FRB 121102
Understanding the nature of FRB 121102 is such a large part of my research focus, I've given it its own page.
Below is a selection of papers about FRB 121102 that I have been contributed to.
2022: The year of large burst samples
- Publication: Jahns et al. 2022, ApJL
- What we did: Analyzed a sample of 849 bursts detected with the Arecibo Observatory at 1.4 GHz during a particularly active period in November 2018.
- What we measured: The burst wait times are characterized by two time scales: one on a time scale of milliseconds and a second on order of 10s of seconds.
- What it means: The short timescale is characteristic of the emission process, while the longer time scale is set by the Poisson detection rate.
- What we measured: We confirmed that the burst energy and luminosity number counts are characterized by two distributions, which leads to more high energy bursts than expected.
- What it means: There may be multiple emission mechanisms at work.
- What we measured: There is a linear relation between the time-frequency drift within a sub-burst and its duration.
- What it means: Likely tells us something about the emission mechanism.
- What is next: Search, analyze, and publish the remaining Arecibo data.
Other papers from 2022 that I am a co-author on
2021: The year of large rotation measure changes
- Publication: Hilmarsson et al. 2021, ApJL
- What we did: Measured the RM from bursts detected at higher frequencies with Arecibo, Effelsberg, and the Jansky Very Large Array.
- What we measured: The RM dropped roughly linearly from roughly 100,000 rad per sq. m to 70,000 rad per sq. m between early 2017 and mid-2018 before leveling off through mid-2019.
- What it means: We found that the RM evolution is consistent with a pulsar wind nebula or environment similar to the Galactic center.
- What is next: Continue monitoring FRB 121102 in order to extend the RM "light curve".
Other papers from 2021 that I am a co-author on
2020: The year periodicity
- Publication: Cruces et al. 2021, MNRAS
- What we did: Performed unbiased observations of FRB 121102 with the Effelsberg 100-m radio telescope at 1.4 GHz.
- What we measured: We confirmed the proposed 160-day activity periodicity using unbiased data and a Lomb-Scargle periodogram analysis
- What it means: This is the second repeater with periodic activity. This periodicity is highly constraining for source models.
- What is next: We want to expand the burst sample to include unpublished data from Arecibo to build up a larger statistical sample.
2019: The year of weird bursts
- Publication: Hessels et al 2019, ApJL
- What we did: Detected several bright bursts with complex time-frequency structure at 1.4 GHz with the Arecibo Observatory during a particularly active period in September 2016
- What we measured: We characterized the durations and bandwidths of the bursts, as well as measuring the drift rate of the components
- What it means: This sort of emission is unusual in other pulsed radio emitters, such as pulsars, but is becoming more common in repeating FRBs. Likely it is telling us something about the emission mechanism responsible for the luminous bursts.
- What is next: We want to continue to monitor FRB 121102 and build up a larger statistical sample.
Other papers from 2019 that I am a co-author on
2018: The year of polarization
- Publication: Michilli et al 2018, Nature
- What we did: Detected bursts from FRB 121102 at 4.5 GHz using the Arecibo Observatory
- What we measured: The bursts were nearly 100% linearly polarized, and the bursts' rotation measures were among the largest ever measured in a radio source.
- What it means: The high fraction of polarization is similar to radio emission from the magnetic fields of Galactic neutron stars. The large rotation measure implies that the source is located in an environment with a hot, ionized plasma threaded with a strong, spatially coherent magnetic field. Our best model is a neutron star either in a highly energetic, young supernova remnant or near a low-luminosity AGN.
- What is next: We want to continue to monitor the rotation measure of the bursts over time to see how it varies. (See 2021.)
Other papers from 2018 that I am a co-author on
2017: The year of localization
- Publication: Chatterjee et al 2017, Nature
- What we did: Detected nine bursts from FRB 121102 using a fast-imaging mode on the Jansky Very Large Array.
- What we measured:
With the VLA we measured the position of the bursting source with a factor of ~100 better precision than before and identified a compact, persistent radio source at the same position.
