Recursos de colección

Caltech Authors (155.447 recursos)

Repository of works by Caltech published authors.

Group = NuSTAR

Mostrando recursos 1 - 20 de 63

  1. The nature of X-ray spectral variability in MCG-6-30-15

    Kammoun, E. S.; Papadakis, I. E.
    The flux-flux plot (FFP) method can provide model-independent clues regarding the X-ray variability of active galactic nuclei. To use it properly, the bin size of the light curves should be as short as possible, provided the average counts in the light curve bins are larger than $\sim 200$. We apply the FFP method to the 2013, simultaneous XMM-Newton and NuSTAR observations of the Seyfert galaxy MCG$-$6-30-15, in the 0.3-40 keV range. The FFPs above $\sim 1.6$ keV are well-described by a straight line. This result rules out spectral slope variations and the hypothesis of absorption driven variability. Our results are fully consistent with a power-law component varying in normalization...

  2. Truncation of the Accretion Disk at One Third of the Eddington Limit in the Neutron Star Low-Mass X-ray Binary Aquila X-1

    Ludlam, Renee M.; Miller, Jon M.; Degenaar, Nathalie; Sanna, Andrea; Cackett, Edward M.; Altamirano, Diego; King, Ashley L.
    We perform a reflection study on a new observation of the neutron star low-mass X-ray binary Aquila X-1 taken with NuSTAR during the August 2016 outburst and compare with the July 2014 outburst. The source was captured at $\sim32\%\ L_{\mathrm{Edd}}$, which is over four times more luminous than the previous observation during the 2014 outburst. Both observations exhibit a broadened Fe line profile. Through reflection modeling, we determine that the inner disk is truncated $R_{in,\ 2016}=11_{-1}^{+2}\ R_{g}$ (where $R_{g}=GM/c^{2}$) and $R_{in,\ 2014}=14\pm2\ R_{g}$ (errors quoted at the 90% confidence level). Fiducial neutron star parameters (M$_{NS}=1.4$ M$_{\odot}$, $R_{NS}=10$ km) give a stellar radius of $R_{NS}=4.85\ R_{g}$; our measurements rule out a...

  3. The active nucleus of the ULIRG IRAS F00183-7111 viewed by NuSTAR

    Iwasawa, K.; Spoon, H. W. W.; Comastri, A.; Gilli, R.; Lanzuisi, G.; Piconcelli, E.; Vignali, C.; Brusa, M.; Puccetti, S.
    We present an X-ray study of the ultra-luminous infrared galaxy IRAS F00183-7111 (z=0.327), using data obtained from NuSTAR, Chandra X-ray Observatory, Suzaku and XMM-Newton. The Chandra imaging shows that a point-like X-ray source is located at the nucleus of the galaxy at energies above 2 keV. However, the point source resolves into diffuse emission at lower energies, extending to the east, where the extranuclear [O III] emission, presumably induced by a galactic-scale outflow, is present. The nuclear source is detected by NuSTAR up to the rest-frame 30 keV. The strong, high-ionization Fe K line, first seen by XMM-Newton, and subsequently by Suzaku and Chandra, is not detected in the...

  4. A Suzaku, NuSTAR, and XMM-Newton view on variable absorption and relativistic reflection in NGC 4151

    Beuchert, T.; Markowitz, A. G.; Dauser, T.; García, J. A.; Keck, M. L.; Wilms, J.; Kadler, M.; Brenneman, L. W.; Zdziarski, A. A.
    We disentangle X-ray disk reflection from complex line-of-sight absorption in the nearby Seyfert NGC 4151, using a suite of Suzaku, NuSTAR, and XMM-Newton observations. Extending upon earlier published work, we pursue a physically motivated model using the latest angle-resolved version of the lamp-post geometry reflection model relxillCp_lp together with a Comptonization continuum. We use the long-look simultaneous Suzaku/NuSTAR observation to develop a baseline model wherein we model reflected emission as a combination of lamp-post components at the heights of 1.2 and 15.0 gravitational radii. We argue for a vertically extended corona as opposed to two compact and distinct primary sources....

