arXiv subjects

S. Gezari

Publications and source records attributed to S. Gezari.

At least 19 recordsLinked to original sources

arXiv2026

The Lazuli Space Observatory: Opportunities for time-domain and multi-messenger astronomy

Advancing time-domain and multi-messenger astronomy requires a multi-wavelength network of observatories capable of rapidly discovering, classifying, and characterizing transient phenomena. A critical gap in current capabilities is the inability to follow up faint, fast-evolving transients with sensitive, wide-band imaging and spectroscopic observations from space on timescales of minutes to hours. We discuss how the Lazuli Space Observatory will address this gap through a large collecting area, optical/NIR photometry and low-resolution integral field spectroscopy, and a rapid-response architecture with a mission requirement of $<$4 hours from trigger to first photon. Based on a latency analysis, we find a credible path to realizing response times well below this requirement, with best-case scenarios below 90 minutes under favorable conditions. We highlight extragalactic science opportunities in currently un(der)explored parts of parameter space, including gravitational wave follow-up, kilonova characterization, supernova progenitor physics, and a wide variety of fast-evolving transients and high redshift events. We further outline new observational capabilities for Galactic time-domain science, including high frequency variability in accreting systems, precision astrometry of compact objects, and the detection of compact and ultracompact binaries, enabled by high-frequency, diffraction-limited imaging and astrometry. Together, its capabilities - combining flagship sensitivity with response times one to two orders of magnitude faster than existing large space observatories - position Lazuli to make transformative contributions across time-domain and multi-messenger astrophysics.

astro-ph.IM↗

arXiv2026

The Wandering Supermassive Black Hole Powering the off-nuclear TDE AT2024tvd

We present an analysis of the spectral energy distribution (SED) of the off-nuclear tidal disruption event (TDE) AT2024tvd during its late-time plateau phase, combining X-ray spectra and UV/optical photometry. Using a fully relativistic, compact accretion disk model with self-consistent inner-disk Comptonization, we reproduce the observed SED without significant residuals. The inferred black hole mass ${\rm log}{10}(M{\bullet}/M_\odot) \approx 6.0 \pm 0.2$, and the inferred disk parameters place AT2024tvd within known TDE-disk scaling relations ($L_{\rm bol}^{\rm disk}/L_{\rm Edd} \propto T_{\rm p}^4 \propto M_{\bullet}^{-1}$, $L_{\rm plat} \propto M_{\bullet}^{2/3}$, $R_{\rm out}/r_{\rm g} \propto M_{\bullet}^{-2/3}$). Our results show that: (i) there is no \textit{detected} star cluster or dwarf galaxy associated with the source, down to a mass limit of $\log_{10}(M_{\rm gal}/M_{\odot}) \leq 7.6$; (ii) the black hole is a wandering supermassive, rather than intermediate-mass, black hole; and (iii) the source represents an extreme case of black hole-to-host mass ratio, with $M_{\bullet}/M_{\rm gal} > 3\%$, consistent with a heavily tidally stripped nucleus. The latter aligns with cosmological simulations predicting that surviving host remnants of most wandering black holes should not retain a detectable stellar overdensity when located at small halo-centric distances. We discuss differences with previous analyses of this source and highlight why our modeling approach provides a more physically consistent solution with more reliable parameter inference.

astro-ph.HE↗

arXiv2025

Compact Accretion Disks in the Aftermath of Tidal Disruption Events: Parameter Inference from Joint X-ray Spectra and UV/Optical Photometry Fitting

We present a multi-wavelength analysis of 14 tidal disruption events (TDEs)-including an off-nuclear event associated with an ultra-compact dwarf galaxy-selected for having available thermal X-ray spectra during their late-time UV/optical plateau phase. We show that at these stages, the full spectral energy distribution - X-ray spectra and UV/optical photometry - is well described by a compact, yet standard accretion disk, the same disk which powers the X-rays at all times. By fitting up to three epochs per source with a fully relativistic disk model, we show that many system properties can be reliably recovered, including importantly the black hole mass ($M_{\bullet}$). These accretion-based $M_{\bullet}$ values, which in this sample span nearly three orders of magnitude, are consistent with galactic scaling relations but are significantly more precise (68\% credible interval $ < \pm 0.3$ dex) and physically motivated. Expected accretion scaling relations (e.g., $L_{Bol}^{ disk} / L_{Edd} \propto T_p^4 \propto M_{\bullet}^{-1}$), TDE-specific physics correlations ($L_{plat} \propto M_{\bullet}^{2/3}$ and $R_{out}/r_g \propto M_{\bullet}^{-2/3}$) and black hole-host galaxy correlations ($M_{\bullet}$-$M_{gal}$ and $M_{\bullet}$-$\sigma_{\star}$) naturally emerge from the data and, for the first time, are self-consistently extended into the intermediate-mass (IMBH, $M_{\bullet} < 10^{5}$) regime. We discuss the implications of these results for TDE physics and modeling. We also review and discuss different methods for $M_{\bullet}$ inference in TDEs, and find that approaches based on physical models of the early-time UV/optical emission are not able to recover (at a statistically significant level) black hole-host galaxy scalings.