- What it means: The source's position is precise enough to identify the host galaxy.
- What is next: We still do not understand the nature of this persistent source, so we want to
measure its brightness at a wider range of frequencies and measure it on a regular basis to see if it varies with time.
- Publication: Tendulkar et al 2017, ApJ
- What we did: Optical imaging and spectral observations of the faint optical source at the position of the radio bursts with the Gemini telescope.
- What we measured: The spectrum was redshifted by 0.193, placing the source at a luminosity distance of around 1 Gpc. Furthermore, we classified the host as a low-metalicity dwarf galaxy with significant star formation.
- What it means: Low-metalicity dwarf galaxies are the preferred hosts of superluminous supernovae and long gamma-ray bursts, perhaps suggesting that there is a link.
- What is next: See Bassa et al 2017, below.
- Publication: Marcote et al 2017, ApJ
- What we did: Detected both the bursting and persistent radio sources with the European VLBI Network.
- What we measured: The upper limit to the size of the persistent source is less than 1 pc, and the persistent and bursting source are at the same position.
- What it means: The persistent and bursting source are most likely physically linked.
- What is next: See Bassa et al 2017, below.
Other papers from 2017 that I am a co-author on
2016: The year of repetition
- Publication: Spitler et al 2016, Nature
- What we did: Monitored the position of FRB 121102 with the Arecibo Observatory.
- What we measured: Ten new bursts from the source, making it the first repeating FRB.
- What it means: The radio bursts can not be produced in a cataclysmic event, which ruled out most models of FRB origins at the time. Also enables more extensive follow-up.
Other papers from 2016 that I am a co-author on
2014: The year of discovery
- Publication: Spitler et al 2014, ApJ
- What we did: Searched through archival data from the PALFA survey, a pulsar survey at low Galactic latitudes undergoing at the Arecibo Observatory.
- What we measured: We discovered FRB 121102, the first FRB from Arecibo and a telescope other than Parkes.
- What it means: At the time it was crucial evidence that FRBs were truly astrophysical sources, because at that time only the Parkes telescope had observed them.
Understanding the nature of FRB 121102 is such a large part of my research focus, I've given it its own page.
Below is a selection of papers about FRB 121102 that I have been contributed to.
2022: The year of large burst samples
- Publication: Jahns et al. 2022, ApJL
- What we did: Analyzed a sample of 849 bursts detected with the Arecibo Observatory at 1.4 GHz during a particularly active period in November 2018.
- What we measured: The burst wait times are characterized by two time scales: one on a time scale of milliseconds and a second on order of 10s of seconds.
- What it means: The short timescale is characteristic of the emission process, while the longer time scale is set by the Poisson detection rate.
- What we measured: We confirmed that the burst energy and luminosity number counts are characterized by two distributions, which leads to more high energy bursts than expected.
- What it means: There may be multiple emission mechanisms at work.
- What we measured: There is a linear relation between the time-frequency drift within a sub-burst and its duration.
- What it means: Likely tells us something about the emission mechanism.
- What is next: Search, analyze, and publish the remaining Arecibo data.
Other papers from 2022 that I am a co-author on
2021: The year of large rotation measure changes
- Publication: Hilmarsson et al. 2021, ApJL
- What we did: Measured the RM from bursts detected at higher frequencies with Arecibo, Effelsberg, and the Jansky Very Large Array.
- What we measured: The RM dropped roughly linearly from roughly 100,000 rad per sq. m to 70,000 rad per sq. m between early 2017 and mid-2018 before leveling off through mid-2019.
- What it means: We found that the RM evolution is consistent with a pulsar wind nebula or environment similar to the Galactic center.
- What is next: Continue monitoring FRB 121102 in order to extend the RM "light curve".
Other papers from 2021 that I am a co-author on
2020: The year periodicity
- Publication: Cruces et al. 2021, MNRAS
- What we did: Performed unbiased observations of FRB 121102 with the Effelsberg 100-m radio telescope at 1.4 GHz.
