Proposal Number: 5004 PI Last Name: TURNER Title: NGC 1194: X-RAY REPROCESSING IN A LOCAL COMPTON THICK MASER AGN Abstract: NGC 1194 is one of the hardest AGN in the local sky and a rare example of a nearby Compton-thick Seyfert galaxy. This AGN houses a water maser, providing an intriguing possible origin for the Compton-thick gas. We request a joint 60 ks NuSTAR/XMM observation to build a model for this spectacular AGN. Availability of an accurate black hole mass and maser disk inclination give a solid framework of scale-size, Eddington ratio and orientation for interpretation of the X-ray data.
Proposal Number: 5007 PI Last Name: TSUJIMOTO Title: HARD X-RAY OBSERVATION OF PI AQR Abstract: Binary evolution is one of the most fundamental ingredients in astronomy. Binaries consisting of a high-mass star and a compact object is an important milestone in the evolution. GammaCas and its analogs are likely the long-sought missing population of Be/WD binaries, though an alternative interpretation exists. Recently, we made a strong case for the Be/WD interpretation by explaining their anomalous X-ray spectrum based on a physical model of accreting WD binaries. The validity of our model is best illustrated by the estimate of M_WD consistent with optical spectroscopic measurement for gammaCas. The dispute will be finalized by applying the same test to the other gammaCas analogs. We propose a 50 ks NuSTAR observation of piAqr and derive M_WD in conjunction with the existing XMM data.
Proposal Number: 5009 PI Last Name: AN Title: CONSTRAINING THE POPULATION OF HIGH-SPIN SUPERMASSIVE BLACK HOLES IN THE EARLY UNIVERSE Abstract: There are four massive quasars discovered at redshifts greater than 5. These sources present a puzzle; how black holes grow to 10^9 solar masses in the limited age of the universe. We would like to address this by estimating the population of such objects. The population estimation requires good constraints on their jet properties, in particular, the Doppler factor. We propose to observe the high-redshift blazar SDSS~J013127.34-032100.1 with XMM and NuSTAR for 40 ks and 100 ks, respectively, in order to model the broadband SED accurately. The broadband X-ray observation will allow us to measure the Doppler factor for the source, constraining the high-a supermassive BH population in the early universe. These measurements will be used to infer the number of similar BHs at high redshifts.
Proposal Number: 5010 PI Last Name: BRANDT Title: IDENTIFYING INTRINSICALLY X-RAY WEAK AGNS WITH NUSTAR Abstract: Luminous X-ray emission is considered a universal property of AGNs. There are few intrinsically X-ray weak AGNs reliably identified so far. Such systems may exist preferentially in BAL quasars, where it is challenging to ascribe the observed X-ray weakness to absorption vs. intrinsic X-ray weakness. Via stacking analysis, our exploratory 21-32 ks NuSTAR observations have demonstrated the unique capability of NuSTAR to discover a significant fraction of intrinsically X-ray weak AGNs among BAL quasars. Thus we propose to obtain 90 and 100 ks additional observations for PG 1254 and PG 1001, respectively, to identify intrinsically X-ray weak AGNs individually and constrain the fraction of such objects among the luminous BAL quasar population.
Proposal Number: 5019 PI Last Name: LEHMER Title: BURIED ALIVE? EXPLAINING THE LARGE DEFICIT OF HMXBS IN THE CIRCUMNUCLEAR STARBURST RING OF NGC 7552 AND LIRGS Abstract: Luminous infrared galaxies (LIRGs; LIR > 10^11 Lsol) have been shown to have significant deficits of X-ray emission compared with that expected from the local LX-SFR correlation. The most likely scenarios are that the XRB population is either (1) missing as a result of the populations being relatively young and/or of high metallicity - factors that influence the formation rates - or (2) buried under nearly Compton-thick obscuring column densities in these high-intensity star-forming regions. We propose to observe with NuSTAR the nearest LIRG that definitively does not contain an AGN, NGC 7552, and decisively determine whether a buried population of XRBs is present.
Proposal Number: 5029 PI Last Name: MATT Title: NGC 5506, THE BEST SEYFERT GALAXY TO SEARCH FOR CORONAL VARIABILITY Abstract: NGC 5506 is one of the brightest Seyfert galaxies, varying in flux up to a factor 2, and in spectral shape to more than DeltaGamma=0.1 on time scales of years. It has the highest NuSTAR-measured value of the high energy cutoff in an AGN (720[+130-190] keV). This value is much higher than, and definitely inconsistent with, the one measured in a XMM-Newton/BeppoSAX simultaneous observation performed in 2001 (140[+40-30] keV), however obtained with a background-dominated spectrum above 10 keV. For all these characteristics, NGC 5506 is arguably the best candidate to study variability of the coronal parameters. We propose a 60 ks NuSTAR observation of this source to confirm the presence of such variability, which would shed light on the temporal evolution of the corona.
Proposal Number: 5046 PI Last Name: WONG Title: NATURE OF HARD X-RAYS FROM A TEV-DETECTED RADIO GALAXY Abstract: We propose to study one of the few FRI radio galaxies with detected TeV emission, 3C 264. It hosts a supermassive black hole emitting at 7x10^-5 Eddington luminosity, generally associated with a radiatively inefficient accretion flow (RIAF). Multiwavelength studies suggest that the X-ray emission comes from a jet. However, it is also possible that the RIAF can contribute significantly to the X-rays. Unfortunately, hard X-ray spectrum above 10 keV is missing, making it hard to distinguish the X-ray emission model. With the excellent sensitivity of NuSTAR, we will study the nature of the hard X-rays from this rare TeV FRI radio galaxy and will distinguish whether the hard X-ray emission comes from a jet or an accretion flow.
