Science White Papers

• Abstract: Four things to do: (1) RealBogus for point sources, (2) RealBogus for streaks, (3) Classification/Characterization of real transients, (4) Transfer learning using other datasets (PTF/iPTF), but also CRTS/Pan-STARRS/…

Tasks: Generating samples, Priors, Labels.

Microlensing of stars in M31 by relics from the Early Universe

• Lead: Ariel Goobar

Science White Papers

• Others Participating: Ariel Goobar & Daniel Goldstein
• Abstract: Strongly lensed Type Ia supernovae (SNe Ia) are rare systems that probe the mass profiles of elliptical galaxies at sub-kiloparsec scales. As cosmological probes, they provide a novel method of measuring H0, Omega_m, and w via time delays, and their magnifications enable studies of supernova evolution to high redshift (z <= 1:8 in ZTF). Studying them can reveal clues about the nature of dark energy, resolve tension between the local and CMB values of H0, and constrain feedback mechanisms that regulate galaxy evolution.
• strongly-lensed-type.pdf: White paper on Lensed SNe.

• MachineLearningwithZTF.pdf: ML White Paper

Science White Papers

• Lead: Scott Adams
• Others participating: Mansi Kasliwal
• Abstract: There is growing evidence that the most massive red supergiants may end their lives with a "failed" supernova, collapsing directly into a black hole without a luminous explosion. Two possible events have been found by searching for disappearing red supergiants. However, the disappearance of the progenitor is not the only possible signature of these events. Models predict that even if the energy released by the core collapse of a red supergiant fails to result in a supernova, the loss of gravitational binding energy from the neutrino emission may result in a low-velocity (~100 km/s) ejection of the weakly-bound hydrogen envelope. This ejection would result in a ~10^7 Lsun ~few days-long shock breakout thermalized to ~10^4 K followed by a fainter, but much longer-lived recombination powered transient. ZTF is uniquely capable of providing the large areal observations with nightly cadence necessary to discover these shock breakouts, which would enable, for the first time, spectroscopic follow-up and characterization of the envelope ejection and early-time fallback, and would dramatically improve the constraint on the rate failed supernovae.

Optically Identified Relativistic Explosions: Dirty Fireballs and Orphan Afterglows

• Lead: Brad Cenko

Science White Papers

• Others participating: Kevin Burdge, Eric Bellm, Paula Szkody, Tom Prince, David Kaplan, Jan van Roestel, Monika Soraisam, Lynne Hillenbrand
• Abstract: We propose to conduct a fast cadence project with continuous lightcurves of a few hours covering the full Northern Galactic Plane. Our survey will provide a comprehensive census of short period variables at low Galactic latitudes. We expect to find several hundred of (ultra)compact binaries with orbital periods well below two hours including double white dwarfs, accreting white dwarfs, helium star binaries or perhaps even neutron star binaries with white dwarf companions. This will allow us to derive, for the first time, an empirical space density for different types of ultracompact binaries in the Galaxy. The study of such systems is important to our understanding of such diverse areas as supernova Ia progenitors, binary evolution and they are predicted to be the dominant Galactic gravitational wave sources in the eLISA band.
• White paper: Galactic Plane fast cadence survey

Microlensing events in the Galactic Bulge and Plane

• Lead: E.Bachelet

• ReviewResponse.pdf: Response to reviewers, Microlensing of stars in M31

Science White Papers

• Abstract: Being able to conduct one 3pi survey every few nights, ZTF will be a valuable tool to conduct a range of solar system science focused on small solar system bodies. We propose surveys focused on three research themes: detection of small near-Earth asteroids, search for super-fast rotators, and long-term observation of comets.

• ztf-solar-system.pdf: ZTF Solar System White paper

Early studies of type I Supernovae

• Lead: S. Kulkarni

Science White Papers

• Others participating: Jakob Nordin, Marek Kowalski, Nora Strotjohann, Mansi Kasliwal
• Abstract: The IceCube neutrino observatory has detected a flux of extragalactic neutrinos. However, the origin of the neutrinos is still unknown. Possible candidates are core-collapse supernovae, active galactic nuclei and tidal disruption events - all are accompanied by a characteristic optical counterpart. Our goal is to identify the neutrino sources by detecting their optical counterpart following two approaches: a) A target of opportunity program, which selects the most interesting astrophysical neutrino candidates in real-time and triggers rapid follow-up observations by ZTF to target rapidly varying transients. b) All-sky near real-time correlation, where we correlate all optical transients found by ZTF with all neutrino candidates detected by IceCube to target slowly varying transients.
• NeutrinoWhitePaper.pdf: Neutrino White paper

