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Caltech Authors (147.369 recursos)

Repository of works by Caltech published authors.

Group = Space Radiation Laboratory

Mostrando recursos 1 - 20 de 1.273

  1. SNLS spectroscopy: testing for evolution in type Ia supernovae

    Bronder, T. J.; Hook, I. M.; Astier, P.; Balam, D.; Balland, C.; Basa, S.; Carlberg, R. G.; Conley, A.; Fouchez, D.; Guy, J.; Howell, D. A.; Neill, J. D.; Pain, R.; Perrett, K.; Pritchet, C. J.; Regnault, N.; Sullivan, M.; Baumont, S.; Fabbro, S.; Filliol, M.; Perlmutter, S.; Ripoche, P.
    Aims. We present a quantitative study of a new data set of high redshift Type Ia supernovae spectra, observed at the Gemini telescopes during the first 34 months of the Supernova Legacy Survey. During this time 123 supernovae candidates were observed, of which 87 have been identified as SNe Ia at a median redshift of z=0.720. Spectra from the entire second year of the survey and part of the third year (59 total SNe candidates with 46 confirmed SNe Ia) are published here for the first time. The spectroscopic measurements made on this data set are used determine if these...

  2. BAT AGN Spectroscopic Survey - IV: Near-Infrared Coronal Lines, Hidden Broad Lines, and Correlation with Hard X-ray Emission

    Lamperti, Isabella; Koss, Michael; Trakhtenbrot, Benny; Schawinski, Kevin; Ricci, Claudio; Oh, Kyuseok; Landt, Hermine; Riffel, Rogério; Rodríguez-Ardila, Alberto; Gehrels, Neil; Harrison, Fiona; Masetti, Nicola; Mushotzky, Richard; Treister, Ezequiel; Ueda, Yoshihiro; Veilleux, Sylvain
    We provide a comprehensive census of the near-infrared (NIR, 0.8–2.4 μm) spectroscopic properties of 102 nearby (z < 0.075) active galactic nuclei (AGN), selected in the hard X-ray band (14–195 keV) from the Swift-Burst Alert Telescope survey. With the launch of the James Webb Space Telescope, this regime is of increasing importance for dusty and obscured AGN surveys. We measure black hole masses in 68 per cent (69/102) of the sample using broad emission lines (34/102) and/or the velocity dispersion of the Ca ii triplet or the CO band-heads (46/102). We find that emission-line diagnostics in the NIR are ineffective at...

  3. The Broadband Spectral Variability of Holmberg IX X-1

    Walton, D. J.; Fürst, F.; Harrison, F. A.; Middleton, M. J.; Fabian, A. C.; Bachetti, M.; Barret, D.; Miller, J. M.; Ptak, A.; Rana, V.; Stern, D.; Tao, L.
    We present results from four new broadband X-ray observations of the extreme ultraluminous X-ray source Holmberg IX X-1 (L_X > 10^(40) erg s^(−1)), performed by Suzaku and NuSTAR in coordination. Combined with the archival data, we now have broadband observations of this remarkable source from six separate epochs. Two of these new observations probe lower fluxes than seen previously, allowing us to extend our knowledge of the broadband spectral variability exhibited. The spectra are well fit by two thermal blackbody components that dominate the emission below 10 keV, as well as a steep (Γ ~ 3.5) power-law tail that dominates...

  4. The Golden Standard Type Ia Supernova 2005cf: Observations from the Ultraviolet to the Near-Infrared Wavebands

    Wang, X.; Li, W.; Filippenko, A. V.; Foley, R. J.; Kirshner, R. P.; Modjaz, M.; Bloom, J.; Brown, P. J.; Carter, D.; Friedman, A. S.; Gal-Yam, A.; Ganeshalingam, M.; Hicken, M.; Krisciunas, K.; Milne, P.; Silverman, J. M.; Suntzeff, N. B.; Wood-Vasey, W. M.; Cenko, S. B.; Challis, P.; Fox, D. B.; Kirkman, D.; Li, J. Z.; Li, T. P.; Malkan, M. A.; Moore, M. R.; Reitzel, D. B.; Rich, R. M.; Serduke, F. J. D.; Shang, R. C.; Steele, T. N.; Swift, B. J.; Tao, C.; Wong, D. S.; Zhang, S. N.
    We present extensive photometry at ultraviolet (UV), optical, and near-infrared (NIR) wavelengths, as well as dense sampling of optical spectra, for the normal Type Ia supernova (SN Ia) 2005cf. The optical photometry, performed at eight different telescopes, shows a 1σ scatter of ≾0.03 mag after proper corrections for the instrument responses. From the well-sampled light curves, we find that SN 2005cf reached a B-band maximum at 13.63 ± 0.02 mag, with an observed luminosity decline rate Δm _(15)(B) = 1.05 ± 0.03 mag. The correlations between the decline rate and various color indexes, recalibrated on the basis of an expanded...