Proposal Number: 5054 PI Last Name: LUDLAM Title: AN ENHANCED NUSTAR VIEW OF SCORPIUS X-1 Abstract: Neutron stars (NSs) are the most compact objects with a surface in the Universe. The elusive equation of state (EoS) sets the radius for a NS of a given mass, therefore determining the mass and radius of a NS can, in-turn, be used to place limits on the EoS. Sco X-1 is a NS low-mass X-ray binary and the brightest X-ray source in the night sky. X-ray spectroscopic studies can place limits of the radial extent of the NS and track changes within the innermost accretion region. We request 60 ks of exposure of Sco X-1 broken up into 3x20 ks observations. The previously determined limits on NS mass and inclination of this system from optical and radio studies makes Sco X-1 a prime target for demonstrating the utility of reflection studies to provide limits on the EoS.
Proposal Number: 5057 PI Last Name: PEREZ Title: A NOVEL PROBE OF LOW-MASS AXION DARK MATTER USING BETELGUESE Abstract: We propose a 50 ks observation of the nearby red supergiant star Betelgeuse in order to probe novel parameter space for low-mass axion-like particles (ALPs). Betelgeuse is not expected to be a standard source of X-rays. However, light ALPs produced in the stellar core could be converted back into photons in the Galactic magnetic field, producing a detectable flux that peaks in the hard X-ray (> 10 keV) band. This observation provides an order of magnitude deeper sensitivity than current limits in the low-mass (m < 10^-10 eV) range, offering the possibility for detection of ALPs, or world-leading limits, in an interesting region of parameter space with minimal observing time.
Proposal Number: 5064 PI Last Name: ZOGHBI Title: THE CHANGING CORONA AND DISTANT REFLECTOR IN NGC 4151 Abstract: We propose a monitoring program of NGC 4151 to track the coronal temperature variations as the source flux changes, and at the same time track how the narrow Fe K line and the Compton hump respond to those flux changes. The pair-dominated model for the corona has a testable prediction for the dependence of cutoff energy on flux and spectral index, while a Compton-thick hypothesis for the narrow Fe Line predicts a correlation between the line flux, the Compton hump and the continuum flux. We will test these predictions and advance our understanding of the corona and the reflector producing the strong Fe K line.
Proposal Number: 5066 PI Last Name: Krucker Title: NUSTAR OBSERVATIONS OF QUIETEST X-RAY SUN: CORONAL HEATING AND AXIONS Abstract: We propose to take the ultimate NuSTAR observations of the quiet Sun during the minimum of the solar cycle. These observations, collected at close to 100% livetime, will be used for the deepest-ever search for X-ray bremsstrahlung signatures to investigate the key question of coronal heating, and they will additionally allow us to search for an axion conversion signal. With solar activity being currently at a minimum and activity expected to pick up again later in 2020 or latest in 2021, the proposed observations are time-critical.
Proposal Number: 5072 PI Last Name: GOTTHELF Title: ENERGETIC PULSARS WITH UNDER-LUMINOUS WIND NEBULAE: UNLOCKING THE PULSAR EMISSION MECHANISM Abstract: Of the hundreds of rotation-powered pulsars with detected PWNe, three stand out by their extremely under-luminous nebulae relative to their spin-down power. PSR J1617-5055, PSR J2022+3842, and PSR J1838-0655 display remarkably similar properties, (1) a PWN to PSR flux ratio of <0.1 in the 2-10 keV band, (2) anomalously flat (Gamma < 1) Chandra spectra, (3) highly modulated pulsations (60-100%), and (4) lack of a Fermi pulsed signal. We propose a NuSTAR and XMM broadband X-ray observation of PSR J1838-0655, the brightest in the NuSTAR band. By studying this rare class of pulsars we hope to address their exceptionalism, key to more fully understanding the emission mechanism of pulsars.
Proposal Number: 5085 PI Last Name: PONTI Title: THE MOTION OF SGR A*'S NIR SOURCE DURING X-RAY FLARES Abstract: We propose two long (186ks) NuSTAR exposures, each covering 5 consecutive nights of VLTI-Gravity guaranteed time observations of SgrA*. Our Gravity team has already measured the astrometric motion of SgrA*'s near infrared (NIR) source during bright NIR flux excursions. We observed that the NIR source was located at few gravitational radii from the supermassive black hole (BH) and rotating, following nearly circular orbits. Simultaneous NuSTAR+Gravity observations will allow us to test whether, during bright X-ray flares, the NIR source will display similar circular orbital motions or whether it will be characterised by a dramatically different pattern, such as by linear motions, reminiscent of jet like ejections. This will provide us with a groundbreaking test of accretion physics.
Proposal Number: 5088 PI Last Name: ZAINO Title: IS THE CIRCUMNUCLEAR ABSORBING AND REFLECTING MATTER THE SAME IN NGC 4388? Abstract: We propose to observe the Seyfert 2 galaxy NGC 4388 simultaneously with Nustar and XMM-Newton for 50 ks and 60 ks, respectively, in order to obtain conclusive evidence on the physical nature of the circumnuclear matter in this source. In 2013 NuSTAR revealed a very weak Compton hump and a very large iron Ka line EW for a source with weak or no reflection, suggesting that the reflecting matter is the same Compton-thin matter responsible for the absorption. Exploiting NuSTAR and XMM complementary capabilities, the requested simultaneous observations will enable us to probe the nature of the absorbing and reflecting matter in NGC 4388 obtaining simultaneously for the first time both a robust measurement of the Compton hump and a detailed study of the physical properties of the iron Ka line.
Proposal Number: 5094 PI Last Name: PARKER Title: REVEALING THE HIGH-VELOCITY ABSORPTION IN IRAS 13349+2438 Abstract: We propose a 200 ks NuSTAR observation of the z=0.1085 quasar IRAS 13349+2438, simultaneous with 100 ks of XMM-Newton exposure. With this, we will be able to reveal the ultra-fast outflow component of the complex absorption found in this intriguing source. With the unique high energy coverage of NuSTAR, combined with high resolution low energy spectroscopy from XMM-Newton, we will be able to map out the high energy absorption lines, completing our knowledge of the ionized absorption. We will explore the link between the low and high velocity absorbers, and determine the origin of the relativistic Fe emission at 7 keV, revealing the geometry of the AGN system.