Early studies of SLSNe with ZTF

• Lead: Lin Yan and Ragnhild Lunnan

Science White Papers

• Abstract: We propose a high-cadence survey of the Andromeda galaxy, monitoring ~1 million resolved stars, in the search for microlensing events with duration from just a few minutes up to several days. This scenario has not been studied systematically and holds great promise to explore Early Universe physics. The lenses we are trying to uncover are not "known" stellar objects, but rather relics from the beginning of time: Cosmic Strings, Axion Miniclusters and Primordial Black Holes. These are hypothetical (dark) macroscopic fossil remnants emerging in many leading theories of the Early Universe. It has been speculated that these objects still exist, and current experimental limits are not very constraining. Surprisingly, we have found a survey mode for ZTF that could shed new light into the physics of the origin of the Universe and the nature of dark matter. The expected contributions to our understanding of stellar astronomy are also very important part of the program.

* proposalv3.pdf: Microlensing of stars in M31 by Early Universe relics

Searching for Optical Counterparts to High-Energy Neutrino Sources

• Lead: Jakob van Santen and Anna Franckowiak

• YoungCC-impact.pdf: Response to the strawman cadence document for the young CC experiment

Science White Papers

Science White Papers

• Others participating: Eran Ofek, Avishay Gal-Yam, Ofer Yaron and others
• Abstract: to come
• White paper on young SLSNe

Solar System Science with ZTF

• Lead: Quan-Zhi Ye

Science White Papers

• Others participating: Ulrich Feindt, Mickael Rigault, Ariel Goobar, Marek Kowalski, Peter Nugent
• Abstract: We propose to discover and obtain lightcurves of 2000 Type Ia SNe out to z<0.1. This sample will allow us to measure the cosmic acceleration directly in the local Universe, test for large scale anisotropies beyond the predictions of LambdaCDM, provide a low-z legacy sample for future studies of the dark energy equation of state, and provide a baseline sample for carrying out Type Ia SN environment and line of sight studies.
• White paper: SN Ia cosmology

Finding transients in Kepler fields for transient and calibration studies

• Lead: Jakob Nordin

Science White Papers

Science White Papers

Science White Papers

• YoungCC3.pdf: Young Core-Collapse ZTF White paper

ZTF White Paper for Young Stripped Envelope Core-Collapse Supernovae

• white_paper_microlens.pdf: White paper for microlensing events in the Galactic Bulge and Plane

Science White Papers

• Lead: Brad Cenko
• Others participating: Shri Kulkarni, Eric Bellm, Anna Ho, Ginny Cunningham
• Relativistic Explosions White Paper

Machine Learning with ZTF

• Lead: Ashish Mahabal

Science White Papers

• Lead: Scott Adams
• Others participating: Mansi Kasliwal
• Abstract: There is growing evidence that the most massive red supergiants may end their lives with a "failed" supernova, collapsing directly into a black hole without a luminous explosion. Two possible events have been found by searching for disappearing red supergiants. However, the disappearance of the progenitor is not the only possible signature of these events. Models predict that even if the energy released by the core collapse of a red supergiant fails to result in a supernova, the loss of gravitational binding energy from the neutrino emission may result in a low-velocity (~100 km/s) ejection of the weakly-bound hydrogen envelope. This ejection would result in a ~10^7 Lsun ~few days-long shock breakout thermalized to ~10^4 K followed by a fainter, but much longer-lived recombination powered transient. ZTF is uniquely capable of providing the large areal observations with nightly cadence necessary to discover these shock breakouts, which would enable, for the first time, spectroscopic follow-up and characterization of the envelope ejection and early-time fallback, and would dramatically improve the constraint on the rate failed supernovae.

Optically Identified Relativistic Explosions: Dirty Fireballs and Orphan Afterglows

• Lead: Brad Cenko

Science White Papers

Fast Cadence Survey in the Galactic Plane

• Lead: Thomas Kupfer

• Abstract: We propose to conduct a fast cadence project with continuous lightcurves of a few hours covering the full Northern Galactic Plane. Our survey will provide a comprehensive census of short period variables at low Galactic latitudes. We expect to find several hundred of (ultra)compact binaries with orbital periods well below two hours including double white dwarfs, accreting white dwarfs, helium star binaries or perhaps even neutron star binaries with white dwarf companions. This will allow us to derive, for the first time, an empirical space density for different types of ultracompact binaries in the Galaxy. The study of such systems is important to our understanding of such diverse areas as supernova Ia progenitors, binary evolution and they are predicted to be the dominant Galactic gravitational wave sources in the eLISA band.

