. We use the likelihood ratio technique to derive the association of optical/infrared counterparts for 97% of the X-ray sources. For most of the remaining 3%, the presence of multiple counterparts or the faintness of the possible counterpart prevented a unique association. For only 10 X-ray sources we were not able to associate a counterpart, mostly due to the presence of a very bright field source close by. Only 2 sources are truly empty fields. Making use of the large number of X-ray sources, we update the "classic locus" of AGN and define a new locus containing 90% of the AGN in the survey with full band luminosity >10^42 erg/s. We present the linear fit between the total i band magnitude and the X-ray flux in the soft and hard band, drawn over 2 orders of magnitude in X-ray flux, obtained using the combined C-COSMOS and XMM-COSMOS samples. We focus on the X-ray to optical flux ratio (X/O) and we test its known correlation with redshift and luminosity, and a recently introduced anti-correlation with the concentration index (C). We find a strong anti-correlation (though the dispersion is of the order of 0.5 dex) between C and X/O, computed in the hard band, and that 90% of the obscured AGN in the sample with morphological information live in galaxies with regular morphology (bulgy and disky/spiral), suggesting that secular processes govern a significant fraction of the BH growth at X-ray luminosities of 10^43- 10^44.5 erg/s.
    The Astrophysical Journal Supplement Series 05/2012; 201(2). · 16.24 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present Chandra High Resolution Camera observations of CID-42, a candidate recoiling supermassive black hole (SMBH) at z=0.359 in the COSMOS survey. CID-42 shows two optical compact sources resolved in the HST/ACS image embedded in the same galaxy structure and a velocity offset of ~1300 km/s between the H\beta\ broad and narrow emission line, as presented by Civano et al. (2010). Two scenarios have been proposed to explain the properties of CID-42: a GW recoiling SMBH and a double Type 1/ Type 2 AGN system, where one of the two is recoiling because of slingshot effect. In both scenario, one of the optical nuclei hosts an unobscured AGN, while the other one, either an obscured AGN or a star forming compact region. The X-ray Chandra data allow to unambiguously resolve the X-ray emission, and unveil the nature, of the two optical sources in CID-42. We find that only one of the optical nuclei is responsible for the whole X-ray unobscured emission observed and a 3sigma upper limit on the flux of the second optical nucleus is measured. The upper limit on the X-ray luminosity plus the analysis of the multiwavelength spectral energy distribution indicate the presence of a starforming region in the second source rather than an obscured SMBH, thus favoring the GW recoil scenario. However the presence of a very obscured SMBH cannot be fully ruled-out. A new X-ray feature, in a SW direction with respect to the main source, is discovered and discussed.
    05/2012;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, we release accurate photometric redshifts for 1692 counterparts to Chandra sources in the central square degree of the Cosmic Evolution Survey (COSMOS) field. The availability of a large training set of spectroscopic redshifts that extends to faint magnitudes enabled photometric redshifts comparable to the highest quality results presently available for normal galaxies. We demonstrate that morphologically extended, faint X-ray sources without optical variability are more accurately described by a library of normal galaxies (corrected for emission lines) than by active galactic nucleus (AGN) dominated templates, even if these sources have AGN-like X-ray luminosities. Preselecting the library on the bases of the source properties allowed us to reach an accuracy \sigma _{\Delta z/(1+z_{spec})}\sim 0.015 with a fraction of outliers of 5.8% for the entire Chandra-COSMOS sample. In addition, we release revised photometric redshifts for the 1735 optical counterparts of the XMM-detected sources over the entire 2 deg2 of COSMOS. For 248 sources, our updated photometric redshift differs from the previous release by Δz > 0.2. These changes are predominantly due to the inclusion of newly available deep H-band photometry (H AB = 24 mag). We illustrate once again the importance of a spectroscopic training sample and how an assumption about the nature of a source together, with the number and the depth of the available bands, influences the accuracy of the photometric redshifts determined for AGN. These considerations should be kept in mind when defining the observational strategies of upcoming large surveys targeting AGNs, such as eROSITA at X-ray energies and the Australian Square Kilometre Array Pathfinder Evolutionary Map of the Universe in the radio band. Based on observations by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of the National Aeronautics Space Administration under contract NAS8-03060. Also based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA Inc., under NASA contract NAS 5-26555. Also based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407. Also based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan; the XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA; the European Southern Observatory under Large Program 175.A-0839, Chile; the Kitt Peak National Observatory, Cerro Tololo Inter-American Observatory and the National Optical Astronomy Observatory, which are operated by the Association of Universities for Research in Astronomy, Inc. (AURA), under cooperative agreement with the National Science Foundation; the Canada-France-Hawaii Telescope with MegaPrime/MegaCam operated as a joint project by the CFHT Corporation, CEA/DAPNIA, the NRC and CADC of Canada, the CNRS of France, TERAPIX, and the University of Hawaii.