  5. The NuSTAR Serendipitous Survey: Hunting for the Most Extreme Obscured AGN at >10 keV

    Lansbury, G. B.; Baloković, M.; Brightman, M.; Harrison, F. A.; Walton, D. J.
    We identify sources with extremely hard X-ray spectra (i.e., with photon indices of Γ ≾ 0.6) in the 13 deg^2 NuSTAR serendipitous survey, to search for the most highly obscured active galactic nuclei (AGNs) detected at > 10 keV. Eight extreme NuSTAR sources are identified, and we use the NuSTARdata in combination with lower-energy X-ray observations (from Chandra, Swift XRT, and XMM-Newton) to characterize the broadband (0.5–24 keV) X-ray spectra. We find that all of the extreme sources are highly obscured AGNs, including three robust Compton-thick (CT; N_H > 1.5 x 10^(24) cm^(−2)) AGNs at low redshift (z < 0.1)...

  6. Multiwavelength Study of Quiescent States of Mrk 421 with Unprecedented Hard X-Ray Coverage Provided by NuSTAR in 2013

    Baloković, M.; Forster, K.; Grefenstette, B.; Harrison, F. A.; Madsen, K. K.; Mao, P. H.; Miyasaka, H.; Rana, V.; Hovatta, T.; Readhead, A. C. R.
    We present coordinated multiwavelength observations of the bright, nearby BL Lacertae object Mrk 421 taken in 2013 January–March, involving GASP-WEBT, Swift, NuSTAR, Fermi-LAT, MAGIC, VERITAS, and other collaborations and instruments, providing data from radio to very high energy (VHE) γ-ray bands. NuSTAR yielded previously unattainable sensitivity in the 3–79 keV range, revealing that the spectrum softens when the source is dimmer until the X-ray spectral shape saturates into a steep Γ ≈ 3 power law, with no evidence for an exponential cutoff or additional hard components up to ~80 keV. For the first time, we observed both the synchrotron and...

  7. Multiwavelength Study of Quiescent States of Mrk 421 with Unprecedented Hard X-Ray Coverage Provided by NuSTAR in 2013

    Baloković, M.; Forster, K.; Grefenstette, B.; Harrison, F. A.; Madsen, K. K.; Mao, P. H.; Miyasaka, H.; Rana, V.; Hovatta, T.; Readhead, A. C. R.
    We present coordinated multiwavelength observations of the bright, nearby BL Lacertae object Mrk 421 taken in 2013 January–March, involving GASP-WEBT, Swift, NuSTAR, Fermi-LAT, MAGIC, VERITAS, and other collaborations and instruments, providing data from radio to very high energy (VHE) γ-ray bands. NuSTAR yielded previously unattainable sensitivity in the 3–79 keV range, revealing that the spectrum softens when the source is dimmer until the X-ray spectral shape saturates into a steep Γ ≈ 3 power law, with no evidence for an exponential cutoff or additional hard components up to ~80 keV. For the first time, we observed both the synchrotron and...

  8. Microflare Heating of a Solar Active Region Observed with NuSTAR, Hinode/XRT, and SDO/AIA

    Wright, Paul J.; Hannah, Iain G.; Grefenstette, Brian W.; Glesener, Lindsay; Krucker, Säm; Hudson, Hugh S.; Smith, David M.; Marsh, Andrew J.; White, Stephen M.; Kuhar, Matej
    NuSTAR is a highly sensitive focusing hard X-ray (HXR) telescope and has observed several small microflares in its initial solar pointings. In this paper, we present the first joint observation of a microflare with NuSTAR and Hinode/XRT on 2015 April 29 at ~11:29 UT. This microflare shows the heating of material to several million Kelvin, observed in soft X-rays with Hinode/XRT, and was faintly visible in the extreme ultraviolet with SDO/AIA. For three of the four NuSTAR observations of this region (pre-flare, decay, and post-flare phases), the spectrum is well fitted by a single thermal model of 3.2–3.5 MK, but...

