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Caltech Authors (169.688 recursos)

Repository of works by Caltech published authors.

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Mostrando recursos 81 - 100 de 281

  1. Metallicity from Type II supernovae from the (i)PTF

    Taddia, F.; Moquist, P.; Sollerman, J.; Rubin, A.; Leloudas, G.; Gal-Yam, A.; Arcavi, I.; Cao, Y.; Filippenko, A. V.; Graham, M. L.; Mazzali, P. A.; Nugent, P. E.; Pan, Y.-C.; Silverman, J. M.; Xu, D.; Yaron, O.
    Type IIP supernovae (SNe IIP) have recently been proposed as metallicity (Z) probes. The spectral models of Dessart et al. (2014, MNRAS, 440, 1856) showed that the pseudo-equivalent width of Fe II λ5018 (pEW_(5018)) during the plateau phase depends on the primordial Z, but there was a paucity of SNe IIP exhibiting pEW_(5018) that were compatible with Z < 0.4 Z⊙. This lack might be due to some physical property of the SN II population or to the fact that those SNe have been discovered in luminous, metal-rich targeted galaxies. Here we use SN II observations from the untargeted (intermediate) Palomar...

  2. The Outer Galactic Halo As Probed By RR Lyr Stars From the Palomar Transient Facility + Keck

    Cohen, Judith; Sesar, Branimir; Banholzer, Sophianna
    We present initial results from our study of the outer halo of the Milky Way using a large sample of RR Lyr(ab) variables datamined from the archives of the Palomar Transient Facility. Of the 464 RR Lyr in our sample with distances exceeding 50 kpc, 62 have been observed spectroscopically at the Keck Observatory. v _r and σ(v_r) are given as a function of distance between 50 and 110 kpc, and a very preliminary rather low total mass for the Milky Way out to 110 kpc of ~7 ± 1.5 × 10^(11) M⊙ is derived from our data.

  3. The Outer Galactic Halo As Probed By RR Lyr Stars From the Palomar Transient Facility + Keck

    Cohen, Judith; Sesar, Branimir; Banholzer, Sophianna
    We present initial results from our study of the outer halo of the Milky Way using a large sample of RR Lyr(ab) variables datamined from the archives of the Palomar Transient Facility. Of the 464 RR Lyr in our sample with distances exceeding 50 kpc, 62 have been observed spectroscopically at the Keck Observatory. v _r and σ(v_r) are given as a function of distance between 50 and 110 kpc, and a very preliminary rather low total mass for the Milky Way out to 110 kpc of ~7 ± 1.5 × 10^(11) M⊙ is derived from our data.

  4. Properties and Evolution of the Redback Millisecond Pulsar Binary PSR J2129-0429

    Bellm, Eric C.; Kaplan, David L.; Breton, Rene P.; Phinney, E. Sterl; Bhalerao, Varun B.; Camilo, Fernando; Dahal, Sumit; Djorgovski, S. G.; Drake, Andrew J.; Hessels, J. W. T.; Laher, Russ R.; Levitan, David B.; Lewis, Fraser; Mahabal, Ashish A.; Ofek, Eran O.; Prince, Thomas A.; Ransom, Scott M.; Roberts, Mallory S. E.; Russell, David M.; Sesar, Branimir; Surace, Jason A.; Tang, Sumin
    PSR J2129−0429 is a "redback" eclipsing millisecond pulsar binary with an unusually long 15.2 hr orbit. It was discovered by the Green Bank Telescope in a targeted search of unidentified Fermi gamma-ray sources. The pulsar companion is optically bright (mean m_R = 16.6 mag), allowing us to construct the longest baseline photometric data set available for such a system. We present 10 years of archival and new photometry of the companion from the Lincoln Near-Earth Asteroid Research Survey, the Catalina Real-time Transient Survey, the Palomar Transient Factory, the Palomar 60 inch, and the Las Cumbres Observatory Global Telescope. Radial velocity...