    The Astrophysical Journal 11/2011; 742:61. · 6.73 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: With this paper, we release accurate photometric redshifts for 1692 counterparts to Chandra sources in the central square degree of the COSMOS field. The availability of a large training set of spectroscopic redshifts that extends to faint magnitudes enabled photometric redshifts comparable to the highest quality results presently available for normal galaxies. We demonstrate that morphologically extended, faint X-ray sources without optical variability are more accurately described by a library of normal galaxies (corrected for emission lines) than by AGN-dominated templates, even if these sources have AGN-like X-ray luminosities. Preselecting the library on the bases of the source properties allowed us to reach an accuracy sigma_(Delta z/(1+z_spec)) \sim0.015 with a fraction of outliers of 5.8% for the entire Chandra-COSMOS sample. In addition, we release revised photometric redshifts for the 1735 optical counterparts of the XMM-detected sources over the entire 2 sq. deg.of COSMOS. For 248 sources, our updated photometric redshift differs from the previous release by Delta z>0.2. These changes are predominantly due to the inclusion of newly available deep H-band photometry H_AB=24 mag. We illustrate once again the importance of a spectroscopic training sample and how an assumption about the nature of a source together with the number and the depth of the available bands influence the accuracy of the photometric redshifts determined for AGN. These considerations should be kept in mind when defining the observational strategies of upcoming large surveys targeting AGN, such as eROSITA at X-ray energies and ASKAP/EMU in the radio band.
    08/2011;
  • 08/2011;
  • 08/2011;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Chandra X-ray Center has adopted Python as the primary scripting language in the Chandra Interactive Analysis of Observations software package (CIAO). Python is a dynamic object-oriented programming language that offers strong support for integration with other languages and tools and comes with extensive standard libraries. Integrating Python into CIAO allows us to develop powerful new scripts for data analysis, as well as rewrite and improve upon popular CIAO contributed scripts. We discuss the coding guidelines that we have developed during this process, using specific CIAO contributed scripts --- available for download online --- as examples.
    07/2011;
  • Anna Wolter, Antonella Fruscione, Nina Bonaventura
    [Show abstract] [Hide abstract]
    ABSTRACT: We present XMM-Newton observations of three high X-ray luminosity ``normal'' galaxies: MS1204.1+2826, MS1143.6+2040 and MS1309.1+3208. These objects are part of a flux limited sample of 8 high X-ray luminosity galaxies from the Einstein Medium Sensitivity Survey. The observations were performed with the aim of confirming that high X-ray luminosity normal galaxies discovered in deep XMM-Newton and Chandra survey, and often classified as new classes of exotic objects, were already present in earlier and much brighter samples. These ``unusual'' populations appearing at low X-ray fluxes represent the low-flux counterparts of the nearby and X-ray bright ``galaxies'' that have been known for decades.
    07/2010;
  • [Show abstract] [Hide abstract]
    ABSTRACT: We present a detailed X-ray spectral analysis of 401 bright sources in the Chandra-COSMOS catalogue with >80 net counts in the 0.5-7 keV band. For 294 sources, with available XMM-Newton spectra with >80 net counts, we performed an indipendent spectral fit of XMM-Newton data, in order to compare the results and look for variability of fit parameters. Finally we performed the simultaneous fit of Chandra and XMM-Newton spectra. The main results concern the distribution of photon index Gamma, the nature of the population of sources classified as passive galaxies from the optical/IR SED, but hosting an obscured AGN, and the mismatch between Chandra and XMM-Newton determination of column density.