astro-ph.HE↗

arXiv2025

A Time-Dependent Solution for GSN 069 Disk Evolution and the Nature of Long-Lived Tidal Disruption Events

We present the implementation of a fully time-dependent relativistic disk model-based on the light curve fitting package FitTeD-into the X-ray spectral fitting environment, pyXspec. This implementation enables simultaneous fitting of multi-epoch and multi-wavelength spectral data, where the only free parameters are those describing the black hole and the initial conditions, while the subsequent evolution is governed by the dynamical equations of an evolving accretion flow. We use it fit seven epochs of X-ray spectra and two epochs of UV spectra of the 'long-lived' tidal disruption event (TDE) and quasi-periodic eruption (QPE) source GSN 069, from 2010 through late-2019. Our results show that such 'long-lived', X-ray-bright TDEs-of which GSN 069 is a prime, but not unique, example-can naturally be explained within the same framework as events with shorter-lived X-ray emission, like ASASSN-14li and AT2019dsg. Their distinction lies in the `viscous' timescale parameter-tied to the disk's angular momentum transport efficiency-which should be treated as a free parameter when modeling the disk evolution of transient events. We examine the implications for QPE models by tracking the time evolution of disk properties such as mass surface density and accretion rate. We argue that existing QPE models may not be able to reproduce the observed connection between the presence (2018) or absence (2014) of eruptions and the disk properties. In the context of orbiter-disk collision models, the change in mass surface density appears insufficient to explain the needed variation in the eruption's temperature. The absence of eruptions in GSN 069 in 2014 remains a challenge for QPE models.

astro-ph.HE↗

arXiv2025

Discovery of a likely Type II SN at $z$=3.6 with JWST

Transient astronomy in the early, high-redshift (z > 3) Universe is an unexplored regime that offers the possibility of probing the first stars and the Epoch of Reionization. During Cycles 1 and 2 of the James Webb Space Telescope (JWST), the JWST Advanced Deep Extragalactic Survey (JADES) program enabled one of the first searches for transients in deep images (~30 AB mag) over a relatively wide area (25 arcmin^2). One transient, AT 2023adsv, was discovered with an F200W magnitude of 28.04 AB mag, and subsequent JWST observations revealed that the transient is a likely supernova (SN) in a host with z_spec = 3.613 +/- 0.001 and an inferred metallicity at the position of the SN of Z_* = 0.3 +/- 0.1 Z_{\odot}. At this redshift, the first detections in F115W and F150W show that AT 2023adsv had bright rest-frame ultraviolet flux at the time of discovery. The multi-band light curve of AT 2023adsv is best matched by a template of an SN IIP with a peak absolute magnitude of M_B ~ -18.3 AB mag. We find a good match to a 20 M_{\odot} red supergiant progenitor star with an explosion energy of 2.0x10^51 ergs, likely higher than normally observed in the local Universe, but consistent with SNe IIP drawn from local, lower metallicity environments. AT 2023adsv is the most distant photometrically classified SN IIP yet discovered with a spectroscopic redshift measurement, and may represent a global shift in SNe IIP properties as a function of redshift.

astro-ph.HE↗

arXiv2025

The properties of GSN 069 accretion disk from a joint X-ray and UV spectral analysis: stress-testing quasi-periodic eruption models