Proposal Number: 5107 PI Last Name: LAMASSA Title: INVESTIGATING THE COMPLEX OBSCURATION AROUND THE COMPTON-THICK QUASAR CANDIDATE 3C 223 Abstract: A 2001 XMM spectrum of radio-loud AGN 3C 223 revealed that the line-of-sight column density is significantly different from the average global column density. Two qualities make 3C 223 remarkable: the implied obscuration geometry is a Compton-thick (>1.7 x 10^24 cm^-2) ring of gas embedded in a global Compon-thin (1.4 x 10^23 cm^-2) medium, and it is one of the very few radio loud Compton-thick AGN candidates known. We request a joint 45 ks NuSTAR obervation and 40 ks XMM observation to confirm 3C 223 as the first bona fide Compton thick radio galaxy, search for absorption variability between the 2001 observation and proposed dataset, and accurately measure the line-of-sight column density which is unconstrained with the XMM data, requiring NuSTAR coverage.
Proposal Number: 5108 PI Last Name: DAI Title: MICROLENSING SIZE OF AGN REFLECTION HUMP Abstract: The origin of the X-ray reflection component of AGN has been debated for more than two decades. We propose to measure the size the reflection hump with microlensing for the first time to the X-ray brightest lensed quasar, RXJ1131-1231. This will provide a crucial independent test of the emerging paradigm for the reflection model for Type I AGN, where the reflection is dominated by regions close to the black hole with strong relativistic and light bending effects. This will further constrain the environment immediately around the black hole, which is essential to accurately measure black hole spins and understand the cosmic X-ray background.
Proposal Number: 5110 PI Last Name: Coppejans Title: NUSTAR OBSERVATIONS OF FAST AND BLUE STELLAR EXPLOSIONS Abstract: We propose an in-depth X-ray study of fast blue optical transients (FBOTs), a new class of transients with luminosities and time scales that challenge traditional SN models. Alternative scenarios include a failed SN of a stripped star, He-shell detonation on a white dwarf, and a SN shock breaking through a dense medium. FBOTs have mostly been studied in the optical/UV regime, which is of thermal origin and it is not sensitive to the nature of the underlying energy source. Here we propose to capitalize on our recent NuSTAR discovery of hard X-rays from the FBOT AT2018cow with unprecedented properties, and start the first hard X-ray monitoring campaign of FBOTs. The primary goal is to test for the presence of engines driving the explosions and constrain their nature.
Proposal Number: 5118 PI Last Name: PORQUET Title: A BROAD BAND VIEW OF THE DISC-CORONA SYSTEM OF MRK 110 Abstract: We propose to probe the disc-corona system and determine the BH spin of the bright bare AGN Mrk 110. Our ``2 in 1'' spectral analysis method is based on the global energetics of the disc-corona system and accounts for the contribution of relativistic reflection and the coronal extension. It has been successfully tested on the moderate accretion rate bright bare AGN, Ark120, where for the first time we tightly constrained its BH spin, and revealed that the corona radius decreases with increasing flux. Here, we propose to apply this method to Mrk 110 in order to probe the corona-disc system at higher accretion rate (~0.3--0.4) and a much lower reverberation BH mass (2.0x10^7 M_odot), thanks to two simultaneous NuSTAR (2x80ks) and XMM-Newton (2x43ks) observations separated by a few months.
Proposal Number: 5121 PI Last Name: ALP Title: HARD X-RAY EVOLUTION OF SN 1987A Abstract: Being the closest observed supernova (SN) in more than four centuries, SN 1987A provides unique opportunities to study the evolution of a SN into a SN remnant (SNR). We propose a 275 ks NuSTAR observation to investigate the ongoing evolution of SN 1987A. The gamma-ray flux detected by Fermi, which is produced by relativistic particles, has increased by at least a factor of 2 over the past years. Hard X-ray observations constrain properties of the relativistic particles and provide insight into cosmic ray acceleration in SNRs. The observations also probe the CSM structure and mass loss history of the progenitor. SN 1987A has been monitored in practically all other wavebands and hard X-ray observations are an important complement and offer unique perspectives of the remnant.
Proposal Number: 5125 PI Last Name: ZHANG Title: UNVEILING THE NATURE OF A GALACTIC CENTER X-RAY FILAMENT G0.13-0.11: PULSAR WIND NEBULAR OR MAGNETIC STRUCTURE? Abstract: A unique phenomenon in the Galactic center region is the existence of numerous radio and X-ray filaments. The origin and formation of of the filaments have been a long-standing question. NuSTAR has detected four X-ray filaments so far. Only one of them, G0.13-0.11, has not been identified due to limited statistics. Based on its location and morphology, this filament is most likely to be a pulsar wind nebular or a magnetic structure fed by a pulsar. However, the current available data is not sufficient for us to test our hypothesis. Therefore, we propose for a deep on-axis observation for this filament, which will allow us to reveal its nature. The new data will extend our understanding on how filaments are powered, and could lead to discovery of the first pulsar in the Galactic center.
Proposal Number: 5131 PI Last Name: CORBET Title: PHYSICAL PROCESSES IN THE NEW GAMMA-RAY BINARY 3FGL J1405.4-6119 Abstract: We have discovered a new member of the rare and poorly understood class of high-mass gamma-ray binaries: 3FGL J1405.4-6119. The system shows gamma-ray, radio and X-ray modulation on its 13.7 day period, with different patterns at each waveband. The existing X-ray data, while clearly showing the period, are insufficient to perform phase-resolved spectroscopy, which is needed to investigate the physics driving the emission and its orbital variability.