  5. Properties and Evolution of the Redback Millisecond Pulsar Binary PSR J2129-0429

    Bellm, Eric C.; Kaplan, David L.; Breton, Rene P.; Phinney, E. Sterl; Bhalerao, Varun B.; Camilo, Fernando; Dahal, Sumit; Djorgovski, S. G.; Drake, Andrew J.; Hessels, J. W. T.; Laher, Russ R.; Levitan, David B.; Lewis, Fraser; Mahabal, Ashish A.; Ofek, Eran O.; Prince, Thomas A.; Ransom, Scott M.; Roberts, Mallory S. E.; Russell, David M.; Sesar, Branimir; Surace, Jason A.; Tang, Sumin
    PSR J2129−0429 is a "redback" eclipsing millisecond pulsar binary with an unusually long 15.2 hr orbit. It was discovered by the Green Bank Telescope in a targeted search of unidentified Fermi gamma-ray sources. The pulsar companion is optically bright (mean m_R = 16.6 mag), allowing us to construct the longest baseline photometric data set available for such a system. We present 10 years of archival and new photometry of the companion from the Lincoln Near-Earth Asteroid Research Survey, the Catalina Real-time Transient Survey, the Palomar Transient Factory, the Palomar 60 inch, and the Las Cumbres Observatory Global Telescope. Radial velocity...

  6. Properties and Evolution of the Redback Millisecond Pulsar Binary PSR J2129-0429

    Bellm, Eric C.; Kaplan, David L.; Breton, Rene P.; Phinney, E. Sterl; Bhalerao, Varun B.; Camilo, Fernando; Dahal, Sumit; Djorgovski, S. G.; Drake, Andrew J.; Hessels, J. W. T.; Laher, Russ R.; Levitan, David B.; Lewis, Fraser; Mahabal, Ashish A.; Ofek, Eran O.; Prince, Thomas A.; Ransom, Scott M.; Roberts, Mallory S. E.; Russell, David M.; Sesar, Branimir; Surace, Jason A.; Tang, Sumin
    PSR J2129−0429 is a "redback" eclipsing millisecond pulsar binary with an unusually long 15.2 hr orbit. It was discovered by the Green Bank Telescope in a targeted search of unidentified Fermi gamma-ray sources. The pulsar companion is optically bright (mean m_R = 16.6 mag), allowing us to construct the longest baseline photometric data set available for such a system. We present 10 years of archival and new photometry of the companion from the Lincoln Near-Earth Asteroid Research Survey, the Catalina Real-time Transient Survey, the Palomar Transient Factory, the Palomar 60 inch, and the Las Cumbres Observatory Global Telescope. Radial velocity...

  7. Properties and Evolution of the Redback Millisecond Pulsar Binary PSR J2129-0429

    Bellm, Eric C.; Kaplan, David L.; Breton, Rene P.; Phinney, E. Sterl; Bhalerao, Varun B.; Camilo, Fernando; Dahal, Sumit; Djorgovski, S. G.; Drake, Andrew J.; Hessels, J. W. T.; Laher, Russ R.; Levitan, David B.; Lewis, Fraser; Mahabal, Ashish A.; Ofek, Eran O.; Prince, Thomas A.; Ransom, Scott M.; Roberts, Mallory S. E.; Russell, David M.; Sesar, Branimir; Surace, Jason A.; Tang, Sumin
    PSR J2129−0429 is a "redback" eclipsing millisecond pulsar binary with an unusually long 15.2 hr orbit. It was discovered by the Green Bank Telescope in a targeted search of unidentified Fermi gamma-ray sources. The pulsar companion is optically bright (mean m_R = 16.6 mag), allowing us to construct the longest baseline photometric data set available for such a system. We present 10 years of archival and new photometry of the companion from the Lincoln Near-Earth Asteroid Research Survey, the Catalina Real-time Transient Survey, the Palomar Transient Factory, the Palomar 60 inch, and the Las Cumbres Observatory Global Telescope. Radial velocity...

  8. Long-rising Type II supernovae from Palomar Transient Factory and Caltech Core-Collapse Project

    Taddia, F.; Sollerman, J.; Fremling, C.; Migotto, K.; Gal-Yam, A.; Armen, S.; Duggan, G.; Ergon, M.; Filippenko, A. V.; Fransson, C.; Hosseinzadeh, G.; Kasliwal, M. M.; Laher, R. R.; Leloudas, G.; Leonard, D. C.; Lunnan, R.; Masci, F. J.; Moon, D.-S.; Silverman, J. M.; Wozniak, P. R.
    Context. Supernova (SN) 1987A was a peculiar hydrogen-rich event with a long-rising (~ 84 d) light curve, stemming from the explosion of a compact blue supergiant star. Only a few similar events have been presented in the literature in recent decades. Aims. We present new data for a sample of six long-rising Type II SNe (SNe II), three of which were discovered and observed by the Palomar Transient Factory (PTF) and three observed by the Caltech Core-Collapse Project (CCCP). Our aim is to enlarge this small family of long-rising SNe II, characterizing their differences in terms of progenitor and explosion parameters....