  5. Spectral and temporal properties of the ultra-luminous X-ray pulsar in M82 from 15 years of Chandra observations and analysis of the pulsed emission using NuSTAR

    Brightman, Murray; Harrison, Fiona; Walton, Dominic J.; Fuerst, Felix; Hornschemeier, Ann; Zezas, Andreas; Bachetti, Matteo; Grefenstette, Brian; Ptak, Andrew; Tendulkar, Shriharsh; Yukita, Mihoko
    The recent discovery by Bachetti et al. of a pulsar in M82 that can reach luminosities of up to 1040 erg s−1, a factor of ~100 times the Eddington luminosity for a 1.4 M⊙ compact object, poses a challenge for accretion physics. In order to better understand the nature of this source and its duty cycle, and in light of several physical models that have been subsequently published, we conduct a spectral and temporal analysis of the 0.5–8 keV X-ray emission from this source from 15 years of Chandra observations. We analyze 19 ACIS observations where the point-spread function (PSF)...

  6. Validation of the effect of cross-calibrated GOES solar proton effective energies on derived integral fluxes by comparison with STEREO observations

    Rodriguez, J. V.; Sandberg, I.; Mewaldt, R. A.; Daglis, I. A.; Jiggens, P.
    The derivation of integral fluxes from instrument coincidence rates requires accurate knowledge of their effective energies. Recent cross calibrations of GOES with the high-energy-resolution Interplanetary Monitoring Platform (IMP) 8 Goddard Medium Energy Experiment (GME) (Sandberg et al., Geophys. Res. Lett, 41, 4435, 2014a) gave significantly lower effective energies than those currently used by the NOAA Space Weather Prediction Center to calculate solar proton integral fluxes from GOES rates. This implies systematically lower integral fluxes than currently produced. This paper quantifies the differences between the current and the cross-calibrated GOES integral fluxes and validates the latter. Care is taken to rule...

  7. The infrared to X-ray correlation spectra of unobscured type 1 active galactic nuclei

    García-Bernete, I.; Ramos Almeida, C.; Landt, H.; Ward, M. J.; Baloković, M.; Acosta-Pulido, J. A.
    We use new X-ray data obtained with the Nuclear Spectroscopic Telescope Array (NuSTAR), near-infrared (NIR) fluxes, and mid-infrared (MIR) spectra of a sample of 24 unobscured type 1 active galactic nuclei (AGN) to study the correlation between various hard X-ray bands between 3 and 80 keV and the infrared (IR) emission. The IR to X-ray correlation spectrum (IRXCS) shows a maximum at ~15-20 micron, coincident with the peak of the AGN contribution to the MIR spectra of the majority of the sample. There is also a NIR correlation peak at ~2 micron, which we associate with the NIR bump observed in some type 1 AGN at ~1-5 micron...

  8. The high-Eddington NLS1 Ark 564 has the coolest corona

    Kara, E.; Garcia, J. A.; Lohfink, A.; Fabian, A. C.; Reynolds, C. S.; Tombesi, F.; Wilkins, D. R.
    Ark 564 is an archetypal Narrow line Seyfert 1 that has been well observed in soft X-rays from 0.3-10 keV, revealing a steep spectrum, strong soft excess, iron K emission line and dramatic variability on the order of hours. Because of its very steep spectrum, observations of the source above 10 keV have been sparse. We report here on the first NuSTAR observation of Ark 564. The source was observed for 200 ks with NuSTAR, 50 ks of which were concurrent with Suzaku observations. NuSTAR and Suzaku observed a dramatic flare, in which the hard emission is clearly delayed with respect to the soft emission, consistent with previous...

