316 research outputs found
The 2016 outburst of PSR J1119-6127: cooling & a spin-down dominated glitch
We report on the aftermath of a magnetar outburst from the young,
high-magnetic-field radio pulsar PSR J1119-6127 that occurred on 2016 July 27.
We present the results of a monitoring campaign using the Neil Gehrels Swift
X-ray Telescope, NuSTAR, and XMM-Newton. After reaching a peak luminosity of
~300 times the quiescent luminosity, the pulsar's X-ray flux declined by factor
of ~50 on a time scale of several months. The X-ray spectra are well described
by a blackbody and a hard power-law tail. After an initial rapid decline during
the first day of the outburst, we observe the blackbody temperature rising from
kT = 0.9 keV to 1.05 keV during the first two weeks of the outburst, before
cooling to 0.9 keV. During this time, the blackbody radius decreases
monotonically by a factor of ~4 over a span of nearly 200 days. We also report
a heretofore unseen highly pulsed hard X-ray emission component, which fades on
a similar timescale to the soft X-ray flux, as predicted by models of
relaxation of magnetospheric current twists. The previously reported spin-up
glitch which accompanied this outburst was followed by a period of enhanced and
erratic torque, leading to a net spin-down of Hz, a
factor of ~24 over-recovery. We suggest that this and other radiatively loud
magnetar-type glitch recoveries are dominated by magnetospheric processes, in
contrast to conventional radio pulsar glitch recoveries which are dominated by
internal physics.Comment: Submitted to Ap
The Rise of SN 2014J in the Nearby Galaxy M82
We report on the discovery of SN 2014J in the nearby galaxy M82. Given its proximity, it offers the best opportunity to date to study a thermonuclear supernova (SN) over a wide range of the electromagnetic spectrum. Optical, near-IR, and mid-IR observations on the rising light curve, orchestrated by the intermediate Palomar Transient Factory, show that SN 2014J is a spectroscopically normal Type Ia supernova (SN Ia), albeit exhibiting high-velocity features in its spectrum and heavily reddened by dust in the host galaxy. Our earliest detections start just hours after the fitted time of explosion. We use high-resolution optical spectroscopy to analyze the dense intervening material and do not detect any evolution in the resolved absorption features during the light curve rise. Similar to other highly reddened SNe Ia, a low value of total-to-selective extinction, R_V ≲ 2, provides the best match to our observations. We also study pre-explosion optical and near-IR images from Hubble Space Telescope with special emphasis on the sources nearest to the SN location
A Magnetar-like Outburst from a High-B Radio Pulsar
Radio pulsars are believed to have their emission powered by the loss of rotational kinetic energy. By contrast, magnetars show intense X-ray and γ-ray radiation whose luminosity greatly exceeds that due to spin down and magnetar luminosity is believed to be powered by intense internal magnetic fields. A basic prediction of this picture is that radio pulsars of high magnetic field should show magnetar-like emission. Here we report on a magnetar-like X-ray outburst from the radio pulsar PSR J1119–6127, heralded by two short bright X-ray bursts on 2016 July 27 and 28. Using target of opportunity data from the Swift X-ray Telescope and NuSTAR, we show that this pulsar's flux has brightened by a factor of >160 in the 0.5–10 keV band, and that its previously soft X-ray spectrum has undergone a strong hardening with strong pulsations appearing for the first time above 2.5 keV, with phase-averaged emission detectable up to 25 keV. By comparing Swift-XRT and NuSTAR timing data with a pre-outburst ephemeris derived from Fermi Large Area Telescope data, we find that the source has contemporaneously undergone a large spin-up glitch of amplitude Δν/ν = 5.74(8) x 10^(-6). The collection of phenomena observed thus far in this outburst strongly mirrors those in most magnetar outbursts and provides an unambiguous connection between the radio pulsar and magnetar populations
Simultaneous X-ray, gamma-ray, and Radio Observations of the repeating Fast Radio Burst FRB 121102
We undertook coordinated campaigns with the Green Bank, Effelsberg, and
Arecibo radio telescopes during Chandra X-ray Observatory and XMM-Newton
observations of the repeating fast radio burst FRB 121102 to search for
simultaneous radio and X-ray bursts. We find 12 radio bursts from FRB 121102
during 70 ks total of X-ray observations. We detect no X-ray photons at the
times of radio bursts from FRB 121102 and further detect no X-ray bursts above
the measured background at any time. We place a 5 upper limit of
erg cm on the 0.5--10 keV fluence for X-ray bursts at
the time of radio bursts for durations ms, which corresponds to a burst
energy of erg at the measured distance of FRB 121102. We also
place limits on the 0.5--10 keV fluence of erg cm and
erg cm for bursts emitted at any time during the
XMM-Newton and Chandra observations, respectively, assuming a typical X-ray
burst duration of 5 ms. We analyze data from the Fermi Gamma-ray Space
Telescope Gamma-ray Burst Monitor and place a 5 upper limit on the
10--100 keV fluence of erg cm ( erg at
the distance of FRB 121102) for gamma-ray bursts at the time of radio bursts.