Proposal Number: 5132 PI Last Name: BRIGHTMAN Title: A BROADBAND X-RAY SPECTRAL STUDY OF TWO NEUTRON-STAR-POWERED ULTRALUMINOUS X-RAY SOURCES IN M51 Abstract: We propose joint observations with NuSTAR and XMM-Newton of the M51 galaxies that will provide the best simultaneous, high-time resolution, and sensitive broadband X-ray spectral dataset on the sources within them yet. The joint dataset will yield the first high-quality broadband spectrum of at least one neutron-star-powered ultraluminous X-ray source in the galaxy, possibly two. This will allow a detailed spectral decomposition and sensitive searches for cyclotron lines. The timing resolution of XMM-Newton will allow us to detect pulsations, yielding an improved orbital solution for one ULX, and perhaps detecting them for the first time in one of the many others in the galaxies.
Proposal Number: 5134 PI Last Name: PRADHAN Title: PROBING THE ORIGIN OF SLOW PULSATIONS IN 4U 0114+65 Abstract: We propose 80 ks observation of the superslow (period of 10,000 s) pulsar and the 'accreting magnetar' candidate, 4U 0114+65 in its brightest orbital phase (0.4 - 0.6) in order to definitively investigate the magnetic field of this pulsar. We plan to carry out (i) direct measurements of the magnetic field by probing into the much debatable cyclotron line and/or (ii) indirect estimates by applying different accreting models. We will also probe the hard energy tail in the NuSTAR average spectrum and the spin phase-resolved spectrum as well as carry out pulse profile and variability studies of 4U 0114+65, thereby linking these intriguing systems to the wider context of other classical HMXBs and SFXTs.
Proposal Number: 5135 PI Last Name: JORSTAD Title: HARD X-RAY COMPONENT OF BL LACERTAE Abstract: We propose to monitor BL Lacertae with NuSTAR at 3-70 keV for 350 ks over 5 consecutive days during the 2019/09/11-2019/10/07 period when the source will be in the FOV of TESS. The hard X-ray and optical fluxes are variable on timescales of hours. The observations will allow us to determine delays between variations at different energies, relative locations of emission regions, and parameters of turbulence involved in photon production at different frequencies. We propose also 50 measurements of 1.5 ks each of the source with the Swift XRT and UVOT during these 5 days to sample variability continuously from hard X-ray to optical bands and to compare mechanisms and origins of hard and soft X-ray emission.
Proposal Number: 5136 PI Last Name: SATYAPAL Title: UNCOVERING A POPULATION OF BURIED AGNS IN BULGELESS GALAXIES: A PILOT STUDY WITH NUSTAR Abstract: Whereas supermassive black holes (SMBHs) are found in essentially every galactic bulge, very few SMBHs areknown in purely bulgeless galaxies. Identifying such a population is crucial to our understanding of the origins of SMBHs and the secular pathways for their growth. However, to date, there are only a handful of confirmed SMBHs in purely bulgeless galaxies known in the Universe. Using the all-sky WISE survey, we discovered several hundred optically normal bulgeless galaxies that display extreme red mid-infrared colors thus far exclusively associated in extragalactic sources with powerful AGNs, with hidden broad lines being discovered in follow-up Keck observations. In this pilot program, we request 50ks to confirm the AGN in a test target and constrain the obscuring column.
Proposal Number: 5143 PI Last Name: Walton Title: THE HUNT FOR NEW PULSAR ULTRALUMINOUS X-RAY SOURCES: NGC7090 ULX Abstract: Following a series of remarkable recent discoveries, we now know that some of the most luminous members of the ultraluminous X-ray source (ULX) population are actually powered by highly super-Eddington neutron stars. Five such systems are now known, but based on the long-term variability characteristics exhibited by these sources, we have compiled a sample of 19 additional ULX pulsar candidates from the broader ULX population. Here we propose a co-ordinated target of opportunity observation with XMM (100ks) and NuSTAR (100ks) of one of the most promising of these candidates, NGC7090 ULX, when the source is bright. Our main aims are to search for pulsations in order to test our prediction that this is another ULX pulsar, and constrain the broadband spectrum.
Proposal Number: 5147 PI Last Name: RICCI Title: THE FIRST SYSTEMATIC BROAD-BAND X-RAY STUDY OF EXTREME ACCRETION ONTO SUPERMASSIVE BLACK HOLES WITH NUSTAR AND XMM Abstract: Super-Eddington accretion periods are expected to be extremely important to explain the fast growth of the first supermassive black holes. However, among all accretion modes, this phase is still the least understood one, and it is still largely debated what are the physical properties of the accretion flow and of the X-ray source at very high accretion rates. We propose here a systematic broad-band X-ray study of super-Eddington AGN at z < 0.1 by simultaneously observing three sources with NuSTAR and XMM-Newton. These three AGN have the highest Eddington ratios in the SEAMBHs sample, which contains exclusively objects with black hole masses estimated from reverberation mapping, making the Eddington ratio estimates extremely reliable.
Proposal Number: 5154 PI Last Name: WILKINS Title: THE HARD X-RAY SPECTRUM & VARIABILITY OF I ZW 1: THE IDEAL LABORATORY FOR ACCRETION PHYSICS & JET LAUNCHING Abstract: We propose to conduct the first hard X-ray study of I Zwicky 1 (I Zw 1), a unique AGN that will yield great insight into the physical processes associated with accretion and the extreme environments around supermassive black holes. Rapid variability is seen in the X-ray emission as the corona evolves as well as complex, variable absorption from outflows. I Zw 1 is the first AGN in which there is evidence for distinct structures within the corona, including a core akin to the base of a jet. We propose to observe I Zw 1 for 250ks using NuSTAR, 130ks simultaneous with XMM-Newton. This will yield the most detailed, dynamic picture of how the corona is structured and how it evolves, transforming our understanding of how the corona and accretion disc drive AGN feedback.