- What we measured: We confirmed the proposed 160-day activity periodicity using unbiased data and a Lomb-Scargle periodogram analysis
- What it means: This is the second repeater with periodic activity. This periodicity is highly constraining for source models.
- What is next: We want to expand the burst sample to include unpublished data from Arecibo to build up a larger statistical sample.
2019: The year of weird bursts
- Publication: Hessels et al 2019, ApJL
- What we did: Detected several bright bursts with complex time-frequency structure at 1.4 GHz with the Arecibo Observatory during a particularly active period in September 2016
- What we measured: We characterized the durations and bandwidths of the bursts, as well as measuring the drift rate of the components
- What it means: This sort of emission is unusual in other pulsed radio emitters, such as pulsars, but is becoming more common in repeating FRBs. Likely it is telling us something about the emission mechanism responsible for the luminous bursts.
- What is next: We want to continue to monitor FRB 121102 and build up a larger statistical sample.
Other papers from 2019 that I am a co-author on
2018: The year of polarization
- Publication: Michilli et al 2018, Nature
- What we did: Detected bursts from FRB 121102 at 4.5 GHz using the Arecibo Observatory
- What we measured: The bursts were nearly 100% linearly polarized, and the bursts' rotation measures were among the largest ever measured in a radio source.
- What it means: The high fraction of polarization is similar to radio emission from the magnetic fields of Galactic neutron stars. The large rotation measure implies that the source is located in an environment with a hot, ionized plasma threaded with a strong, spatially coherent magnetic field. Our best model is a neutron star either in a highly energetic, young supernova remnant or near a low-luminosity AGN.
- What is next: We want to continue to monitor the rotation measure of the bursts over time to see how it varies. (See 2021.)
Other papers from 2018 that I am a co-author on
2017: The year of localization
- Publication: Chatterjee et al 2017, Nature
- What we did: Detected nine bursts from FRB 121102 using a fast-imaging mode on the Jansky Very Large Array.
- What we measured: With the VLA we measured the position of the bursting source with a factor of ~100 better precision than before and identified a compact, persistent radio source at the same position.
- What it means: The source's position is precise enough to identify the host galaxy.
- What is next: We still do not understand the nature of this persistent source, so we want to measure its brightness at a wider range of frequencies and measure it on a regular basis to see if it varies with time.
- Publication: Tendulkar et al 2017, ApJ
- What we did: Optical imaging and spectral observations of the faint optical source at the position of the radio bursts with the Gemini telescope.
- What we measured: The spectrum was redshifted by 0.193, placing the source at a luminosity distance of around 1 Gpc. Furthermore, we classified the host as a low-metalicity dwarf galaxy with significant star formation.
- What it means: Low-metalicity dwarf galaxies are the preferred hosts of superluminous supernovae and long gamma-ray bursts, perhaps suggesting that there is a link.
- What is next: See Bassa et al 2017, below.
- Publication: Marcote et al 2017, ApJ
- What we did: Detected both the bursting and persistent radio sources with the European VLBI Network.
- What we measured: The upper limit to the size of the persistent source is less than 1 pc, and the persistent and bursting source are at the same position.
- What it means: The persistent and bursting source are most likely physically linked.
- What is next: See Bassa et al 2017, below.
Other papers from 2017 that I am a co-author on
2016: The year of repetition
- Publication: Spitler et al 2016, Nature
- What we did: Monitored the position of FRB 121102 with the Arecibo Observatory.
- What we measured: Ten new bursts from the source, making it the first repeating FRB.
- What it means: The radio bursts can not be produced in a cataclysmic event, which ruled out most models of FRB origins at the time. Also enables more extensive follow-up.
Other papers from 2016 that I am a co-author on
2014: The year of discovery
- Publication: Spitler et al 2014, ApJ
- What we did: Searched through archival data from the PALFA survey, a pulsar survey at low Galactic latitudes undergoing at the Arecibo Observatory.
- What we measured: We discovered FRB 121102, the first FRB from Arecibo and a telescope other than Parkes.
- What it means: At the time it was crucial evidence that FRBs were truly astrophysical sources, because at that time only the Parkes telescope had observed them.