IGR J17480-2446

Other name = CXOG1b J174804.8-244648

Type Spin/Orb. Period Optical Counterpart Infrared/Optical Counterpart
R.A. (J2000) Dec. (J2000) References R.A. (J2000) Dec. (J2000) References
LMXB, Burster 0.090535s /21.327 hr 17h 48m 04.86s -24 ° 46' 49.24" (+-0.3") Patruno et al. 2012 ATel 3924 17h 48m 04.829s
-24o 46' 49.10" Testa et al. ATel 3264
Published Papers
Miscellaneous :
Bozzo et al. 2010 ATel 2922:
  • Swift XRT spectral analysis =>fit with an absorbed (NH = 0.50x1022 cm-2) blackbody of temperature kT~1.27 keV.
Chenevez et al. 2010 ATel 2924:
  • Type I X-ray burst seen with JEM X
Strohmayer et al. 2010 ATel 2929:
  • Pulsation at 11.0452 Hz (P = 0.090535 s) and an eclipse lasting 512s detected with RXTE
Altamirano et al. 2010 ATel 2932:
  • Burst oscillations at frequency compatible with that of the spin
Mukherjee et al. 2010 ATel 2935:
  • RXTE => QPO at 690 Hz
Kennea et al. 2010 ATel 2937:
  • Refinement of Swift position
  • SOurce is at 6.8" from Chandra position of EXO 1745-248. Sources are not associated
Papitto et al. 2010, ATel 2939 (see also Papitto et al. 2011, A&A):
  • Orbital solution of the source with orbital period = 21.327 hr
  • Projected semi-major axis of asin(i) = 2.46(12) lt-s,
  • T0 (MJD)=55481.783
  • Consitent with the eclipse interpretation
Galloway et al. 2010 ATel 3000:
  • Further analysis of RXTE obs. => 202 X-ray bursts
  • Time resolved spectro of bursts => well fitted by an absorbed black body
  • After October 13 burst likely type-II bursts due to episodic accretion
  • Relatively wide orbit, slow pulsations, and type-II bursts are characteristics shared by the bursting pulsar, GRO J1744-28 => second such source ever discovered, and first to show a type-I (thermonuclear) burst
Chakraborty & Bhattacharyya 2010 ATel 3044:
  • significant cooling during decay of the bursts observed on 2010 November 13, 14, 15, 18
  • Might indicate return of thermonuclear bursts as the persistent intensity
  • Suggest other scenario for apparent disappearance of bursts during the high intensity state of the source
Chakraborty & Bhattacharyya 2011 (ApJ):
  • Analyse whole RXTE/PCA data set
  • Total of ~400 X-ray bursts
  • Studied spectral properties of the source during the bursts
  • All the bursts from the source originate from the same mechanism : thermonuclear origin
  • Clear cooling may not always be present during a thermonuclear burst decay
Degenaar & Wijnands 2011 (MNRAS):
  • Archival Chandra data of the field around IGR J17480-2446 during inactivity of the source
  • Quiescent spectra of the source: no difference between the 2 observations; soft spectra with most photons detected below 2 keV.
  • Absorbed NS atmosphere yields a good chi square with NH = 2.1X 1022 /cm2 and kT= 72.7 eV
  • Comparison of the spectral properties of this source during quiescence with 5 other accreting ms pulsars
  • Estimating duty cycle of the source => > 100 years in quiescence
  • Scenario for low quiescent luminosity presented
Motta et al. 2011 (MNRAS):
  • Study of the morphological, spectral and temporal properties of the bursts as observed by RXTE
  • Recurrence time and fluence of bursts anticorrelate with increase of persistent X-ray flux
  • Helium ignited in a Hydrogen rich layer
  • All the bursts of this source = Type-I X-Ray bursts
  • Pulsations detected in all brightest bursts with no drifts of the frequency within 0.25 Hz of the spin frequency
Miller et al. 2011 (ApJL):
  • Chandra/HETG spectra=> blue-shifted absorption lines from helium-like Fe XXV and hydrogen-like Fe XXVI
  • Suggest presence of accretion disk wind which does show strong variations with X-ray bursts or flares.
  • Clearest detection yet of such a wind in a neutron star system.
  • Fits to the broad Fe K emission line => inner accretion disk radially-truncated =>Stellar magnetic field strength of ~(1-4)x109 G
  • Results discussed in context of accretion onto compact objects, and difference with disk winds in stellar-mass black holes
Degenaar & Wijnands 2011 (MNRAS):
  • Chandra observations seven weeks after the end of 2010 outburst
  • Thermal emission (~100 eV) from the neutron star elevated compared to the quiescent value (~70 eV)
  • Interpret as evidence for crustal heating during the outburst
Linares et al. 2011 (ApJ):
  • Extensive analysis of all (373) X-ray bursts observed with RXTE
  • All bursts have a thermonuclear origin (type I burst), even those without a cooling tail.
Testa et al. 2011 ATel 3264:
  • VLT observations => two possible IR source within 0.3" of the Chandra position