  9. Broadband X-ray spectral analysis of the Seyfert 1 galaxy GRS 1734-292

    Tortosa, A.; Marinucci, A.; Matt, G.; Bianchi, S.; La Franca, F.; Ballantyne, D. R.; Boorman, P. G.; Fabian, A. C.; Farrah, D.; Fuerst, F.; Gandhi, P.; Harrison, F. A.; Koss, M. J.; Ricci, C.; Stern, D.; Ursini, F.; Walton, D. J.
    We discuss the broad-band X-ray spectrum of GRS 1734−292 obtained from non-simultaneous XMM–Newton and NuSTAR (Nuclear Spectroscopic Telescope Array) observations, performed in 2009 and 2014, respectively. GRS1734−292 is a Seyfert 1 galaxy, located near the Galactic plane at z = 0.0214. The NuSTAR spectrum (3–80 keV) is dominated by a primary power-law continuum with Γ = 1.65 ± 0.05 and a high-energy cut-off E_c=53^(+11)_(−8) keV, one of the lowest measured by NuSTAR in a Seyfert galaxy. Comptonization models show a temperature of the coronal plasma of kT_e=11.9^(+1.2)_(−0.9) keV and an optical depth, assuming a slab geometry, τ=2.98^(+0.16)_(−0.19) or a similar...

  10. Contemporaneous broadband observations of three high-redshift BL Lac Objects


    We have collected broadband spectral energy distributions (SEDs) of three BL Lac objects, 3FGL J0022.1−1855 (z=0.689), 3FGL J0630.9−2406 (z >∼1.239), and 3FGL J0811.2−7529 (z=0.774), detected by Fermi with relatively flat GeV spectra. By observing simultaneously in the near-IR to hard X-ray band, we can well characterize the high end of the synchrotron component of the SED. Thus, fitting the SEDs to synchro-Compton models of the dominant emission from the relativistic jet, we can constrain the underlying particle properties and predict the shape of the GeV Compton component. Standard extragalactic background light (EBL) models explain the high-energy absorption well, with poorer fits for high UV models. The fits show...

  11. Detection of the high energy cut-off from the Seyfert 1.5 galaxy NGC 5273

    Pahari, Mayukh; McHardy, I. M.; Mallick, Labani; Dewangan, G. C.; Misra, R.
    We perform the NuSTAR and Swift/XRT joint energy spectral fitting of simultaneous observations from the broad-line Seyfert 1.5 galaxy NGC 5273. When fitted with the combination of an exponential cut-off power-law and a reflection model, a high energy cut-off is detected at 143$^{+96}_{-40}$ keV with 2-sigma significance. Existence of such cut-off is also consistent with the observed Comptonizing electron temperature when fitted with a Comptonization model independently. We observe a moderate hard X-ray variability of the source over the time-scale of ~12 years using INTEGRAL/ISGRI observations in the energy range of 20-100 keV. When the hard band count rate (6-20 keV) is plotted against the soft band count...

  12. Disentangling the Complex Broadband X-ray Spectrum of IRAS 13197-1627 with NuSTAR, XMM-Newton and Suzaku

    Walton, D. J.; Brightman, M.; Risaliti, G.; Fabian, A. C.; Fürst, F.; Harrison, F. A.; Lohfink, A. M.; Matt, G.; Miniutti, G.; Parker, M. L.; Stern, D.
    We present results from a coordinated XMM-Newton+NuSTAR observation of the type 1.8 Seyfert galaxy IRAS 13197-1627. This is a highly complex source, with strong contributions from relativistic reflection from the inner accretion disk, neutral absorption and further reprocessing by more distant material, and ionised absorption from an outflow. We undertake a detailed spectral analysis combining the broadband coverage provided by XMMNewton+NuSTAR with a multi-epoch approach incorporating archival observations performed by XMM-Newton and Suzaku. Our focus is on characterising the reflection from the inner accretion disk, which previous works have suggested may dominate the AGN emission, and constraining the black hole spin. Using lamppost disk reflection models, we find...

