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Caltech Authors (162.509 recursos)

Repository of works by Caltech published authors.

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Mostrando recursos 181 - 200 de 285

  1. Discovery of a Cosmological, Relativistic Outburst via its Rapidly Fading Optical Emission

    Cenko, S. Bradley; Kulkarni, S. R.; Horesh, Assaf; Corsi, Alessandra; Carpenter, John; Perley, Daniel A.; Groot, Paul J.; Hallinan, G.; Sesar, Branimir; Kasliwal, M. M.
    We report the discovery by the Palomar Transient Factory (PTF) of the transient source PTF11agg, which is distinguished by three primary characteristics: (1) bright (R_peak = 18.3 mag), rapidly fading (ΔR = 4 mag in Δt = 2 days) optical transient emission; (2) a faint (R = 26.2 ± 0.2 mag), blue (g' – R = 0.17 ± 0.29 mag) quiescent optical counterpart; and (3) an associated year-long, scintillating radio transient. We argue that these observed properties are inconsistent with any known class of Galactic transients (flare stars, X-ray binaries, dwarf novae), and instead suggest a cosmological origin. The detection...

  2. Discovery of a Cosmological, Relativistic Outburst via its Rapidly Fading Optical Emission

    Cenko, S. Bradley; Kulkarni, S. R.; Horesh, Assaf; Corsi, Alessandra; Carpenter, John; Perley, Daniel A.; Groot, Paul J.; Hallinan, G.; Sesar, Branimir; Kasliwal, M. M.
    We report the discovery by the Palomar Transient Factory (PTF) of the transient source PTF11agg, which is distinguished by three primary characteristics: (1) bright (R_peak = 18.3 mag), rapidly fading (ΔR = 4 mag in Δt = 2 days) optical transient emission; (2) a faint (R = 26.2 ± 0.2 mag), blue (g' – R = 0.17 ± 0.29 mag) quiescent optical counterpart; and (3) an associated year-long, scintillating radio transient. We argue that these observed properties are inconsistent with any known class of Galactic transients (flare stars, X-ray binaries, dwarf novae), and instead suggest a cosmological origin. The detection...

  3. The UV/optical spectra of the Type Ia supernova SN 2010jn: a bright supernova with outer layers rich in iron-group elements

    Hachinger, S.; Mazzali, P. A.; Sullivan, M.; Ellis, R. S.; Maguire, K.; Gal-Yam, A.; Howell, D. A.; Nugent, P. E.; Baron, E.; Cooke, J.; Arcavi, I.; Bersier, D.; Dilday, B.; James, P. A.; Kasliwal, M. M.; Kulkarni, S. R.; Ofek, E. O.; Laher, R. R.; Parrent, J.; Surace, J.; Yaron, O.; Walker, E. S.
    Radiative transfer studies of Type Ia supernovae (SNe Ia) hold the promise of constraining both the density profile of the SN ejecta and its stratification by element abundance which, in turn, may discriminate between different explosion mechanisms and progenitor classes. Here we analyse the Type Ia SN 2010jn (PTF10ygu) in detail, presenting and evaluating near-ultraviolet (near-UV) spectra from the Hubble Space Telescope and ground-based optical spectra and light curves. SN 2010jn was discovered by the Palomar Transient Factory (PTF) 15 d before maximum light, allowing us to secure a time series of four near-UV spectra at epochs from −10.5 to +4.8 d relative to B-band...

  4. The UV/optical spectra of the Type Ia supernova SN 2010jn: a bright supernova with outer layers rich in iron-group elements

    Hachinger, S.; Mazzali, P. A.; Sullivan, M.; Ellis, R. S.; Maguire, K.; Gal-Yam, A.; Howell, D. A.; Nugent, P. E.; Baron, E.; Cooke, J.; Arcavi, I.; Bersier, D.; Dilday, B.; James, P. A.; Kasliwal, M. M.; Kulkarni, S. R.; Ofek, E. O.; Laher, R. R.; Parrent, J.; Surace, J.; Yaron, O.; Walker, E. S.
    Radiative transfer studies of Type Ia supernovae (SNe Ia) hold the promise of constraining both the density profile of the SN ejecta and its stratification by element abundance which, in turn, may discriminate between different explosion mechanisms and progenitor classes. Here we analyse the Type Ia SN 2010jn (PTF10ygu) in detail, presenting and evaluating near-ultraviolet (near-UV) spectra from the Hubble Space Telescope and ground-based optical spectra and light curves. SN 2010jn was discovered by the Palomar Transient Factory (PTF) 15 d before maximum light, allowing us to secure a time series of four near-UV spectra at epochs from −10.5 to +4.8 d relative to B-band...