  9. Long-rising Type II supernovae from Palomar Transient Factory and Caltech Core-Collapse Project

    Taddia, F.; Sollerman, J.; Fremling, C.; Migotto, K.; Gal-Yam, A.; Armen, S.; Duggan, G.; Ergon, M.; Filippenko, A. V.; Fransson, C.; Hosseinzadeh, G.; Kasliwal, M. M.; Laher, R. R.; Leloudas, G.; Leonard, D. C.; Lunnan, R.; Masci, F. J.; Moon, D.-S.; Silverman, J. M.; Wozniak, P. R.
    Context. Supernova (SN) 1987A was a peculiar hydrogen-rich event with a long-rising (~ 84 d) light curve, stemming from the explosion of a compact blue supergiant star. Only a few similar events have been presented in the literature in recent decades. Aims. We present new data for a sample of six long-rising Type II SNe (SNe II), three of which were discovered and observed by the Palomar Transient Factory (PTF) and three observed by the Caltech Core-Collapse Project (CCCP). Our aim is to enlarge this small family of long-rising SNe II, characterizing their differences in terms of progenitor and explosion parameters....

  10. An Intermediate Type Ia Supernova Between Normal And Super-Chandrasekhar

    Cao, Yi; Johansson, J.; Nugent, Peter E.; Goobar, A.; Nordin, Jakob; Kulkarni, S. R.; Cenko, S. Bradley; Fox, Ori; Kasliwal, Mansi M.; Fremling, C.; Amanullah, R.; Hsiao, E. Y.; Perley, D. A.; Bue, Brian D.; Masci, Frank J.; Lee, William H.; Chotard, Nicolas
    While recent observations provide evidence that super-Chandrasekhar Type Ia supernovae and at least a fraction of normal Type Ia supernovae probably originate from double-degenerate systems, these two subclasses show distinct characteristics observationally. Here we report an intermediate supernova iPTF13asv that may bridge this gap. On the one hand, similar to normal Type Ia supernovae, the over-luminous iPTF13asv follows the empirical relation between the peak magnitude, the lightcurve shape and its intrinsic color, and shows a near-IR secondary maximum like normal supernovae. On the other hand, similar to super-Chandrasekhar events, it has strong UV emission around maximum, low expansion velocities and persistent...

  11. Absence of Fast-moving Iron in an Intermediate Type Ia Supernova between Normal and Super-Chandrasekhar

    Cao, Yi; Johansson, J.; Nugent, Peter E.; Goobar, A.; Nordin, Jakob; Kulkarni, S. R.; Cenko, S. Bradley; Fox, Ori; Kasliwal, Mansi M.; Fremling, C.; Amanullah, R.; Hsiao, E. Y.; Perley, D. A.; Bue, Brian D.; Masci, Frank J.; Lee, William H.; Chotard, Nicolas
    In this paper, we report observations of a peculiar SN Ia iPTF13asv (a.k.a., SN2013cv) from the onset of the explosion to months after its peak. The early-phase spectra of iPTF13asv show an absence of iron absorption, indicating that synthesized iron elements are confined to low-velocity regions of the ejecta, which, in turn, implies a stratified ejecta structure along the line of sight. Our analysis of iPTF13asv's light curves and spectra shows that it is an intermediate case between normal and super-Chandrasekhar events. On the one hand, its light curve shape (B-band Δm_(15) = 1.03 ± 0.01) and overall spectral features...

  12. Absence of Fast-moving Iron in an Intermediate Type Ia Supernova between Normal and Super-Chandrasekhar

    Cao, Yi; Johansson, J.; Nugent, Peter E.; Goobar, A.; Nordin, Jakob; Kulkarni, S. R.; Cenko, S. Bradley; Fox, Ori; Kasliwal, Mansi M.; Fremling, C.; Amanullah, R.; Hsiao, E. Y.; Perley, D. A.; Bue, Brian D.; Masci, Frank J.; Lee, William H.; Chotard, Nicolas
    In this paper, we report observations of a peculiar SN Ia iPTF13asv (a.k.a., SN2013cv) from the onset of the explosion to months after its peak. The early-phase spectra of iPTF13asv show an absence of iron absorption, indicating that synthesized iron elements are confined to low-velocity regions of the ejecta, which, in turn, implies a stratified ejecta structure along the line of sight. Our analysis of iPTF13asv's light curves and spectra shows that it is an intermediate case between normal and super-Chandrasekhar events. On the one hand, its light curve shape (B-band Δm_(15) = 1.03 ± 0.01) and overall spectral features...