We present an analysis of Hubble Space Telescope (HST) and XMM-Newton data of the tidal disruption event (TDE) candidate and quasi-periodic eruption (QPE) source GSN 069. Using ultraviolet (UV) and optical images at HST resolution, we show that GSN 069's emission consists of a point source superimposed on a diffuse stellar component. The latter accounts for $\leq 5\%$ of the UV emission in the inner 0.5"$\times$0.5" region, while the luminosity of the former cannot be attributed to stars. Analyzing the 2014/2018 \hst UV spectra, we show that to leading order the intrinsic spectral shape is $\nu\,L_{\nu}\propto\nu^{4/3}$, with $\sim10\%$ far UV flux variability between epochs. The contemporaneous X-ray and UV spectra can be modeled self-consistently in a thin disk framework. At observed epochs, the disk had an outer radius ($R_{\rm out}$) of $\mathcal{O}(10^3R_{\rm g})$, showing both cooling and expansion over four years. Incorporating relativistic effects via numerical ray tracing, we constrain the disk inclination angle ($i$) to be $30^\circ\,\lesssim\,i\,\lesssim\,65^\circ$ and identify a narrow region of spin-inclination parameter space that describes the observations. These findings confirm that GSN 069 hosts a compact, viscously expanding accretion disk likely formed after a TDE. Implications for QPE models are: (i) No published disk instability model can explain the disk's stability in 2014 (no QPEs) and its instability in 2018 (QPEs present); (ii) While the disk size in 2018 allows for orbiter/disk interactions to produce QPEs, in 2014 the disk was already sufficiently extended, yet no QPEs were present. These findings pose challenges to existing QPE models.

astro-ph.HE↗

arXiv2024

Testing for Intrinsic Type Ia Supernova Luminosity Evolution at z>2 with JWST

The James Webb Space Telescope} (JWST) is opening new frontiers of transient discovery and follow-up at high-redshift. Here we present the discovery of a spectroscopically confirmed Type Ia supernova (SN Ia; SN $2023$aeax) at $z=2.15$ with JWST, including a NIRCam multi-band light curve. SN $2023$aeax lands at the edge of traditional low-$z$ cosmology cuts because of its blue color (peak rest-frame $B-V\sim-0.3$) but with a normal decline rate ($\Delta m_{15}(B)\sim1.25$), and applying a fiducial standardization with the BayeSN model we find the SN $2023$aeax luminosity distance is in $\sim0.1\sigma$ agreement with $\Lambda$CDM. SN $2023$aeax is only the second spectroscopically confirmed SN Ia in the dark matter-dominated Universe at $z>2$ (the other is SN $2023$adsy), giving it rare leverage to constrain any potential evolution in SN Ia standardized luminosities. Similar to SN $2023$adsy ($B-V\sim0.8)$, SN $2023$aeax has a fairly extreme (but opposite) color, which may be due to the small sample size or a secondary factor, such as host galaxy properties. Nevertheless, the SN $2023$aeax spectrum is well-represented by normal low-$z$ SN Ia spectra and we find no definitive evolution in SN Ia standardization with redshift. Still, the first two spectroscopically confirmed $z>2$ SNe Ia have peculiar colors and combine for a $\sim1\sigma$ distance slope relative to $\Lambda$CDM, though in agreement with recent SN Ia cosmological measurements.

astro-ph.CO↗

arXiv2024

Lensed Type Ia Supernova "Encore" at z=2: The First Instance of Two Multiply-Imaged Supernovae in the Same Host Galaxy

A bright ($m_{\rm F150W,AB}$=24 mag), $z=1.95$ supernova (SN) candidate was discovered in JWST/NIRCam imaging acquired on 2023 November 17. The SN is quintuply-imaged as a result of strong gravitational lensing by a foreground galaxy cluster, detected in three locations, and remarkably is the second lensed SN found in the same host galaxy. The previous lensed SN was called "Requiem", and therefore the new SN is named "Encore". This makes the MACS J0138.0$-$2155 cluster the first known system to produce more than one multiply-imaged SN. Moreover, both SN Requiem and SN Encore are Type Ia SNe (SNe Ia), making this the most distant case of a galaxy hosting two SNe Ia. Using parametric host fitting, we determine the probability of detecting two SNe Ia in this host galaxy over a $\sim10$ year window to be $\approx3\%$. These observations have the potential to yield a Hubble Constant ($H_0$) measurement with $\sim10\%$ precision, only the third lensed SN capable of such a result, using the three visible images of the SN. Both SN Requiem and SN Encore have a fourth image that is expected to appear within a few years of $\sim2030$, providing an unprecedented baseline for time-delay cosmography.

astro-ph.CO↗

arXiv2024

Discovery of An Apparent Red, High-Velocity Type Ia Supernova at z = 2.9 with JWST