  9. Coronal properties of the luminous radio-quiet quasar QSO B2202–209

    Kammoun, E. S.; Risaliti, G.; Stern, D.; Jun, H. D.; Graham, M.; Celotti, A.; Behar, E.; Elvis, M.; Harrison, F. A.; Matt, G.; Walton, D. J.
    We present an analysis of the joint XMM–Newton and NuSTAR observations of the radio-quiet quasar QSO B2202–209. Using an optical observation from the Hale Telescope at the Palomar Observatory, we revise the redshift of the source from the previously reported z = 1.77 to z = 0.532, and we estimate the mass of the central black hole, log (M_(BH)/M_⊙) = 9.08 ± 0.18. The X-ray spectrum of this source can be well described by a power law of photon index Γ = 1.82 ± 0.05 with E_(cut) = 152^(+103)_(−54) keV, in the rest frame of the source. Assuming a Comptonization model,...

  10. A powerful flare from Sgr A* confirms the synchrotron nature of the X-ray emission

    Ponti, G.; George, E.; Scaringi, S.; Zhang, S.; Jin, C.; Dexter, J.; Terrier, R.; Clavel, M.; Degenaar, N.; Eisenhauer, F.; Genzel, R.; Gillessen, S.; Goldwurm, A.; Habibi, M.; Haggard, D.; Hailey, C.; Harrison, F. A.; Merloni, A.; Mori, K.; Nandra, K.; Ott, T.; Pfuhl, O.; Plewa, P. M.; Waisberg, I.
    We present the first fully simultaneous fits to the NIR and X-ray spectral slope (and its evolution) during a very bright flare from Sgr A⋆, the supermassive black hole at the Milky Way’s center. Our study arises from ambitious multi-wavelength monitoring campaigns with XMMNewton, NuSTAR and SINFONI. The average multi-wavelength spectrum is well reproduced by a broken power-law with ΓN IR = 1.7 ± 0.1 and ΓX = 2.27 ± 0.12. The difference in spectral slopes (∆Γ = 0.57 ± 0.09) strongly supports synchrotron emission with a cooling break. The flare starts first in the NIR with a flat and bright NIR spectrum, while X-ray radiation is...

  11. The Phoenix galaxy as seen by NuSTAR

    Masini, A.; Comastri, A.; Puccetti, S.; Baloković, M.; Gandhi, P.; Guainazzi, M.; Bauer, F. E.; Boggs, S. E.; Boorman, P. G.; Brightman, M.; Christensen, F. E.; Craig, W. W.; Farrah, D.; Hailey, C. J.; Harrison, F. A.; Koss, M. J.; LaMassa, S. M.; Ricci, C.; Stern, D.; Walton, D. J.; Zhang, W. W.
    Aims. We study the long-term variability of the well-known Seyfert 2 galaxy Mrk 1210 (also known as UGC 4203, or the Phoenix galaxy). Methods. The source was observed by many X-ray facilities in the last 20 yr. Here we present a NuSTAR observation and put the results in the context of previously published observations. Results. NuSTAR observed Mrk 1210 in 2012 for 15.4 ks. The source showed Compton-thin obscuration similar to that observed by Chandra, Suzaku, BeppoSAX and XMM-Newton over the past two decades, but different from the first observation by ASCA in 1995, in which the active nucleus was caught in a low...

  12. Metrology system for measuring mast motions on the NuSTAR mission

    Liebe, Carl Christian; Burnham, Jill; Cook, Rick; Craig, Bill; Decker, Todd; Harp, D. Isaiah; Kecman, Branislav; Meras, Patrick; Raffanti, Mike; Scholz, Christopher; Smith, Christopher; Waldman, Jeff; Wu, James
    A metrology system designed and built for the NuSTAR mission is described. The NuSTAR mission is an orbiting X-ray telescope with a 10 meter focal length. The system consists of two laser pointers mounted rigidly together with a star tracker and the X-ray optics. The focused laser beams illuminates two metrology detectors mounted rigidly with the X-ray detectors. The detectors and optics/lasers are separated by a ∼10 meter deployable (and somewhat flexible) carbon fiber mast. Details about the implementation of the metrology system is discussed in this paper.