Cosmology with Type Ia Supernovae

• Lead: Rahman Amanullah and Jakob Nordin

Young Stars in Star Forming Regions with ZTF

• Lead: Lynne Hillenbrand

• Abstract: Variability in young pre-main sequence stars is driven by a combination of stellar (spot-modulated rotation, flares, binary eclipses) and circumstellar (accretion "burster" events, standard magnetospheric accretion, extinction "dipper" events) phenomena. The typical short-term behavior occurring on time scales of hours to months has now been fully sampled by CoRoT (in NGC 2264), MOST (for a few selected objects) and Kepler/K2 (in Oph and Upper Scorpius, Taurus, and M8). The longer term behavior that is associated primarily with circumstellar disk phenomena is the domain of ground-based surveys with longer baselines. PTF has provided steady cadence over 3-8 years on a few key star forming regions. ZTF will continue this legacy with better time sampling and sensitivity, and provide definitive statistics on accretion events such as FU Ori and EX Lup outbursts.
• White paper: young stars

• ztf.sfrs.pdf: ZTF White paper: young stars

Science White Papers

Searching for Optical Counterparts to High-Energy Neutrino Sources

• Lead: Jakob van Santen and Anna Franckowiak

• Abstract: The IceCube neutrino observatory has detected a flux of extragalactic neutrinos. However, the origin of the neutrinos is still unknown. Possible candidates are core-collapse supernovae, active galactic nuclei and tidal disruption events - all are accompanied by a characteristic optical counterpart. Our goal is to identify the neutrino sources by detecting their optical counterpart following two approaches: a) A target of opportunity program, which selects the most interesting astrophysical neutrino candidates in real-time and triggers rapid follow-up observations by ZTF to target rapidly varying transients. b) All-sky near real-time correlation, where we correlate all optical transients found by ZTF with all neutrino candidates detected by IceCube to target slowly varying transients.
• NeutrinoWhitePaper.pdf: Neutrino White paper

Science White Papers

• MachineLearningwithZTF.pdf: ML White Paper

Science White Papers

• Lead: Lynne Hillenbrand
• Others participating: TBD
• Abstract: Variability in young pre-main sequence stars is driven by a combination of stellar (spot-modulated rotation, flares, binary eclipses) and circumstellar (accretion "burster" events, standard magnetospheric accretion, extinction "dipper" events) phenomena. The typical short-term behavior occurring on time scales of hours to months has now been fully sampled by CoRoT (in NGC 2264), MOST (for a few selected objects) and Kepler/K2 (in Oph and Upper Scorpius, Taurus, and M8). The longer term behavior that is associated primarily with circumstellar disk phenomena is the domain of ground-based surveys with longer baselines. PTF has provided steady cadence over 3-8 years on a few key star forming regions. ZTF will continue this legacy with better time sampling and sensitivity, and provide definitive statistics on accretion events such as FU Ori and EX Lup outbursts.

Tidal Disruption Events in ZTF: Creating a Statistical Sample

• Lead: Suvi Gezari

Science White Papers

Optically Identified Relativistic Explosions: Dirty Fireballs and Orphan Afterglows

• Lead: Brad Cenko

Machine Learning with ZTF

• Lead: Ashish Mahabal

Science White Papers

• Lead: Mansi M. Kasliwal
• Other participating: On behalf of a large EM-GW science working group
• Abstract: P48/ToO observations to follow up GW triggers.

Seeing stars as they explode: young core-collapse supernova observations with ZTF

• Lead: Avishay Gal-Yam

Science White Papers

Science White Papers

• Abstract: Strongly lensed Type Ia supernovae (SNe Ia) are rare systems that probe the mass profiles of elliptical galaxies at sub-kiloparsec scales. As cosmological probes, they provide a novel method of measuring H0, Omega_m, and w via time delays, and their magnifications enable studies of supernova evolution to high redshift (z <= 1:8 in ZTF). Studying them can reveal clues about the nature of dark energy, resolve tension between the local and CMB values of H0, and constrain feedback mechanisms that regulate galaxy evolution.
• strongly-lensed-type.pdf: White paper on Lensed SNe.

Science White Papers

Early studies of type I Supernovae

• Lead: S. Kulkarni
• Abstract: Observations of supernovae at early times are one of the ways to diagnose the progenitors of supernovae. With sufficient early observations the radius of the exploding star can be inferred (e.g. PTF11kly). Early observations will also reveal the distribution of Nickel in the pre-supernova star. Finally, the circumstellar is the richest at smallest radius. With early alerts the circumstellar medium can be probed by a variety of techniques (radio, X-ray and optical spectroscopy). This effort is focused on Type Ia, Ib and Ic supernovae.

