Unveiling the temporal properties of MAXI J1820+070 through AstroSat observations
Sneha Prakash Mudambi, Bari Maqbool, Ranjeev Misra, Sabhya Hebbar, J. S. Yadav, Shivappa B. Gudennavar, Bubbly S. G
备注：
Accepted for publication in Astrophysical Journal Letters (ApJL). The article contains 8 pages, 4 figures and 1 Table. Missing reference added. Some typos corrected
We present here the results of the first broadband simultaneous spectral and temporal studies of the newly detected black hole binary MAXI J1820+070 as seen by SXT and LAXPC on-board AstroSat.The observed combined spectra in the energy range 0.7-80 keV were well modeled using disk black-body emission, thermal Comptonization and a reflection component. The spectral analysis revealed that the source was in its hard spectral state (Gamma=1.61) with a cool disk (kTin=0.22 keV). We report the energy dependent time-lag and root mean squared (rms) variability at different frequencies in the energy range 3-80 keV using LAXPC data. We also modeled the flux variability using a single zone stochastic propagation model to quantify the observed energy dependence of time-lag and fractional rms variability and then compared the results with that of Cygnus X-1. Additionally, we confirm the detection of a quasi-periodic oscillation with the centroid frequency at 47.7 mHz.
We present the results of Target of Opportunity (ToO) observations made with AstroSat of the newly discovered black hole binary MAXI J1535-571. We detect prominent C-type Quasi-periodic Oscillations (QPOs) of frequencies varying from 1.85 Hz to 2.88 Hz, along with distinct harmonics in all the AstroSat observations. We note that while the fundamental QPO is seen in the 3 - 50 keV energy band, the harmonic is not significant above ~ 35 keV. The AstroSat observations were made in the hard intermediate state, as seen from state transitions observed by MAXI and Swift. We attempt spectral modelling…
We present broadband X-ray spectral-timing analysis of the new Galactic X-ray transient MAXI~J1348--630 using five simultaneous {\it AstroSat} and {\it NICER} observations. Spectral analysis using {\it AstroSat} data identify the source to be in the soft state for the first three observations and in a faint and bright hard state for the next two. Quasi-periodic oscillations at $\sim 0.9$ and $\sim 6.9$\,Hz, belonging to the type-C and type-A class are detected. In the soft state, the power density spectra are substantially lower (by a factor $> 5$) for the {\it NICER} (0.5--12 keV) band compar…
MAXI J1820+070 is a newly discovered transient black hole X-ray binary, which showed several spectral and temporal features. In this work, we analyse the broadband X-ray spectra from all three simultaneously observing X-ray instruments onboard AstroSat, as well as contemporaneous X-ray spectra from NuSTAR, observed during the hard state of MAXI J1820+070 in March 2018. Implementing a combination of multi-colour disc model, relativistic blurred reflection model relxilllpCp and a distant reflection in the form of xillverCp, we achieve reasonable and consistent fits for AstroSat and NuSTAR spectr…
We present broadband X-ray spectral analysis of the black hole X-ray binary MAXI J1348--630, performed using five AstroSat observations. The source was in the soft spectral state for the first three and in the hard state for the last two observations. The three soft state spectra were modelled using a relativistic thin accretion disc with reflection features and thermal Comptonization. Joint fitting of the soft state spectra constrained the spin parameter of the black hole $a_*$ $>$ 0.97 and the disc inclination angle $i$ = 32.9$\substack{+4.1 \\ -0.6}$ degrees. The bright and faint hard state…
We report the results of the analysis of an AstroSat observation of the Black Hole candidate MAXI J1535-571 during its Hard Intermediate state. We studied the evolution of the spectral and timing parameters of the source during the observation. The observation covered a period of $\sim$5 days and consisted of 66 continuous segments, corresponding to individual spacecraft orbits. Each segment was analysed independently. The source count rate increased roughly linearly by $\sim$30 %. We modelled the spectra as a combination of radiation from a thermal disk component and a power-law. The timing a…