  13. BAT AGN Spectroscopic Survey – III. An observed link between AGN Eddington ratio and narrow-emission-line ratios

    Oh, Kyuseok; Schawinski, Kevin; Koss, Michael; Trakhtenbrot, Benny; Lamperti, Isabella; Ricci, Claudio; Mushotzky, Richard; Veilleux, Sylvain; Berney, Simon; Crenshaw, D. Michael; Gehrels, Neil; Harrison, Fiona; Masetti, Nicola; Soto, Kurt T.; Stern, Daniel; Treister, Ezequiel; Ueda, Yoshihiro
    We investigate the observed relationship between black hole mass (MBH), bolometric luminosity (Lbol) and Eddington ratio (λEdd) with optical emission-line ratios ([N ii] λ6583/Hα, [S ii] λλ6716, 6731/Hα, [O i] λ6300/Hα, [O iii] λ5007/Hβ, [Ne iii] λ3869/Hβ and He ii λ4686/Hβ) of hard X-ray-selected active galactic nuclei (AGN) from the BAT AGN Spectroscopic Survey. We show that the [N ii] λ6583/Hα ratio exhibits a significant correlation with λEdd (RPear = −0.44, p-value = 3 × 10−13, σ = 0.28 dex), and the correlation is not solely driven by MBH or Lbol. The observed correlation between [N ii] λ6583/Hα ratio and...

  14. The response of relativistic outflowing gas to the inner accretion disk of a black hole

    Parker, Michael L.; Pinto, Ciro; Fabian, Andrew C.; Lohfink, Anne M.; Buisson, Douglas J. K.; Alston, William N.; Kara, Erin; Cackett, Edward M.; Chiang, Chia-Ying; Dauser, Thomas; De Marco, Barbara; Gallo, Luigi C.; García, Javier A.; Harrison, Fiona A.; King, Ashley L.; Middleton, Matthew J.; Miller, Jon M.; Miniutti, Giovanni; Reynolds, Christopher S.; Uttley, Phil; Vasudevan, Ranjan; Walton, D. J.; Wilkins, Daniel R.; Zoghbi, Abderahmen
    The brightness of an active galactic nucleus is set by the gas falling onto it from the galaxy, and the gas infall rate is regulated by the brightness of the active galactic nucleus; this feedback loop is the process by which supermassive black holes in the centres of galaxies may moderate the growth of their hosts1. Gas outflows (in the form of disk winds) release huge quantities of energy into the interstellar medium2, potentially clearing the surrounding gas. The most extreme (in terms of speed and energy) of these—the ultrafast outflows—are the subset of X-ray-detected outflows with velocities higher than...

  15. Evidence for Relativistic Disk Reflection in the Seyfert 1h Galaxy/ULIRG IRAS 05189–2524 Observed by NuSTAR and XMM-Newton

    Xu, Yanjun; Baloković, Mislav; Walton, Dominic J.; Harrison, Fiona A.; García, Javier A.; Koss, Michael J.
    We present a spectral analysis of the NuSTAR and XMM-Newton observations of the Seyfert 1h galaxy/ULIRG IRAS 05189–2524 taken in 2013. We find evidence for relativistic disk reflection in the broadband X-ray spectrum: a highly asymmetric broad Fe Kα emission line extending down to 3 keV and a Compton scattering component above 10 keV. Physical modeling with a self-consistent disk reflection model suggests that the accretion disk is viewed at an intermediate angle with a supersolar iron abundance, and a mild constraint can be put on the high-energy cutoff of the power-law continuum. We test the disk reflection modeling under...

  16. Particle acceleration and reconnection in the solar wind

    Zank, G. P.; Hunana, P.; Mostafavi, P.; le Roux, J. A.; Webb, G. M.; Khabarova, O.; Cummings, A. C.; Stone, E. C.; Decker, R. B.
    An emerging paradigm for the dissipation of magnetic turbulence in the supersonic solar wind is via localized quasi-2D small-scale magnetic island reconnection processes. An advection-diffusion transport equation for a nearly isotropic particle distribution describes particle transport and energization in a region of interacting magnetic islands [1; 2]. The dominant charged particle energization processes are 1) the electric field induced by quasi-2D magnetic island merging, and 2) magnetic island contraction. The acceleration of charged particles in a “sea of magnetic islands” in a super-Alfvénic flow, and the energization of particles by combined diffusive shock acceleration (DSA) and downstream magnetic island reconnection...