Luminous Red Novae - rates and statistical properties

• Lead: Scott Adams and N. Blagorodnova

Science White Papers

Tidal Disruption Events in ZTF: Creating a Statistical Sample

• Lead: Suvi Gezari

Discovering Failed Supernovae with ZTF

• Lead: Scott Adams

Science White Papers

• young-slsn-ztf_submit.pdf: White paper on Early studies of SLSNe with ZTF

Science White Papers

• Lead: Lin Yan and Ragnhild Lunnan
• Others participating: Eran Ofek, Avishay Gal-Yam, Ofer Yaron and others
• Abstract: to come

Solar System Science with ZTF

• Lead: Quan-Zhi Ye

• EarlySECCSNWhitepaper.pdf: ZTF White Paper for Young Stripped Envelope Core-Collapse Supernovae

Science White Papers

• Lead: Jakob Nordin
• Others participating: Rahman Amanullah, Ulrich Feindt, Mickael Rigault, Ariel Goobar, Eric Bellm, Brad Cenko, Dave Cook
• Abstract: The Kepler satellite will for ~five months, starting Dec 2017, monitor more than 20 000 galaxies well suited for ground-based follow-up, with a 30 min cadence. Kepler single-band photometry provides unique data for studies of variability in general and the early rise-time of supernovae in particular, but requires complementary multi-color and spectroscopic observations. ZTF will be ideally positioned to find and follow SNe for which Kepler data will eventually be down-linked. Through matching the Kepler lightcurves with multi-band P48 photometry we can create a critical dataset for studies of CC SN shock-breakout and SNIa progenitors while improving ZTF calibration and determining the transient detection efficiency.

Young Stars in Star Forming Regions with ZTF

• Lead: Lynne Hillenbrand

Science White Papers

Science White Papers

• Lead: Jakob van Santen and Anna Franckowiak
• Others participating: Jakob Nordin, Marek Kowalski, Nora Strotjohann
• Abstract: The IceCube neutrino observatory has detected a flux of extragalactic neutrinos. However, the origin of the neutrinos is still unknown. Possible candidates are core-collapse supernovae, active galactic nuclei and tidal disruption events - all are accompanied by a characteristic optical counterpart. Our goal is to identify the neutrino sources by detecting their optical counterpart following two approaches: a) A target of opportunity program, which selects the most interesting astrophysical neutrino candidates in real-time and triggers rapid follow-up observations by ZTF to target rapidly varying transients. b) All-sky near real-time correlation, where we correlate all optical transients found by ZTF with all neutrino candidates detected by IceCube to target slowly varying transients.

Early studies of SLSNe with ZTF

• Lead: Lin Yan and Ragnhild Lunnan

Science White Papers

• Others participating: Dennis Bodewits, Chan-Kao Chang, George Helou, Hsing-Wen Lin, Frank Masci, Chow-Choong Ngeow, Carrie Nugent, Thomas Prince and others
• Abstract: Being able to conduct one 3pi survey every few nights, ZTF will be a valuable tool to conduct a range of solar system science focused on small solar system bodies. We propose surveys focused on three research themes: detection of small near-Earth asteroids, search for super-fast rotators, and long-term observation of comets.

Early studies of type I Supernovae

• Lead: S. Kulkarni
• Abstract: Observations of supernovae at early times are one of the ways to diagnose the progenitors of supernovae. With sufficient early observations the radius of the exploding star can be inferred (e.g. PTF11kly). Early observations will also reveal the distribution of Nickel in the pre-supernova star. Finally, the circumstellar is the richest at smallest radius. With early alerts the circumstellar medium can be probed by a variety of techniques (radio, X-ray and optical spectroscopy). This effort is focused on Type Ia, Ib and Ic supernovae.

Science White Papers

Machine Learning with ZTF

• Lead: Ashish Mahabal

• Abstract: Four things to do: (1) RealBogus for point sources, (2) RealBogus for streaks, (3) Classification/Characterization of real transients, (4) Transfer learning using other datasets (PTF/iPTF), but also CRTS/Pan-STARRS/…

Tasks: Generating samples, Priors, Labels.

Science White Papers

Machine Learning with ZTF

• Lead: Ashish Mahabal

• Abstract: Four things to do: (1) RealBogus for point sources, (2) RealBogus for streaks, (3) Classification/Characterization of real transients, (4) Transfer learning using other datasets (PTF/iPTF), but also CRTS/Pan-STARRS/…

Tasks: Generating samples, Priors, Labels.

Science White Papers

• Lead: Rahman Amanullah and Jakob Nordin
• Others participating: Ulrich Feindt, Mickael Rigault, Ariel Goobar, Marek Kowalski, Peter Nugent
• Abstract: We propose to discover and obtain lightcurves of 2000 Type Ia SNe out to z<0.1. This sample will allow us to measure the cosmic acceleration directly in the local Universe, test for large scale anisotropies beyond the predictions of LambdaCDM, provide a low-z legacy sample for future studies of the dark energy equation of state, and provide a baseline sample for carrying out Type Ia SN environment and line of sight studies.