We present the JWST discovery of SN 2023adsy, a transient object located in a host galaxy JADES-GS$+53.13485$$-$$27.82088$ with a host spectroscopic redshift of $2.903\pm0.007$. The transient was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Photometric and spectroscopic followup with NIRCam and NIRSpec, respectively, confirm the redshift and yield UV-NIR light-curve, NIR color, and spectroscopic information all consistent with a Type Ia classification. Despite its classification as a likely SN Ia, SN 2023adsy is both fairly red (E(B-V)$\sim0.9$) despite a host galaxy with low-extinction and has a high Ca II velocity ($19,000\pm2,000$km/s) compared to the general population of SNe Ia. While these characteristics are consistent with some Ca-rich SNe Ia, particularly SN 2016hnk, SN 2023adsy is intrinsically brighter than the low-z Ca-rich population. Although such an object is too red for any low-z cosmological sample, we apply a fiducial standardization approach to SN 2023adsy and find that the SN 2023adsy luminosity distance measurement is in excellent agreement ($\lesssim1σ$) with $Λ$CDM. Therefore unlike low-z Ca-rich SNe Ia, SN 2023adsy is standardizable and gives no indication that SN Ia standardized luminosities change significantly with redshift. A larger sample of distant SNe Ia is required to determine if SN Ia population characteristics at high-z truly diverge from their low-z counterparts, and to confirm that standardized luminosities nevertheless remain constant with redshift.

astro-ph.GA↗

arXiv2024

Discovery of a Relativistic Stripped Envelope Type Ic-BL Supernova at z = 2.83 with JWST

We present JWST NIRCam and NIRSpec observations of a Type Ic supernova (SN Ic) and its host galaxy (JADES-GS+53.13533-27.81457) at $z = 2.83$. This SN (named SN 2023adta) was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) Program. Follow-up observations with JWST/NIRSpec provided a spectroscopic redshift of $z = 2.83$ and the classification as a SN Ic-BL. The light curve of SN 2023adta matches well with other stripped envelope supernovae and we find a high peak luminosity, $M_V = -19.0 \pm 0.2$ mag, based on the distribution of best-fit SNe. The broad absorption features in its spectrum are consistent with other SNe Ic-BL 1-3 weeks after peak brightness. We measure a Ca II NIR triplet expansion velocity of $29{,}000 \pm 2{,}000$ km s$^{-1}$. The host galaxy of SN 2023adta is irregular, and modeling of its spectral energy distribution (SED) indicates a metallicity of $Z = 0.35^{+0.16}_{-0.08} Z_{\odot}$. This environment is consistent with the population of low-$z$ SNe Ic-BL which prefer lower metallicities relative to other stripped envelope supernovae, and track long duration $\gamma$-ray burst (LGRB) environments. We do not identify any GRBs that are coincident with SN 2023adta. Given the rarity of SNe Ic-BL in the local universe, the detection of a SN Ic-BL at $z = 2.83$ could indicate that their rates are enhanced at high redshift.

astro-ph.HE↗

arXiv2024

Delayed X-ray brightening accompanied by variable ionized absorption following a tidal disruption event

Supermassive black holes can experience super-Eddington peak mass fallback rates following the tidal disruption of a star. The theoretical expectation is that part of the infalling material is expelled by means of an accretion disk wind, whose observational signature includes blueshifted absorption lines of highly ionized species in X-ray spectra. To date, however, only one such ultra-fast outflow (UFO) has been reported in the tidal disruption event (TDE) ASASSN-14li. Here we report on the discovery of transient absorption-like signatures in X-ray spectra of the TDE AT2020ksf/Gaia20cjk (at a redshift of $z$=0.092), following an X-ray brightening $\sim 230$ days after UV/optical peak. We find that while no statistically significant absorption features are present initially, they appear on a timescale of several days, and remain detected up to 770 days after peak. Simple thermal continuum models, combined with a power-law or neutral absorber, do not describe these features well. Adding a partial covering, low velocity ionized absorber improves the fit at early times, but fails at late times. A high velocity (v$_w$ $\sim$ 42000 km s$^{-1}$, or -0.15c), ionized absorber (ultra-fast outflow) provides a good fit to all data. The few day timescale of variability is consistent with expectations for a clumpy wind. We discuss several scenarios that could explain the X-ray delay, as well as the potential for larger scale wind feedback. The serendipitous nature of the discovery could suggest a high incidence of UFOs in TDEs, alleviating some of the tension with theoretical expectations.