We present an in-depth spectral and timing analysis of the Black Hole binary 4U 1630-472 during 2016 and 2018 outbursts as observed by \textit{AstroSat} and \textit{MAXI}. The extensive coverage of the outbursts with \textit{MAXI} is used to obtain the Hardness Intensity Diagram (HID). The source follows a `c'-shaped profile in agreement with earlier findings. Based on the HIDs of previous outbursts, we attempt to track the evolution of the source during a `super'-outburst and `mini'-outbursts. We model the broadband energy spectra ($0.7-20.0$ keV) of \textit{AstroSat} observations of both out…
We present a detailed spectral and timing analysis of Cygnus X-1 with multi-epoch observations, during $2016$ to $2019$, by SXT and LAXPC on-board AstroSat. We model the spectra in broad energy range of $0.5\!-\!70.0\,\rm{keV}$ to study the evolution of spectral properties while Cygnus X-1 transited from hard state to an extreme soft state via intermediate states in 2017. Simultaneous timing features are also examined by modelling the power density spectra in $3.0\!-\!50.0\,\rm{keV}$ . We find that during high-soft state observations, made by AstroSat on Oct $24,\,2017$ (MJD $58050$), the ener…
Galactic transient black hole candidate (BHC) MAXI J1535-571 was discovered on 2017 September 02 simultaneously by {\it MAXI}/GSC and {\it Swift}/BAT instruments. It has also been observed by India's first multi-wavelength astronomy-mission satellite {\it AstroSat}, during the rising phase of its 2017-18 outburst. We make both the spectral and the temporal analysis of the source during 2017 September 12-17 using data of {\it AstroSat}'s Large Area X-ray Proportional Counter (LAXPC) in the energy range of $3-40$~keV to infer the accretion flow properties of the source. Spectral analysis is done…
Soft X-ray transients are systems that are detected when they go into an outburst, wherein their X-ray luminosity increases several orders of magnitude. These outbursts are markers of the poorly understood change in the spectral state of these systems from low/hard state to high/soft state. We report the spectral properties of one such soft X-ray transient: MAXI J0637$-$430, with data from the \textit{SXT} and \textit{LAXPC} instruments on-board \textit{AstroSat} mission. The source was observed for a total of $\sim$ 60 ks over two observations on 8$^{th}$ and 21$^{st}$ November, 2019 soon aft…
We present the results obtained from broadband X-ray timing and spectral analysis of black hole candidate MAXI J1803-298 using an AstroSat observation on May 11-12, 2021. Four periodic absorption dips with a periodicity of $7.02 \pm 0.18$ hour are detected in the light curve. AstroSat observe the source when it was undergoing a transition from hard-intermediate state to soft-intermediate state. Our timing analysis reveals the presence of a sharp type-C quasi periodic oscillation (QPO) in the power density spectra (PDS) with an evolving QPO frequency ranging from $5.31 \pm 0.02$ Hz to $7.61\pm …
We present the X-ray spectral and timing analysis of the transient black hole X-ray binary 4U 1630-47, observed with the AstroSat, Chandra and MAXI space missions during its soft X-ray outburst in 2016. The outburst, from the rising phase until the peak, is neither detected in hard X-rays (15-50 keV) by the Swift/BAT nor in radio. Such non-detection along with the source behavior in the hardness-intensity and color-color diagrams obtained using MAXI data confirm that both Chandra and AstroSat observations were performed during the high soft spectral state. The High Energy Grating (HEG) spectru…
We perform comprehensive temporal and spectral analysis of the newly discovered X-ray transient MAXI~J1803--298 using an AstroSat target of opportunity observation on May 11, 2021 during its outburst. The source was found to be in the hard intermediate state. We detect type C quasi-periodic oscillations (QPOs) at the frequencies of $\sim5.4$ Hz and $\sim6.3$ Hz along with a sub-harmonic at $\sim2.8$ Hz in the $3-15$ keV band. The frequency and fractional rms amplitude of the QPO in the $15-30$ keV band are found to be higher than those in the $3-15$ keV band. We find soft lags of $\sim3.8$ ms …