  5. Five new outbursting AM CVn systems discovered by the Palomar Transient Factory

    Levitan, David; Kupfer, Thomas; Groot, Paul J.; Kulkarni, Shrinivas R.; Prince, Thomas A.; Simonian, Gregory V.; Arcavi, Iair; Bloom, Joshua S.; Laher, Russ; Nugent, Peter E.; Ofek, Eran O.; Sesar, Branimir; Surace, Jason
    We present five new outbursting AM CVn systems and one candidate discovered as part of an ongoing search for such systems using the Palomar Transient Factory (PTF). This is the first large-area, systematic search for AM CVn systems using only large-amplitude photometric variability to select candidates. Three of the confirmed systems and the candidate system were discovered as part of the PTF transient search. Two systems were found as part of a search for outbursts through the PTF photometric data base. We discuss the observed characteristics of each of these systems, including the orbital periods of two systems. We also...

  6. Five new outbursting AM CVn systems discovered by the Palomar Transient Factory

    Levitan, David; Kupfer, Thomas; Groot, Paul J.; Kulkarni, Shrinivas R.; Prince, Thomas A.; Simonian, Gregory V.; Arcavi, Iair; Bloom, Joshua S.; Laher, Russ; Nugent, Peter E.; Ofek, Eran O.; Sesar, Branimir; Surace, Jason
    We present five new outbursting AM CVn systems and one candidate discovered as part of an ongoing search for such systems using the Palomar Transient Factory (PTF). This is the first large-area, systematic search for AM CVn systems using only large-amplitude photometric variability to select candidates. Three of the confirmed systems and the candidate system were discovered as part of the PTF transient search. Two systems were found as part of a search for outbursts through the PTF photometric data base. We discuss the observed characteristics of each of these systems, including the orbital periods of two systems. We also...

  7. Five new outbursting AM CVn systems discovered by the Palomar Transient Factory

    Levitan, David; Kupfer, Thomas; Groot, Paul J.; Kulkarni, Shrinivas R.; Prince, Thomas A.; Simonian, Gregory V.; Arcavi, Iair; Bloom, Joshua S.; Laher, Russ; Nugent, Peter E.; Ofek, Eran O.; Sesar, Branimir; Surace, Jason
    We present five new outbursting AM CVn systems and one candidate discovered as part of an ongoing search for such systems using the Palomar Transient Factory (PTF). This is the first large-area, systematic search for AM CVn systems using only large-amplitude photometric variability to select candidates. Three of the confirmed systems and the candidate system were discovered as part of the PTF transient search. Two systems were found as part of a search for outbursts through the PTF photometric data base. We discuss the observed characteristics of each of these systems, including the orbital periods of two systems. We also...

  8. Five new outbursting AM CVn systems discovered by the Palomar Transient Factory

    Levitan, David; Kupfer, Thomas; Groot, Paul J.; Kulkarni, Shrinivas R.; Prince, Thomas A.; Simonian, Gregory V.; Arcavi, Iair; Bloom, Joshua S.; Laher, Russ; Nugent, Peter E.; Ofek, Eran O.; Sesar, Branimir; Surace, Jason
    We present five new outbursting AM CVn systems and one candidate discovered as part of an ongoing search for such systems using the Palomar Transient Factory (PTF). This is the first large-area, systematic search for AM CVn systems using only large-amplitude photometric variability to select candidates. Three of the confirmed systems and the candidate system were discovered as part of the PTF transient search. Two systems were found as part of a search for outbursts through the PTF photometric data base. We discuss the observed characteristics of each of these systems, including the orbital periods of two systems. We also...