astro-ph.HE↗

arXiv2023

Multiwavelength study of extreme variability in LEDA 1154204: A changing-look event in a type 1.9 Seyfert

Context. Multiwavelength studies of transients in actively accreting supermassive black holes have revealed that large-amplitude variability is frequently linked to significant changes in the optical spectra -- a phenomenon known as changing-look AGN (CLAGN).} Aims. In 2020, the Zwicky Transient Facility detected a transient flaring event in the type 1.9 AGN LEDA 1154204, wherein brightness sharply increased by 0.55 mag in one month, then began to decay. Spectrum Roentgen Gamma (SRG)/eROSITA also observed the object as part of its all-sky X-ray surveys, after the flare had started decaying. Methods. We performed a three-year, multiwavelength follow-up campaign to track the source's spectral and temporal characteristics, during the post-flare fading. This campaign included optical spectroscopy, X-ray spectroscopy and photometry, and UV, optical, and IR continuum photometry. Results. Optical spectra taken near the flare peak revealed a broad double-peaked H$\beta$ emission and a blue continuum, both undetected in a 2005 archival spectrum; broad H$\beta$ had increased by a factor $>$5--6. Then, from late 2020 through 2023, broad Balmer line flux faded as the continuum faded, with Balmer decrement increasing by $\sim$2.2, consistent with the expected ionization response. The X-ray spectrum exhibits no significant spectral variability despite dramatic flux variation -- a factor of 17. There is no evidence of a soft X-ray excess, indicating an energetically unimportant warm corona. Conclusions. The transient event was likely triggered by a disk instability in a pre-existing AGN-like accretion flow, culminating in the observed multiwavelength variability -- X-rays via thermal Comptonization, BLR illumination, and IR dust echo -- and CLAGN event.

astro-ph.HE↗

arXiv2023

A radio-emitting outflow produced by the tidal disruption event AT2020vwl

A tidal disruption event (TDE) occurs when a star is destroyed by a supermassive black hole. Broadband radio spectral observations of TDEs trace the emission from any outflows or jets that are ejected from the vicinity of the supermassive black hole. However, radio detections of TDEs are rare, with less than 20 published to date, and only 11 with multi-epoch broadband coverage. Here we present the radio detection of the TDE AT2020vwl and our subsequent radio monitoring campaign of the outflow that was produced, spanning 1.5 years post-optical flare. We tracked the outflow evolution as it expanded between $10^{16}$ cm to $10^{17}$ cm from the supermassive black hole, deducing it was non-relativistic and launched quasi-simultaneously with the initial optical detection through modelling the evolving synchrotron spectra of the event. We deduce that the outflow is likely to have been launched by material ejected from stream-stream collisions (more likely), the unbound debris stream, or an accretion-induced wind or jet from the supermassive black hole (less likely). AT2020vwl joins a growing number of TDEs with well-characterised prompt radio emission, with future timely radio observations of TDEs required to fully understand the mechanism that produces this type of radio emission in TDEs.

astro-ph.HE↗

arXiv2021

Discovery of a Fast Iron Low-ionization Outflow in the Early Evolution of the Nearby Tidal Disruption Event AT2019qiz

We report the results of ultraviolet (UV) and optical photometric and spectroscopic analysis of the tidal disruption event (TDE) AT2019qiz. Our follow-up observations started $<$10 days after the source began to brighten in the optical and lasted for a period of six months. Our late-time host-dominated spectrum indicates that the host galaxy likely harbors a weak active galactic nucleus. The initial {\it Hubble Space Telescope (HST)} spectrum of AT2019qiz exhibits an iron and low-ionization broad absorption line (FeLoBAL) system that is seen for the first time in a TDE. This spectrum also bears a striking resemblance to that of Gaia16apd, a superluminous supernova. Our observations provide insights into the outflow properties in TDEs and show evidence for a connection between TDEs and engine-powered supernovae at early phase, as originally suggested in Metzger & Stone (2016). In a time frame of 50 days, the UV spectra of AT2019qiz started to resemble previous TDEs with only high-ionization BALs. The change in UV spectral signatures is accompanied by a decrease in the outflow velocity, which began at $15,000$ km s$^{-1}$ and decelerated to $\sim10,000$ km s$^{-1}$. A similar evolution in the H$α$ emission line width further supports the speculation that the broad Balmer emission lines are formed in TDE outflows. In addition, we detect narrow absorption features on top of the FeLoBAL signatures in the early HST UV spectrum of AT2019qiz. The measured HI column density corresponds to a Lyman-limit system whereas the metal absorption lines, such as NV, CIV, FeII, and MgII, are likely probing the circumnuclear gas and interstellar medium in the host galaxy.