Proposal Number: 5166 PI Last Name: PARKER Title: UNDERSTANDING THE REPEAT CHANGING-LOOK AGN NGC 1566 Abstract: We propose a deep 200 ks NuSTAR observations of the nearby (z = 0.005) repeat changing-look AGN NGC 1566 as it returns to quiescence, simultaneous with a 10 ks XMM-Newton exposure, to complete the X-ray picture of this unique source. With this observation, we will follow the properties of the X-ray corona as the source transitions back to a Seyfert 2, combining this with Swift monitoring to track the evolution of the accretion disk.
Proposal Number: 5169 PI Last Name: WALTON Title: IS J1042+1641 THE FIRST EXAMPLE OF A GRAVITATIONALLY LENSED, COMPTON-THICK QUASAR? Abstract: Previous X-ray observations of the quadruply lensed quasar J1042+1641 (z=2.517) with Swift XRT reveal evidence for strong obscuration, unusual among the lensed quasar population. However, the current data are not sufficient to robustly determine the level of the absorption. Both Compton-thick and Compton-thin solutions provide equivalent fits, meaning J1042+1641 is potentially the first example of a gravitationally lensed, Compton-thick quasar. We request a modest, coordinated X-ray observation of this remarkable source with XMM (25ks) and NuSTAR (50ks). These exposures will enable us to robustly determine the nature of the obscuration (Compton-thick vs Compton-thin), a key step towards determining the intrinsic power of this system, and to constrain the geometry of the absorber itself.
Proposal Number: 5172 PI Last Name: PERNA Title: CLASH IN MKN 848. AGN- OR STARBURST-DRIVEN OUTFLOWS? Abstract: Galactic outflows are now commonly observed in starburst and active galactic nuclei (AGN) host galaxies. Yet, there is no clear consensus on their physical driving mechanism(s), and whether the observed outflows are powered by stellar winds and supernovae explosions or by AGN winds. We propose to observe with NuSTAR the starburst Mkn 848, a merging system at z = 0.04 showing powerful kpc-scale multi-phase outflows. The properties of these outflows are compatible with the presence of winds driven by AGN, but available observations are strongly limited by absorption and prevent a direct identification of AGN emission. Our proposal is designed to study the 3-30 keV emission of this target, by looking for a direct evidence of the presence of an highly-obscured AGN.
Proposal Number: 5176 PI Last Name: MORI Title: X-RAY AND TEV OBSERVATIONS OF HESS J0632+057'S PULSAR WIND COLLIDING INTO THE STELLAR WIND AND CIRCUMSTELLAR DISK Abstract: HESS J0632+057 is one of the rare, six binary systems detected above 100 GeV. Besides its peculiar double-peak X-ray lightcurve, HESS J0632+057 is unique among the TeV binaries since the effects of the pulsar wind interacting with the stellar wind and Be disk are observable throughout its 315 day orbit in the X-ray and TeV bands. We propose simultaneous NuSTAR + VERITAS observations of the secondary X-ray peak (whose origin is still unknown), including the periastron and pulsar-disk interaction passage. These observations, combined with our wind-collision shock model, will probe the enhanced shock acceleration at periastron, determine the orbital solution and offer a rare opportunity of studying relativistic hydrodynamics on how the pulsar wind interacts with the dense circumstellar disk.
Proposal Number: 5181 PI Last Name: DUNCAN Title: COORDINATED SOLAR OBSERVATION BETWEEN NUSTAR AND PARKER SOLAR PROBE Abstract: The goal of this proposal is to take advantage of a unique
co-observation window: we propose a coordinated observation
between NuSTAR and the Parker Solar Probe (PSP) during
its January 2020 perihelion. The location of PSP near the
Earth-Sun line during this perihelion leads to a compelling
opportunity to combine NuSTAR s capability for highly sensitive
remote X-ray observation with PSP s powerful suite of in-situ
instruments. By arranging this co-observation, we will
be able to utilize the capacity of both NuSTAR and PSP
to examine the connectivity between the corona and the
Proposal Number: 5182 PI Last Name: RICCI Title: DESTRUCTION AND RECREATION OF THE X-RAY CORONA IN A CHANGING-LOOK AGN Abstract: Our group recently caught a local AGN, 1ES 1927+654, during an optical changing-look event. Our X-ray monitoring campaign has shown an extremely peculiar X-ray emission, with a supersoft X-ray spectrum, dominated by a blackbody component, with only a weak contribution from the power-law, which suggests that the X-ray corona was destroyed during the optical-UV transient event. Our observations have finally shown a recent hardening of the X-ray emission, indicative of a re-creation of the X-ray corona. We propose here two 45ks NuSTAR observations of this intriguing source, simultaneous with two XMM-Newton observations that we were recently awarded, to monitor its spectral behaviour, and in particular to study the reappearance of the hard component and the evolution of the cutoff.
Proposal Number: 5184 PI Last Name: MIDDEI Title: ESO511-G030: THE ULTIMATE TEST BENCH FOR THE TWO-CORONA MODEL Abstract: We propose a nustar/xmm monitoring composed by 5x30ks observations spaced by 3-4 days of the bright Radio-Quiet Seyfert 1 ESO511-G030. Its spectrum is characterised by a relativistic Fe Kalpha line (significance >5sigma) and a strong soft excess, thus making ESO511-G030 the ideal candidate for testing the warm Comptonisation origin of soft excess in AGN. In fact, warm corona has been proved to be a viable physical model in sources without a relativistic reflection component, but it has never been properly tested in a source hosting a relativistic iron line where the soft excess is reproduced via relativistic reflection. The proposed monitoring will allow us to test the general validity of the warm Comptonisation by breaking its spectral degeneracy with relativistic reflection.