  • Favor the one located at RA=17:48:04.829, DEC=-24:46:49.10 (+/-0.3"), with Ks = 16.6 as the candidate counterpart due to its absence in previous catalogues.
Chakraborty et al. 2011 , MNRAS:
  • RXTE spectral analysis => large hysteresis in the C-like HID during the Atoll state
  • Nature of spectral evolution does not depend on the peak luminosity
  • Spectra: two components (+iron line in emission): black body and power law
  • Components probably connected and somehow linked to cause the spectral evolution
  • A possible analogue to the clock burster GS 1826-238
Cavecchi et al. 2011 , ApJL:
  • Properties of the all bursts from this source as seen with RXTE
  • Typical duration of 100-200 s
  • Type I burst when persistent luminosity is <15% Ledd
  • No classification due to the lack of evidence for cooling for burst occurring when L=15-35% Ledd
  • Burst oscillations detected in all bursts
  • In this source: burst oscillations probably due to magnetic confinement of the burning material.
Patruno et al. 2012 ATel 3924:
  • Possible identification of the optical Counterpart in HST archival observations
  • Resolve a close-by red giant object and the optical counterpart to the previously suggested faint IR candidate counterpart, therefore identified as one candidate optical counterpart
  • Magnitudes F606W = 22.46 and F814W=19.14
  • Finding chart at http://www.astro.uva.nl/~apatruno/17480.html
Papitto et al. 2012 (MNRAS):
  • Analysis of all the RXTE, INTEGRAL and Swift observations of IGR J17480-2446 during October-November 2010 outburst
  • NS average spin up rate ~1.48e-12Hz/s over this period
  • Compatible with spin up due to disc accretion => disc inner radius of 47-93 km estimated at the peak luminosity
  • Spectral analysis => spectrum due to thermal comptonisation of 1 keV photons probably emitted by NS surface
  • Coptonising medium evolves from kt~20 keV plasma to kt~3 keV with larger optical depth
  • In the mean time pulse fraction decreases significantly =>a part of the accreted matter is not channeled to the pole but accreted evenly by the NS
Barret 2012 (ApJ):
  • Timing analysis of RXTE observations => discovery of HF QPOs at frequencies between ~803 and ~875Hz
  • Does not confirm the marginal detection previously reported from another study.
  • As usually observed in Z sources, the QPO have low RMS amplitudes and coherences
  • Highest frequency + assuming it is orbital frequency at the inner disc radius => lower limit of 18.5 km for a neutron star of 1.4 Msun.
Patruno et al. 2012 (ApJ):
  • Source indeed is spun up at 1.4e-12 Hz/s
  • Discuss the history of the evolution of this system.
  • 3 distinct evolutionary epochs: a dipole dominated spin down one, a wind one, a the current roche lobe overflow epoch
  • Source has not yet reached spin equilibrium; it has been spun up in the current phase for a few 1e7 years, and that it is in a exceptionnaly early Roche lobe overflow phase.
  • Further discuss the apparent discrepancy between the age of this system and that of the globular cluster.
Testa et al. 2012 (A&A):
  • Near IR observations with VLT, plus archival HST
  • Identification of likely counterpart in the Ks band
  • Source visible in quiescence both in the NIR and optical
  • Study of the properties during outburst, and discussion of the original population of the companion
Riggio et al. 2012 (ApJ):
  • sub arsec localisation of IGR J17480-2446 with RXTE and and lunar occultation of the source
Altamirano et al. 2012 (ApJ):
  • Timing analysis of 6 RXTE observations
  • Power spectra resemble those of Z sources with QPO in the 35-50 Hz range and a kHz QPO at 815 Hz
  • 35-50 Hz QPO not due to Lense-Thirring precession
Jiang & Li 2013 (ApJ):
  • Study of the formation of the source
  • Discuss the validity of source being a mildly recycled NS at very early phases of mass transfer
  • Instead of previous scenario suggest binary formed during an exchange encounter either between a binary and the current donor or between a binary and an isolated NS
  • Observational implications of this scenario are discussed
Degenaar et al. 2013 (ApJ):
  • Chandra observation extending the monitoring into 2.2 year in quiescence
  • Thermal flux has continued to decrease but remains still higher than pre-outburst values =>Crust has not thermally relaxed
Bonanno & Urpin 2015 (A&A):
  • Spin period and accretion rate should imply B~1e10G (instead of 1-4e-9) => accreting pulsar with clear departure from spin up line
  • Numerical study of magnetothermal evolution => long period, low B pulsars expected, and IGR source is a member of this class of objects

Last updated 4 March 2015

Jerome Rodriguez