astro-ph.HE↗

arXiv2021

Great Observatories: The Past and Future of Panchromatic Astrophysics

NASA's Great Observatories have opened up the electromagnetic spectrum from space, providing sustained access to wavelengths not accessible from the ground. Together, Hubble, Compton, Chandra, and Spitzer have provided the scientific community with an agile and powerful suite of telescopes with which to attack broad scientific questions, and react to a rapidly changing scientific landscape. As the existing Great Observatories age, or are decommissioned, community access to these wavelengths will diminish, with an accompanying loss of scientific capability. This report, commissioned by the NASA Cosmic Origins, Physics of the Cosmos and Exoplanet Exploration Program Analysis Groups (PAGs), analyzes the importance of multi-wavelength observations from space during the epoch of the Great Observatories, providing examples that span a broad range of astrophysical investigations.

astro-ph.IM↗

arXiv2021

AT 2019avd: A novel addition to the diverse population of nuclear transients

We report on SRG/eROSITA, ZTF, ASAS-SN, Las Cumbres, NEOWISE-R, and Swift XRT/UVOT observations of the unique ongoing event AT 2019avd, located in the nucleus of a previously inactive galaxy at $z=0.029$. eROSITA first observed AT 2019avd on 2020-04-28 during its first all sky survey, when it was detected as an ultra-soft X-ray source ($kT\sim 85$ eV) that was $\gtrsim 90$ times brighter in the $0.2-2$ keV band than a previous 3$σ$ upper flux detection limit (with no archival X-ray detection at this position). The ZTF optical light curve in the $\sim 450$ days preceding the eROSITA detection is double peaked, and the eROSITA detection coincides with the rise of the second peak. Follow-up optical spectroscopy shows the emergence of a Bowen fluorescence feature and high-ionisation coronal lines ([\ion{Fe}{X}] 6375 Å, [\ion{Fe}{XIV}] 5303 Å), along with persistent broad Balmer emission lines (FWHM$\sim 1400$ km s$^{-1}$). Whilst the X-ray properties make AT 2019avd a promising tidal disruption event (TDE) candidate, the optical properties are atypical for optically selected TDEs. We discuss potential alternative origins that could explain the observed properties of AT 2019avd, such as a stellar binary TDE candidate, or a TDE involving a super massive black hole binary.

astro-ph.HE↗

arXiv2019

Supermassive Black Hole Binary Candidates from the Pan-STARRS1 Medium Deep Survey

We present a systematic search for periodically varying quasar and supermassive black hole binary (SMBHB) candidates in the Pan-STARRS1 Medium Deep Survey. From $\sim9,000$ color-selected quasars in a $\sim50$ deg$^{2}$ sky area, we initially identify $26$ candidates with more than $1.5$ cycles of variation. We extend the baseline of observations via our imaging campaign with the Discovery Channel Telescope and the Las Cumbres Observatory network and reevaluate the candidates using a more rigorous, maximum likelihood method. Using a range of statistical criteria and assuming the Damped Random Walk model for normal quasar variability, we identify one statistically significant periodic candidate. We also investigate the capabilities of detecting SMBHBs by the Large Synoptic Survey Telescope using our study with MDS as a benchmark and explore any complementary, multiwavelength evidence for SMBHBs in our sample.

astro-ph.HE↗

arXiv2019

Infrastructure and Strategies for Time Domain and MMA and Follow-Up

Time domain and multi-messenger astrophysics are growing and important modes of observational astronomy that will help define astrophysics in the 2020s. Significant effort is being put into developing the components of a follow-up system for dynamically turning survey alerts into data. This system consists of: 1) brokers that will aggregate, classify, and filter alerts; 2) Target Observation Managers (TOMs) for prioritizing targets and managing observations and data; and 3) observatory interfaces, schedulers, and facilities along with data reduction software and science archives. These efforts need continued community support and funding in order to complete and maintain them. Many of the efforts can be community open-source software projects but they will benefit from the leadership of professional software developers. The coordination should be done by institutions that are involved in the follow-up system such as the national observatories (e.g. LSST/Gemini/NOAO Mid-scale/Community Science and Data Center) or a new MMA institute. These tools will help the community to produce the most science from new facilities and will provide new capabilities for all users of the facilities that adopt them.

astro-ph.IM↗