Finding transients in Kepler fields for transient and calibration studies

• Lead: Jakob Nordin

Science White Papers

Fast Cadence Survey in the Galactic Plane

• Lead: Thomas Kupfer

• Abstract: We propose to conduct a fast cadence project with continuous lightcurves of a few hours covering the full Northern Galactic Plane. Our survey will provide a comprehensive census of short period variables at low Galactic latitudes. We expect to find several hundred of (ultra)compact binaries with orbital periods well below two hours including double white dwarfs, accreting white dwarfs, helium star binaries or perhaps even neutron star binaries with white dwarf companions. This will allow us to derive, for the first time, an empirical space density for different types of ultracompact binaries in the Galaxy. The study of such systems is important to our understanding of such diverse areas as supernova Ia progenitors, binary evolution and they are predicted to be the dominant Galactic gravitational wave sources in the eLISA band.

Cosmology with Type Ia Supernovae

Science White Papers

• YoungCC3.pdf: Young Core-Collapse ZTF White paper

Science White Papers

• Other participating: Rahman Amanullah, Edvard Mörtsell (OKC), Thomas Kupfer (Caltech) and contributions from external theory colleagues
• Abstract: We propose a high-cadence survey of the Andromeda galaxy, monitoring ~1 million resolved stars, in the search for microlensing events with duration from just a few minutes up to several days. This scenario has not been studied systematically and holds great promise to explore Early Universe physics. The lenses we are trying to uncover are not "known" stellar objects, but rather relics from the beginning of time: Cosmic Strings, Axion Miniclusters and Primordial Black Holes. These are hypothetical (dark) macroscopic fossil remnants emerging in many leading theories of the Early Universe. It has been speculated that these objects still exist, and current experimental limits are not very constraining. Surprisingly, we have found a survey mode for ZTF that could shed new light into the physics of the origin of the Universe and the nature of dark matter. The expected contributions to our understanding of stellar astronomy are also very important part of the program.

Searching for Optical Counterparts to High-Energy Neutrino Sources

• Lead: Jakob van Santen and Anna Franckowiak
• Others participating: Jakob Nordin, Marek Kowalski, Nora Strotjohann

• YoungCC3.pdf: Young Core-Collapse ZTF White paper

Science White Papers

• Other participating: On behalf of a large EM-GW science working group
• Abstract: P48/ToO observations to follow up GW triggers.

Science White Papers

Microlensing of stars in M31 by relics from the Early Universe

• Lead: Ariel Goobar

• Abstract: We propose a high-cadence survey of the Andromeda galaxy, monitoring ~1 million resolved stars, in the search for microlensing events with duration from just a few minutes up to several days. This scenario has not been studied systematically and holds great promise to explore Early Universe physics. The lenses we are trying to uncover are not "known" stellar objects, but rather relics from the beginning of time: Cosmic Strings, Axion Miniclusters and Primordial Black Holes. These are hypothetical (dark) macroscopic fossil remnants emerging in many leading theories of the Early Universe. It has been speculated that these objects still exist, and current experimental limits are not very constraining. Surprisingly, we have found a survey mode for ZTF that could shed new light into the physics of the origin of the Universe and the nature of dark matter. The expected contributions to our understanding of stellar astronomy are also very important part of the program.

Searching for Optical Counterparts to High-Energy Neutrino Sources

Science White Papers

• Lead: Ariel Goobar

Searching for Optical Counterparts to High-Energy Neutrino Sources

• Lead: Jakob van Santen and Anna Franckowiak

Science White Papers

• Other participating: Mansi Kasliwal
• Abstract: Luminous red novae (LRNe) are transient events discovered in our nearby Universe. During outburst, their luminosities are in between novae and supernovae and their temperatures are unusually cold, resembling M or K type giant stars. Their lightcurves, while quickly fading in the optical, do usually remain bright in IR wavelengths, revealing the formation of warm dust surrounding the main star. Such observables have been associated with the onset of extremely dense, massive stellar envelopes. The origin of such events is still very speculative: stellar mergers, partial ejections of the common envelope surrounding a close binary pair, planets swallowed by giant stars or accretion induced jets. The rate of LRNe is predicted to be as high as one every 3 to 10 years in a Milky Way-like galaxy. Because of their cool temperatures, ZTF will be well-suited to detect them in nearby galaxies, specially in longer wavelengths (I-band). We propose high cadence survey in g+I bands targeting both the Galactic plane and nearby galaxies. These will allow to improve the Galactic LRN rates and link the outburst properties to the progenitor star.

Science White Papers

• Abstract: Observations of supernovae at early times are one of the ways to diagnose the progenitors of supernovae. With sufficient early observations the radius of the exploding star can be inferred (e.g. PTF11kly). Early observations will also reveal the distribution of Nickel in the pre-supernova star. Finally, the circumstellar is the richest at smallest radius. With early alerts the circumstellar medium can be probed by a variety of techniques (radio, X-ray and optical spectroscopy). This effort is focused on Type Ia, Ib and Ic supernovae.