We also present a deep search for a persistent X-ray source using all of the
X-ray observations taken to date and place a 5 upper limit on the
0.5--10 keV flux of erg s cm (
erg~s at the distance of FRB 121102). We discuss these non-detections in
the context of the host environment of FRB 121102 and of possible sources of
fast radio bursts in general.Comment: 13 pages, 5 figures, published in Ap
The repeating Fast Radio Burst FRB 121102: Multi-wavelength observations and additional bursts
We report on radio and X-ray observations of the only known repeating Fast
Radio Burst (FRB) source, FRB 121102. We have detected six additional radio
bursts from this source: five with the Green Bank Telescope at 2 GHz, and one
at 1.4 GHz at the Arecibo Observatory for a total of 17 bursts from this
source. All have dispersion measures consistent with a single value (
pc cm) that is three times the predicted maximum Galactic value. The
2-GHz bursts have highly variable spectra like those at 1.4 GHz, indicating
that the frequency structure seen across the individual 1.4 and 2-GHz
bandpasses is part of a wideband process. X-ray observations of the FRB 121102
field with the Swift and Chandra observatories show at least one possible
counterpart; however, the probability of chance superposition is high. A radio
imaging observation of the field with the Jansky Very Large Array at 1.6 GHz
yields a 5 upper limit of 0.3 mJy on any point-source continuum
emission. This upper limit, combined with archival WISE 22-m and IPHAS
H surveys, rules out the presence of an intervening Galactic HII
region. We update our estimate of the FRB detection rate in the PALFA survey to
be 1.1 FRBs sky day (95% confidence)
for peak flux density at 1.4 GHz above 300 mJy. We find that the intrinsic
widths of the 12 FRB 121102 bursts from Arecibo are, on average, significantly
longer than the intrinsic widths of the 13 single-component FRBs detected with
the Parkes telescope.Comment: 18 pages, 5 figures. Accepted for publication in Ap
A Multi-telescope Campaign on FRB 121102: Implications for the FRB Population
We present results of the coordinated observing campaign that made the first
subarcsecond localization of a Fast Radio Burst, FRB 121102. During this
campaign, we made the first simultaneous detection of an FRB burst by multiple
telescopes: the VLA at 3 GHz and the Arecibo Observatory at 1.4 GHz. Of the
nine bursts detected by the Very Large Array at 3 GHz, four had simultaneous
observing coverage at other observatories. We use multi-observatory constraints
and modeling of bursts seen only at 3 GHz to confirm earlier results showing
that burst spectra are not well modeled by a power law. We find that burst
spectra are characterized by a ~500 MHz envelope and apparent radio energy as
high as erg. We measure significant changes in the apparent
dispersion between bursts that can be attributed to frequency-dependent
profiles or some other intrinsic burst structure that adds a systematic error
to the estimate of DM by up to 1%. We use FRB 121102 as a prototype of the FRB
class to estimate a volumetric birth rate of FRB sources Mpc yr, where is the number of bursts per
source over its lifetime. This rate is broadly consistent with models of FRBs
from young pulsars or magnetars born in superluminous supernovae or long
gamma-ray bursts, if the typical FRB repeats on the order of thousands of times
during its lifetime.Comment: 17 pages, 7 figures. Submitted to AAS Journal
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