Proposal Number: 5189 PI Last Name: MORI Title: IS THE BRIGHTEST GAMMA-RAY SOURCE ABOVE 100 TEV POWERED BY BOW SHOCK PULSAR WIND NEBULA OR HADRONIC INTERACTION? Abstract: The proposed NuSTAR observation will provide a unique opportunity to identify the brightest Galactic gamma-ray source above 100 TeV, 2HWC J1825-134 (HESS J1826-130). It is still unclear whether the TeV gamma-ray emission has leptonic or hadronic origin. In the leptonic scenario, the PWN of the fast-moving pulsar PSR J1826-1256 emits TeV gamma-rays via inverse Compton scattering through very energetic electrons at ~300 TeV. In the hadronic scenario, relativistic protons from the nearby supernova remnants bombarding the molecular clouds produce TeV gamma-rays. Our multi-wavelength SED models predict distinct X-ray spectral indices between the two scenarios. NuSTAR's broad-band spectroscopy will test whether the bow-shock PWN or hadronic interactions power the brightest Galactic HAWC source.
Proposal Number: 5192 PI Last Name: CIVANO Title: DEEP NUSTAR OBSERVATIONS OF THE JWST-NEP TIME DOMAIN FIELD Abstract: The JWST Deep Time-Domain Field in the north ecliptic pole (NEP DTDF) is a GTO target that will have continuous visibility and excellent 8-band deep (m~28) imaging and grism spectra in the NIR by JWST. In the past few years, the NEP DTDF has grown into a comprehensive survey with deep radio to X-ray data, becoming the most promising new field for extragalactic studies and time-domain investigations. We propose to perform a 585 ks NuSTAR survey in this field, reaching a sensitivity comparable to the deepest NuSTAR extragalactic surveys, detecting 20-30 sources in 3-24 keV, to focus on: X-ray variability (3-8 keV monitoring and the first 8-24 keV studies!), the true obscured AGN fraction, 0.5-24 keV spectroscopy combining NuSTAR and Chandra, and the bright NLSy1 in the field.
Proposal Number: 5193 PI Last Name: MARCOTULLI Title: CHASING THE MOST POWERFUL BLAZARS Abstract: We request to observe 2 high redshift blazars with NuSTAR for a total of 100 ks. Detected in gamma-rays, these sources are some of the most powerful of their class, but crucially lack of X-ray measurements. We propose to observe it in the X-ray with NuSTAR, which will allow us to accurately measure the rising part of the inverse Compton (IC) spectrum, expected to be very hard, up to 70 keV. Together with the LAT data, the X-rays will be fundamental to pinpointing the IC peak, determining the power of the jet, deriving the underlying electron population responsible for the emission and measuring the location of the emission region.
Proposal Number: 5196 PI Last Name: FUERST Title: TRACKING THE SPIN OF THE NEUTRON STAR ULX NGC7793 P13 WITH NUSTAR Abstract: NGC7793 P13 is part of the small group of ultra-luminous X-ray pulsars (ULXPs), i.e., neutron stars that accrete orders of magnitude above their Eddington limit. It is an almost persistent source, with a relatively high flux and strong pulsations, making it an ideal target to study super-Eddington accretion. Additionally, it is one of only two ULXPs for which the mass donor is known, allowing us to determine the complete orbital ephemeris through pulse timing. Here we propose two NuSTAR observations of P13 to follow-up on our successful campaigns in AO 3 and AO 4. We aim to track the evolution of the pulse period and study possible glitches. We will improve the orbital ephemeris, characterise the timing noise, and investigate a tentative super-orbital period on the order of 1500d.
Proposal Number: 5197 PI Last Name: MARCHESI Title: THE COMPTON THICK AGN LEGACY PROJECT: A COMPLETE SAMPLE OF NUSTAR-OBSERVED NEARBY COMPTON THICK AGN Abstract: The X-ray spectral analysis of Compton thick (CT-, i.e., having intrinsic obscuration NH>1E24 cm^-2) active galactic nuclei (AGN) is key to understand the physics of the obscuring material surrounding accreting supermassive black holes. We propose to target with a combined NuSTAR/XMM-Newton observation the last 10 candidate CT-AGN the BAT 100-month survey still lacking of NuSTAR data. With this proposal, each CT-AGN candidate of this sample will have a NuSTAR observation, thus enabling the best characterization to date of CT-AGN. Thanks to the excellent statistics (both in terms of spectral counts and sample size) we will study the sample physical properties, and put tighter constraints on the true intrinsic fraction of CT-AGN in the nearby Universe and on their contribution to the CXB.
Proposal Number: 5205 PI Last Name: WALTON Title: SEARCHING FOR RELATIVISTIC DISC REFLECTION IN THE HIGH MASS AGN PG1426+015 Abstract: Spin measurements for high-mass active galactic nuclei are currently very sparse, but are critical for testing correlations between mass and spin hinted at in the current sample of AGN with spin constraints, and testing theoretical models of supermassive black hole growth. We request a coordinated broadband X-ray observation of PG1426+015, which has the largest reverberation-mapped mass to date (log[Mbh/Msun] = 9.01 (+0.11,-0.16)), with XMM-Newton (100ks) and NuSTAR (100ks). The quality of the data will enable us to robustly search for relativistically broadened iron emission, an unambigous signature of reflection from the innermost accretion disc, and take an important first step towards constrining the spin for this key source.
Proposal Number: 5213 PI Last Name: Tomsick Title: MONITORING A BRIGHT OUTBURST FROM A BLACK HOLE TRANSIENT Abstract: Much of our understanding of the properties of accretion disks, relativistic jets, and the regions of strong gravity near black holes (BHs) come from observations of BH X-ray binaries. NuSTAR has made significant contributions to these studies especially through improved measurements of reflection components that have allowed us to access the inner disk and constrain the spins of BHs. Recently, comparisons between BH spins in X-ray binaries and in binary BH mergers have further increased the level of interest in BH spins, and a main focus of this proposal is to improve assessments of the uncertainties in BH spin measurements. We propose to do this by monitoring a bright BH transient with NuSTAR to systematically quantify the effect of the changing continuum on the BH spin measurement.