Luminous Red Novae - rates and statistical properties

• Abstract: Luminous red novae (LRNe) are transient events discovered in our nearby Universe. During outburst, their luminosities are in between novae and supernovae and their temperatures are unusually cold, resembling M or K type giant stars. Their lightcurves, while quickly fading in the optical, do usually remain bright in IR wavelengths, revealing the formation of warm dust surrounding the main star. Such observables have been associated with the onset of extremely dense, massive stellar envelopes. The origin of such events is still very speculative: stellar mergers, partial ejections of the common envelope surrounding a close binary pair, planets swallowed by giant stars or accretion induced jets. The rate of LRNe is predicted to be as high as one every 3 to 10 years in a Milky Way-like galaxy. Because of their cool temperatures, ZTF will be well-suited to detect them in nearby galaxies, specially in longer wavelengths (I-band). We propose high cadence survey in g+I bands targeting both the Galactic plane and nearby galaxies. These will allow to improve the Galactic LRN rates and link the outburst properties to the progenitor star.

Science White Papers

• Others participating: Shri Kulkarni, Eric Bellm, Anna Ho, Assaf Horesh
• Abstract: To come.

• Lead: Ashish Mahabal

Microlensing of stars in M31 by relics from the early universe

Science White Papers

Luminous Red Novae - rates and statistical properties

• Lead: N. Blagorodnova

• Abstract: Luminous red novae (LRNe) are transient events discovered in our nearby Universe. During outburst, their luminosities are in between novae and supernovae and their temperatures are unusually cold, resembling M or K type giant stars. Their lightcurves, while quickly fading in the optical, do usually remain bright in IR wavelengths, revealing the formation of warm dust surrounding the main star. Such observables have been associated with the onset of extremely dense, massive stellar envelopes. The origin of such events is still very speculative: stellar mergers, partial ejections of the common envelope surrounding a close binary pair, planets swallowed by giant stars or accretion induced jets. The rate of LRNe is predicted to be as high as one every 3 to 10 years in a Milky Way-like galaxy. Because of their cool temperatures, ZTF will be well-suited to detect them in nearby galaxies, specially in longer wavelengths (I-band). We propose high cadence survey in g+I bands targeting both the Galactic plane and nearby galaxies. These will allow to improve the Galactic LRN rates and link the outburst properties to the progenitor star.

Science White Papers

• Others participating: Jakob Nordin, Marek Kowalski, Nora Strotjohann
• Abstract: The IceCube neutrino observatory has detected a flux of extragalactic neutrinos. However, the origin of the neutrinos is still unknown. Possible candidates are core-collapse supernovae, active galactic nuclei and tidal disruption events - all are accompanied by a characteristic optical counterpart. Our goal is to identify the neutrino sources by detecting their optical counterpart following two approaches: a) A target of opportunity program, which selects the most interesting astrophysical neutrino candidates in real-time and triggers rapid follow-up observations by ZTF to target rapidly varying transients. b) All-sky near real-time correlation, where we correlate all optical transients found by ZTF with all neutrino candidates detected by IceCube to target slowly varying transients.

• Lead: Lin Yan and Ragnhild Lunnan
• Others participating: Eran Ofek, Avishay Gal-Yam, Ofer Yaron and others
• Abstract: to come

Science White Papers

• Others participating: Jakob Nordin, Marek Kowalski, Nora Strotjohann
• Abstract: The IceCube neutrino observatory has detected a flux of extragalactic neutrinos. However, the origin of the neutrinos is still unknown. Possible candidates are core-collapse supernovae, active galactic nuclei and tidal disruption events - all are accompanied by a characteristic optical counterpart. Our goal is to identify the neutrino sources by detecting their optical counterpart following two approaches: a) A target of opportunity program, which selects the most interesting astrophysical neutrino candidates in real-time and triggers rapid follow-up observations by ZTF to target rapidly varying transients. b) All-sky near real-time correlation, where we correlate all optical transients found by ZTF with all neutrino candidates detected by IceCube to target slowly varying transients.

• Abstract: to come

Solar System Science with ZTF

Science White Papers

• Lead: S. Kulkarni
• Abstract: Observations of supernovae at early times are one of the ways to diagnose the progenitors of supernovae. With sufficient early observations the radius of the exploding star can be inferred (e.g. PTF11kly). Early observations will also reveal the distribution of Nickel in the pre-supernova star. Finally, the circumstellar is the richest at smallest radius. With early alerts the circumstellar medium can be probed by a variety of techniques (radio, X-ray and optical spectroscopy). This effort is focused on Type Ia, Ib and Ic supernovae.