We report the results from \textit{AstroSat} observations of the transient Galactic black hole X-ray binary MAXI J1535-571 during its hard-intermediate state of the 2017 outburst. We systematically study the individual and joint spectra from two simultaneously observing \textit{AstroSat} X-ray instruments, and probe and measure a number of parameter values of accretion disc, corona and reflection from the disc in the system using models with generally increasing complexities. Using our broadband ($1.3-70$ keV) X-ray spectrum, we clearly show that a soft X-ray instrument, which works below $\si…
The newly discovered galactic black hole candidate (BHC) MAXI~J1348-630 showed two major outbursts in 2019, just after its discovery. Here, we provide a detailed spectral and temporal analysis of the less-studied second outburst using archive data from multiple satellites, namely Swift, MAXI, NICER, NuSTAR and AstroSat. The outburst continued for around two and a half months. Unlike the first outburst from this source, this second outburst was a `failed' one. The source did not transition to soft or intermediate spectral states. During the entire outburst, the source was in the hard state with…
NGC1566 is a changing-look active galaxy that exhibited an outburst during 2017-2018 with a peak in June 2018. We triggered AstroSat observations of NGC 1566 twice in August and October 2018 during its declining phase. Using the AstroSat observations along-with two XMM-Newton observations in 2015 (pre-outburst) and June 2018 (peak-outburst), we found that the X-ray power-law, the soft X-ray excess, and the disk components showed extreme variability during the outburst. Especially, the soft excess was negligible in 2015 before the outburst, it increased to a maximum level by a factor of $>200$ …
We present the observational results from a detailed timing analysis of the black hole candidate Swift J1658.2-4242 during its 2018 outburst with the observations of Hard X-ray Modulation Telescope (Insight-HXMT), Neutron Star Interior Composition Explorer (NICER) and AstroSat in 0.1-250keV. The evolution of intensity, hardness and integrated fractional root mean square (rms) observed by Insight-HXMT and NICER are presented in this paper. Type-C quasi-periodic oscillations (QPOs) observed by NICER (0.8-3.5Hz) and Insight-HXMT (1-1.6Hz) are also reported in this work. The features of the QPOs a…
We report the analysis of simultaneous multi-wavelength data of the high energy peaked blazar RGB J0710+591 from the LAXPC, SXT and UVIT instruments on-board AstroSat. The wide band X-ray spectrum (0.35 -- 30 keV) is modelled as synchrotron emission from a non-thermal distribution of high energy electrons. The spectrum is unusually curved, with a curvature parameter $β_p \sim 6.4$ for a log parabola particle distribution, or a high energy spectral index $p_2 > 4.5$ for a broken power-law distribution. The spectrum shows more curvature than an earlier quasi-simultaneous analysis of Swift-XRT/Nu…
We present a comprehensive study of GRS 1915+105 in wide energy band ($0.5-60$ keV) using AstroSat observations during the period of $2016-2019$. The MAXI X-ray lightcurve of the source shows rise and decay profiles similar to canonical outbursting black holes. However, the source does not follow the exemplary 'q'-diagram in the Hardness-Intensity Diagram (HID). Model independent analysis of lightcurves suggests that GRS 1915+105 displays various types of variability classes ($δ,χ,ρ,κ,ω$ and $γ$). We also report possible transitions from one class to another ($χ\rightarrowρ,ρ\rightarrowκ$ via …
We present the first results of extragalactic black hole X-ray binaries LMC X-1 and LMC X-3 using all the archival and legacy observations by AstroSat during the period of $2016-2020$. Broadband energy spectra ($0.5-20$ keV) of both sources obtained from the SXT and LAXPC on-board AstroSat are characterized by strong thermal disc blackbody component ($kT_{in}\sim1$keV, $f_{disc}>79\%$) along with a steep power-law ($Γ\sim2.4-3.2$). Bolometric luminosity of LMC X-1 varies from $7-10\%$ of Eddington luminosity ($L_{Edd}$) and for LMC X-3 is in the range $7-13\%$ of $L_{Edd}$. We study the long-t…
We study the spectral and temporal properties of MAXI J0637-430 during its 2019-2020 outburst using \textit{NICER}, \textit{AstroSat} and \textit{Swift-XRT} data. The source was in a disc dominant state within a day of its detection and traces out a `c' shaped profile in the HID, similar to the `mini'-outbursts of the recurrent BHB 4U 1630-472. Energy spectrum is obtained in the $0.5-10$ keV band with \textit{NICER} and \textit{Swift-XRT}, and $0.5-25$ keV with \textit{AstroSat}. The spectra can be modelled using a multicolour disc emission (\textit{diskbb}) convolved with a thermal Comptonisa…