Proposal Number: 5216 PI Last Name: BACHETTI Title: MEASURING THE MASS TRANSFER IN THE PULSATING ULTRALUMINOUS X-RAY SOURCE M82 X-2 Abstract: M82 X-2 is the archetipal pulsating ultraluminous X-ray source (PULX), a class of ultraluminous X-ray sources (ULX) whose accretor is a neutron star. The extreme luminosity of ULXs suggests that these sources are undergoing strongly super-Eddington accretion, and this is confirmed by the detection of strong relativistic outflows in many of these systems. The supply of matter that powers these accreting systems is likely to come from Roche Lobe overflow from a more massive companion star. The predicted mass transfer is so extreme that it should produce changes of orbital period observable in time scales of ~years. This program aims at detecting this orbital period derivative through pulsar timing, and measure accurately (or set an upper limit to) the mass transfer.
Proposal Number: 5218 PI Last Name: GOTTHELF Title: MONITORING THE 2018 X-RAY OUTBURST OF XTE J1810-197 Abstract: Two days following reports of an outburst from the transient anomalous X-ray pulsar (AXP) XTE J1810-197, we obtained a NuSTAR DDT observation to characterize its outburst properties. Thus, 15 years after the 2003 discovery of this, the first known transient and radio AXP, it is possible to study the origin and decay of magnetar emission in exquisite detail from the beginning of the outburst in a uniquely accessible source. We have already identified, for the first time in this object, new hard spectral component and energy-dependent pulse phasing. We propose here to monitor the early X-ray spectral and pulsed evolution of XTE J1810-197, measuring its surface thermal hot spots and magnetic field configuration, to compare with the original outburst at a similar epoch.
Proposal Number: 5220 PI Last Name: NOWAK Title: REVEALING THE RELATION BETWEEN HARD AND SOFT QUIESCENT X-RAY SPECTRA IN CEN X-4 Abstract: We propose a campaign of joint NuSTAR and NICER observations of the quiescent neutron star Cen X-4, to study the relationship between its soft X-ray flux level and its hard X-ray spectrum. The hard X-ray spectrum has been hypothesized to be due to thermal bremsstrahlung from active accretion onto the neutron star, and may transit to synchrotron emission at low flux. If the bremsstrahlung/active accretion hypothesis is correct, we should be able to measure spectral changes with our proposed campaign.
Proposal Number: 5238 PI Last Name: Garcia Title: THE PROPERTIES AND EVOLUTION OF ACCRETION DISKS IN BLACK HOLE BINARIES Abstract: We propose a series of 4 Target of Opportunity (ToO) observations with NuSTAR and NICER for any of the five following recurrent black hole binaries: GX 339-4, H1743-322, 4U 1630-47, XTE J1550-564, or XTE 1752-223. We aim to obtain high signal-to-noise spectra of these sources at different accretion states as they go into outburst. Our principal goal is to use X-ray reflection spectroscopy to track the evolution of the inner edge of the accretion disk as a function of luminosity; estimate the spin of the black hole; and measure the accretion disk inclination, density, ionization and iron abundance. These observations will provide crucial constraints to support a large-scale data analysis program for these sources.
Proposal Number: 5240 PI Last Name: BODAGHEE Title: NUSTAR BRINGS INTO FOCUS FAINT AGN CANDIDATES FROM THE SWIFT-INTEGRAL X-RAY SURVEY Abstract: NuSTAR observations are requested for three unclassified hard X-ray sources that were detected by merging mosaic images from the Swift-BAT and INTEGRAL-ISGRI surveys. We know little about these sources other than a crude X-ray position and flux, but they are good candidates for being high-redshift blazars or Compton-thick AGN that appear missing from those surveys. Our scientific objectives are: to obtain an improved X-ray position that will narrow down the list of possible counterparts in the optical/infrared bands; and create X-ray spectra to combine with the OIR data to generate their broadband spectral energy distribution. The targets are too faint to be detected by BAT or ISGRI alone, but they are easily detected by NuSTAR with minimal exposure times.
Proposal Number: 5242 PI Last Name: LIN Title: NUSTAR SURVEY OF BRIGHT X-RAY SOURCES IN M31 Abstract: X-ray binaries (XBs) in nearby galaxies have been studied for decades. However, their nature largely remains illusive, mainly due to the lack of hard X-ray coverage. With the extraordinary sensitivity of NuSTAR in hard X-rays, we propose to observe two luminous hard X-ray sources (Lx>2e38 erg/s) in M31 to complete the survey of such objects. The observations will allow us to differentiate between black-hole XBs in the hard state and luminous neutron star (NS) low-mass XBs (LMXBs) by measuring the spectral shape in hard X-rays. The program is important for understanding the origin and evolution of LMXBs. It also allows us to identify supercritically accreting NSs and provides a valuable test for our recently discovered simple, yet effective, source identification method in the Chandra band.
Proposal Number: 5252 PI Last Name: Vestergaard Title: MONITORING AND TOO OF A RE-AWAKENING AGN: CATCHING THE MONSTER IN THE ACT! Abstract: After a 10-year hiatus Mrk590 is rekindling its nuclear activity! Our Swift monitoring strongly suggests that the AGN is likely to turn on again soon. We wish to seize this rare opportunity to document, for the first time ever, the onset of AGN activity when it occurs since this can lead to significant insight on the long-standing issue of how AGNs are fueled. We ask to monitor Mrk590 bi-weekly with Swift and based thereon trigger a joint 3-visit program with NuSTAR and Swift. We aim to establish at which accretion luminosity the expected emission features of a standard accretion disk appear as the AGN turns on. This program is an important part of a broad-scoped, multi-wavelength study of this remarkable AGN.