Science White Papers

Microlensing of stars in M31 by relics from the early universe

• Lead: Ariel Goobar
• Other participating (TBD!): David F. Chernoff (Cornell University), Thomas Kupfer (Caltech), Monika Soraisam (MPA), OKC colleagues..

Searching for Optical Counterparts to High-Energy Neutrino Sources

• Lead: Jakob van Santen and Anna Franckowiak

Science White Papers

Early studies of type I Supernovae

Science White Papers

• Others participating: Dennis Bodewits, Chan-Kao Chang, George Helou, Hsing-Wen Lin, Frank Masci, Chow-Choong Ngeow, Carrie Nugent, Thomas Prince and others
• Abstract: Being able to conduct one 3pi survey every few nights, ZTF will be a valuable tool to conduct a range of solar system science focused on small solar system bodies. We propose surveys focused on three research themes: detection of small near-Earth asteroids, search for super-fast rotators, and long-term observation of comets.

Science White Papers

• Others participating: Ragnhild Lunnan, Eran Ofek, Avishay Gal-Yam, Ofer Yaron and others
• Abstract: to come

Science White Papers

• Others participating: Jakob Nordin, Marek Kowalski, Nora Strotjohann
• Abstract: The IceCube neutrino observatory has detected a flux of extragalactic neutrinos. However, the origin of the neutrinos is still unknown. Possible candidates are core-collapse supernovae, active galactic nuclei and tidal disruption events - all are accompanied by a characteristic optical counterpart. Our goal is to identify the neutrino sources by detecting their optical counterpart following two approaches: a) A target of opportunity program, which selects the most interesting astrophysical neutrino candidates in real-time and triggers rapid follow-up observations by ZTF to target rapidly varying transients. b) All-sky near real-time correlation, where we correlate all optical transients found by ZTF with all neutrino candidates detected by IceCube to target slowly varying transients.

Science White Papers

Microlensing of stars in M31 by relics from the early universe

• Lead: Ariel Goobar
• Other participating (TBD!): David F. Chernoff (Cornell University), Thomas Kupfer (Caltech), Monika Soraisam (MPA), OKC colleagues..

Searching for Optical Counterparts to High-Energy Neutrino Sources

• Lead: Jakob van Santen and Anna Franckowiak

Science White Papers

• Other participating (TBD!): David F. Chernoff (Cornell University), Thomas Kupfer (Caltech), Monika Soraisam (MPA), OKC colleagues..
• Abstract: At the beginning of time, the universe is believed to have grown exponentially in size via the mechanism of Inflation. Inflation offers solutions to some of the outstanding problems of the Big Bang theory: the horizon problem, the flatness problem and the monopole problem. However, the precise inflationary scenario remains a profound problem for cosmology and for fundamental physics. String theory, provides models of inflation and testable predictions: large string loops are likely to survive in the hot big bang that followed inflation. They appear as ``cosmic strings'' (CS) , which can have intricate properties. Such strings cluster in a manner similar to dark matter leading to hugely enhanced densities. As a result, numerous fossil remnants may exist within the galaxies. They can be revealed through microlensing of background stars. Stars in Andromeda (M31) are particularly well-suited, as they can give rise to microlensing events lasting several hours. Microlensing by CS can be easily differentiated from lensing by astrophysical objects, making this experiment particularly exciting to probe early universe physics. With the large FoV of ZTF, Andromeda can be studied with single pointing observations. The project requires high-cadence observations of M31. Redder filters are perferred to minimize the impact of extinction and scattered moonlight.

Science White Papers

• Other (hopefully) participating: Adam Miller, Frank, [Brian, Umaa]
• Abstract: Soon. Will not require tweaking cadence

Science White Papers

• Others participating: Shri Kulkarni, Eric Bellm, Anna Ho, Assaf Horesh
• Abstract: To come.

Science White Papers

• Others participating: Mansi Kasliwal
• Abstract: There is growing evidence that the most massive red supergiants may end their lives with a "failed" supernova, collapsing directly into a black hole without a luminous explosion. Two possible events have been found by searching for disappearing red supergiants. However, the disappearance of the progenitor is not the only possible signature of these events. Models predict that even if the energy released by the core collapse of a red supergiant fails to result in a supernova, the loss of gravitational binding energy from the neutrino emission may result in a low-velocity (~100 km/s) ejection of the weakly-bound hydrogen envelope. This ejection would result in a ~10^7 Lsun ~few days-long shock breakout thermalized to ~10^4 K followed by a fainter, but much longer-lived recombination powered transient. ZTF is uniquely capable of providing the large areal observations with nightly cadence necessary to discover these shock breakouts, which would enable, for the first time, spectroscopic follow-up and characterization of the envelope ejection and early-time fallback, and would dramatically improve the constraint on the rate failed supernovae.