IGR J17091--3624 is a transient galactic black hole which has a distinct quasi-periodic variability known as `heartbeat', similar to the one observed in GRS 1915+105. In this paper, we report the results of $\sim 125$ ks \textit{AstroSat} observations of this source during the 2016 outburst. For the first time a double peaked QPO (DPQ) is detected in a few time segments of this source with a difference of $δf ~\sim12$ mHz between the two peaks. The nature of the DPQ was studied based on hardness ratios and using the static as well as the dynamic power spectrum. Additionally, a low frequency (2…
A NICER and AstroSat view of the neutron star low-mass X-ray binary 1A 1246-588
University of Alabama（阿拉巴马大学）；University of Mumbai（孟买大学）；Tata Institute of Fundamental Research（塔塔基础研究所）；INAF–Osservatorio Astronomico di Cagliari（意大利国家天体物理研究所卡利亚里天文台）
Bright in the Black: Searching for Electromagnetic Counterparts to Gravitational-Wave Candidates in LIGO-Virgo-KAGRA Observation Runs with AstroSat-CZTI
MAXI J1957+032 is a transient Low-mass X-ray binary (LMXB) that underwent four short outbursts in 1.5 years since its discovery in 2015. The nature of the compact object in MAXI J1957+032 is not clear, but it was proposed to be a neutron star based on the short-duration of its outbursts. Here, we report the results obtained after performing spectral analysis using data obtained with the X-ray telescope aboard the Neil Gehrels Swift satellite. When describing the spectrum with an absorbed power law, we found that the spectra softens (the power-law index increases from $\sim$ 1.8 to 2.5) as the …
We present a 140ks observation of NGC 4593 with XMM-Newton providing simultaneous and continuous PN X-ray and OM UV (UVW1 2910Å) lightcurves which sample short-timescale variations better than previous observations. These observations were simultaneous with 22d of Swift X-ray and UV/optical monitoring, reported previously, and 4d of AstroSat X-ray (SXT), far (FUV 1541Å), and near (NUV 2632Å) UV allowing lag measurements between them and the highly-sampled XMM. From the XMM we find that UVW1 lags behind the X-rays by 29.5$\pm$1.3ks, $\sim$half the lag previously determined from the Swift monito…
We present a comprehensive spectral and temporal study of the black hole X-ray transient MAXI J1820+070 during its outbursts in 2018 using Swift/XRT, NICER, NuSTAR and AstroSat observations. The Swift/XRT and NICER spectral study shows a plateau in the light curve with spectral softening (hardness changes from $\sim$ $2.5$ to $2$) followed by a gradual decline without spectral softening during the first outburst. Also, spectral modelling suggests that the first outburst is in the low/hard state throughout with a truncated disk whereas the thermal disk emission dominates during the second outbu…
We report the results of AstroSat observations of GRS 1915$+$105 obtained using 100 ks guaranteed-time (GT) during the soft state. The Color-Color Diagram (CCD) indicates a variability class of $δ$ with the detection of High Frequency QPO (HFQPO) in the power density spectra (PDS). The HFQPO is seen to vary in the frequency range of $67.96 - 70.62$ Hz with percentage rms $\sim 0.83 - 1.90$ % and significance varying from $1.63 - 7.75$. The energy dependent power spectra show that the HFQPO features are dominant only in $6 - 25$ keV energy band. The broadband energy spectra ($0.7 - 50$ keV) of …
We present a time-resolved X-ray spectral study of the high energy peaked blazar Mkn 421 using simultaneous broadband observations from the LAXPC and SXT instruments on-board AstroSat. The ~ 400 ksec long observation taken during 3-8 January, 2017 was divided into segments of 10 ksecs. Each segment was fitted using synchrotron emission from particles whose energy distribution was represented by a log-parabola model. We also considered particle energy distribution models where (i) the radiative cooling leads to a maximum energy (ξ max model), (ii) the system has energy dependent diffusion (EDD)…