Proposal Number: 5273 PI Last Name: FORNASINI Title: A NUSTAR-XMM SURVEY OF NGC 55: A HOLISTIC VIEW OF A LOW METALLICITY X-RAY BINARY POPULATION Abstract: With NuSTAR, it is possible for the first time to determine the compact object type and accretion state of large samples of X-ray binaries (XRBs) in nearby galaxies. This classification, based on hard X-ray luminosity and hardness ratios, can provide valuable insights into how XRB properties vary with variables such as metallicity (Z), age, and specific star formation rate (sSFR). Vulic et al. (2018) classified 90 XRBs in nearby galaxies observed by NuSTAR, but the sample contains few galaxies with low-Z or low sSFR. Furthermore, variability studies of XRB populations have been limited to M31. We propose joint NuSTAR-XMM observations of the NGC 55 to expand studies of the compact objects, accretion states, and variability of XRBs to lower luminosities in a low-Z galaxy.
Proposal Number: 5277 PI Last Name: SANTANDER Title: PROBING THE HADRONIC EMISSION FROM THE CANDIDATE NEUTRINO BLAZAR TXS 0506+056 Abstract: On Sept 22, 2017, the IceCube observatory reported the detection of the high-energy astrophysical neutrino candidate event IC170922A. A large multiwavelength observation campaign of the neutrino location involving led to the detection of enhanced broadband EM emission from the blazar TXS 0506+056. This detection represents the first evidence for an electromagnetic counterpart to the high-energy astrophysical neutrinos detected by IceCube. The soft-to-hard X-ray emission from the source provides the most sensitive diagnostics of the hadronic contribution to the source SED. We here propose an ambitious observational program of TXS 0506+056 involving NuSTAR, Swift, VERITAS and Fermi.
Proposal Number: 5280 PI Last Name: NEILSEN Title: X-RAY JETS & BH SHADOWS: NUSTAR, EHT, AND CHANDRA ON M87 Abstract: With a large, well-studied jet and the second largest event horizon on the sky, the radio galaxy M87 is one of the primary targets for the Event Horizon Telescope. In light of the incredible success of the 2017 campaign, we are eagerly planning for observations in 2020. To this end, we request 100 ks of NuSTAR time on M87 to be coordinated with Chandra. In addition to the potential tests of GR, coordinated NuSTAR/EHT observations offer an incredible opportunity: a chance to a chance to observe structures near the event horizon while tracking their high-energy variability. In synergy with Chandra, NuSTAR spectra of M87 (and multiwavelength SEDs) will place tight constraints on the energetics and acceleration of particles near the event horizon of this supermassive black hole.
Proposal Number: 5283 PI Last Name: LANZ Title: NGC 1377: A LOW-MASS GALAXY WITH AGN FEEDBACK? Abstract: The evolution of low-mass galaxies may follow a different path to quiescence than more massive galaxies, particular with regards to the prevalence of stellar versus active galactic nuclei (AGN) feedback. It is only recently that we have begun to detect AGN activity in dwarf galaxies. NGC 1377, a local post-starburst lenticular with a young molecular outflow, will provide useful insights into AGN feedback in low-mass galaxies. ALMA observations of molecular gas indicate a likely Compton-thick obscuration, explaining the marginal nuclear X-ray detection in previous Chandra observations. We propose to observe NGC 1377 for 60 ks to detect and characterize the X-ray emission and intrinsic luminosity of this heavily obscured AGN and shed light on its relation to the molecular outflow.
Proposal Number: 5284 PI Last Name: Steiner Title: A CONTINUED NUSTAR & NICER LOOK AT REFLECTION AND THERMAL EMISSION IN CYGNUS X-1 Abstract: Understanding the corona and disk-coronal interaction is a forefront challenge in black hole systems. While NuSTAR is the leading instrument at probing the high-energy spectral reflection component, NICER provides a complementary view of the thermal accretion disk. Both components are very strong for Cyg X-1, but the disk is cool and out of reach for NuSTAR alone. This proposal is a continuation of a previously approved NuSTAR Cycle 3 program on Cyg X-1 using the uniquely powerful capability of combined continuum and reflection modeling provided with both instruments together. By chance, our first program covered the soft state only. We propose to expand and target hard states and request 3x20 ks NuSTAR (3x4 ks NICER) observations of Cyg X-1 for triggered monitoring of hard states.
Proposal Number: 5289 PI Last Name: BALOKOVIC Title: STRUCTURE OF THE OBSCURER IN THE HEAVILY OBSCURED LUMINOUS QUASAR IRAS 09104+4109 Abstract: We propose three 40-ks observations of IRAS 09104+4109, a heavily obscured highly luminous quasar. Our target is uniquely accessible because of its relatively low redshift in comparison to similarly luminous obscured quasars found only at higher redshift. With the proposed observations we will be able to 1) characterize potential variability above 10 keV, and 2) build up the photon statistics to model its X-ray spectrum with physically motivated models for the obscuring structure usually called the torus. With modeling of the torus applied to the wealth of available infrared data, we will be able to make some of the first direct comparisons of the constraints implied from both of these spectral windows.
Proposal Number: 5295 PI Last Name: ROJAS Title: MAPPING THE TEMPERATURE STRUCTURE OF THE COMPLEX HOT MERGING GALAXY CLUSTER MACS J0717 Abstract: The most energetic events in the Universe since the Big Bang have been the merging of 2 galaxy clusters. In rare cases, such as with MACSJ0717, 4 subclusters have been observed to be undergoing a merger. This produces a complex merger structure with very hot (T > 20 keV) gas, only observed in clusters containing shocks with high Mach number shocks (M > 2) such as the Bullet Cluster and A665. While Chandra measurements have been performed on this cluster, the constraints placed on this hot gas are inconclusive. NuSTARS ability to probe into the hard X-ray band can provide better constraints on the temperature, as well as provide an opportunity to constrain potential Inverse Compton scattering that may occur for the reacceleration of electrons by the shock.