  17. A New Compton-thick AGN in Our Cosmic Backyard: Unveiling the Buried Nucleus in NGC 1448 with NuSTAR

    Annuar, A.; Alexander, D. M.; Gandhi, P.; Lansbury, G. B.; Asmus, D.; Ballantyne, D. R.; Bauer, F. E.; Boggs, S. E.; Boorman, P. G.; Brandt, W. N.; Brightman, M.; Christensen, F. E.; Craig, W. W.; Farrah, D.; Goulding, A. D.; Hailey, C. J.; Harrison, F. A.; Koss, M. J.; LaMassa, S. M.; Murray, S. S.; Ricci, C.; Rosario, D. J.; Stanley, F.; Stern, D.; Zhang, W.
    NGC 1448 is one of the nearest luminous galaxies (L_(8–1000μm) > 10^9 L⊙) to ours (z = 0.00390), and yet the active galactic nucleus (AGN) it hosts was only recently discovered, in 2009. In this paper, we present an analysis of the nuclear source across three wavebands: mid-infrared (MIR) continuum, optical, and X-rays. We observed the source with the Nuclear Spectroscopic Telescope Array (NuSTAR), and combined these data with archival Chandra data to perform broadband X-ray spectral fitting (≈0.5–40 keV) of the AGN for the first time. Our X-ray spectral analysis reveals that the AGN is buried under a Compton-thick...

  18. A Long Look at MCG-5-23-16 with NuSTAR. I. Relativistic Reflection and Coronal Properties

    Zoghbi, Abderahmen; Matt, G.; Miller, J. M.; Lohfink, A. M.; Walton, D. J.; Ballantyne, D. R.; García, J. A.; Stern, D.; Koss, M. J.; Farrah, D.; Harrison, F. A.; Boggs, S. E.; Christensen, F. E.; Craig, W.; Hailey, C. J.; Zhang, W. W.
    MCG-5-23-16 was targeted in early 2015 with a half mega-second observing campaign using NuSTAR. Here we present the spectral analysis of these data sets along with an earlier observation and study the relativistic reflection and the primary coronal source. The data show strong reflection features in the form of both narrow and broad iron lines plus a Compton reflection hump. A cutoff energy is significantly detected in all exposures. The shape of the reflection spectrum does not change in the two years spanned by the observations, suggesting a stable geometry. A strong positive correlation is found between the cutoff energy...

  19. Global Energetics of Solar Flares. V. Energy Closure in Flares and Coronal Mass Ejections

    Aschwanden, Markus J.; Caspi, Amir; Cohen, Christina M. S.; Holman, Gordon; Jing, Ju; Kretzschmar, Matthieu; Kontar, Eduard P.; McTiernan, James M.; Mewaldt, Richard A.; O’Flannagain, Aidan; Richardson, Ian G.; Ryan, Daniel; Warren, Harry P.; Xu, Yan
    In this study we synthesize the results of four previous studies on the global energetics of solar flares and associated coronal mass ejections (CMEs), which include magnetic, thermal, nonthermal, and CME energies in 399 solar M- and X-class flare events observed during the first 3.5 yr of the Solar Dynamics Observatory (SDO) mission. Our findings are as follows. (1) The sum of the mean nonthermal energy of flare-accelerated particles (E_(nt)), the energy of direct heating (E_(dir)), and the energy in CMEs (E_(CME)), which are the primary energy dissipation processes in a flare, is found to have a ratio of E_(nt)...

  20. IACHEC Cross-Calibration of Chandra, NuSTAR, Swift, Suzaku, and XMM-Newton with 3C 273 and PKS 2155-304

    Madsen, Kristin K.; Beardmore, Andrew P.; Forster, Karl; Guainazzi, Matteo; Marshall, Herman L.; Miller, Eric D.; Page, Kim L.; Stuhlinger, Martin
    On behalf of the International Astronomical Consortium for High Energy Calibration, we present results from the cross-calibration campaigns in 2012 on 3C 273 and in 2013 on PKS 2155-304 between the then active X-ray observatories Chandra, NuSTAR, Suzaku, Swift, and XMM-Newton. We compare measured fluxes between instrument pairs in two energy bands, 1–5 keV and 3–7 keV, and calculate an average cross-normalization constant for each energy range. We review known cross-calibration features and provide a series of tables and figures to be used for evaluating cross-normalization constants obtained from other observations with the above mentioned observatories.

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