    07/2010;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present a detailed study of a peculiar source detected in the COSMOS survey at z = 0.359. Source CXOC J100043.1+020637, also known as CID-42, has two compact optical sources embedded in the same galaxy. The distance between the two, measured in the HST/ACS image, is 0495 ± 0005 that, at the redshift of the source, corresponds to a projected separation of 2.46 ± 0.02 kpc. A large (~1200 km s–1) velocity offset between the narrow and broad components of Hβ has been measured in three different optical spectra from the VLT/VIMOS and Magellan/IMACS instruments. CID-42 is also the only X-ray source in COSMOS, having in its X-ray spectra a strong redshifted broad absorption iron line and an iron emission line, drawing an inverted P-Cygni profile. The Chandra and XMM-Newton data show that the absorption line is variable in energy by ΔE = 500 eV over four years and that the absorber has to be highly ionized in order not to leave a signature in the soft X-ray spectrum. That these features—the morphology, the velocity offset, and the inverted P-Cygni profile—occur in the same source is unlikely to be a coincidence. We envisage two possible explanations, both exceptional, for this system: (1) a gravitational wave (GW) recoiling black hole (BH), caught 1-10 Myr after merging; or (2) a Type 1/Type 2 system in the same galaxy where the Type 1 is recoiling due to the slingshot effect produced by a triple BH system. The first possibility gives us a candidate GW recoiling BH with both spectroscopic and imaging signatures. In the second case, the X-ray absorption line can be explained as a BAL-like outflow from the foreground nucleus (a Type 2 AGN) at the rearer one (a Type 1 AGN), which illuminates the otherwise undetectable wind, giving us the first opportunity to show that fast winds are present in obscured active galactic nuclei (AGNs), and possibly universal in AGNs.
    The Astrophysical Journal 06/2010; 717(1):209. · 6.73 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report the final optical identifications of the medium-depth (~60 ks), contiguous (2 deg2) XMM-Newton survey of the COSMOS field. XMM-Newton has detected ~1800 X-ray sources down to limiting fluxes of ~5 × 10–16, ~3 × 10–15, and ~7 × 10–15 erg cm–2 s–1 in the 0.5-2 keV, 2-10 keV, and 5-10 keV bands, respectively (~1 × 10–15, ~6 × 10–15, and ~1 × 10–14 erg cm–2 s–1, in the three bands, respectively, over 50% of the area). The work is complemented by an extensive collection of multiwavelength data from 24 μm to UV, available from the COSMOS survey, for each of the X-ray sources, including spectroscopic redshifts for 50% of the sample, and high-quality photometric redshifts for the rest. The XMM and multiwavelength flux limits are well matched: 1760 (98%) of the X-ray sources have optical counterparts, 1711 (~95%) have IRAC counterparts, and 1394 (~78%) have MIPS 24 μm detections. Thanks to the redshift completeness (almost 100%) we were able to constrain the high-luminosity tail of the X-ray luminosity function confirming that the peak of the number density of log LX > 44.5 active galactic nuclei (AGNs) is at z ~ 2. Spectroscopically identified obscured and unobscured AGNs, as well as normal and star-forming galaxies, present well-defined optical and infrared properties. We devised a robust method to identify a sample of ~150 high-redshift (z > 1), obscured AGN candidates for which optical spectroscopy is not available. We were able to determine that the fraction of the obscured AGN population at the highest (LX > 1044 erg s–1) X-ray luminosity is ~15%-30% when selection effects are taken into account, providing an important observational constraint for X-ray background synthesis. We studied in detail the optical spectrum and the overall spectral energy distribution of a prototypical Type 2 QSO, caught in a stage transitioning from being starburst dominated to AGN dominated, which was possible to isolate only thanks to the combination of X-ray and infrared observations.
    The Astrophysical Journal 05/2010; 716(1):348. · 6.73 Impact Factor

Publication Stats

1k Citations
377.48 Total Impact Points

Institutions

  • 2013
    • University of Exeter
      Exeter, England, United Kingdom
  • 2012
    • Max Planck Institute for Astronomy
      Heidelburg, Baden-Württemberg, Germany
    • Harvard University
      • Department of Astronomy
      Cambridge, Massachusetts, United States
  • 1998–2011
    • Harvard-Smithsonian Center for Astrophysics
      • Smithsonian Astrophysical Observatory
      Cambridge, Massachusetts, United States
  • 2010
    • Universities Space Research Association
      Houston, Texas, United States
  • 2009
    • Max Planck Institute for Extraterrestrial Physics
      Arching, Bavaria, Germany
  • 1997
    • George Mason University
      Fairfax, Virginia, United States
  • 1994–1996
    • University of California, Berkeley
      • Space Sciences Laboratory
      Berkeley, California, United States
  • 1993
    • University of Chicago
      Chicago, Illinois, United States