  13. Radio observations of a sample of broad-lined type Ic supernovae discovered by PTF/iPTF: A search for relativistic explosions

    Corsi, A.; Gal-Yam, A.; Kulkarni, S. R.; Frail, D. A.; Mazzali, P. A.; Cenko, S. B.; Kasliwal, M. M.; Cao, Y.; Horesh, A.; Palliyaguru, N.; Perley, D. A.; Laher, R. R.; Taddia, F.; Leloudas, G.; Maguire, K.; Nugent, P. E.; Sollerman, J.; Sullivan, M.
    Long duration γ-ray bursts are a rare subclass of stripped-envelope core-collapse supernovae (SNe) that launch collimated relativistic outflows (jets). All γ-ray-burst-associated SNe are spectroscopically Type Ic, with broad-lines, but the fraction of broad-lined SNe Ic harboring low-luminosity γ-ray bursts remains largely unconstrained. Some SNe should be accompanied by off-axis γ-ray burst jets that initially remain invisible, but then emerge as strong radio sources (as the jets decelerate). However, this critical prediction of the jet model for γ-ray bursts has yet to be verified observationally. Here, we present K. G. Jansky Very Large Array observations of 15 broad-lined SNe of Type...

  14. Flash Spectroscopy: Emission Lines from the Ionized Circumstellar Material around <10-Day-Old Type II Supernovae

    Khazov, D.; Kulkarni, S. R.; Kasliwal, M. M.; Cao, Y.; Perley, D.; Laher, R. R.; Surace, J.
    Supernovae (SNe) embedded in dense circumstellar material (CSM) may show prominent emission lines in their early-time spectra (≤ 10 days after the explosion), owing to recombination of the CSM ionized by the shock-breakout flash. From such spectra (“flash spectroscopy”), we can measure various physical properties of the CSM, as well as the mass-loss rate of the progenitor during the year prior to its explosion. Searching through the Palomar Transient Factory (PTF and iPTF) SN spectroscopy databases from 2009 through 2014, we found 12 Type II SNe showing flash-ionized (FI) signatures in their first spectra. All are younger than 10 days. These...

  15. Flash Spectroscopy: Emission Lines from the Ionized Circumstellar Material around <10-Day-Old Type II Supernovae

    Khazov, D.; Kulkarni, S. R.; Kasliwal, M. M.; Cao, Y.; Perley, D.; Laher, R. R.; Surace, J.
    Supernovae (SNe) embedded in dense circumstellar material (CSM) may show prominent emission lines in their early-time spectra (≤10 days after the explosion), owing to recombination of the CSM ionized by the shock-breakout flash. From such spectra ("flash spectroscopy"), we can measure various physical properties of the CSM, as well as the mass-loss rate of the progenitor during the year prior to its explosion. Searching through the Palomar Transient Factory (PTF and iPTF) SN spectroscopy databases from 2009 through 2014, we found 12 SNe II showing flash-ionized (FI) signatures in their first spectra. All are younger than 10 days. These events...

  16. The SDSS-IV extended Baryon Oscillation Spectroscopic Survey: Quasar Target Selection

    Myers, Adam D.; Kulkarni, Shrinivas R.; Miller, Adam A.; Laher, Russ; Surace, Jason; Levitan, David
    As part of the Sloan Digital Sky Survey (SDSS) IV the extended Baryon Oscillation Spectroscopic Survey (eBOSS) will improve measurements of the cosmological distance scale by applying the Baryon Acoustic Oscillation (BAO) method to quasar samples. eBOSS will adopt two approaches to target quasars over 7500 deg^2. First, a "CORE" quasar sample will combine the optical selection in ugriz using a likelihood-based routine called XDQSOz, with a mid-IR-optical color cut. eBOSS CORE selection (to g < 22 or r < 22) should return ~70 deg^(−2) quasars at redshifts 0.9 < z < 2.2 and ~7 deg^(−2)z > 2.1 quasars. Second,...