  13. XMM-Newton and NuSTAR joint observations of Mrk 915: a deep look into the X-ray properties

    Ballo, L.; Severgnini, P.; Della Ceca, R.; Braito, V.; Campana, S.; Moretti, A.; Vignali, C.; Zaino, A.
    We report on the X-ray monitoring programme (covering slightly more than 11 days) carried out jointly by XMM-Newton and NuSTAR on the intermediate Seyfert galaxy Mrk 915. The light curves extracted in different energy ranges show a variation in intensity but not a significant change in spectral shape. The X-ray spectra reveal the presence of a two-phase warm absorber: a fully covering mildly ionized structure [log xi/(erg cm/s)~2.3, NH~1.3x10^21 cm-2] and a partial covering (~90 per cent) lower ionized one [log xi/(erg cm/s)~0.6, NH~2x10^22 cm-2]. A reflection component from distant matter is also present. Finally, a high-column density (NH~1.5x10^23 cm-2) distribution of neutral matter covering a small fraction of...

  14. X-ray bolometric corrections for Compton-thick active galactic nuclei

    Brightman, M.; Baloković, M.; Ballantyne, D. R.; Bauer, F. E.; Boorman, P. G.; Buchner, J.; Brandt, W. N.; Comastri, A.; Del Moro, A.; Farrah, D.; Gandhi, P.; Harrison, F. A.; Koss, M.; Lanz, L.; Masini, A.; Ricci, C.; Stern, D.; Vasudevan, R.; Walton, D. J.
    We present X-ray bolometric correction factors, κ_(Bol) (≡L_(Bol)/LX), for Compton-thick (CT) active galactic nuclei (AGN) with the aim of testing AGN torus models, probing orientation effects, and estimating the bolometric output of the most obscured AGN. We adopt bolometric luminosities, L_(Bol), from literature infrared (IR) torus modeling and compile published intrinsic 2–10 keV X-ray luminosities, L_X, from X-ray torus modeling of NuSTAR data. Our sample consists of 10 local CT AGN where both of these estimates are available. We test for systematic differences in κ_(Bol) values produced when using two widely used IR torus models and two widely used X-ray...

  15. The X-Ray Reflection Spectrum of the Radio-loud Quasar 4C 74.26

    Lohfink, Anne M.; Fabian, Andrew C.; Ballantyne, David R.; Boggs, S. E.; Boorman, Peter; Christensen, F. E.; Craig, W. W.; Farrah, Duncan; García, Javier; Hailey, C. J.; Harrison, F. A.; Ricci, Claudio; Stern, Daniel; Zhang, W. W.
    The relativistic jets created by some active galactic nuclei are important agents of AGN feedback. In spite of this, our understanding of what produces these jets is still incomplete. X-ray observations, which can probe the processes operating in the central regions in the immediate vicinity of the supermassive black hole, the presumed jet launching point, are potentially particularly valuable in illuminating the jet formation process. Here, we present the hard X-ray NuSTAR observations of the radio-loud quasar 4C 74.26 in a joint analysis with quasi-simultaneous, soft X-ray Swift observations. Our spectral analysis reveals a high-energy cutoff of 183^(+51)_(-35) keV and...

  16. Swift, XMM-Newton, and NuSTAR observations of PSR J2032+4127/MT91 213

    Li, K. L.; Kong, A. K. H.; Tam, P. H. T.; Hou, X.; Takata, J.; Hui, C. Y.
    We report our recent Swift, NuSTAR, and XMM-Newton X-ray and Lijiang optical observations on PSR J2032+4127/MT91 213, the gamma-ray binary candidate with a period of 45-50 years. The coming periastron of the system was predicted to be in November 2017, around which high-energy flares from keV to TeV are expected. Recent studies with Chandra and Swift X-ray observations taken in 2015/16 showed that its X-ray emission has been brighter by a factors of ~10 than that before 2013, probably revealing some on-going activities between the pulsar wind and the stellar wind. Our new Swift/XRT lightcurve shows no strong evidence of a single vigorous brightening trend, but rather several...

  17. The NuSTAR View of the Seyfert 2 Galaxy NGC 4388

    Kamraj, N.; Rivers, E.; Harrison, F. A.; Brightman, M.; Baloković, M.
    We present an analysis of NuSTAR X-ray observations in the 3–79 keV energy band of the Seyfert 2 galaxy NGC 4388, taken in 2013. The broadband sensitivity of NuSTAR, covering the Fe Kα line and Compton reflection hump, enables tight constraints to be placed on reflection features in AGN X-ray spectra, thereby providing insight into the geometry of the circumnuclear material. In this observation, we found the X-ray spectrum of NGC 4388 to be well described by a moderately absorbed power law with non-relativistic reflection. We fit the spectrum with phenomenological reflection models and a physical torus model and find...