  9. Disk-related Bursts and Fades in Young Stars

    Findeisen, Krzysztof; Hillenbrand, Lynne; Ofek, Eran; Levitan, David; Sesar, Branimir; Laher, Russ; Surace, Jason
    We present first results from a new, multiyear, time domain survey of young stars in the North America Nebula complex using the Palomar Transient Factory. Our survey is providing an unprecedented view of aperiodic variability in young stars on timescales of days to years. The analyzed sample covers R_(PTF) ≈ 13.5-18 and spans a range of mid-infrared color, with larger-amplitude optical variables (exceeding 0.4 mag root mean squared) more likely to have mid-infrared evidence for circumstellar material. This paper characterizes infrared excess stars with distinct bursts above or fades below a baseline of lower-level variability, identifying 41 examples. The light...

  10. R Coronae Borealis Stars in M31 from the Palomar Transient Factory

    Tang, Sumin; Cao, Yi; Bildsten, Lars; Nugent, Peter; Bellm, Eric; Kulkarni, Shrinivas R.; Laher, Russ; Levitan, David; Masci, Frank; Ofek, Eran O.; Prince, Thomas A.; Sesar, Branimir; Surace, Jason
    We report the discovery of R Coronae Borealis (RCB) stars in the Andromeda galaxy (M31) using the Palomar Transient Factory (PTF). RCB stars are rare hydrogen-deficient, carbon-rich supergiant variables, most likely the merger products of two white dwarfs. These new RCBs, including two confirmed ones and two candidates, are the first to be found beyond the Milky Way and the Magellanic Clouds. All of M31 RCBs showed >1.5 mag irregular declines over timescales of weeks to months. Due to the limiting magnitude of our data (R ≈ 21-22 mag), these RCB stars have R ≈ 19.5-20.5 mag at maximum light,...

  11. R Coronae Borealis Stars in M31 from the Palomar Transient Factory

    Tang, Sumin; Cao, Yi; Bildsten, Lars; Nugent, Peter; Bellm, Eric; Kulkarni, Shrinivas R.; Laher, Russ; Levitan, David; Masci, Frank; Ofek, Eran O.; Prince, Thomas A.; Sesar, Branimir; Surace, Jason
    We report the discovery of R Coronae Borealis (RCB) stars in the Andromeda galaxy (M31) using the Palomar Transient Factory (PTF). RCB stars are rare hydrogen-deficient, carbon-rich supergiant variables, most likely the merger products of two white dwarfs. These new RCBs, including two confirmed ones and two candidates, are the first to be found beyond the Milky Way and the Magellanic Clouds. All of M31 RCBs showed >1.5 mag irregular declines over timescales of weeks to months. Due to the limiting magnitude of our data (R ≈ 21-22 mag), these RCB stars have R ≈ 19.5-20.5 mag at maximum light,...

  12. R Coronae Borealis Stars in M31 from the Palomar Transient Factory

    Tang, Sumin; Cao, Yi; Bildsten, Lars; Nugent, Peter; Bellm, Eric; Kulkarni, Shrinivas R.; Laher, Russ; Levitan, David; Masci, Frank; Ofek, Eran O.; Prince, Thomas A.; Sesar, Branimir; Surace, Jason
    We report the discovery of R Coronae Borealis (RCB) stars in the Andromeda galaxy (M31) using the Palomar Transient Factory (PTF). RCB stars are rare hydrogen-deficient, carbon-rich supergiant variables, most likely the merger products of two white dwarfs. These new RCBs, including two confirmed ones and two candidates, are the first to be found beyond the Milky Way and the Magellanic Clouds. All of M31 RCBs showed >1.5 mag irregular declines over timescales of weeks to months. Due to the limiting magnitude of our data (R ≈ 21-22 mag), these RCB stars have R ≈ 19.5-20.5 mag at maximum light,...

  13. An outburst from a massive star 40 days before a supernova explosion

    Ofek, E. O.; Sullivan, M.; Cenko, S. B.; Kasliwal, M. M.; Gal-Yam, A.; Kulkarni, S. R.; Arcavi, I.; Bildsten, L.; Bloom, J. S.; Horesh, A.; Howell, D. A.; Filippenko, A. V.; Laher, R.; Murray, D.; Nakar, E.; Nugent, P. E.; Silverman, J. M.; Shaviv, N. J.; Surace, J.; Yaron, O.
    Some observations suggest that very massive stars experience extreme mass-loss episodes shortly before they explode as supernovae, as do several models. Establishing a causal connection between these mass-loss episodes and the final explosion would provide a novel way to study pre-supernova massive-star evolution. Here we report observations of a mass-loss event detected 40 days before the explosion of the type IIn supernova SN 2010mc (also known as PTF 10tel). Our photometric and spectroscopic data suggest that this event is a result of an energetic outburst, radiating at least 6 × 10^(47) erg of energy and releasing about 10^(−2) solar masses of material at typical velocities of 2,000 km s^(−1)....