  17. The SDSS-IV extended Baryon Oscillation Spectroscopic Survey: Quasar Target Selection

    Myers, Adam D.; Kulkarni, Shrinivas R.; Miller, Adam A.; Laher, Russ; Surace, Jason; Levitan, David
    As part of the Sloan Digital Sky Survey (SDSS) IV the extended Baryon Oscillation Spectroscopic Survey (eBOSS) will improve measurements of the cosmological distance scale by applying the Baryon Acoustic Oscillation (BAO) method to quasar samples. eBOSS will adopt two approaches to target quasars over 7500 deg^2. First, a "CORE" quasar sample will combine the optical selection in ugriz using a likelihood-based routine called XDQSOz, with a mid-IR-optical color cut. eBOSS CORE selection (to g < 22 or r < 22) should return ~70 deg^(−2) quasars at redshifts 0.9 < z < 2.2 and ~7 deg^(−2)z > 2.1 quasars. Second,...

  18. The detection rate of early UV emission from supernovae: A dedicated GALEX/PTF survey and calibrated theoretical estimates

    Ganot, Noam; Gal-Yam, Avishay; Ofek, Eran O.; Sagiv, Ilan; Waxman, Eli; Lapid, Ofer; Kulkarni, Shrinivas R.; Ben-Ami, Sagi; Kasliwal, Mansi M.; Chelouche, Doron; Rafter, Stephen; Behar, Ehud; Laor, Ari; Poznanski, Dovi; Nakar, Udi; Maoz, Dan; Trakhtenbrot, Benny; Neill, James D.; Barlow, Thomas A.; Martin, D. Christopher; Gezari, Suvi; Arcavi, Iair; Bloom, Joshua S.; Nugent, Peter E.; Sullivan, Mark
    The radius and surface composition of an exploding massive star, as well as the explosion energy per unit mass, can be measured using early UV observations of core collapse supernovae (SNe). We present the first results from a simultaneous GALEX/PTF search for early UV emission from SNe. Six Type II SNe and one Type II superluminous SN (SLSN-II) are clearly detected in the GALEX NUV data. We compare our detection rate with theoretical estimates based on early, shock-cooling UV light curves calculated from models that fit existing Swift and GALEX observations well, combined with volumetric SN rates. We find that...

  19. The detection rate of early UV emission from supernovae: A dedicated GALEX/PTF survey and calibrated theoretical estimates

    Ganot, Noam; Gal-Yam, Avishay; Ofek, Eran O.; Sagiv, Ilan; Waxman, Eli; Lapid, Ofer; Kulkarni, Shrinivas R.; Ben-Ami, Sagi; Kasliwal, Mansi M.; Chelouche, Doron; Rafter, Stephen; Behar, Ehud; Laor, Ari; Poznanski, Dovi; Nakar, Udi; Maoz, Dan; Trakhtenbrot, Benny; Neill, James D.; Barlow, Thomas A.; Martin, D. Christopher; Gezari, Suvi; Arcavi, Iair; Bloom, Joshua S.; Nugent, Peter E.; Sullivan, Mark
    The radius and surface composition of an exploding massive star, as well as the explosion energy per unit mass, can be measured using early UV observations of core collapse supernovae (SNe). We present the first results from a simultaneous GALEX/PTF search for early UV emission from SNe. Six Type II SNe and one Type II superluminous SN (SLSN-II) are clearly detected in the GALEX NUV data. We compare our detection rate with theoretical estimates based on early, shock-cooling UV light curves calculated from models that fit existing Swift and GALEX observations well, combined with volumetric SN rates. We find that...

  20. Tests of the planetary hypothesis for PTFO 8-8695b

    Yu, Liang; Winn, Joshua N.; Gillon, Michaël; Albrecht, Simon; Rappaport, Saul; Bieryla, Allyson; Dai, Fei; Delrez, Laetitia; Hillenbrand, Lynne; Holman, Matthew J.; Howard, Andrew W.; Huang, Chelsea X.; Isaacson, Howard T.; Jehin, Emmanuel; Lendl, Monika; Montet, Benjamin T.; Muirhead, Philip; Sanchis-Ojeda, Roberto; Triaud, Amaury H. M. J.
    The T Tauri star PTFO 8-8695 exhibits periodic fading events that have been interpreted as the transits of a giant planet on a precessing orbit. Here we present three tests of the planet hypothesis. First, we sought evidence for the secular changes in light-curve morphology that are predicted to be a consequence of orbital precession. We observed 28 fading events spread over several years and did not see the expected changes. Instead, we found that the fading events are not strictly periodic. Second, we attempted to detect the planet's radiation, based on infrared observations spanning the predicted times of occultations....

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