  18. Galactic Sources Detected in the NuSTAR Serendipitous Survey

    Tomsick, John A.; Lansbury, George B.; Rahoui, Farid; Clavel, Maïca; Fornasini, Francesca M.; Hong, JaeSub; Aird, James; Alexander, David M.; Bodaghee, Arash; Chiu, Jeng-Lun; Grindlay, Jonathan E.; Hailey, Charles J.; Harrison, Fiona A.; Krivonos, Roman A.; Mori, Kaya; Stern, Daniel
    The Nuclear Spectroscopic Telescope Array (NuSTAR) provides an improvement in sensitivity at energies above 10 keV by two orders of magnitude over non-focusing satellites, making it possible to probe deeper into the Galaxy and universe. Lansbury and collaborators recently completed a catalog of 497 sources serendipitously detected in the 3–24 keV band using 13 deg^2 of NuSTAR coverage. Here, we report on an optical and X-ray study of 16 Galactic sources in the catalog. We identify 8 of them as stars (but some or all could have binary companions), and use information from Gaia to report distances and X-ray luminosities...

  19. Sagittarius A* High Energy X-ray Flare Properties During NuSTAR Monitoring of the Galactic Center from 2012 to 2015

    Zhang, Shuo; Baganoff, Frederick K.; Ponti, Gabriele; Neilsen, Joseph; Tomsick, John A.; Dexter, Jason; Clavel, Maïca; Markoff, Sera; Hailey, Charles J.; Mori, Kaya; Barrière, Nicolas M.; Nowak, Michael A.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Grefenstette, Brian W.; Harrison, Fiona A.; Madsen, Kristin K.; Stern, Daniel; Zhang, William W.
    Understanding the origin of the flaring activity from the Galactic center supermassive black hole Sagittarius A* is a major scientific goal of the NuSTAR Galactic plane survey campaign. We report on the data obtained between 2012 July and 2015 April, including 27 observations on Sgr A*, with a total exposure of ≃1 Ms. We found a total of 10 X-ray flares detected in the NuSTAR observation window, with luminosities in the range of L_(3-79 keV) ~(0.2-4.0) x 10^(35) erg s^(-1). With this largest hard X-ray Sgr A* flare data set to date, we studied the flare spectral properties. Seven flares...

  20. The weak Fe fluorescence line and long-term X-ray evolution of the Compton-thick active galactic nucleus in NGC 7674

    Gandhi, P.; Annuar, A.; Lansbury, G. B.; Stern, D.; Alexander, D. M.; Bauer, F. E.; Bianchi, S.; Boggs, S. E.; Boorman, P. G.; Brandt, W. N.; Brightman, M.; Christensen, F. E.; Comastri, A.; Craig, W. W.; Del Moro, A.; Elvis, M.; Guainazzi, M.; Hailey, C. J.; Harrison, F. A.; Koss, M.; Lamperti, I.; Malaguti, G.; Masini, A.; Matt, G.; Puccetti, S.; Ricci, C.; Rivers, E.; Walton, D. J.; Zhang, W. W.
    We present NuSTAR X-ray observations of the active galactic nucleus (AGN) in NGC 7674. The source shows a flat X-ray spectrum, suggesting that it is obscured by Compton-thick gas columns. Based upon long-term flux dimming, previous work suggested the alternate possibility that the source is a recently switched-off AGN with the observed X-rays being the lagged echo from the torus. Our high-quality data show the source to be reflection-dominated in hard X-rays, but with a relatively weak neutral Fe Kα emission line (equivalent width [EW] of ≈ 0.4 keV) and a strong Fe xxvi ionized line (EW ≈ 0.2 keV). We...

Aviso de cookies: Usamos cookies propias y de terceros para mejorar nuestros servicios, para análisis estadístico y para mostrarle publicidad. Si continua navegando consideramos que acepta su uso en los términos establecidos en la Política de cookies.