  14. An outburst from a massive star 40 days before a supernova explosion

    Ofek, E. O.; Sullivan, M.; Cenko, S. B.; Kasliwal, M. M.; Gal-Yam, A.; Kulkarni, S. R.; Arcavi, I.; Bildsten, L.; Bloom, J. S.; Horesh, A.; Howell, D. A.; Filippenko, A. V.; Laher, R.; Murray, D.; Nakar, E.; Nugent, P. E.; Silverman, J. M.; Shaviv, N. J.; Surace, J.; Yaron, O.
    Some observations suggest that very massive stars experience extreme mass-loss episodes shortly before they explode as supernovae, as do several models. Establishing a causal connection between these mass-loss episodes and the final explosion would provide a novel way to study pre-supernova massive-star evolution. Here we report observations of a mass-loss event detected 40 days before the explosion of the type IIn supernova SN 2010mc (also known as PTF 10tel). Our photometric and spectroscopic data suggest that this event is a result of an energetic outburst, radiating at least 6 × 10^(47) erg of energy and releasing about 10^(−2) solar masses of material at typical velocities of 2,000 km s^(−1)....

  15. An outburst from a massive star 40 days before a supernova explosion

    Ofek, E. O.; Sullivan, M.; Cenko, S. B.; Kasliwal, M. M.; Gal-Yam, A.; Kulkarni, S. R.; Arcavi, I.; Bildsten, L.; Bloom, J. S.; Horesh, A.; Howell, D. A.; Filippenko, A. V.; Laher, R.; Murray, D.; Nakar, E.; Nugent, P. E.; Silverman, J. M.; Shaviv, N. J.; Surace, J.; Yaron, O.
    Some observations suggest that very massive stars experience extreme mass-loss episodes shortly before they explode as supernovae, as do several models. Establishing a causal connection between these mass-loss episodes and the final explosion would provide a novel way to study pre-supernova massive-star evolution. Here we report observations of a mass-loss event detected 40 days before the explosion of the type IIn supernova SN 2010mc (also known as PTF 10tel). Our photometric and spectroscopic data suggest that this event is a result of an energetic outburst, radiating at least 6 × 10^(47) erg of energy and releasing about 10^(−2) solar masses of material at typical velocities of 2,000 km s^(−1)....

  16. X-Ray Emission from Supernovae in Dense Circumstellar Matter Environments: A Search for Collisionless Shocks

    Ofek, E. O.; Fox, D.; Cenko, S. B.; Sullivan, M.; Gnat, O.; Frail, D. A.; Horesh, A.; Corsi, A.; Quimby, R. M.; Gehrels, N.; Kulkarni, S. R.; Gal-Yam, A.; Nugent, P. E.; Yaron, O.; Filippenko, A. V.; Kasliwal, M. M.; Bildsten, L.; Bloom, J. S.; Poznanski, D.; Arcavi, I.; Laher, R. R.; Levitan, D.; Sesar, B.; Surace, J.
    The optical light curve of some supernovae (SNe) may be powered by the outward diffusion of the energy deposited by the explosion shock (the so-called shock breakout) in optically thick (τ ≳ 30) circumstellar matter (CSM). Recently, it was shown that the radiation-mediated and radiation-dominated shock in an optically thick wind must transform into a collisionless shock and can produce hard X-rays. The X-rays are expected to peak at late times, relative to maximum visible light. Here we report on a search, using Swift/XRT and Chandra, for X-ray emission from 28 SNe that belong to classes whose progenitors are suspected...