In $2016-17$, the Galactic transient black hole candidate GRS 1716-249 exhibited an outburst event after a long period of quiescence of almost 23 years. The source remained in the outbursting phase for $\sim 9$ months. We study the spectral and temporal properties of the source during this outburst using archival data from four astronomy satellites, namely MAXI, Swift, NuSTAR and AstroSat. Initial spectral analysis is done using combined disk black body and power-law models. For a better understanding of the accretion flow properties, we studied spectra with the physical two component advectiv…
Local interstellar spectra (LIS) for protons, helium and antiprotons are built using the most recent experimental results combined with the state-of-the-art models for propagation in the Galaxy and heliosphere. Two propagation packages, GALPROP and HelMod, are combined to provide a single framework that is run to reproduce direct measurements of cosmic ray (CR) species at different modulation levels and at both polarities of the solar magnetic field. To do so in a self-consistent way, an iterative procedure was developed, where the GALPROP LIS output is fed into HelMod that provides modulated …
Unveiling SN 2022eyw: A Bright Member of the Type Iax Supernova Subclass
Indian Institute of Astrophysics（印度天体物理研究所）；Pondicherry University（本地治里大学）；Department of Physics and Astronomy, Michigan State University（密歇根州立大学物理与天文学系）；Tsung-Dao Lee Institute, Shanghai Jiao Tong University（上海交通大学李政道研究所）
SN 2022eyw是Iax型超新星中明亮成员，其光谱和光度学特征表明其起源于部分熄火的Chandrasekhar质量白矮星。
We carried a detailed spectral and temporal study of blazar, \mbox{PKS\,0903-57} using the \emph{Fermi}-LAT and \emph{Swift}-XRT/UVOT observations, during its brightest flaring period MJD\,58931--58970. During this period, the maximum daily averaged $γ$-ray flux ($\rm F_{0.1-500\,GeV}$) of $\rm9.42\times10^{-6}\,ph\,cm^{-2}\,s^{-1}$ is observed on MJD\,58951.5, the highest $γ$-ray flux detected from \mbox{PKS\,0903-57} till now. Several high-energy (HE) photons ($>\,10$\,GeV) consistent with the source location at high probability (>\,99\%) are detected, and the $γ$-ray lightcurve in the activ…
Previous analysis of AstroSat observations of the black hole system MAXI J1535-571, have revealed the presence of a strong Quasi-Periodic Oscillation (QPO) whose frequency is correlated with the high energy spectral index. Here, we fit the spectra as emitted from a truncated disc with an inner hot corona, study the QPO frequency dependence on other spectral parameters and model the energy dependent r.m.s and time-lag of the QPO to identify the physical spectral parameters whose variation are responsible for the QPO. The QPO frequency is found to also correlate with the scattering fraction (i.e…
In this paper, we employ Machine Learning algorithms on multi-mission observations for the classification of accretion states of outbursting Black hole X-ray binaries for the first time. Archival data from RXTE, Swift, MAXI and AstroSat observatories are used to generate the hardness intensity diagrams (HIDs) for outbursts of the sources XTE J1859+226 (1999 outburst), GX 339-4 (2002, 2004, 2007 and 2010 outbursts), IGR J17091-3624 (2016 outburst), and MAXI J1535-571 (2017 outburst). Based on variation of X-ray flux, hardness ratios, presence of various types of Quasi-periodic Oscillations (QPO…
Extragalactic black hole X-ray binaries LMC X-1 and LMC X-3 are the persistent sources, usually found in soft spectral state. We present the results from spectral and timing study of these sources using MAXI, NICER, NuSTAR and AstroSat observations carried out during 2014-2020. Study of long-term MAXI lightcurve shows that the fractional variability of flux in 2-10keV is moderate ($\sim$20%) in LMCX-1 and high ($\sim$50%) in LMCX-3. The energy spectra of both sources are characterized by a disc blackbody and a Comptonization component with LMCX-1 having an additional Fe-line emission feature. …
The chi-squared based covariance approach allows one to estimate the correlations among desired observables related to nuclear matter directly from a set of fit data without taking recourse to the distributions of the nuclear matter parameters (NMPs). Such an approach is applied to study the correlations of tidal deformability of neutron star with the slope and the curvature parameters of nuclear symmetry energy governed by an extensive set of fit data on the finite nuclei together with the maximum mass of the neutron star. The knowledge of the distributions of NMPs consistent with the fit dat…