Science White Papers

Tidal Disruption Events in ZTF: Creating a Statistical Sample

• Lead: Suvi Gezari
• Others participating: Brad Cenko, Tiara Hung, Nadia Blagorodnova, Shri Kulkarni, Lin Yan

Discovering Failed Supernovae with ZTF

• Lead: Scott Adams

Science White Papers

• Others participating: Brad Cenko, Tiara Hung, Nadia Blagorodnova, Shri Kulkarni, Lin Yan
• Abstract: Our goal is to produce a pure and complete sample of 50-100 tidal disruption events (TDEs) over the 3 year ZTF suvey in order to study rates and TDE parameters (black hole mass, star mass and radius, impact parameter, etc) as a function of host galaxy properties and redshift. This sample will be the first statistically significant sample of TDEs from any survey to date (previous surveys have produced <4 TDEs each). In order to determine the characteristic timescales of the events, which are important probes of the central black hole mass, we require well sampled light curves with data points on the rise to peak. An important obstacle to overcome in creating this sample will be efficient filtering of more common interlopers (nuclear SNe and flaring AGN). This will be necessary in real time, if we want to enable prompt spectroscopy of bonafide TDEs in order to catch transient emission lines powered by the events. We plan to run simulations in order to determine what cadence and filters are needed to provide light curves of sufficient quality for extracting TDE parameters, and for filtering out interlopers.

Science White Papers

• Others participating: TBD
• Abstract: Variability in young pre-main sequence stars is driven by a combination of stellar (spot-modulated rotation, flares, binary eclipses) and circumstellar (accretion "burster" events, standard magnetospheric accretion, extinction "dipper" events) phenomena. The typical short-term behavior occurring on time scales of hours to months has now been fully sampled by CoRoT (in NGC 2264), MOST (for a few selected objects) and Kepler/K2 (in Oph and Upper Scorpius, Taurus, and M8). The longer term behavior that is associated primarily with circumstellar disk phenomena is the domain of ground-based surveys with longer baselines. PTF has provided steady cadence over 3-8 years on a few key star forming regions. ZTF will continue this legacy with better time sampling and sensitivity, and provide definitive statistics on accretion events such as FU Ori and EX Lup outbursts.

Science White Papers

• Others participating: Rahman Amanullah, Ulrich Feindt, Mickael Rigault, Ariel Goobar, Eric Bellm, Brad Cenko, Dave Cook
• Abstract: The Kepler satellite will for ~five months, starting Dec 2017, monitor more than 20 000 galaxies well suited for ground-based follow-up, with a 30 min cadence. Kepler single-band photometry provides unique data for studies of variability in general and the early rise-time of supernovae in particular, but requires complementary multi-color and spectroscopic observations. ZTF will be ideally positioned to find and follow SNe for which Kepler data will eventually be down-linked. Through matching the Kepler lightcurves with multi-band P48 photometry we can create a critical dataset for studies of CC SN shock-breakout and SNIa progenitors while improving ZTF calibration and determining the transient detection efficiency.

Science White Papers

• Others participating: Ulrich Feindt, Mickael Rigault, Ariel Goobar, Marek Kowalski, Peter Nugent
• Abstract: We propose to discover and obtain lightcurves of 2000 Type Ia SNe out to z<0.1. This sample will allow us to measure the cosmic acceleration directly in the local Universe, test for large scale anisotropies beyond the predictions of LambdaCDM, provide a low-z legacy sample for future studies of the dark energy equation of state, and provide a baseline sample for carrying out Type Ia SN environment and line of sight studies.

Science White Papers

Cosmology with Type Ia Supernovae

• Lead: Rahman Amanullah and Jakob Nordin
• Others participating: Ulrich Feindt, Mickael Rigault, Ariel Goobar, Marek Kowalski, Peter Nugent

Science White Papers

• Others participating: Eric Bellm, Paula Szkody, Tom Prince, David Kaplan
• Abstract: We propose to conduct a fast cadence project with continuous lightcurves of a few hours covering the full Northern Galactic Plane. Our survey will provide a comprehensive census of short period variables at low Galactic latitudes. We expect to find several hundred of (ultra)compact binaries with orbital periods well below two hours including double white dwarfs, accreting white dwarfs, helium star binaries or perhaps even neutron star binaries with white dwarf companions. This will allow us to derive, for the first time, an empirical space density for different types of ultracompact binaries in the Galaxy. The study of such systems is important to our understanding of such diverse areas as supernova Ia progenitors, binary evolution and they are predicted to be the dominant Galactic gravitational wave sources in the eLISA band.

Science White Papers

White Papers in Preparation

Fast Cadence Survey in the Galactic Plane

• Lead: Thomas Kupfer

Science White Papers