  17. X-Ray Emission from Supernovae in Dense Circumstellar Matter Environments: A Search for Collisionless Shocks

    Ofek, E. O.; Fox, D.; Cenko, S. B.; Sullivan, M.; Gnat, O.; Frail, D. A.; Horesh, A.; Corsi, A.; Quimby, R. M.; Gehrels, N.; Kulkarni, S. R.; Gal-Yam, A.; Nugent, P. E.; Yaron, O.; Filippenko, A. V.; Kasliwal, M. M.; Bildsten, L.; Bloom, J. S.; Poznanski, D.; Arcavi, I.; Laher, R. R.; Levitan, D.; Sesar, B.; Surace, J.
    The optical light curve of some supernovae (SNe) may be powered by the outward diffusion of the energy deposited by the explosion shock (the so-called shock breakout) in optically thick (τ ≳ 30) circumstellar matter (CSM). Recently, it was shown that the radiation-mediated and radiation-dominated shock in an optically thick wind must transform into a collisionless shock and can produce hard X-rays. The X-rays are expected to peak at late times, relative to maximum visible light. Here we report on a search, using Swift/XRT and Chandra, for X-ray emission from 28 SNe that belong to classes whose progenitors are suspected...

  18. X-Ray Emission from Supernovae in Dense Circumstellar Matter Environments: A Search for Collisionless Shocks

    Ofek, E. O.; Fox, D.; Cenko, S. B.; Sullivan, M.; Gnat, O.; Frail, D. A.; Horesh, A.; Corsi, A.; Quimby, R. M.; Gehrels, N.; Kulkarni, S. R.; Gal-Yam, A.; Nugent, P. E.; Yaron, O.; Filippenko, A. V.; Kasliwal, M. M.; Bildsten, L.; Bloom, J. S.; Poznanski, D.; Arcavi, I.; Laher, R. R.; Levitan, D.; Sesar, B.; Surace, J.
    The optical light curve of some supernovae (SNe) may be powered by the outward diffusion of the energy deposited by the explosion shock (the so-called shock breakout) in optically thick (τ ≳ 30) circumstellar matter (CSM). Recently, it was shown that the radiation-mediated and radiation-dominated shock in an optically thick wind must transform into a collisionless shock and can produce hard X-rays. The X-rays are expected to peak at late times, relative to maximum visible light. Here we report on a search, using Swift/XRT and Chandra, for X-ray emission from 28 SNe that belong to classes whose progenitors are suspected...

  19. X-Ray Emission from Supernovae in Dense Circumstellar Matter Environments: A Search for Collisionless Shocks

    Ofek, E. O.; Fox, D.; Cenko, S. B.; Sullivan, M.; Gnat, O.; Frail, D. A.; Horesh, A.; Corsi, A.; Quimby, R. M.; Gehrels, N.; Kulkarni, S. R.; Gal-Yam, A.; Nugent, P. E.; Yaron, O.; Filippenko, A. V.; Kasliwal, M. M.; Bildsten, L.; Bloom, J. S.; Poznanski, D.; Arcavi, I.; Laher, R. R.; Levitan, D.; Sesar, B.; Surace, J.
    The optical light curve of some supernovae (SNe) may be powered by the outward diffusion of the energy deposited by the explosion shock (the so-called shock breakout) in optically thick (τ ≳ 30) circumstellar matter (CSM). Recently, it was shown that the radiation-mediated and radiation-dominated shock in an optically thick wind must transform into a collisionless shock and can produce hard X-rays. The X-rays are expected to peak at late times, relative to maximum visible light. Here we report on a search, using Swift/XRT and Chandra, for X-ray emission from 28 SNe that belong to classes whose progenitors are suspected...

  20. Discovery and Early Multi-wavelength Measurements of the Energetic Type Ic Supernova PTF12gzk: A Massive-star Explosion in a Dwarf Host Galaxy

    Ben-Ami, Sagi; Horesh, Assaf; Kulkarni, Shrinivas R.; Perley, Daniel; Becker, Juliette C.; Bottom, Michael; Muirhead, Philip S.; Kasliwal, M. M.
    We present the discovery and extensive early-time observations of the Type Ic supernova (SN) PTF12gzk. Our light curves show a rise of 0.8 mag within 2.5 hr. Power-law fits (f(t)α(t – t_0)^n ) to these data constrain the explosion date to within one day. We cannot rule out a quadratic fireball model, but higher values of n are possible as well for larger areas in the fit parameter space. Our bolometric light curve and a dense spectral sequence are used to estimate the physical parameters of the exploding star and of the explosion. We show that the photometric evolution of...

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